Hyperstriatal function in the pigeon: response inhibition or response shift?

Experiment 1 showed that pigeons with lesions of the anterior or posterior hyperstriatum were impaired relative to unoperated controls and to control operates having neostriatal lesions on both acquisition and reversal of a simultaneous position discrimination. The observation that hyperstriatal birds showed more tendency than controls to halt responding altogether in this situation cast doubt on the notion that the reversal deficit was due to a loss of response inhibition. A second experiment supported an alternative hypothesis, that hyperstriatal birds have a deficit in the ability to shift responding to an alternative stimulus as a consequence of nonreinforcement.