Abstract
While limitations on visual working memory (VWM) are well established, less is known about what it takes for stimuli to enter this precious space. Using dense displays adapted from the visual-search literature, it was recently demonstrated that stimulus saliency strongly influences VWM performance (Constant & Liesefeld, 2021, https://doi.org/10/gjk9jh). In the present work, we performed two EEG experiments (16 participants each) with similar tasks adapted for extracting lateralized event-related potentials to gain more insight into the cognitive mechanisms by which saliency affects VWM performance. Participants memorized the color of 3 tilted target bars (12°, 28° or 45°) presented in a dense array of colored vertical non-target bars for later recall. In Experiment 1, all targets of a given memory display shared the same tilt and were presented in the same visual hemifield. The N2pc was larger for more salient displays, potentially indicating enhanced attentional processing. We also observed a significant effect of saliency on the evoked lateralized theta power at the electrodes and time range of the N2pc. The CDA increased only marginally with saliency, potentially indicating relatively saliency-independent utilization of visual working memory storage. To reveal more complex dynamics , memory displays of Experiment 2 contained three targets, each with a different saliency level and including conditions with two targets presented on the midline (in order to isolate activity induced by a single lateralized target). Some interesting exploratory results were that, when in competition with more salient targets, the least salient target produced very little lateralized activity, maybe because it was not attended nor stored. We also found indication that the most salient target evoked a contralateral positivity (reminiscent of a Pd) after its N2pc. This could indicate that it needs to be attentionally suppressed in order to attend the next salient target.