Relating perception and memory for a novel set of reconfigurable auditory stimuli: a noisy exemplar approach

While many real-life events are complex and temporally extended, most memory research employs discrete, static stimuli. We begin to bridge this gap by developing a set of novel auditory stimuli constructed by adjusting the distribution of power across upper frequency bands. Across three studies, participants rated similarity between pairs of these sounds and engaged in a recognition memory task. We applied non-metric multidimensional scaling to similarity ratings to obtain a three-dimensional psychological representation of the stimuli. The first dimension appeared to correspond to timbral roughness and the second to timbral brightness, while the third did not admit a simple verbal label. There were also individual differences in the degree to which participants attended to each of these dimensions, potentially as a function of musical expertise, as well as encoding strategy, and personality variables such as conscientiousness. The representation inferred from similarity ratings predicted recognition memory performance for single probe sounds following sequential presentation of two sounds, consistent with similarity-based exemplar models of memory. Recognition false alarms increased with subjective similarity between the probe and the first memory item but not the second, suggesting that the most recent sound was represented in a form that is less susceptible to incidental similarity. We also observed a list homogeneity effect: hits and false alarms decreased with similarity between studied sounds. We build on these results to discuss implications for the development of an integrated theory of perceptual similarity and recognition memory in the auditory domain using a novel computational model that extends on elements from the exemplar-based random walk (EBRW; Nosofsky & Palmeri, 1997b) model. Model fits to behavioral data from the similarity rating and recognition tasks provide preliminary evidence for this theory.