Comparative investigation of the relationship between cerebral indices and learning abilities

Indices of cerebral development were computed for 23 different species in order to assess their capacity to accurately reflect differences in learning ability. The resulting correlations between index values and performance on a variety of tasks strongly suggest that this approach may offer the best type of continuum for the comparative study of learning. It was further suggested that if the index proposed by Jerison were expanded to reflect possible neuronal connections, a more powerful measure might be obtained.