Early Ipsilateral Orienting of Attention in Patients with Contralateral Neglect

Three experiments were carried out to investigate whether early orienting of attention to the side of space ipsilateral to the lesion could mediate unilateral spatial neglect. The first was designed to evaluate forms of lateral orienting of attention so severe as to provoke an overt gaze deviation; this was achieved by assessing systematically the phenomenon of “magnetic gaze attraction”. The second investigation evaluated milder forms of automatic orienting of attention by analysing the temporal sequence followed by patients in identifying the pictures of an overlapping figures task: A tendency to initiate the scanning of the pattern from the half space ipsilateral to the lesion was predicted in neglect patients. The third investigation tested whether the ipsilateral orienting of attention would be observed also in conditions requiring central eye fixation. Simple reaction times were recorded in contrasting conditions with and without positional expectancy square “boxes”: The ipsilesional box was predicted to attract the patients’ attention, increasing reaction times to contralesional targets. The results showed that: 1. right brain-damaged patients tend automatically to orient attention toward the ipsilesional half space more than left brain-damaged patients; 2. this tendency is tightly linked to the presence of behavioural manifestations of neglect; 3. the early rightwards orienting of attention can be observed both in tasks requiring central eye fixation and in tasks where no such constraint is given, provided that stimuli (not necessarily targets) coexist on both sides of space. 206 Our data are consistent with the hypothesis viewing unilateral spatial neglect as a multi-component syndrome with one characteristic being early orienting of attention toward the half space ipsilateral to the lesion.