Level-of-processing effects in word-completion priming: a neuropsychological study.

Recent reviews (A.S. Brown & D.B. Mitchell, 1994; B. Challis & D.R. Brodbeck, 1992) concluded that level-of-processing (LOP) manipulations affect priming in perceptual tasks, contrary to earlier suggestions that such tasks are insensitive to LOP. In 3 experiments with amnesic patients and control subjects, the authors examined the effect of LOP manipulations on priming in word-stem and word-fragment completion and on recognition memory. Amnesic patients exhibited reduced or near-zero LOP effects in word-completion priming compared with control subjects. LOP affected recognition memory for both amnesic patients and control subjects, confirming that the LOP manipulation affected explicit memory. When the effect of explicit retrieval on control performance was reduced by using a low-level encoding task, priming was the same for amnesic patients and control subjects. The authors suggest that LOP effects in word-completion priming tasks reflect the influence of explicit retrieval, which can be used usefully by control subjects but much less so by amnesic patients.