Left of what? The role of egocentric coordinates in neglect
- aUSL 2, Unità Operativa di Gallarate, Ospedale Bellini, Somma Lombardo (Va), Italy, bDipartimento di Psicologia dello Sviluppo e della Socializzazione, Universita’ di Padova, Italy, cNeuropsychology Research Division, Department of Psychology, University of Aberdeen, UK
- Professor S Della Sala, Department of Psychology, University of Aberdeen, Kings College, Aberdeen AB24 2UB, UK.
- Received 30 October 1996
- Revised 7 April 1997
- Accepted 8 April 1997
Abstract
OBJECTIVES Egocentric coordinate systems centred on the trunk, head, and gaze have been investigated in a patient who displays severe extrapersonal neglect and in five control subjects.
METHODS The subjects were tested with a blind tactile exploration task in five different experimental conditions in which the role of the three distinct frames of reference was individually controlled.
RESULTS Only the trunk centred coordinates significantly influenced the performance of the patient, therefore proving of paramount importance in determining the boundaries of the neglected field. Similar results emerged from a single word reading task, in which the patient’s performance improved when the stimuli were presented to the right of his body’s midline.
CONCLUSION These findings point to the importance of the body centred coordinate system in determining the area of extrapersonal spatial neglect.
