The Features Underlying the Memorability of Objects

Despite decades of study of memory, it remains unclear what makes an image memorable. There is considerable debate surrounding the underlying determinants of memory, including the roles of semantic (e.g., animacy, utility) and visual features (e.g., brightness) as well as whether the most prototypical or most atypical items are best remembered. Prior studies have relied on constrained stimulus sets, limiting any generalized view of the features that may contribute to memory. Here, we collected over one million memory ratings (N=13,946) for THINGS (Hebart et al., 2019), a naturalistic dataset of 26,107 object images designed to comprehensively sample concrete objects. First, we establish a model of object features that is predictive of image memorability, capturing over half of the explainable variance. For this model, we find that semantic features have a stronger influence than visual features on what people will remember. Second, we examined whether memorability could be accounted for by the typicality of the objects, by comparing human behavioral data, object feature dimensions, and deep neural network features. While prototypical objects tend to be the most memorable, the relationship between memorability and typicality is more complex than a simple positive or negative association and typicality alone cannot account for memorability. SIGNIFICANCE STATEMENT Why is it that we seem to remember and forget the same things? Our lived experiences differ, but there is remarkable consistency in what is remembered across people. Here, we collected memory performance scores for a comprehensive and diverse collection of natural object images to identify which properties determine our ability to remember. We created a model for predicting memory from object features showing that semantic properties more than visual properties contribute primarily to memorability. Further, we find that it is neither the most prototypical or atypical images that are best remembered, which suggests that typicality alone cannot account for memorability. Our findings challenge decades of prior research that suggest that the most atypical items are most memorable, informing our understanding of the features and organizational principles of memory.