20 years later: a second look on DF's motor behaviour
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Updated: May 26, 2026

Methods to Explore the Influence of Top-down Visual Processes on Motor Behavior
Published on: April 16, 2014
Marc Himmelbach1, Rebecca Boehme, Hans-Otto Karnath
1Center of Neurology, Division of Neuropsychology, Hertie-Institute for Clinical Brain Research, Eberhard Karls University, Hoppe-Seyler-Str. 3, 72076 Tübingen, Germany. marc.himmelbach@uni-tuebingen.de
Abstract:
The so-called action vs. perception model represents one of the currently dominating models addressing visual processing in primates. One of the crucial cornerstones of the action vs. perception model of visual processing is the dissociation of impaired perception versus intact visuomotor control in neurological patients with visual form agnosia (VFA). In fact, virtually all evidence related to VFA supporting the model was reported from only one patient: patient D.F. Through the last two decades D.F. became as important as only very few other exemplar cases in the neurosciences. However, a large corpus of experiments with this individual used methods that were insufficient to reveal less obvious impairments on a single subject level. We reanalysed the data of D.F. and identified basic visuomotor impairments that had been overlooked so far. Our reanalysis underlines the fact that the widespread and popular presentation of strong dissociations between distinct visual systems seems to be exaggerated.
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