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Leila Montaser-Kouhsari, Marisa Carrasco; Does visual short term memory vary as a function of visual field location. Journal of Vision 2007;7(9):851. doi: 10.1167/7.9.851.
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© ARVO (1962-2015); The Authors (2016-present)
Goal: It is known that visual performance differs across the visual field, even at isoeccentric locations. Performance is better at the horizontal than the vertical meridian, and is worse at the upper than the lower vertical meridian, a phenomenon referred to as vertical meridian asymmetry (Carrasco et al., 2001), which has a neural basis at the earliest stages of cortical visual processing (Liu et al., 2006). It is also known that performance in many visual tasks decays with delay. In this study we investigated whether visual short term memory (VSTM), as assessed by a spatial frequency judgment task, is affected by the location at which the stimuli appear.
Method: Eight observers performed a VSTM spatial frequency judgment at 4 different locations of the visual field (North, South, East and West). Each trial consisted of two intervals separated by either a short (1s) or a long (3s) delay. In each interval a vertical Gabor patch was presented at 6 deg of eccentricity for 100 ms. The test had a spatial frequency of either 6.5 or 7.5 cpd, and the probe had a spatial frequency of 7 cpd. Observers were asked to report which of the two Gabors, the former or the latter, had a higher spatial frequency.
Results: For all observers, performance was more accurate at short than long delays at all 4 locations. In addition, performance was equivalent at the East, West and South locations, and all three were superior to the North location in both the short and the long delays. These results indicate that visual short term memory varies as a function of the visual field location. The quality with which we encode information affects VSTM.
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