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David C Cappadocia, Denise YP Henriques; The effect of gaze shifts, pointing, and saccadic adaptation on the relative position judgments of a remembered object. Journal of Vision 2009;9(8):1097. doi: 10.1167/9.8.1097.
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© ARVO (1962-2015); The Authors (2016-present)
Henriques et al. (1998) showed that people re-map the location of an object with respect to gaze when pointing to its remembered location. In this study, we wanted to see if people's representation of the relative location of a remembered object also re-maps with respect to gaze. We also investigated the effect of pointing and saccadic adaption on relative location judgments following a gaze shift. METHOD: Head-fixed subjects in a dark room indicated the location of a previously displayed object (a vertical bar) relative to a second bar. This was done with gaze fixed 5°–15° horizontally from the first bar, or after the first bar was foveated followed by a 5°–15° horizontal gaze shift. In the pointing conditions, subjects pointed to the first bar following the gaze shift, and then judged its remembered location relative to a second bar. In the saccadic adaption condition, following a training session subjects performed saccades that were approximately 25% hypometric. RESULTS: When gaze was fixed, people judged the remembered bar as being closer to the fovea. When subjects shift their gaze after viewing the first bar, however, there was no such bias, i.e., they were accurate. Pointing affected the relative position judgment in the gaze-shifted condition by introducing a similar bias to the fovea. Saccadic adaptation did not significantly alter localization, but there was a trend in the direction of adaptation. CONCLUSIONS: Our results suggest that the brain does not update with respect to gaze for perceptual judgments following an eye movement. Likewise, saccadic adaptation does not significantly affect perceptual localization. However, pointing did affect perceptual localization following an eye movement, suggesting that perception of the object's relative location may have been re-mapped when accompanied by a simultaneous action.
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