Perceptual Load Modulates the Effect of Lightness/Pitch Correspondence on Visual Working Memory Performance

Prior studies demonstrate that cross-modal correspondence, the seemingly arbitrary association of features across different sensory modalities, enhances working memory performance. Incongruent background noise has also been shown to aid visual working memory. The current study builds on these premises to investigate the effect of lightness/pitch audiovisual correspondence on visual working memory. We designed a black-and-white orientation change detection task, where the visual stimuli were paired with high- and low-pitched sounds. We compared change-detection performance in conditions with audiovisual correspondence with performance under non-corresponding and visual-only conditions. Additionally, we explored the impact of perceptual load, the stage of memory processing during which audiovisual correspondence is displayed, and the direction of attention to the auditory modality. We found that, in the lightness/pitch domain, cross-modal correspondence does not automatically enhance visual working memory accuracy and reaction time; instead, the salience of the effect is moderated by perceptual load. Lightness/pitch correspondence improved performance only under high perceptual load, with the effect being strongest when corresponding stimuli were displayed during both memory encoding and recall. In contrast, under conditions of low perceptual load, the mere presence of auditory pitch, irrespective of cross-modal correspondence, improved performance, likely by increasing alertness. The study demonstrates that lightness/pitch correspondence does not depend on conscious selective attention and suggests that cross-modal correspondence may serve a functional role beyond sensory integration. We frame our interpretation considering Bayesian theory with the cognitive system relying more heavily on statistical learning principles under high perceptual demands.