Investigating secondary-distinctiveness-based effects in aging and Alzheimer's disease patients.

The aim of the present study was 2-fold. First, two experiments were devised to further investigate secondary distinctiveness-based effects in relation to aging. By using a repeated study-test procedure, it aimed at restoring the bizarreness effect (Experiment 1) or at amplifying the orthographic distinctiveness (OD) effect in older adults (Experiment 2). Second, by including Alzheimer's disease patients (AD patients) in both experiments, it also aimed at instigating research on secondary distinctiveness-based effects in relation to Alzheimer disease. The results of Experiment 1 revealed that a repeated study-test procedure may to some extent facilitate the free recalling of bizarre images in older adults. However, the benefit of such procedure does not seem to be durable in older adults (no bizarreness effect for the last study-test cycle) and is inefficient in AD patients. Surprisingly, for both older adults and AD patients, results of Experiment 2 revealed a similar OD effect across all study-test cycles. The findings of both experiments were related to previous work suggesting that the bizarreness effect and the OD effect are mediated by different processing.