Tasfia Ahsan¹ (), Laurie M. Wilcox¹, Erez Freud¹; ¹Department of Psychology, York University

Depth cues influence how we perceive and act upon objects, with near-space stimuli receiving prioritized processing. This prioritization of near space is reflected in the “close advantage effect” in perceptual and attentional processing, a phenomenon that occurs even when depth is defined only by pictorial cues. Some studies show that spatial memory can differ between near and far space, but it remains unknown whether perceived depth influences memory for visual objects. To assess this, we used the Mnemonic Similarity Task (MST) to examine whether perceived depth modulates memory fidelity. Participants viewed a series of objects, presented either on the near or far surface of the Ponzo illusion. They were not told they would be asked to do a recall task. In our first experiment, we kept object size constant, irrespective of position (near or far). Recognition accuracy, which serves as an indicator of familiarity-based memory, was significantly higher for items encoded on the close surface. However, lure discrimination (LDI), which reflects the ability of the hippocampus to separate similar items into distinct representations, did not vary with perceived depth. Thus, perceived proximity strengthens recognition without altering memory precision. Our second study evaluated whether this version of the close advantage reflected size-distance scaling, where an object perceived as nearer is interpreted as smaller than an identical object placed farther away. A size-matching pretest was performed to equate the perceived size of the stimuli presented on the close and far surfaces; then we repeated Experiment 1 using these equivalent-size stimuli. We found that the close-surface recognition advantage persisted, and again there was no change in LDI. Taken together, these findings show that perceived proximity enhances recognition memory even when size cues are controlled, consistent with privileged encoding of near-space stimuli. Follow-up studies probing the limits of this effect will also be discussed.

Acknowledgements: Natural Sciences Research Council of Canada (NSERC); CF-REF program Vision Sciences to Applications (VISTA)