Misprojection of landmarks onto the spatial map.
It has been suggested that neglect patients misrepresent the metric spatial relations along the horizontal axis (anisometry). The "fabric" of their internal spatial medium would be distorted in such a way that physically equal distances appear relatively shorter on the contralesional side (canonical anisometry). The case of GL, a 76-year-old lady with left neglect on visual search tasks, is presented. GL showed severe relative overestimation on the left (contralesional) side on two independent tasks evaluating the metrics of her internal representation. A qualitatively similar pattern was found in two out of 10 other neglect patients who performed the second task. This behavior cannot be accounted for by the canonical anisometry hypothesis. Nevertheless, GL produced a relative left overextension (underestimation) when trying to set the endpoints of a virtual line given its midpoint (Endpoints Task). An interpretation of these results is offered in terms of a misprojection of relevant landmarks onto the internal representation without assuming distortion of its "fabric."
Toraldo
Alessio
A
Cognitive Neuroscience Sector, International School for Advanced Studies, Trieste, Italy. alessio.toraldo@unipv.it
Reverberi
Carlo
C
D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D002545:Brain Ischemia / Q000150:complications / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality; D006423:Hemianopsia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010468:Perceptual Disorders / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D010775:Photic Stimulation; D013028:Space Perception; D013037:Spatial Behavior