Conditions of visual verbal extinction: does the ipsilesional stimulus have to be identified?
Six left-neglect patients were presented with four-letter words in the left and/or right hemifield, in different contextual conditions: unilateral, bilateral-x in which one word appears on one side and a string of "x" appears on the other side (the side of "x'' was not predictable), and bilateral-word (presentation of one word in each hemifield). In Experiment 1, left extinction occurred even if the right stimulus was an easily discriminable string of "x." Experiment 2 showed that increasing the size of the left stimuli reduced extinction when a string of "x" was presented on the right hemifield. However, extinction was stronger with bilateral-word presentation. These results indicate the presence of an early component in the extinction phenomenon, i.e., a "magnetic" attraction toward the ipsilesional hemifield, but are also in favor of some additional deficit, at a later stage of information processing.
Siéroff
Eric
E
Laboratoire de Psychologie Expérimentale, CNRS UMR 8581, Université René Descartes Paris V, Institut de Psychologie, Boulogne-Billancourt, France.
Urbanski
Marika
M
D001921:Brain / Q000503:physiopathology; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D010468:Perceptual Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D014794:Visual Fields / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*