The effects of changes in consequences on hens' performance in delayed-matching-to-sample tasks.
A delayed-matching-to-sample (DMTS) task was used to investigate remembering with domestic hens. In Conditions 1 and 3 of Experiment 1, six hens responded under a mixed-delay procedure with delays of 0.25, 2, and 8 s. In Condition 2, the reinforcer for correct responding was delayed for 6 s after each correct matching response on 2-s delay trials. In Condition 1, discrimination performance decreased monotonically over the three delays. With the delay to the reinforcer, the decreases were non-monotonic as a result of the considerable drop in the accuracy of discrimination on the 2-s delay trials. Performance at the 2-s delay did not recover completely in Condition 3. In Conditions 1 and 3 of Experiment 2, five hens responded under a mixed-delay procedure with delays of 0, 4, and 16 s. In Condition 2 no reinforcers were provided for correct responding on 0- and 16-s delay trials. When reinforcers were available on all trials discrimination performance decreased monotonically with delay. There were non-monotonic changes in discrimination with delay when there was extinction at two delays resulting mainly from a large drop in discrimination performance at 0 s. In addition, response latencies increased markedly at the two delays associated with extinction. Performance recovered completely in Condition 3. The data support the ideas that remembering involves a temporal discrimination that the effects of delaying reinforcement and removing reinforcement may differ, and that the measurement of response latencies may be a useful tool in DMTS procedures.
Nakagawa
Shinichi
S
University of Waikato, Hamilton, New Zealand. s.nakagawa@sheffield.ac.uk
Etheredge
Richard J M
RJ
Foster
T Mary
TM
Sumpter
Catherine E
CE
Temple
William
W
D000818:Animals; D001522:Behavior, Animal; D002645:Chickens; D004192:Discrimination, Psychological; D005108:Extinction, Psychological; D008568:Memory / Q000502:physiology*; D011200:Poultry; D011930:Reaction Time; D012054:Reinforcement, Psychology