Impact of the number of alternatives in a forced choice recognition memory task on performance in normal aging

Forced-choice recognition memory tasks are often used to test visual episodic memory, notably to assess the effect of age on memory performance. However, no study has examined the impact of the number of alternatives on memory performance. In this experiment, we evaluated whether memory performance of young and older participants is influenced by, on the one hand, the number of proposed alternatives - two or three - and on the other hand the degree of similarity between the target and its lures. The study included 48 young participants and 43 healthy older participants. During the encoding phase, they saw 36 photographs of faces twice. During the recognition task, we asked them to choose the previously presented face among two or three photographs. Half of the target-lure sets were more similar than the other half (60% of common characteristics versus 40%). After the memory task, participants completed the Cambridge Face Perception Test to measure their capacity of perception and processing of faces. The analysis of correct recognition responses (ANOVA 2 (groups) x 2 (alternatives) x 2 (similarity) with repeated measures on the last two variables) showed that older adults had poorer performance than young adults and an effect of the degree of similarity but no effect of the number of alternatives. Interestingly, the age effect on recognition performance disappeared when controlling for face perception abilities. Thus, part of the difficulties in visual recognition memory for faces of older participants could be underpinned by weak perceptual capacities.