Studies on Visual Learning in Split-Brain Monkeys

Citation

Trevarthen, Colwyn Boyd (1962) Studies on Visual Learning in Split-Brain Monkeys. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/YFG6-1968. https://resolver.caltech.edu/CaltechTHESIS:08192011-102232875

Abstract

The unity of perception and its divisibility were examined by a method of double learning. Polarized light and polarizing filters were used to present monkeys with two contradictory visual tasks simultaneously, one visible to each eye. Subjects were trained after surgical division of the visual pathways at the optic chiasm, and after the cerebral cortices were separated by cutting the corpus callosum. The distribution of learning between the two halves of the brain gave information about the location of visual learning, and about the relationship between visual attention and the intention to respond with a particular limb. Two subjects learned conflicting tasks simultaneously. In many tests, however, there remained some interaction between the two halves of the brain. This led to selective learning by one eye, the other eye remaining unretentive though it was open throughout training. In tasks involving brightness and color discriminations, there was significant interocular transfer of learning in spite of the surgery. It is concluded that the two surgically separated cerebral hemispheres may function independently in memorizing a visual pattern, but that there are also avenues for their communication. The motor system remains coordinated after split-brain surgery, although there is a tendency for preferential pairing of eye and hand of opposite sides of the body after surgery. Some visual tasks were found to involve interhemispheric processes to a higher degree than others. Visual recognition of comparative size, requiring interocular comparison, was found to survive chiasm and callosum section.

Thesis Files