Delayed visuomotor performance is not generally impaired in visual form agnosic patient DF C Hesse1, T Schenk2 |
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1School of Psychology, University of Aberdeen, United Kingdom |
| It was suggested that while movements directed at visible targets are processed within the dorsal stream, movements executed after delay rely on the visual representations of the ventral stream [Milner and Goodale, 2006, The Visual Brain in Action, Oxford, University Press]. This interpretation was supported by the observation that a patient with ventral stream damage (DF) has trouble performing accurate movements after a delay, but performs normally when the target is visible during movement programming. We tested DF’s visuomotor performance in a letter-posting task whilst varying the amount of visual feedback available. Additionally, we also varied whether DF received haptic feedback at the end of each trial (posting through a letter box vs. posting on a screen) and whether environmental cues were available during the delay period (removing the target only vs. suppressing vision completely with shutter glasses). We found that DF’s visuomotor performance was only impaired in conditions in which the target was removed from view while the surrounding environment remained visible. We suggest that in these conditions, healthy participants can resort to cues from the visual environment to compensate for the withdrawal of target information. These cues are allocentric in nature and therefore presumably not available to DF. |
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