On the development and mechanics of delayed matching-to-sample performance.
Despite its frequent use to assess effects of environmental and pharmacological variables on short-term memory, little is known about the development of delayed matching-to-sample (DMTS) performance. This study was designed to examine the dimensions and dynamics of DMTS performance development over a long period of exposure to provide a more secure foundation for assessing stability in future research. Six pigeons were exposed to a DMTS task with variable delays for 300 sessions (i.e., 18,000 total trials; 3,600 trials per retention interval). Percent-correct and log-d measures used to quantify the development of conditional stimulus control under the procedure generally and at each of five retention intervals (0, 2, 4, 8 and 16-s) individually revealed that high levels of accuracy developed relatively quickly under the shorter retention intervals, but increases in accuracy under the longer retention intervals sometimes were not observed until 100-150 sessions had passed, with some still increasing at Session 300. Analyses of errors suggested that retention intervals induced biases by shifting control from the sample stimulus to control by position, something that was predicted by observed response biases during initial training. These results suggest that although it may require a great deal of exposure to DMTS prior to obtaining asymptotic steady state, quantification of model parameters may help predict trends when extended exposure is not feasible.
['Kangas|Brian D|BD|', 'Berry|Meredith S|MS|', 'Branch|Marc N|MN|']
D000818:Animals D001245:Association Learning D003118:Color Perception D010856:Columbidae D003216:Conditioning, Operant D004193:Discrimination Learning D008570:Memory, Short-Term D009949:Orientation D011930:Reaction Time D012055:Reinforcement Schedule D012153:Retention, Psychology
delayed matching-to-sample memory pigeons steady state extended exposure conditional discrimination key peck response bias