Lateralized-temporal-lobe-lesion effects on learning and memory: examining the contributions of stimulus novelty and presentation mode.

Previous studies have attributed poor memory for words after left temporal lobectomy (LTL) to a verbal memory deficit and poor memory for abstract designs after right temporal lobectomy (RTL) to a difficulty in remembering nonverbal/visual stimuli. In this investigation, the contribution of stimulus novelty to lateralised-lesion-effects was evaluated by testing list learning in 11 LTL, 8 RTL and 14 normal control subjects, using four types of material (familiar verbal, novel verbal, familiar designs and novel designs). In addition, the effect of presentation modality (spoken vs. written) on word-list learning was examined. We found that novelty enhanced material-specific-side-of lesion effects and that the LTL group had greater difficulty in learning spoken than written words.