Contextual stimulus control over operant responding in pigeons

Gave pigeons (N = 48) 17 days of single stimulus (S) training with a house light and tone context. Ss were then given 20 days of discrimination training with a 555-nm green response key (S+) and a line (S-). For Group 1 the light and tone were paired with S+ (S+/context), for Group 2 they were paired with S- (S-/context), and for Group 3 they were paired with both (no context change, or NCC). For each group a matched control group experienced the same stimulus configurations without the prior single stimulus training. Then all groups were tested for wavelength generalization. Of the 3 experimental groups, the S+/context group acquired the discrimination the fastest, the S-/context group started poorly but eventually mastered the discrimination, and the NCC group never mastered it. The experimental groups yielded flatter wavelength gradients than did their matched controls, which suggests blocking by the contextual stimuli. (25 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).