Can we reconstruct how prehistoric people perceived things ? This challenge is made more difficult by the traditional disciplinary assumptions built into prehistoric art studies, for instance focusing narrowly upon a single body of art in isolation. This paper proposes an alternative approach, using comparative study to reveal broad regional changes in visual culture. Although prehistoric art specialists rarely work comparatively, art historians are familiar with describing continent-wide general developments in visual culture and placing them in social context . This paper does the same for Neolithic (6000–2500 BC) vs. Bronze Age (2500–800 BC) and Iron Age  rock and cave art from sites across Europe, uncovering broad patterns of change. The principal pattern is a shift from a Neolithic iconic art which uses heavily encoded imagery, often schematic geometric motifs, to a Bronze/Iron Age narrative art, which increasingly involves imagery of identifiable people, animals and objects. Moreover, there is also an increasing tendency for motifs to be associated in scenes rather than purely accumulative, and with contextual changes in how art is used—a movement from hidden places to more open or accessible places. Underlying all these changes is a shift in how rock and cave art was used, from citations reproducing ritual knowledge to composed arrays telling narratives of personhood. This paper attempts to look at prehistoric art in a way which is both new and old—entirely new for prehistoric art studies, but deeply familiar for visual culture in general. Imagine a range of the images commonly encompassed by the term “Western Art”. Without even thinking about it, you will almost certainly recognise what “period” they belong to. Their formal features—what subjects they depict, how “naturalistic” they are, how they use space and perspective and so on—place them stylistically within the canonical history of Western art: Classical, Medieval, Renaissance, neo-Classical, Impressionist, Modernist and so on. Moreover, these features, and others such as the place these images were originally designed to be seen in and the kinds of viewers they anticipate, helped form “ways of seeing” which were deeply intertwined with the pictures’ social context and historical moment. Visual culture changes historically as society changes; we can therefore write a big history of art. Indeed, though most art historians write specialist studies of particular artists and their oeuvres, all such studies assume and build upon a canonical big history of art; it would be impossible to understand Monet without understanding Impressionism or Michelangelo without Renaissance art.Yet, a broad-brush, large-scale social history of prehistoric visual culture has never been attempted, or even contemplated. This is not for lack of material to study; Europe has 40,000 years of prehistoric imagery, in contrast with a mere 2800 years of historic art. It is not for lack of change to study; Spanish or French art made 30 or 40 millennia ago differs in every possible sense from late Iron Age art made 2000 years ago. It is not from lack of social change to contextualise such a history; the worlds of Palaeolithic foragers, Neolithic villagers and Bronze and Iron Age people differed from each other far more than the urban, stratified art worlds of medieval and modern people do. Instead, the reasons this project has never been attempted are disciplinary. One issue concerns the goal of interpretation; traditionally, archaeologists have focused overwhelmingly on what prehistoric art “meant” rather than on how it worked as visual or material culture. But above all, there is a relentless tradition of studying prehistoric art as single bodies of art rather than comparatively or analytically. The modal study of European prehistoric art is an authoritative descriptive analysis of a single corpus of material. Only rarely do analysts cross the boundaries between closely related corpora to talk about specific periods or areas. Even so, they rarely venture beyond synthesising homogeneous bodies such as “Ice Age Art” or “Celtic Art”. Larger scale efforts restrict themselves entirely to descriptive overviews Sandars . And, itThus, a big history of prehistoric European art has never been attempted, not because it is inherently impossible, or because it would not be worth doing, but simply because we have never imagined it as a possible goal. I argue that not only can we create such a history, we must do so. Looking at prehistoric art comparatively as visual culture can reveal things we would never understand from studies of individual corpora or periods, particularly about broad social change. Such a synthesis in no way threatens or supplants studies of individual bodies of art, any more than formulating the general ways in which Renaissance art differed from medieval art obviates a specialist study of Michelangelo or Leonardo. Instead, it provides an essential context for them.The “greatest hits” of European prehistoric art are familiar. The most famous images bracket prehistory. At the beginning, we have Ice Age caves such as Lascaux, Altamira and Chauvet, painted with vivid deer, bison, wild horses and lions; at the end, on the threshold of the Classical world, we have the beautiful swirling patterns of circles and spirals on “Celtic” metalwork. But such well-known images are only a tiny proportion of what is out there. If we define “prehistoric art” in the conventional archaeological sense of representative and decorative imagery, including cave art, rock art, tomb and megalithic art, statuary, stelae, figurines, figured objects of metal, clay and bone, and many other less common genres, there are hundreds of bodies of “art” known Robb . Much ofper se begins around 2400 BC in most of Europe and develops continuously into the Iron Age between about 1000 and 800 BC. In many areas, the Iron Age ends with incorporation into historical Greek or Roman worlds, but in Northern Europe, Eastern Europe and Ireland, it continues organically into the early medieval period. In this article, I broadly contrast Neolithic art with Copper, Bronze and Iron Age art. This bears two caveats. First, while bringing together materials from across Europe allows us to identify a broad transition between the two periods, this provides a general heuristic rather than a mechanism driving changes in rigid lockstep. Nobody doubts that a general transition occurred from medieval to Renaissance art, but that does not mean this change occurred instantly at 1450 AD and synchronously everywhere in Europe; the same holds true for prehistoric art histories. Secondly, in keeping with related changes in prehistoric society, the transition in art varies regionally, occurring earlier south of the Alps and east, and later in Atlantic areas. Thus, for instance, Central Alpine rock art dating to the mid-3rd millennium BC embodies new themes and styles which continue on into the Bronze Age; at the same moment, in Atlantic France and Britain, rock art and megalithic art continued to work in long-standing Neolithic traditions which would not end there for several centuries more.This analysis discusses a significant subset of prehistoric European art, Holocene pictures. Building upon the first statistical overview of prehistoric art in Europe Robb , it inclIn this analysis, I discuss two-dimensional visual imagery, mostly from rock art, cave art and architectural art . I exclude three-dimensional imagery such as statuary and figurines, as these are likely to involve different systems of visual representation. I also exclude small decorative motifs on pottery, bone and metalwork. These are ubiquitous in almost all prehistoric and historic material culture, and thus form a massive, unbounded dataset, and they give little purchase for a history of change; every period has bone objects decorated with small circles and pots decorated with geometric motifs. Moreover, prehistoric art occurs in “macro-traditions”, broad groupings of multiple, distinct but generically related bodies of material which share materials and conventions Robb : Table 3Within these limits, this review attempts to be comprehensive, including about 20 major traditions of rock, cave and architectural art Table  and 2. IThe term “art” is used in this article in the conventional archaeological sense of “representational and decorated objects” such as figurines, sculptures, paintings and so on; I explicitly disavow any notion that these objects must have been meant principally for aesthetic enjoyment or to express discursive meanings and creative mastery of the people who made them. Indeed, in Gell’s  sense ofCritically, modes of vision are enmeshed with identities and power relations. One example is the gendered male gaze, at the heart of much Western art since Classical times . Visual culture works with and reproduces these reflexes, and indeed in some cases provides explicit clues to how it should be interpreted.This is heterogeneous ground to summarise briefly, but all of these establish useful foundational principles:In prehistory, power took radically different forms than it did in the urban, class-stratified societies visual culture studies typically deal with, but this general line of inquiry—examining art to see what it tells us about the act of seeing—is worth extending to prehistoric worlds. Archaeologists have rarely adopted a visual culture approach to prehistoric art, but some pioneering efforts have yielded important insights Bradley . It has Where is it located? What kind of context was this, what kind of people had access to it and what did they do there?Does it depict things we can