Probability learning in pigeons (Columba livia) is not impaired by hyperstriatal lesions

Three experiments investigated the effects of hyperstriatal lesions on spatial and visual probability learning in pigeons. The lesions did not affect choice accuracy although they did reduce positional responding on error trials in the visual task. The results gave support to a perseverative, as opposed to an attentional, interpretation of the lesion effects. Increasing intertrial interval in the visual task resulted in decreased accuracy in both lesion and control groups, and the absence of a differential effect on the lesioned birds ran counter to an earlier suggestion that increased perseveration might be due to increased frustration. A fourth experiment confirmed that the lesions disrupted both acquisition and reversal of a conventional orientation discrimination; the deficits again appeared to be due to increased perseveration rather than to shifts in attention.