Distractibility of cats with lesions of the superior colliculus-pretectum during performance of a 4-choice visual discrimination.

(1) Intact cats and cats with bilateral lesions of the superior colliculus-pretectum were trained on 4-choice, luminous flux discriminations in an apparatus consisting of a 6-foot square open field with 4 stimulus panels along one wall. After cats attained a high performance criterion on a 4-choice dark-light discrimination they were tested for 'distractibility' by flashing a light behind one of the stimulus panels. (2) All intact cats and cats with lesions of the superior colliculus-pretectum learned the 4-choice luminous flux discriminations. Cats with lesions of the superior colliculus-pretectum, however, followed longer paths and had longer latencies to the correct door, even after attaining criterional performance. (3) All intact cats and cats with lesions of the superior colliculus-pretectum were distracted by the flashing light, as indicated by increased commission of errors, increased path lengths and increased response latencies on trials in which the distracting stimulus was presented. However, both intact cats and cats with lesions of the superior colliculus-pretectum habituated to the distracting stimulus. (4) These results are consistent with previous findings that cats with lesions of the superior colliculus-pretectum have difficulty in withholding incorrect responses or in shifting attention or response tendencies from the incorrect to the correct stimulus. (5) These results do not support the hypothesis that lesions of the superior colliculus produce deficits in attention as measured by distractibility to novel stimuli.