The Influence of Unimanual Response on Pseudoneglect Magnitude

McCourt, Mark E.; Freeman, Pierre; Tahmahkera-Stevens, Cindi; Chaussee, Matthew

doi:10.1006/brcg.2000.1255

Cited by 64 publications

(52 citation statements)

References 67 publications

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“…The trend for greater leftward errors of control subjects when making bisections using the left hand, while not achieving statistical significance in the present study, is also congruent with previous literature (McCourt et al, 2001a).…”

Section: Discussionsupporting

confidence: 92%

“…The mean leftward bisection error of the control group (−0.155°; 1.2% line length) is comparable to that reported in numerous previous studies using the forced-choice tachistoscopic line bisection procedure (Foxe et al, 2003;McCourt & Jewell, 1999;McCourt, 2001;McCourt et al, , 2001aMcCourt et al, , 2001bMcCourt et al, , 2005, and replicates the nearly universal finding that neurologically normal observers exhibit a modest, yet significant and systematic, leftward error on line bisection tasks, i.e., pseudoneglect; see Jewell & McCourt (2000), for a meta-analytic treatment and review of this literature. The trend for greater leftward errors of control subjects when making bisections using the left hand, while not achieving statistical significance in the present study, is also congruent with previous literature (McCourt et al, 2001a).…”

Section: Discussionsupporting

confidence: 85%

“…A second noteworthy and novel finding is that, whereas control subjects evince a highly significant correlation between bisection errors committed using the two hands (see also McCourt et al, 2001a), the patient sample exhibits a remarkable lack of intermanual correlation. This finding is intriguing since, in addition to the cited evidence that schizophrenia involves alterations of normal cerebral laterality, there is a growing consensus that patients with schizophrenia manifest structural and/or functional deficits of the corpus callosum (Barnett, 2006;Green, 1978;Mohr et al, 2000;Woodruff et al, 1995).…”

Section: Discussionmentioning

confidence: 92%

“…There is a significant correlation between bisection errors made using the right-and left-hands for controls, r(19) = 0.46, p = 0.041, whereas this correlation is nonsignificant for patients, r(33) = 0.15, p = 0.409. Because the number of control subjects tested in the current study is modest, panel (c) plots right-versus left-hand bisection judgments obtained from a large group (N=184) of control subjects from a previously published study (McCourt et al, 2001a) which utilized a nearly identical methodology. The degree of consistency between bisections executed with the two hands in this larger control group is highly significant, r(183) = 0.76, p < .001, in agreement with results from the current control group, but in stark contrast to the uncorrelated hand-related bisections exhibited by patients.…”

Section: Resultsmentioning

confidence: 99%

“…It should be noted that all of the previous studies utilized method-of-adjustment manual line bisection procedures which require subjects to make gross motor gestures using the hand and arm, and allow for unlimited oculomotor scanning of the line stimuli. Oculomotor or limb scanning is a significant contributor to bisection error, as disclosed by a recent meta-analysis (Jewell & McCourt, 2000), and unilateral motor activity has also been shown to significantly affect bisection error (McCourt et al, 2001a). When gross motor activation is minimized, and scanning eye movements are disallowed by tachistoscopic presentation, the effect size (Cohen's d-statistic; Cooper & Hedges, 1994) of pseudoneglect is tripled relative to that found using manual line bisection procedures (d = −1.32 versus −0.40, respectively; Jewell & McCourt, 2000).…”

Section: Line Bisection In Patients With Schizophreniamentioning

confidence: 99%

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Hemispheric asymmetry and callosal integration of visuospatial attention in schizophrenia: A tachistoscopic line bisection study

