The effect of categorization on verbal memory after temporal lobectomy.

Epileptic patients with left or right temporal lobectomies were compared with normal subjects on a verbal memory task involving recall and recognition of categorized and uncategorized word lists. The left temporal group recalled significantly fewer words than the normal control subjects, and recognition performance was also poorer. The right temporal group did not differ significantly from the normal controls on recognition, although differences neared significance on recall. Categorization improved performance in all the groups. The left temporal patients improved if words were presented in order of category membership, but recalled less if category membership was randomized over order of presentation.