Representation Strength in Pigeon Short-Term Memory: Effect of Delay Training
Animal Learning and Behavior
An attempt was made to manipulate the strength of internal stimulus representations by ex- posing pigeons to brief delays between sample offset and comparison onset in a delayed conditional discrimination. In Experiment 1, pigeons were first trained on delayed conditional discrimination with either short (0.5-sec) delays or no delays. When delays were increased by 2.0 sec, birds trained with a delay performed at a higher level than did birds trained with no delays. In Experiment 2, subjects were first trained on a delayed simplediscrimination. Following a circle stimulus, responses to a white key were reinforced; however, following a dot stimulus, responses to the white key were not reinforced. The pigeons were then trained on a delayed conditional discrimination involving hue samples and line-orientation comparisons with differential outcomes. Choice ofvertical following redyielded food; choice of horizontalfollowinggreen yielded no food. Mixed delayswere then introducedtobirdsin Group Delay, whereas birds inthe control group received overtraining. When tested on a delayed simple discrimination with hue stimuli (red and green initialstimuli followed by white responsestimulus), pigeons inGroupDelaytended to perform at a higher level than did birds in the control group (i.e., although the birds in both groups responded more following red than following green, birds in Group Delay did this to a greater extent than did birds in the control group). Thus, experience with delays appears to strengthen stimulus representations established during training.
Steirn, Janice, Thomas R. Zentall, Lou M. Sherburne.
"Representation Strength in Pigeon Short-Term Memory: Effect of Delay Training."
Animal Learning and Behavior, 21 (2): 113-119.
doi: 10.3758/BF03213390 source: http://www.uky.edu/~zentall/pdfs/52.pdf