Abnormal spatial but normal temporal resolution in the Siamese cat: a behavioral correlate of a genetic disorder of the parallel visual pathways.

Six ordinary and one Siamese cat were tested for spatial frequency contrast sensitivity and for flicker discrimination thresholds. The Siamese cat was markedly impaired in the former task but performed normally in the latter. This result is consistent with single-cell physiological evidence showing an abnormally high Y/X cell ratio in the area centralis of Siamese cats. Under a more general perspective, this genetically related dissociation of visual impairments confirms the idea of parallel pathways subserving spatial and temporal resolution, respectively.