Prism adaptation changes perceptual awareness for chimeric visual objects but not for chimeric faces in spatial neglect after right-hemisphere stroke
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Updated: Aug 7, 2026

Virtual Prism Adaptation Therapy: Protocol for Validation in Healthy Adults
Published on: February 12, 2020
Margarita Sarri1, Lalit Kalra, Richard Greenwood
1Institute of Cognitive Neuroscience and Department of Psychology, University College London, London, UK. m.sarri@ucl.ac.uk
Abstract:
Prism adaptation can ameliorate some symptoms of left spatial neglect after right-hemisphere stroke. The mechanisms behind this remain unclear. Prism therapy may increase exploration towards the contralesional side, yet without improving perceptual awareness, as apparently for the left side of chimeric face stimuli (Ferber et al. 2003). However, other prism studies suggest that perceptual awareness might be improved (e.g., Maravita et al., 2003). We tested the impact of prism therapy on visual awareness for the left side of chimeric objects as well as chimeric faces, in three neglect patients. Prism therapy dramatically improved awareness for the identity of the left side of chimeric non-face objects, but had no effect on judging expressions for chimeric faces. The latter may thus be unique in showing no prism benefit.
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