Hemispatial neglect affected by non‐neglected stimuli

Mark, Victor W.; Kooistra, Carol A.; Heilman, Kenneth M.

doi:10.1212/wnl.38.8.1207

Cited by 247 publications

(120 citation statements)

References 3 publications

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“…It has been repeatedly demonstrated that patients do not simply neglect left objects, but are attracted by right ones. In an ingenious variant of the line cancellation task, Mark et al [86] had 10 patients with left neglect erase lines or draw over them with a pencil mark, and found lesser neglect in the`erase' than in the`draw' condition. Mark et al concluded that right-sided lines attracted patients' attention when they were crossed by a pencil mark, whereas rendering these lines invisible by erasing them obviously nulli®ed this effect, thus decreasing neglect.…”

Section: A Rightward Attentional Bias In Left Neglectmentioning

confidence: 99%

Orienting of attention in left unilateral neglect

Bartolomeo

Chokron

2002

Neuroscience & Biobehavioral Reviews

284

137

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After right posterior brain damage, patients may ignore events occurring on their left, a condition known as unilateral neglect. Although de®cits at different levels of impairment may be at work in different patients, the frequency and severity of attentional problems in neglect patients have been repeatedly underlined. Recent advances in the knowledge of the mechanisms of spatial attention in normals may help characterizing these de®cits. The present review focuses on studies exploring several aspect of attentional processing in unilateral neglect, with particular reference to the dichotomy between`exogenous', or stimulus-related, and`endogenous', or strategy-driven, orienting of attention. A large amount of neuropsychological evidence suggests that a basic mechanism leading to left neglect behavior is an impaired exogenous orienting toward left-sided targets. In contrast, endogenous processes seem to be relatively preserved, if slowed, in left unilateral neglect. Other component de®cits, such as a general slowing of the operations of spatial attention, might contribute to neglect behavior. These results are presented and discussed, and their implications for hemispheric specialization in attentional orienting and for the mechanisms of visual consciousness are explored. q

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Section: A Rightward Attentional Bias In Left Neglectmentioning

confidence: 99%

Orienting of attention in left unilateral neglect

Bartolomeo

Chokron

2002

Neuroscience & Biobehavioral Reviews

284

137

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“…However, the location of omissions can change as a function of starting position (Robertson & North, 1993) and search strategy (Chatterjee et al, 1992b). The number of omissions can change as a function of demands on selective attention (Rapcsak et al, 1989), the presence and location of distracting stimuli (Kaplan et al, 1991), and the method of cancellation (Ishiai et al, 1990;Mark et al, 1988;Robertson & North, 1993). In addition, Chatterjee et al (1992a,b,c) demonstrated a stimulus-response relationship on cancellation tests in neglect such that a greater proportion of target stimuli are omitted as the total number of cancellation items increases.…”

Section: Introductionmentioning

confidence: 99%

A Search for the Optimal Stimulus

Mennemeier

Rapcsak

Dillon

et al. 1998

Brain and Cognition

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How do stimulus size and item number relate to the magnitude and direction of error on center estimation and line cancellation tests? How might this relationship inform theories concerning spatial neglect? These questions were addressed by testing twenty patients with right hemisphere lesions, eleven with left hemisphere lesions and eleven normal control subjects on multiple versions of center estimation and line cancellation tests. Patients who made large errors on these tests also demonstrated an optimal or pivotal stimulus value, i.e., a particular size center estimation test or number of lines on cancellation that either minimized error magnitude relative to other size stimuli (optimal) or marked the boundary between normal and abnormal performance (pivotal). Patients with right hemisphere lesions made increasingly greater errors on the center estimation test as stimuli were both larger and smaller than the optimal value, whereas those with left hemisphere lesions made greater errors as stimuli were smaller than a pivotal value. In normal subjects, the direction of errors on center estimation stimuli shifted from the right of true center to the left as stimuli decreased in size (i.e., the crossover effect). Right hemisphere lesions exaggerated this effect, whereas left hemisphere lesions diminished and possibly reversed the direction of crossover. Error direction did not change as a function of stimulus value on cancellation tests. The demonstration of optimal and pivotal stimulus values indicates that performances on center estimation and cancellation tests in neglect are only relative to the stimuli used. In light of other studies, our findings indicate that patients with spatial neglect grossly overestimate the size of small stimuli and underestimate the size of large stimuli, that crossover represents an "apparent" shift in error direction that actually results from normally occurring errors in size perception, and that the left hemisphere is specialized for one aspect of size estimation, whereas the right performs dual roles.

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“…Mark et al (1988) required neglect patients to draw on targets scattered on a sheet with a pencil mark or to erase them, found more left omission in the 'draw' than in the 'erase' condition, and concluded that right-sided (cancelled) targets continued to attract patients' attention, thereby increasing left neglect. In a Posner-type reaction time paradigm (see Posner, Walker, Friedrich, & Rafal, 1984), D'Erme, Robertson, Bartolomeo, Daniele, and Gainotti (1992) found slower responses to left-sided targets when targets occurred in one of two bilateral boxes than when they occurred without boxes, as if the right-sided box again attracted patient's attention.…”

Section: Discussionmentioning

confidence: 99%

“…Per contra, some attentional accounts of neglect (e.g. Gainotti et al, 1991;Kinsbourne, 1993) have stressed that right-sided items are likely to attract patients' attention; the more objects presented on the 'unaffected' side, the greater the neglect (Mark, Kooistra, & Heilman, 1988). In the present study, the aim was to explore the effect of the presence or absence of such competing stimuli on a task similar to that employed by Halligan and Marshall (1991), in the expectation that this additional experimental condition would help elucidate the effects of any attentional deficit.…”

Section: Introductionmentioning

confidence: 99%

Neglected attention in apparent spatial compression

et al. 2004

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Halligan and Marshall [Cortex 27 (1991) 623] devised a new test to evaluate the hypothesis that in visual neglect, left space is systematically compressed rightwards. In the critical condition of the original study, rows of horizontally arranged numbers with a target arrow pointing to one of them from the opposite margin of the display were presented. When asked to verbally identify the number indicated by the arrow, a right brain-damaged patient with left neglect and hemianopia often indicated a number to the right of the target. The more the target was located on the left, the greater the response shift rightward, as if rightward compression were linearly proportional to the co-ordinates of Euclidian space. However, a possible alternative account could be that the patient's attention was attracted by the numbers located to the right of the target digit, thus biasing her responses toward numbers on the right. To explore this hypothesis, we asked normal participants and patients with right hemisphere lesions, with and without neglect or hemianopia, to mark on the margin of a sheet the approximate location indicated by an arrow situated on the opposite margin. In three different conditions, the arrow indicated either one of several numbers or lines in a row, or a blank location on the sheet margin. Only patients with left neglect, and especially those with associated hemianopia, deviated rightward, and then crucially only on those conditions where visible targets were present, consistent with the attentional bias account.

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Hemispatial neglect affected by non‐neglected stimuli

Cited by 247 publications

References 3 publications

Orienting of attention in left unilateral neglect

Orienting of attention in left unilateral neglect

A Search for the Optimal Stimulus

Neglected attention in apparent spatial compression

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