Hyperstriatal lesions and attention in the pigeon.

In two experiments, pigeons with bilateral lesions of the hyperstriatum were compared with unoperated control birds on tasks designed to test an attentional account of hyperstriatal function. In both experiments, hyperstriatal lesions disrupted reversal learning but did not influence the retardation of learning associated with either nonreinforced preexposure to the to-be-conditioned stimulus (Experiment 1) or prior nondifferential reinforcement to the to-be-discriminated stimuli (Experiment 2). There was, however, evidence of an impairment in both the acquisition and maintenance of autoshaped responding in lesioned birds, an impairment which may reflect a disruption of classical associations in hyperstriatal pigeons.