identify? How do these tell us about its social context and meanings? How are things depicted? Is it part of a coherent visual strategy?How are the art’s motifs arranged? Are images grouped spatially or related thematically? Is there an overall spatial or thematic order, or are they random accumulations of independent motifs?While prehistorians can take inspiration from modern visual culture studies, for methods, we are on our own. Our data are necessarily coarse-grained, and the social context we can assign them often is as well. Moreover, we necessarily work with “formal” methods deriving interpretive clues from the material itself rather than “informed” methods which place it within a long-standing ethnographically known tradition, as in Australia, South Africa and the Americas  is the Copper Age art of Mount Bego, France. Like contemporary rock art in Valcamonica, this includes a mixture of third-millennium motifs such as weapons, oxen and ploughing, but also some figures which may represent cosmological anthropomorphs and symbols. The Mount Bego art is found at very high altitudes (above 2000 m), well above farmable zones and probably frequented only seasonally by special purpose groups.Later art contrasts strongly with this. Art was no longer especially associated either with the dead, or with remote or difficult to access places. Nor were caves chosen as a location to place images; there is almost no cave art after the third millennium BC. Instead, art moves out into frequented zones. In Thrace, rock art occurs around the edges of lowland basins Pivalaki . The twoper se), or perhaps some animals, usually deer. This typifies Italian Neolithic cave art and Iberian megalithic art. Breton rock art contains highly repetitive, highly stylised motifs, but almost always connoting a referent we can only guess at; triangles may or may not represent axe heads, a doubly curved line may represent ox horns, and so on. There are also stereotyped motifs such as the “buckler” and the “Mané axe” . It can be useful when you want to invoke or summarise complex or immaterial referents compactly (a cross summarises Christianity as a complex set of beliefs). It can also be useful for depicting things that can have meanings on multiple or shifting levels, or that mean different things to different audiences. For example, some Australian aborigine groups represent narratives through highly schematic, polysemic iconography; while each sign can have multiple referents, their combination restricts possible meanings and constructs a specific interpretation Munn . This maAs we go from the Neolithic to the Iron Age, therefore, we are not really seeing a shift from “abstract” to “representational” art. Instead, we see a shift in visual strategy, from highly schematised images to more detailed and explicit images. In terms of what acts of interpretation they required of the viewer, it is a shift from more highly encoded, contextually defined meanings to meanings which are more visually transparent and tied to single concrete referents—even to the point where uninformed viewers such as ourselves can identify them.If you look at a panel of rock art, cave art or tomb art, do the motifs touch each other? Are they in some evident spatial arrangement? Do thematic relations among them group them into sets of related objects?Neolithic visual culture rarely includes composed scenes. Motifs are typically jumbled on a surface in a way which suggests that they were added one by one. Moreover, they do not often form recurrent sets. To the extent that we can deduce a spatial logic, it is minimal: motifs usually avoid directly intersecting one another. The rest appears randomised and accumulative. To take an example, Porto Badisco Cave has one or two famous (and often reproduced) panels that form scenes, but all the rest of the cave’s art consists of apparently random scatters of motifs, and this is true of the rest of Italian Neolithic cave art. Throughout Neolithic art, the only consistent spatial arrangements occur in Sardinian, Breton and Irish tomb art, where there are some weak but consistent patterns of how different motifs are distributed within tombs to define architectural spaces Robin , 2010. TFrom the 3rd millennium BC onwards, tendencies to spatial patterning in rock art appear. A simple test is to ask how many motifs touch another motif, are grouped thematically with other motifs, or occur in clear spatial arrangements such as arrays. Third-millennium sites in the Alps already show these features. At Valcamonica, Copper Age rock art contains repetitive arrays of animals and weapons. At Mount Bego, oxen motifs are shown yoked in pairs, occasionally with a plough. This tendency towards spatial order accentuates in the later Bronze and Iron Age. In southern Scandinavia, the Central Alps, and Thrace, rock art is full of arrays, connected motifs and even scenes. Boats and animals form lines. A human figure holds a sword, shield, bow or spear. A horse has a rider on its back. A boat motif is combined with line-strokes representing its crew members. People face each other, fighting. A human drives a team of animals. A hunter chases deer, helped by dogs. Such composed groups appear in almost every rock art panel. There may also be less obvious thematic groupings, as with the Scandinavian sun-boat-cart-snake-horse narrative Kaul . In someInterestingly, it is at the same time that composed scenes appear in other media, usually as small inset scenes Fig. . PrehistBesides parallels in other media, the Bronze Age reorganisation of vision has strong echoes in burial practice. Neolithic deathways varied, but they often involved disassembling the body into fragments and dispersing it among landscapes or sites. There is little attempt to preserve or portray a recognisable individual; the body is unbundled into cosmological citations, perhaps much as art motifs are. Beginning in the 3rd millennium BC, it is increasingly common to present the dead person as a composed individual defined by key objects tying him or her to stable story lines of social prestige. This echoes the emergence of individuals in art, not only in themes such as gendered action, but also in the idea of the body as a central, constant and recognisable unit giving continuity to social presence. Such close parallels are not surprising, given that burial itself is a form of visual culture, and Bronze and Iron Age burial in particular was often aimed at composing a memory-fixing tableau of the social persona in death.Between the Neolithic and the Iron Age, art increasingly comes out in the open, moving from caves, tombs and sometimes remote areas to well-frequented landscapes.Between the Neolithic and the Iron Age, images become less schematic, increasingly detailed, and more transparently recognisable.The unit of visual communication shifts increasingly from single motifs to arranged groups of motifs, often in action poses or scenes.Compare the imagery in Figures These trends are not visible in any single body of material, since virtually all bodies of prehistoric art are restricted to a single period and thus cannot reveal long-term change; moreover, the available corpora are patchily distributed and provide geographically scattered windows into what must have been a continuous, widespread process. And these are not black and white changes. Neolithic art contains some recognisable motifs and composed scenes; there are plenty of schematic and unarranged motifs in the Bronze and Iron Ages. But if we view all prehistoric pictures collectively, as a kind of single, diverse super-corpus attesting prehistoric visual culture, the outlines of a big history of prehistoric art begin to emerge.To move from describing this change to interpreting it, the key is asking how people interacted with imagery. Fortunately, the art’s context and structure themselves contain clues to this. People often encountered Neolithic art in unusual or out of the way places such as tombs or inaccessible caves, not everyday places; many of the sites are what might be broadly characterised as specialised ritual settings. When people encountered it, its highly schematised mode of representation demanded contextual knowledge; understanding it correctly required them to already know which of the many things a circle or wavy line could connote was meant in a particular context. The same is true on the scale of a whole panel of motifs. Except in a few cases in which imagery was used to customise architectural areas of built structures, the viewer is not presented with an overall pattern to recognise. The grain of the assemblage is that of episodic single acts accumulating on a surface which was important for some reason.This raises the question of the ontology of “art”. Perhaps because we understand imagery representationally ourselves, we tend to see something like a carved circle or painted line semiotically, as a communicational medium which represents something to a viewer. Indeed, our reflex to ask about the “meaning” of imagery inherently invokes a representational paradigm in which signification is distinct from the thing itself, which merely acts as a vehicle. But, as colleagues have pointed out Jones , represeThis is consistent with what we know of European Neolithic society. Many Neolithic groups show clear evidence for a preoccupation with ritual activities. From henges and “temples” to monumental tombs and complex processing of the dead, we can see a concern with understanding and intervening in the cosmos. At the same time, there is little convincing evidence anywhere for political or economic inequality. Building and using ritual structures may have required