McCourt¹,

Shpaner²,

Javitt³

et al. 2008

Schizophrenia Research

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Background-A hallmark of visuospatial neglect syndrome is that patients with lesions to right parietal cortex misbisect horizontal lines far rightward of veridical center. Neurologically normal subjects misbisect lines with a systematic leftward bias (pseudoneglect). Both phenomena, as well as neuroimaging studies, disclose a predominant right hemisphere control of spatial attention. Numerous studies of patients with schizophrenia have implicated global deficits of either right or left hemisphere function, as well as compromised integrity of the corpus callosum.Methods-To better understand the functional implications of schizophrenia we utilized a forcedchoice tachistoscopic line bisection task to probe the status of right hemisphere control of spatial attention, and compared left-versus right-hand unimanual responses to index the degree of callosal transfer of visuospatial information in both patient and control groups.Results-In contrast to the significant leftward bisection errors of control subjects, patients exhibit no significant leftward error. Whereas control subjects evince a significant correlation between leftand right-hand bisection errors, patients lack a significant intermanual correlation.Conclusions-The lack of significant leftward bisection error of patients implies a deficit of right hemisphere function. The lack of a significant correlation between left-and right-hand bisection errors in patients implies a loss of callosal integrity.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Line Bisection In Patients With Schizophreniamentioning

confidence: 99%

See 3 more Smart Citations

Hemispheric asymmetry and callosal integration of visuospatial attention in schizophrenia: A tachistoscopic line bisection study

McCourt¹,

Shpaner²,

Javitt³

et al. 2008

Schizophrenia Research

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Time-on-task effect in pseudoneglect

2006

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Neurologically normal subjects systematically misbisect space during visual line-bisection or similar tasks, generally erring to the left of the veridical center when bisecting horizontal lines, a phenomenon referred to as pseudoneglect. This phenomenon is usually interpreted as enhanced attention toward the left hemispace resulting in an overestimation of the leftward extent of a line. While most studies have examined the role of attention in spatial bias using spatial cueing methods in bisection tasks, Manly et al. (Neuropsychologia 43(12):1721-1728, 2005) proposed an original paradigm in which the participants' alertness was diminished by sleep deprivation or prolonged execution of a line-bisection task. The authors reported a significant rightward shift in attention related to declining alertness, but they did not control eye movements and, consequently, modifications of scanning and fixation strategies with fatigue cannot be ruled out in their study. Here we examine whether a diminution in alertness induced by a 60-min-long Landmark task would diminish (or even reverse) this attentional bias, when eye movements are absent. Participants performed a forced-choice judgment about the location of a transaction mark in relation to the veridical center of a horizontal line. The results confirmed a significant decrease in the leftward bias over the course of the session but, in contrast to the findings of Manly et al. (2005), we did not observe a reverse bias from the left to the right hemispace. The results are discussed within the context of the hemisphere-activation model.

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“Graspability” of objects affects gaze patterns during perception and action tasks

Desanghere

Marotta

2011

Exp Brain Res

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When grasping an object, our gaze marks key positions to which the fingertips are directed. In contrast, eye fixations during perceptual tasks are typically concentrated on an object's centre of mass (COM). However, previous studies have typically required subjects to either grasp the object at predetermined sites or just look at computer-generated shapes "as a whole". In the current study, we investigated gaze fixations during a reaching and grasping task to symmetrical objects and compared these fixations with those made during a perceptual size estimation task using real (Experiment 1) and computer-generated objects (Experiment 2). Our results demonstrated similar gaze patterns in both perception and action to real objects. Participants first fixated a location towards the top edge of the object, consistent with index finger location during grasping, followed by a subsequent fixation towards the object's COM. In contrast, during the perceptual task to computer-generated objects, an opposite pattern in fixation locations was observed, where first fixations were closer to the COM, followed by a subsequent fixation towards the top edge. Even though differential fixation patterns were observed between studies, the area in which these fixations occurred, between the centre of the object and top edge, was the same in all tasks. These results demonstrate for the first time consistencies in fixation locations across both perception and action tasks, particularly when the same type of information (e.g. object size) is important for the completion of both tasks, with fixation locations increasing relative to the object's COM with increases in block height.

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The Influence of Unimanual Response on Pseudoneglect Magnitude

Cited by 64 publications

References 67 publications

Hemispheric asymmetry and callosal integration of visuospatial attention in schizophrenia: A tachistoscopic line bisection study

Hemispheric asymmetry and callosal integration of visuospatial attention in schizophrenia: A tachistoscopic line bisection study

Time-on-task effect in pseudoneglect

“Graspability” of objects affects gaze patterns during perception and action tasks

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