Visual information about object size and object position are retained differently in the visual brain: Evidence from grasping studies. (October 2016)

• Record Type: Journal Article
• Authors: Hesse, Constanze; Miller, Louisa; Buckingham, Gavin
• Is Part Of: Neuropsychologia. Volume 91(2016)
• Page Start: 531
• Page End: 543
• Publication Date: 2016-10
• Subjects: Perception -- Action -- Delay -- Grip forces -- Visual memory -- Dorsal-ventral; Neuropsychology -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Neuropsychologie -- Périodiques; Neuropsychology; Periodicals; Electronic journals; 616.8
• DOI: 10.1016/j.neuropsychologia.2016.09.016
• Languages: English
• ISSNs: 0028-3932

Abstract

Abstract: Many experiments have examined how the visual information used for action control is represented in our brain, and whether or not visually-guided and memory-guided hand movements rely on dissociable visual representations that are processed in different brain areas (dorsal vs. ventral). However, little is known about how these representations decay over longer time periods and whether or not different visual properties are retained in a similar fashion. In three experiments we investigated how information about object size and object position affect grasping as visual memory demands increase. We found that position information decayed rapidly with increasing delays between viewing the object and initiating subsequent actions – impacting both the accuracy of the transport component (lower end-point accuracy) and the grasp component (larger grip apertures) of the movement. In contrast, grip apertures and fingertip forces remained well-adjusted to target size in conditions in which positional information was either irrelevant or provided, regardless of delay, indicating that object size is encoded in a more stable manner than object position. The findings provide evidence that different grasp-relevant properties are encoded differently by the visual system. Furthermore, we argue that caution is required when making inferences about object size representations based on alterations in the grip component as these variations are confounded with the accuracy with which object position is represented. Instead fingertip forces seem to provide a reliable and confound-free measure to assess internal size estimations in conditions of increased visual uncertainty. Highlights: Object size and object position are encoded differently in the visual brain. Visual representations of object location decay rapidly. Visual representation of object size are comparatively stable. Memory demands change the grasp component due to localisation uncertainty. Grip forces may be a more reliable indicator for remembered size than grip aperture.