people in positions of authority, but such inequality as existed was probably restricted to the ritual sphere rather than involving generalised social control. This is typical of what Spielmann  has callThings changed dramatically in the late 4th and 3rd millennia BC. Between 3500 BC and 2400 BC, in a transition beginning earlier in southern and eastern Europe and reaching north-western Europe later, there was a continent-wide reorganisation of society. As generations of archaeologists have noted, Bronze Age society differed profoundly from Neolithic society, with the 3rd millennium as a pivotal age of transition. Economically, people diversified from subsistence horticulture, with the widespread use of ploughing and with extended pastoralism as a way of colonising mountain landscapes. People mined, principally for exchangeable substances such as high-quality flint, copper and tin. Metals were important above all as a social valuable and a visually impressive body enhancement for both men and women. Both trade and new methods of transport  meant that societies were more interconnected than ever before. The era of big ritual systems ended, and ritual as a whole was much less prominent; as a collective social project tying society and societies together, it may have been supplanted by trade systems. In many areas, collective burials were replaced by individual burials with grave goods displaying gender and status; even where collective burials persisted (as in Mediterranean collective tombs), burials were often deposited with status kits of individual goods.These changes were clearly closely related within a basic social charter. What changed? Mass migration models have been discredited as over-simplistic; in every region of Europe, there is clear evidence for substantial continuity from the Neolithic. Technological and economic models correctly highlight the importance of metals and the “secondary products revolution” Sherratt , but tenThese changes provide a context for the macro-changes in art identified here. In terms of location, Bronze and Iron Age art was placed in less particular or specified locations than previously. It may not have been made or used equally by all members of society, but it is less restricted. It is part of a discourse less segregated from ordinary life and groups, part of a more integrated discourse of social process. It is also more accessible cognitively. Its imagery contains more explicit information about what it is and how to interpret it, making it less dependent upon the viewer to supply context. It is more transparent, an art of surfaces rather than layers. And in adding detail to elements, and combining elements into groupings, it is increasingly about representation, about carrying a greater semantic burden than a single schematic motif can convey.Above all, the Bronze Age sees the birth of narrative art. Archaeologists have often recognised a narrative element in Bronze and Iron Age art, either explicitly . On a thematic level, it reflects new concerns: gender, economic production, hunting, warfare. As visual culture, it works differently, with more detail and more grouped images tying in to narratives about protagonists and their situations. It is also more transparently representational. Representational narrative art created a new way of seeing (Explicitly or implicitly, art histories work from and against the baseline of a big history which brings major forms of visual culture together into a continuous narrative. In any study of a particular artist’s oeuvre, writer and reader both already know what makes a work “Classical” or “Medieval”, “Impressionist” or “Modernist”. Indeed, such knowledge forms the background for understanding the unique features of each artist or school and the ways their works must be viewed. For prehistoric visual culture, we have never had such a history. This article aims to show that such a history is both possible and useful. Here, I have discussed only two-dimensional imagery, leaving aside 3D works such as figurines and sculptures, which may have followed their own pathways. Both the patterns I identify and the interpretations I give them are simple and obvious in retrospect. Prehistorians have long acknowledged that Neolithic art works differently than we expect it to and have related this to the alterity of Neolithic society. Similarly, they have responded, usually implicitly, to the comprehensible style of transparent imagery and narrative reference of Bronze and Iron Age art, and the fact that the narratives involved reflect the gendered prestige and politics of the time. The provocative element of this paper is simply posing the question of how the two periods relate as part of a general history, a project prehistorians have never really conceived of, much less tackled seriously. As a first attempt, it is tentative, and future work will no doubt prove some aspects incorrect. But if it inspires future work, even to contradict it, it will have accomplished its goal. The potential is great. Here I explore merely one moment in such a history, albeit a central one; much as histories of art have built progressively outwards over time from a focus upon the medieval-to-Renaissance transition, the transition from Neolithic to Bronze Age art can anchor a global prehistory of art yet to be developed. Such a history would encompass periods of alterity such as Palaeolithic and Mesolithic art and the fascinating world of Iron Age to early medieval art in Northern Europe, different genres—how does three-dimensional art tell the same or different stories?—and relations with alternative traditions such as circum-Arctic, North African and Near Eastern palaeo-art.


Mothers’ reports about pregnancy, maternity and their experiences during the perinatal period have been associated with infants’ later quality of attachment and development. Yet, there has been little research with mothers of very preterm newborns. This study aimed to explore mothers’ experiences related to pregnancy, premature birth, relationship with the newborn, and future perspectives, and to compare them in the context of distinct infants’ at-birth-risk conditions.A semi-structured interview was conducted with women after birth, within the first 72 h of the newborn’s life. A total of 150 women participated and were divided in three groups: (1) 50 mothers of full-term newborns  ≥ 37 weeks; FT), (2) 50 mothers of preterm newborns  and (3) 50 mothers of very preterm newborns .Mothers of full-term infants responded more often that their children were calm and that they did not expect difficulties in taking care of and providing for the baby. Mothers of preterm newborns although having planned and accepted well the pregnancy  and while being optimistic about their competence to take care of the baby, mentioned feeling frightened because of the unexpected occurrence of a premature birth and its associated risks. Mothers of very preterm newborns reported more negative and distressful feelings while showing more difficulties in anticipating the experience of caring for their babies.The results indicate that Health Care Systems and Neonatal Care Policy should provide differentiated psychological support and responses to mothers, babies and families, taking into account the newborns’ GA and neonatal risk factors. Generally, in the third trimester of pregnancy, women develop a clear and rich representation of their infants , 2, infl“real baby”, in contrast to the “idealized baby” and, as such, prenatal representations are subject to change as a result of the interactions with the “real baby” [“real newborn” [castles in the sand” [Birth reveals the al baby” , 8. Shornewborn” . For mothe sand” , 9.In a preterm birth, the experience of pregnancy, childbirth and early childbearing can be considerably altered due to the associated risks and danger of survival but also health risks  and possible developmental sequelae  . ConcomiIndeed, mothers of premature infants exhibit higher levels of post-traumatic stress and depressive symptoms compared with controls, without recovery even 14 months after birth , 18, 20.Maternal representations have been defined as mothers’ own mental and subjective representations of their experiences interacting with their infants, even before their infant’s birth, which may influence the parents’ interpretation of infant behavior and their later behavioral responses to their infant . SeveralIt is well documented that mothers’ balanced and positive maternal representations of early pre- and postpartum experiences are positively associated with later secure mother-infant attachment in normative samples –32. For “characterized by narratives that convey coherence, openness to change, richness of detail, and a sense of the mother as engrossed in her relationship with her infant, as they value and enjoy their relationship with their infant and are aware that this relationship affects their child’s behavior and development” [In the case of a very preterm birth, due to the extreme and traumatizing circumstances, mothers are even less likely to develop balanced maternal representations lopment” . Howeverlopment” . Availablopment” , 41; (2)lopment” , 43; (3)lopment” , 45 and lopment” , 47. Morlopment” .As a contribution to the body of knowledge concerning maternal representations and to the development of psychological tailored interventions to promote maternal early adjustment and later secure mother-infant relationship in the context of different neonatal birth conditions , we aimed to explore prenatal and early maternal representations concerning pregnancy, birth, maternity and future perspectives. Furthermore, we aim to