More persistence during task acquisition by intact vs. castrated Japanese Quail

Abstract

Introduction: In view of reports that circulating testosterone levels can lead to the persistence of the selection of previously used stimulus specifications in selective attention mechanisms (Andrew and Rogers, 1972), adult male Japanese Quail with and without circulating gonadal steroids were tested in on a match to sample task in a T-maze. As the specifications (sample) change from trial to trial, it would be predicted that testosterone would not facilitate acquisition of this task if a type of stimulus controls response, but would enhance acquisition if the steroid acts on the activation of a set. Methods: Treatment: Data from 13 castrated and 12 intact male Japanese Quail (Coturnix japonica) are reported. Testing: Birds were tested with and without prior experience of simple T-maze discrimination. The main test consisted of responding to the same colour door (black or white) in one of the two arms as had been encountered in the runway (i.e. match-to-sample). Results: 1/ Both groups of birds acquired the simple discrimination rapidly and at similar rates. 2/ On the match-to-sample task intact birds exhibited a relatively stable performance with longer response sequences, while castrates showed a more variable pattern of responding - increasing then decreasing error rates across sessions. 3/ Sequences of 3 or more responses to position or to brightness were more numerous in birds with circulating gonadal steroids. 4/ All birds showed a preference for longer sequences of response to position than to brightness . 5/ Birds with prior experience of the T-maze discrimination made fewer errors. Conclusions: The results support a role for testosterone in the persistent selection of familiar or learned sets for controlling response - as suggested in the introduction the effect is on the "rule" used in attention not the nature of an individual stimulus.