We present imaging and behavioral experiments, establishing that visual short-term memory (VSTM) load, similar to perceptual load (e.g. Macdonald and Lavie (2008), but opposite to task-unrelated verbal working memory load (see Konstantinou & Lavie, 2010), can reduce both detection sensitivity (d') and the related signal in V1 for peripheral stimuli presented during the memory delay. Participants in the fMRI scanner were required to maintain the color and position of a memory set (consisting of colored squares) and detect a contrast increment (CI) presented in one of the four quadrants during the delay. VSTM load was varied through the memory set size. Both the CI related stimulus-induced retinotopic V1 response and detection sensitivity were significantly reduced under the high (vs. low) load condition demonstrating a??VSTM load-induced blindnessa??. Moreover, a significant negative correlation between the magnitude of VSTM load effects on memory capacity (i.e. Cowan's K) and on detection sensitivity showed that the impact of VSTM load on detection sensitivity was reliably predicted by the extent to which VSTM was occupied. This trade-off between the estimated number of items held in VSTM and detection sensitivity further demonstrates shared resources between VSTM and conscious perception.
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