compare these representations among three groups: (1) mothers of full-term newborns ; (2) mothers of preterm newborns  and (3) mothers of very preterm newborns . This study uses qualitative methods, which are best suitable to explore individuals’ idiosyncratic experiences. To our best knowledge this is the first study comparing maternal reports of pre- and postpartum experiences between these three groups.A total of 150 mothers participated in this study, divided in 3 groups: (1) 50 mothers of FT newborns , (2) 50 were mothers of PT newborns , and (3) 50 mothers of VPT newborns . Mothers’ eligibility criteria included: (1) Portuguese language fluency; (2) admission in a maternity hospital following delivery ; (3) with no known drug/alcohol addiction problems; and (4) with no history of mental illness.The total number of eligible mothers, in the three participating hospitals, was 177, among which 27 mothers in the preterm group refused to participate, resulting in 150 participants.Table n = 15), intrauterine growth restriction (n = 11), placental abruption (n = 9), early dilation (n = 3), preeclampsia (n = 2), uterine contractility (n = 3), baby’s bradycardia (n = 2), elevated urinary levels of the amino acid lysine (n = 2), and other non-specified causes (n = 3). In this group, 6 mothers used In-Vitro Fertilization (IVF) to conceive. The preterm births were due to: rupture of the membrane (n = 13), intrauterine growth restriction (n = 13), infection (n = 6), preeclampsia (n = 5), loss of amniotic fluid (n = 6), hypertension (n = 3), placental abruption (n = 3), and baby’s bradycardia (n = 1). Similarly, in this group, 17 mothers were enrolled in the infertility consultation to become pregnant and 6 of them used IVF to conceive. Although a small number, in the group of very premature infants, parents (n = 6) did not cohabit at the time of the baby’s birth  and it was also in this group that we found a higher frequency of emigrant mothers (n = 12). In the full-term and in the preterm groups, the number of primiparous mothers was equally or approximately the same as the number of multiparous mothers , while in the very preterm group the number of primiparous mothers was lower (VPT: n = 10 vs. n = 40).In what concerns birth characteristics, the number of instrumental births , was higher in the group of preterm infants (72%) and very preterm infants (68%). In the sample of full-term infants, the distribution of the two types of delivery was equally distributed. The occurrence of a very preterm birth was caused by: rupture of the membrane , before conducting any assessment or data collection. All procedures involving human subjects in this study were approved by the Ethics Commission at the Mothers’ eligibility to participate in the study was determined through data collected from clinical files. Two female research assistants contacted personally eligible mothers after delivery and explained the study’s purpose and procedures. In this contact, their free participation was guaranteed in accordance with the American Psychological Association ethical research conduction guidelines. Eligible, consenting parents gave their written informed consent to participate. Once consent was obtained, mothers participated in an interview to collect: socio-demographic information , prenatal, perinatal and postnatal information  and post-discharge situation . Through the hospital medical record, additional clinical information regarding the prenatal and perinatal conditions, of both mother and baby, relevant to the study, were obtained.Within the first 72 h after birth, a semi-structured interview was conducted face-to-face, at a time and date that were convenient for mothers, in Portuguese maternities of three hospitals in Porto and Lisbon, where the newborns were admitted with their mothers. Interviews were audio-recorded and transcribed verbatim for qualitative analysis. The temporal window of 72 h to conduct the maternal interview was decided because: (1) it was intended to evaluate the maternal experiences in the immediate postpartum period, which is generally defined as the period between the first 48 and 96 h of postpartum hospital stay ; (2) in During design, data collection, and analysis, we adhered to the consolidated criteria for reporting qualitative research (COREQ) when possible as outlined in pregnancy ; (2) reaction to early birth and prematurity ; (3) maternal experience and relationship with the newborn child ; (4) baby’s temperament ; and (5) future perspectives . The interviews were audio-recorded and lasted approximately 1 h. The validity of the interview was tested and confirmed in past research  future perspectives. Several subthemes, discussed below, emerged in the data further describing how mothers viewed both their pre- and perinatal experiences.Overall, five main themes were discerned in the data: (1) pregnancy; (2) early birth and prematurity; (3) maternal experience and the relationship with the newborn; (4) babypregnancy and the subtheme of planned pregnancy, most mothers of PT infants (80%) and VPT infants (62%) planned their pregnancy, in contrast with 36% in the group of FT mothers . Non-acceptance of pregnancy was found in 8% of FT mothers, 4% of mothers of PT infants and 2% of mothers of VPT infants. Moreover, 4% of mothers of VPT infants reported feeling ambivalent about their pregnancy: “I did not want a baby, I was on a diet. My eldest son is fourteen, and now I wanted to have my own life. My husband was so happy that it irritated me. It was only when I started reviewing my son’s baby pictures, that I started liking her” (M70)  or totally (96%) supported during pregnancy, both by health professionals and/or by closed ones such as family/friends. Likewise, 92% of mothers of PT infants felt fully supported and only one mother said she felt she had no support (2%). As for the group of mothers of VPT infants, 60% reported feeling totally supported, while 14% mentioned not having received any support. For instance, one mother noted: “The pregnancy was complicated. I was very nervous; my husband was arrested. I was alone and pregnant; I had another child and I still had to work because there was no one who could help me financially and someone had to pay the bills” (M21) . Interestingly, 30% of mothers of PT newborns and 14% of mothers of VPT newborns said that they were not afraid for the baby’s life. As an example: “They  reassured me that there are a lot of babies like him that turn out okay. I believe in them because I have cousins who were born premature who are now big and strong adults” (M46).As for the second theme of maternal experience and relationship with the newborn child, and in the subtheme feeling love for the baby for the first time . Other mothers only described the emergence of this feeling later, namely, at birth (14% of mothers of FT babies and 22% of mothers of VPT babies), when they saw the “real” baby, as one mother explained: “As soon as I saw him it was clear to me how much I loved him!” (M19).In the third theme of first separation from the baby . In the same group, this feeling was followed by detailed descriptions that revealed a lot of suffering and pain as well as the emergence of feelings of fear/guilt (34%), as in the following case: “My first thought was: I did something wrong, I failed! I felt ashamed and scared” (M60). In both groups (FT and VPT), three mothers did not know how to describe their experience or “how to translate into words” (M14) what they felt when they were first separated from their babies (6%): “I do not know what to say … sure I wanted to go with my baby, but I could not” (M14).In the subtheme of baby’s temperament , as in “she is very peaceful, silent and quite, observant and attentive … she is so calm that sometimes I think that she believes she is still in my belly … she is loving, sometimes I cuddle her in the nose and she smiles. I thought that she would be bossy because she was electric while on my belly, she moved a lot during the pregnancy but actually she is a doll and I just feel like cuddling her” (M22), while 10% considered their baby to be agitated and constantly weeping, pointing for instance, “she has quite a temper! She has a strong personality and she only does what she feels she wants to do … she is also very nervous, agitated … she is a difficult baby, very demanding, she cries a lot and does not sleep well, she can’t even stop at night, at least she could let me sleep so that I could rest in order to meet her needs during the day, she does not make things easier” (M15). The responses of mothers of VPT babies were more diverse, fluctuating between agitated/weeping (40%), calm (26%), and not knowing how to describe them (32%).In the fourth theme of future perspectives ; “It will be very good, to finally take care of her, not being dependent on any medical equipment” (M34). Contrary, some mothers  mentioned that it would be difficult, but that they were willing to learn.In the fifth theme of by Table , 60% of expecting difficulties in the future . Beyond the difficulty revealed in the process of anticipating the future, 22% of these mothers preferred not to think about it: “I have started to think about it, but I do not want to think about it too much because those kind of thoughts do not help me and I feel like I have to focus on the present moment and live day-by-day, one day at a time” (M31).Regarding the subtheme of In this study, we explored maternal early experiences related to pregnancy, early birth, maternity and the relationship with the newborn, and future perspectives regarding parenting. Furthermore, we compared them in the context of distinct infants’ at-birth-risk