Eye-fixation patterns in homonymous hemianopia and unilateral spatial neglect

Impaired visual search in patients with unilateral neglect: an oculographic analysis

“…This is reflected in the higher proportion of fixations and longer durations in the far-left quartile band and the tendency to look even beyond the boundaries of the left boundary of the board. These findings conform well with the data reported previously for hemianopic patients on similar types of tasks [30,51,67].…”

“…Because the pattern of eye movements is often taken as a robust and transparent index of the distribution of attention [19,27,44,45], we might gain insight into the nature of the attentional deficit underlying the visuospatial behavior of these patients through a detailed oculographic analysis. While deficits in eye movement pattern have been documented previously in patients with brain damage and visuospatial deficits (e.g., [9,16,20,30]), there has been little consideration of what gives rise to the observed deficit. To this end, we compared the behavioral report and the eye movement performance of normal subjects, hemianopic patients without neglect and a relatively large group of patients with hemispatial neglect during search for a predefined target in a random visual search display.…”

Fast responses to neglected targets in visual search reflect pre-attentive processes: an exploration of response times in visual neglect

“…The outcome would then necessarily be a premature conclusion about the absence of the target. This account seems to us highly consistent with well-known aspects of the phenomenology of neglect, like the presence of ineffective attentional and ocular shifts or "hypodirectionality" of movement [8,12,[40][41][42][43]71] or the inability to "disengage" from a previous stimulus that is right-sided in relation to a left-sided target [65,66]. In the former case, searches may be based on incorrect information or in the latter cases simply aborted.…”

“…The attention window may not move away from a currently attended location [53] or a shift could be quickly aborted or be guided by incomplete, weakened, or biased spatial information so as to undershoot the target's position (cf. [8,40,41]). Because we assume that a present target is acknowledged as such only when the attributes stored in the target template's representation and the content of the attention window match, all of the above forms of impairment would result in AE giving fast responses to present targets while at the same time not acknowledging their presence.…”

A non-spatial bias favouring fixated stimuli revealed in patients with spatial neglect

“…Since the planning of eye movements is closely linked to spatial attention (Shepherd et al, 1986), saccadic eye movements of neglect patients should be particularly affected by their spatial orienting bias. Indeed, neglect patients show a strong tendency to direct their first saccade ipsilesionally when exploring a visual scene (Behrmann et al, 1997;Pflugshaupt et al, 2004) and spend more time looking at details located in the right half of the scene (Ishiai et al, 1987;Hornak, 1992;Behrmann et al, 1997;, often re-fixating the same ipsilesional items (Husain et al, 2001;Mannan et al, 2005). In spatial search tasks, ocular fixations and exploratory hand movements of neglect patients show a very similar rightward bias, suggesting that-irrespective of output modality-orienting responses of neglect patients are biased by the same mechanism favouring ipsilesional items (Karnath and Perenin, 1998;Schindler et al, 2006).…”