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Visual perception and saccadic eye-movements are more precise when directed at isoeccentric locations along the horizontal compared to vertical meridian. This effect is known as horizontal-vertical anisotropy (HVA). Given that the eye-movement system plays an important role in spatial short-term memory (STM) it was hypothesized that spatial STM would also show a horizontal-vertical anisotropy. Consistent with this hypothesis an online experiment revealed a significant HVA in spatial STM (Experiment 1). This effect persisted even when eye-movements were precluded by using very short display durations (Experiment 2). However, there was no HVA in a colour span or orientation change detection task. It is argued that the HVA in spatial STM may result from greater imprecision in the representation of spatial locations along the vertical meridian relative to the horizontal meridian in the spatial maps underpinning spatial STM, a bilateral field advantage, or some combination of these mechanisms. [ABSTRACT FROM AUTHOR]

Visual perception can be influenced by the content of working memory. Previous studies have shown this influence can be enough to improve unconscious visual discrimination in healthy participants and conscious visual discrimination in neuropsychological patients with extinction. Here, these findings are extended by examining the effects of holding an object in working memory on unconscious visual perception in a person with hemianopia. The results revealed significantly enhanced detection accuracy when there was an exact match between the colour and orientation of the discrimination target and the item in working memory. However, the facilitatory effect was greatly reduced when only colour or orientation was matched with the item being held in memory. A control experiment confirmed these effects were not due to visual priming. These results are consistent with the proposal that working memory guided perceptual facilitation is driven by signal enhancement. More broadly, the data are interpreted in terms of a biased competition account of visual perception. [ABSTRACT FROM AUTHOR]