conditions, by including in our sample mothers of full-term, preterm, and very preterm newborns. A semi-structured interview was conducted 72 h after delivery and results allowed to distinguish both similarities and differences among these groups.full-term (FT) mothers, most mothers did not plan their pregnancy, but the majority mentioned they had accepted it. The larger part of mothers reported to have felt love for their baby when they found they were expecting. Almost all mothers felt supported by both health professionals and/or family/friends during gestation. During their hospital stay, most mothers described their baby’s temperament as calm and only about a quarter described them as restless or difficult. Anticipating the future, these mothers felt that it would be good to take care of their babies, but the majority expected to find difficulties to be overcome with the help from family support (which they anticipated having).In the group of mothers of preterm (PT) babies planned and accepted well their pregnancies. In fact, a large part of mothers in this group was enrolled in the infertility medical consultation (assisted reproduction) to become pregnant. These mothers reported having felt love for their child as soon as they learned they were pregnant. Despite these positive aspects, when birth occurred prematurely, mothers felt concern or great concern and guilt. As in previous studies, mothers of PT infants described feelings of distress and despair regarding the experience of pregnancy and birth [Most nd birth . Howevernd birth  with motnd birth , 53 repomothers of very preterm (VPT) infants. The pregnancy and early postpartum experience reported by mothers of very preterm infants is equally accepted, but compared to the other two groups, the feeling of love for the newborn occurs much less frequently at an early stage, for instance, when mothers first are informed about their pregnancy. Worryingly, in this group, the first feeling of love is described as occurring only after birth by about one-third of the mothers and, even more serious, three mothers did not express this affection for their baby at all. Regarding this dimension it is important to note that we did not present mothers with any definition of the expression “feeling love”. In fact, some mothers expressed having doubts about the meaning of “feeling love” and were not sure about having ever felt that sensation while others defined “feeling love” as the “urgency” of being close, to care, to hold, to love, to protect and as a complex, confusing and to some extent scary but positive and strong bonding feeling. To our best knowledge, no previous study found differences between the three groups of mothers concerning the moment when these feelings arouse for the first time.The most striking results of this study concern the narratives of Furthermore, since several studies found that the prevalence of depression is higher in mothers of very or extremely preterm infants , we wondActually, not only did the life scripts of these mothers carry more risk indicators  but, also, they reported more cumulative risk situations at that present moment. For example, some of them had not received any personal support during pregnancy or clinical/health follow-up, which is rare in the Portuguese context . These mWhen asked to describe their babies’ temperament a large group of mothers of VPT infants reported perceiving their infant as agitated, and a significant number of mothers showed difficulties in characterizing the baby’s temperament. These results may be explained by both (1) the mothers’ emotions and their main focus on their newborn struggle for survival in the immediate moment which prevent them from being sensitive to other characteristics of their baby; and (2) by the physical immaturity of the very preterm newborn which, as reported in other studies, results in greater difficulty for parent-newborn interaction .When asked to reflect upon their perceptions and expectations for the future, mothers of VPT infants were so focused on their newborn struggle for survival in the immediate moment that they showed reluctance in looking into the future. Again, these findings may be due to the frightening uncertainty about their baby’s survival in this phase. Uncertainty and grief usually prevent mothers from being able to perceive and to reflect about potential difficulties in the future.Lastly, although it was not defined in our initial research aims, given the high and unexpected number of births by caesarean section, we decided to analyze the impact of this variable on our findings. Indeed, the type of delivery affected mother’s perception of the baby’s temperament (mothers who gave birth by caesarean section described more often their newborns as agitated) as well as the anticipation of prospective problems or potential future difficulties see . Like inIn summary, mothers’ early perception of their experiences with full-term, preterm and very preterm infants showed some similarities but equally important differences. These results reinforce previous evidence indicating that maternal experiences in these three groups are distinct , especiaIn fact, the growing recognition that parents’ negative emotions  and stress are associated not only with prematurity but also with the quality of their experience during their stay at the NICU contributed to the significant enhancement of Family-Centered Care (FCC) within NICU and to the development of family-centered interventions during NICU hospitalization , 60. TheIn our study, mothers of very preterm newborns showed more negative emotions and more difficulty in facing the future. The fragile clinical conditions of very preterm infants, the incidence of mortality among these babies and the extremely stressful conditions of anxiety and depression may prevent mothers from engaging with their baby . These sFurthermore, mothers of VPT infants face a long stay in the NICU which frequently has repercussions in their personal and family lives. Their specific needs pose new challenges that must be addressed in the NICU, and more generally by the Health Care Systems and Neonatal Care Policy, including government and global maternal and child health care agencies.Our study has both strengths and limitations. The current study was developed within a descriptive and interpretative paradigm, using a qualitative methodology, without generalization concerns. Indeed, one of our limitations it that our results mainly mirror the reality of Portuguese mothers living in urban areas. However, it is noteworthy that our study includes a large sample of 150 mother-infant dyads which, although distributed across three study groups, allows us to deepen our data exploration and the uniqueness of each group experience.Importantly, in our sample, the three study groups are distinct from the point of view of family conditions, history of pregnancy and attempts to conceive , which should be considered when reading our results. In fact, in addition to the risk-factors associated with a preterm birth, the group of very premature infants presents more risk-factors associated with pregnancy and family relationships (support network), compared with the other two groups, which may increase mothers’ sense of insecurity, influencing the nature of their postpartum experiences. Future studies must address questions of diversity, marginalization, and interlocking oppressions in this particular group.Mothers experience in each group, also, varied regarding breastfeeding experiences  and labor . Although the samples vary in these aspects, in fact, they reflect the different experience in these groups. The unexpected and high number of caesarean sections deserves further investigation, namely regarding its causes and consequences.To learn more about the participants’ perspectives, we invited a group of 10 parents (both mothers and fathers) in the preterm group to participate in a videotaped focus group to discuss and reflect about the study findings. The parents confirmed that the identified themes and subthemes reflected their experience, demonstrating an identification with the study results and stressing the need for more effective support responses in the hospital maternity and after discharge. Further research addressing the temporal continuity of these early experiences, namely the impact of parental stress and early relationships on infants’ development, is pivotal. For instance, although it is generally accepted that parental stress is influenced by infants’ gestational age and weight at-birth, and particularly with pre- and perinatal complications , some pa“call to action” has been proposed highlighting the urgent need to understand the etiology and the context of a preterm birth , focusing on the need to use new strategies, namely prevention strategies  to tackle the combined biological and social factors associated with an early birth [At last, it is important to stress that preterm birth is the most common single cause of perinatal and infant mortality, affecting 15 million infants worldwide each year with global rates increasing exponentially . In recely birth –97. For ly birth .We believe that this study contributes to the body of knowledge that describes maternal pre- and perinatal experiences with their newborns in the context of different neonatal risk factors. The exploration and understanding of early life subjective experiences and their causes are fundamental in enhancing successful evidence-based mother-infant intervention strategies and medical-clinical practice, while simultaneously informing theoretical, practical, research, policy-making and public health decisions.


