Abstract
A definite relation is shown between interhemispheric transfer and speed of learning. Split-brain cats were trained in a variety of discriminations, and the success or failure of interhemispheric transfer was evaluated with regard to rate of learning. When interhemispheric transfer succeeds, learning time is normal; when interhemispheric transfer fails, learning time is prolonged, becoming at least twice that of normal. Retention is also poor in those animals that exhibit prolonged learning. A normal learning curve appears to be the product of interaction between both cerebral hemispheres during learning.