Neglect without extinction

A patient, AB, is reported who showed clear signs of neglect but no extinct ion (N+ E-). Several hypotheses proposed to account for this dissociation w ere put to the test. The postulated association between motor neglect and e xtinction did not hold good, nor did the possibility that the N+ E- dissoci ation may be traced back to the difference in test requirements and therefo re observed only in patients with object-centred neglect. Likewise, manipul ating the physical features of the stimuli (relative size, exposure time, p resentation synchrony) did not elicit extinction. However, when the task de mands were modified by asking the patient to perform a further spatial anal ysis of the stimuli, rather than simply detect them, extinction emerged. Si nce AB performed well on several neglect tasks requiring parallel processin g, while failing all tasks calling for Serial processing, the hypothesis is put forward that AB's N+ E- dissociation could be interpreted within the p arallel/serial distinction framework.