More than 40 years ago, János Kornai introduced his famous supermarket metaphor. Socioeconomic systems cannot be constructed from purposely selected features, similar to customers in a supermarket, who can freely put into their shopping trolley whatever they like. Systems constitute an organic whole. They contain good and bad features in fixed proportions. After 1990, Kornai and most Western commentators expected that as market integration and private property expand, China would eventually turn into a liberal democracy. Prior to the worldwide fall of communism, Kornai had three primary criteria to determine whether a country was socialist or capitalist; later he amended this with six secondary ones. The present paper introduces into this list an additional 11 criteria—i.e. 20 quantifiable metrics altogether. Kornai was among the very first to recognize that with President Xi Jinping taking charge, China made a U-turn. While capitalist elements remain strong, in the final analysis, the country is on its way back to where it was before 1978. Socioeconomic systems, he argued, cannot be constructed from randomly or scientifically selected pieces, similar to customers in a supermarket, who are free to put into their shopping trolley whatever they find on the shelves. Structures like socialismstrong linkage to) state-owned property, while market coordination has a natural affinity for private property. By contrast, the linkage between market coordination and state property is weak, meaning that one cannot use the market as a neutral instrument to promote state ownership.3In 1979, János Kornai introduced his famous supermarket metaphor to challenge the theory of the “third way”, an capitalist dictatorship. The Communist Party was communist only in its name, he asserted; it was more nationalist or Confucian.communist, dictatorial practices. The regime retains and even extends governmental interference into markets and private property .The objective of the present paper, based partly on our new book , when the entire world is occupied with the fight against the coronavirus, such a “categorization game” is very relevant for the interpretation of President Xi’s “people’s war against the epidemic with the most comprehensive and rigorous measures”.6final victory of the Western-type liberal, capitalist system. He wrote it in a few months between November 1989  and the beginning of Boris Yeltsin’s rule in July 1991 (as president of the newly “re-created” Russia). But history continued. Fukuyama’s point of departure was the fall of communism, the only historically proven, 20th century viable alternative to the capitalist market economy and liberal political systems. 7In a path-breaking article, the American political scientist Francis Fukuyama  predicteIndeed, as Szelenyi and Mihályi  explaine8Size matters: The Union of Soviet Socialist Republics (USSR) was and the People’s Republic of China (PRC) is a global superpower. Had the Soviet-type planned economy not been abandoned by the USSR and its allies in Eastern Europe, and the socialist world system remained a more or less credible alternative to the capitalist market economy, China, or even India and Brazil—i.e., the largest and politically strongest states of the “third world”—might not ever have opened their markets to Western multinational companies to the extent that they did. Thus, globalization would not have happened either—at least not with the same speed as it did happen.It is well known that the Chinese economic reforms arising from the dismal performance of the classical socialist model started earlier, in 1978. However, what matters from the perspective of this paper is that the reforms continued after 1989. In 1978, the term “reform” referred merely to modernization, more specifically the “Four Modernizations Program” of Deng Xiaoping Shi , p. 5. IDeng Xiaoping was one of the most complex and consequential politicians of the 20th century. He joined the Communist Party of China (CPC) in 1924 when he was just 20 years old, fought with the communists against the Kuomintang and Japanese, and was rewarded with a vice-premiership in 1952. His main allies were the reformer Zhou Enlai and Liu Shaoqi. Deng opposed including “Mao’s thoughts” in the Chinese constitution;11after 1989.The post-1978 reforms were not merely a reincarnation of the Four Modernizations Program. Given China’s cultural respect for tradition, Deng realized that he could not break with Mao like Khrushchev and Gorbachev had rejected Stalin. Hence, Deng’s famous verdict on Mao’s historical role: “He was 70 per cent good and 30 per cent bad”. Whatever we know about him today, Deng was hardly a communist ideologue like Mao or Stalin, who ruled their empires for nearly 30 years. His famous statement that “it does not matter if the cat is black or white so long as it catches mice” made the Chinese reform work. The only problem with that quotation is that Deng said it at a Communist Youth League conference in 1962; therefore, it was not meant for a moment to be interpreted as the CPC’s attitude Southern Tour in 1992 that the reform was back on track, and it was now officially equated with the transformation of China into a “socialist market economy”  and significant decentralization measures, which included more power for village and township governments and a substantial move towards some democracy at the local level Oi . The bigomy” Shi , p. 6.rural system of people’s communes was replaced by townships . Our interpretation is that China for more than three decades after 1978 was cautiously building “capitalism from below”ships Oi . The reffied Nee , the reffied Nee .Similar to the agrarian reforms in Hungary from the mid-1960s onwards, agricultural prices were gradually deregulated. Production quotas were lowered and later eliminated. The result was a closing of the gap between urban and rural incomes. The big winners were the peasants. When China began reforms in 1978, it was still primarily a rural, agrarian country. To some extent, the nation’s extraordinary economic growth explosion can be attributed to its inexhaustible labor supply.Unlike many other countries , an ample “historical reservoir” of rural entrepreneurship is found in China. As Huang  also empfree-trade zones attracting mainly small-scale Chinese capital from Hong Kong and Taiwan. After 1985, and especially after 1989, the reform began to shift from the countryside to the cities. The creation of private property rights in state-owned enterprise happened much later, but even when the enterprise sector was privatized to a large extent, the word “privatization” was never used in official documents. Instead, Chinese authors preferred to speak about cross-border mergers and acquisitions, a terribly misleading euphemism  and its insistence on standing for the cause of socialism , it was not the same party that existed at the time of Mao Zedong. Daniel A. Bell , who in that unique way have created their own stakes in the Chinese economy’s transformation.not a very high price to pay to avoid a civil war, he asserted at that time. Furthermore, Kornai was pleased to acknowledge that, relative to Mao’s time, even the dictatorship’s brutality had softened considerably. In a 2014 paper published in Hungarian only, he still saw a “50–50” chance for “democratization of political institutions”, as opposed to the possibility of ruthless and naked repression. There, Kornai turned the customary argument in the opposite direction. The slowdown of Chinese GDP growth—which coincided with the aftermath of the 2008 international financial crisis—can lead to aggressive pro-growth government policies, to an increase in investment, and to cuts in wages and welfare spending. If that was the direction in which things would go, Kornai warned, tensions and protests could be met by more forceful retaliation, the country’s leaders might set out to incite nationalism or even try a foreign military adventure. But there was an equal amount of chance for a good outcome—continued democratization, welfare reforms, and the curtailment of corruption.For many years, János Kornai’s overall assessment was not very different from that of the Western academic mainstream. He admired many aspects of the reforms  has led to a gradual rebuilding of a communist political system—not seen since the death of Mao in 1976. As of 2020, we observe more and more signs of Xi accumulating power in his own hands, of a developing personality cult and of the “selective criminalization” of his political opponents, clothed in the ideologically more acceptable garb of an anti-corruption campaign. In our interpretation, three things have been unfolding in parallel.before the above-mentioned constitutional reform, Kornai  op-ed on 11 July 2019.A few weeks , Kornai  gave a s, Kornai  shocked The Financial Times (and its Hungarian translation) generated echoes both in Hungary and abroad that, in turn, motivated Kornai to write a longer and more detailed exposition of his views.27This short piece in Foreign Affairs, the leading US magazine for analysis of and debate about foreign policy, five lengthy papers were devoted to the assessment of President Xi’s policies and the risks emanating from them. One of those papers  legitimates the party.Let us consider the three arguments in the framework of Table property rights usually are regarded as a major precondition for capitalism and dynamic economic development, yet China has proven to be an outlier in that respect.nomenklaturade nouveaux domestic private firms, albeit with some limits. It is very difficult to measure personal wealth accurately in China. Some billionaires may hide it. Others, like princelings , may oversee large companies that formally are SOEs but could be de facto private businesses owned by their princeling-managers.We believe that at least three reasons can be found to explain why arguments that China is socialist should be seriously considered.arenda system that spread during the USSR’s New Economic Policy (NEP) of 1921–1926. Some commentators regard the October 2008 resolution of the party’s Central Committee as a landmark event  into second- or third-class citizens. Land reform, it was hoped, might boost the income and consumption of former rural hukou registrants.The private ownership of agricultural land remains restricted or, to be more precise, banned constitutionally. Even though family farming was restored during