Stimulus repetition effects on texture-based visual search by pigeons

Four experiments investigated the effects of within-session stimulus repeti tion on texture discrimination. Six pigeons (Columba livia) searched for a contrasting target region (color or shape) randomly embedded within a large r distracter region for food reinforcement. Experiment 1 found that repeati ng features of the distracters, but not those of the target, across trials increased the accuracy of target localization relative to baseline. Experim ent 2 found that subsequently switching the identity of a repeated distract er feature to the target decreased accuracy. Experiment 3 found that the ef fects of repeating a distracter feature influenced search performance for a t least 60 trials after this learning. Experiment 4 found that differential stimulus-outcome relations can produce control by repeated target features . The results are discussed in terms of the factors and strategies involved in the control of avian visual search behavior.