Visual interference can help and hinder memory: Measuring memory fidelity using a novel circular shape space

Previous work suggests that the similarity of distracting information differentially alters how memories are forgotten. Though these effects have been shown for color memory, it is unclear if they extend to other modalities such as shape. In a first experiment, we created the Validated Circular Shape Space (VCS space), the first perceptually uniform “Shape Wheel” whereby subjective similarity was empirically quantified by angular distance on a 2D circle. In a second experiment, we utilized VCS space to examine the impact of distractor similarity on shape memory. A converging set of mixture model and model-free analyses revealed that distractor similarity differentially impacted memory detail. Dissimilar distractors disrupted both fine- and coarse-grained information, rendering the memory inaccessible. In contrast, similar distractors disrupted fine-grained but increased the reliance on coarse-grained information, rendering the memory blurred. As these effects were consistent across domains for both color and shape, we suggest these findings provide converging evidence for a set of general principles regarding how the nature of distracting information impacts memory. More generally, VCS space can be used to not only quantify subjective similarity but to also quantify memory fidelity for shape, a currently underexplored feature type in memory experiments.