the early 1980s, peasants did not receive titles to the lands they till. They lease land from the villages; the terms of the leases were gradually extended up to 30 years in 1984. Although leases had practically become indefinite by October 2008, still no titles were granted to private individuals. As Nuti  noted fievent Li  since itsecondary characteristics of idealized economic systems—i.e., capitalism versus socialism. As we have noted already above, the points included there are taken directly from Kornai . We conclude that on 10 dimensions of the 11 dimensions listed, present-day China seems to closely resemble the well-known, classical socialist model. Looking at the dimensions of the analysis one by one, our judgments are not fully justified, but we believe that the overarching conclusion of Block C is convincing: China has kept many of the features of its pre-1989 version of communism.Since 1989, Kornai has never changed his position on the political evaluation of the Chinese system. While he noted the gradual, but significant, softening of the CPC’s power monopoly, he never questioned that China is a dictatorship. Yes, it was, but it was shifting for a while towards a “non-electoral autocracy”, with term limits imposed on presidents, with significant powers allocated to the Politburo’s rather diverse executives, and some liberal legislation at least for foreign investors . We also refer to a vague, nonetheless very forceful definition Mao Zedong gave to characterize his system: “politics in command”.China is socialism with Chinese characteristics.In our vocabulary, “illiberalism” and “dictatorships” have different meanings. Illiberalism is a project to create an authoritarian regime, with few limits on the executive branch, but in illiberal regimes elections still take place, the judiciary still has some autonomy, and the media is somewhat free. None of those meanings really hold for China today. Questioning the logic of the Varieties of Capitalism (VoC) paradigm, as it was originally formulated by Hall and Soskice , we see The classification of China is enormously important. Socialist countries are all dictatorships driven by Marxist-Leninist, one-party states and communist ideologies. If China is considered to be a capitalist dictatorship, then only a few unimportant countries like Cuba and North Korea would remain in the [what?] box. In other words, if our analysis is valid, then Fukuyama  was entipolitico-ethical value system and would at the same time provide for the efficiency of the economy. (Kornai History does not provide such supermarkets in which we can make our choice as we like. Every real economic system constitutes an organic whole. They may contain good and bad features, and more or less in fixed proportions. The choice of system lies only among various ‘package deals’. It is not possible to pick out from the different ‘packages’ the components we like and to exclude what we dislike. It seems to me that it is impossible to create a closed and consistent socioeconomic normative theory which would assert, without contradiction, a Let us close our paper with a direct quote from Kornai’s seminal writing, when he first coined the supermarket metaphor, with which we started our present paper.We agree with Kornai, with one qualification. China was on its way to market capitalism with the possibility of turning eventually into a liberal democracy. The road was rocky, with many back-and-forths. But the shift to liberal democracy did not happen. The 1989 massacre at Tiananmen Square, approved by Deng, was a more alarming setback than contemporary Western observers realized. Today, we are much like Kornai, increasingly skeptical about what has been happening in China for the past eight years. Kornai did a U-turn in his theorizing about China, but what is more important, China seems to be taking a U-turn back to the pre-1978 epoch.


Information entropy metrics have been applied to a wide range of problems that were abstracted as complex networks. This growing body of research is scattered in multiple disciplines, which makes it difficult to identify available metrics and understand the context in which they are applicable. In this work, a narrative literature review of information entropy metrics for complex networks is conducted following the PRISMA guidelines. Existing entropy metrics are classified according to three different criteria: whether the metric provides a property of the graph or a graph component (such as the nodes), the chosen probability distribution, and the types of complex networks to which the metrics are applicable. Consequently, this work identifies the areas in need for further development aiming to guide future research efforts. A wide range of problems, such as social network analysis, communications routing, protein interactions, identification of key players in transaction networks, vulnerability of water distribution networks, and city traffic studies, deals with determining the entropy of relational structures, such as complex networks or graphs. Given the great differences in routes and flow types that these varied networks follow, a great body of research has been developed that presents varied information entropy metrics. Each entropy metric provides different characteristics of a network or its components. Furthermore, it is accepted that not all of the metrics are applicable to all networks. Unfortunately, this growing body of research is scattered in multiple disciplines. Thus, it is difficult to identify the available metrics and understand the context in which they are applicable, as well as to determine areas in need of further development. Consequently, a systematic literature review of information entropy metrics for graphs is direly needed. This work aims at conducting a survey of existing graph entropy metrics that are specifically based on information entropy, as described by Shannon’s formulation . In addiThis work is organized, as follows. G is composed of a finite set of nodes V and a set of edges E. The set of nodes cannot be empty, E are pairs of nodes A complex network or graph G can be completely described by means of an adjacency matrix G is generally described while using a weight matrix Graph G is said to be connected, if, for every pair of distinct nodes A graph i are considered to be equivalent, In this work, the node notations i is the number of nodes j to which i is adjacent. The degree For an undirected graph, the degree of a node For directed graphs, the in- and out-degree, mponents :(2)ki=kiThe node strength is the natural generalization of the node degree for weighted graphs. Thus, it can be calculated from the weight matrix. For undirected graphs, it is defined asv falls on the geodesic path i and j. This metric captures the potential that node v has to control the communication between nodes i and j. It can be calculated asThe betweenness centrality  Freeman  and it ri to j, in which neither nodes nor edges are repeated.Note that a geodesic path is the shortest possible sequence of linked nodes from i and j, C of node i is defined asCloseness centrality is defined in terms of distance and it can be interpreted either as a metric of independence from control by others or as a measure of access or efficiency . Given di is proportional to the sum of the centralities of the nodes to which it is connected. This metric can also be interpreted as a weighted sum of not only direct neighbors, but indirect ones of every length. The eigenvector centrality is defined asx is the corresponding eigenvector.Being originally suggested by Bonacich ,6, eigeni are adjacent, i.e., the ratio between the number of triangles i as one vertex and the number of all possible triangles that i could form The clustering coefficient, which was first introduced in , indicatThe original formulation  is applif of graph G as a function that is capable of capturing structural information of the underlying graph. S is an abstract set. In addition, f is assumed to always be monotonous. Because f has to be defined concretely, arbitrary graph-theoretical properties or quantities can be used. Thus, an information functional f can be, for example, any of the centrality measures defined in the previous Section.Dehmer  defined f is an arbitrary information functional. Because An information functional quantifies structural information of a graph and produces a derived probability distribution, as followsn different symbols in less than Information theory originated in the need to quantify fundamental limits on signal processing. Shannon  developea system . It alloDefinition 1.For an ensemble where calculating e or 10 without loss of generality.However, it must be noted that the Shannon’s information measure can be based on logarithms of base 2, H increases as the probabilities H attains its maximum possible value when all of the Because Shannon’s information entropy is a measure of uncertainty, the entropy H increases with n.For equiprobable outcomes, the value of the entropy When there is only one possible outcome, the system is perfectly predictable and, thus, H.The mathematical formulation that is presented in Equation  is that H.Equation  is a symShannon’s information entropy formulation has a number of properties worth mentioning:Paths are a sequence of linked nodes in which neither nodes nor edges are repeated. A path of length n from node i to node j is an ordered sequence of distinct nodes Geodesics are shortest paths. The notation is analogous to paths, with the caveat that P is the shortest path from i to j. Trails allow for nodes to be repeated; however, each edge walks allow for both nodes and edges to be repeated.Borgatti  explainei and j in graph G is written as The distance between two nodes G is the greatest distance between any two vertices in G. It is denoted as The diameter of a graph The present literature synthesis is the result of a systematic review that was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram  in FigurThe “other sources” are mostly constituted by articles identified through Google Scholar. Any other articles referenced in those identified through database search and deemed interesting were further explored and they are also accounted in the “other sources” set.After removing duplicate records, these were screened by title and then by abstract to identify records dealing with entropy in the context of complex network analysis. Full text assessment was conducted on 52 records and 50 of them were included in the study that was presented in this work. These two records were excluded, because they use Shannon’s entropy in order to calculate the weight coefficients of a decision matrix instead of using it to calculate the entropy of the nodes or network itself.Is Shannon’s entropy used as a network or node metric?When Shannon’s entropy is used with the objective of ranking nodes by importance , is the entropy of the node calculated directly or obtained as the difference between the entropy of the graph before and after node removal?What is the definition of the probability distribution To which type of complex network is the metric applicable? Undirected or directed graph? Weighted or unweighted? Should the graph be strongly connected? Are self-loops allowed? And so on.The present study focuses on identifying a number of elements in the records evaluated:The 50 records that are included in this literature review are summarized, in chronological order, in i and its edges had been removed are calculated. Subsequently, the entropy change i can be obtained A number of authors use information entropy as a network or graph metric ,41,50,53Traditional graph entropy metrics are based on graph invariants, such as the number of nodes or edges or the degree distribution . These mIt is also possible to produce graph entropy metrics that are based on information functionals ,22 see . In factInformation entropy may also be used as a centrality metric to rank nodes (or edges) by importance. In this sense, several authors ,61,62,63i and its edges have been removed, As explained in the previous Section, entropy metrics can be used as centrality metric in a similar fashion to degree or betweenness centrality. This type of entropy metrics produces node rankings and aids in the identification of the most central node . These rankings can be of two types: direct and indirect. The former implies the calculation of node entropy “Each measure of centrality makes assumptions about the importance of the various types of traffic flow and, thus, each measure of centrality can be assessed by where it falls in the typology (refers to Borgatti’s typology )” 14]14]“Key players are those elements in the network that are considered to be important, in regard to some criteria.” “... in any centrality application one should take into account the characteristics of the flow of traffic through the network.” “Choosing the right centrality for a specific problem is usually a hard task and [a] common approach is comparing different centralities for the same network and building hypothesis about the discovered central nodes.” “Different measures of centrality capture different aspects of what it means for a node to be ‘central’ to the network.” “A centrality is optimal for one application, yet is often sub-optimal for a different application.” “Centrality is an important concept in network theory, yet there is no unique definition.” “Centrality is a measure of the importance of a node in a complex network with respect to a specific criterion, where several centrality criteria have been proposed.” “... a specific centrality is ideal for one application, yet regularly imperfect for an alternate application.” “The significance [the authors mean importance] of a node can have different meanings depending on its application.” “What most important’ means is not universally defined, therefore numerous notions of centrality have been proposed.” “[centrality measures] ... are intended to capture the role played by each node within the network by optimizing an opportunely defined objective function.” “The meaning of ‘important’ depends on the nature of the problem analyzed.” “... all of these methods [centrality metrics] have some limitations and specific application scenarios that are related to the way they consider the problem. A valid method for ranking nodes in a complex network remains an open issue.” “In general, each network has a specific node importance ranking, and different identification methods consider different structural properties of the network, which would give different ranking lists.” “Various centrality metrics establish different aspects for the meaning of an actor to be central to the network.” It should be noted that, like traditional centrality metrics, node rankings that are based on entropy are calculated based on a number of assumptions as well as the characteristics of the underlying graph. Consequently, not all centrality metrics are applicable to all graphs. This was originally stated by Borgatti , who expdegree or strength (18 records),betweenness (eight records),paths (five records),walks (six records),closeness (four records),distance (three records),eigenvector (two records), andother definitions (nine records).The probability distribution By far, the largest number of entropy metrics are based on node degree ,49,56,62i, i.e., The first group corresponds to entropy metrics, where the probability distribution i has been removed. In Serin et al.’s work [Ortiz-Arroyo et al.  defined .’s work , pi=kinolarly to , Serin’sq degree power of node i, and defined q degree power, they do define the sum of degree powers, as follows q is an arbitrary real number. In literature [Lu et al.  used theEquation ). While terature  it is exi is removed. Similarly, Wang et al. [Likewise, Ai  used theg et al.  used inf work in  for q=1.k. They also studied the Wu Structure Entropy (WSE), where the definition is equivalent to that of [Cai et al.  studied  that of  for q=1.i et al.  also coni and j belong to. The i and j from community h. The external density probability distribution, For Wiedermann et al. , the entu et al.  defined Finally, Barucca et al.  proposedi, A second group of metrics is formed by entropy definitions that are based on node strength ects. In , the autn et al.  previousn et al.  wrote thi et al.  defined i et al. .i , the prZareie et al.  proposedeighbors , Guo et eighbors  defined Li et al.  proposedi et al.  also defi’s neighbors. The probability distribution is defined as Ni et al.  defined i, i.e., i, giving Wang et al.  proposedEquation  is conduj, which is a neighbor of node i, thus Finally, Saxena et al.  based thi , thus pi et al.  developei et al. .i’s neighbors. While the authors named this metric “entropy”, just like in the case of Nie et al. [Gialampoukidis et al.  furtheree et al. , this isi ends in node j. i and j of the stopping probability in node j multiplied by the product of the transfer probability of all the nodes appearing in the path before j. The formulation of Tutzauer’s work [Some authors based their entropy metrics on paths, i.e., a sequence of linked nodes, in which neither nodes nor edges are repeated. r’s work  is availr’s work  to definr’s work  continuei as a starting point and the total number of paths in graph G. The authors calculate the centrality entropy for the full graph and after the removal of a node. They associate the largest change in entropy to the most central node.Ortiz-Arroyo et al.  proposedi, as opposed to fully transferred to a single neighbor. In this case, i and j of the product among all nodes in the path of the split-and-transfer probability times the ratio between the incoming flow and the number of edges it can split to. The authors claim that flow originating at highly central nodes spreads more evenly across the graph. The authors furthered their work in [Oggier et al.  extended work in , where tG. However, the number of paths grows combinatorially as the number of nodes and edges grows. While some solutions that disregard paths whose probability falls under an arbitrary threshold have been reported, these metrics have not had wide adoption for medium to big graphs. Some authors [Computational complexity is an important issue that was discussed by several of the authors that developed path-based metrics ,17,46,54 authors  contend An alternative to paths that forgoes the computational complexity are walks. A walk is a sequence of linked nodes, where both nodes and edges can be repeated. A number of authors have used walks to define their entropy metrics. t. The authors determined that the probability t from node i to node j does not depend on the intermediate vertices. In fact, u is the non-negative left eigenvector for v is the non-negative right eigenvector for Delvenne and Libert  proposedFewell et al.  used a ni and finishing at the same node. It is understood as a measure of how much a walker is localized in a few nodes. The probability distribution represents the probability of selecting at random a closed walk among all such walks in the graph, thus Estrada et al.  defined h. Benzi  furthereh. Benzi  by proviG and using walks of length t instead. This method solves computational efficiency issues, given that the entropy of node i for a walk of length t can be calculated exactly while using matrix multiplication. For this, the authors defined Nikolaev et al.  furthere of flow , Nikolaei, where Caravelli’s work  also intAs discussed previously, Serin et al.  proposedness see . The autDehmer et al.  studied ∑jCj see . Their w∑jCj see . The clo∑jCj see ), where  case of   is condA summary of these metrics can be found in Jimenez et al.  quantifiZarghami et al.  developeA summary of these metrics can be found in i. Wang et al. [i is from the origin-destination pair s. Zareie et al. [i and the sum of the IKS of the neighbors of i. Thus, l around node i giving A number of authors have proposed entropy metrics whose probability distributions do not correspond to any of the groups discussed previously. g et al. , as explg et al.  presentee et al.  used then et al.  used theo et al.  predicteo et al.  used nodComplex networks can be either directed, where This narrative review has identified a number of ways to classify information entropy metrics for complex networks. In G  hindering adoption [ary work  reduced adoption ,29,46,54Finally, information entropy metrics for complex networks can be classified based on the types of graphs to which they are applicable, as in In conclusion, it must be recognized that, although the development of information entropy metrics for complex networks has been ongoing for 15 years, the existing body of research is limited. Thus, it can be fairly argued that the field is in its infancy. This feeling is shared by other authors. In fact, Ni et al.  stated,