Why is there a left side underestimation in rod bisection?

Bradshaw, John L.; Nathan, Greg; Nettleton, Norman C.; Wilson, Lyn; Pierson, Jane

doi:10.1016/0028-3932(87)90067-4

Cited by 110 publications

(47 citation statements)

References 9 publications

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“…Indeed, leftward MI bias increased for trials starting on the left as compared with trials starting on the right. This is consistent with prior studies investigating the effects of directional scanning on line bisection, in which responses shifted toward the scanning startside (Bradshaw, Nathan, Nettleton, Wilson, & Pierson, 1987;Chokron, Bartolomeo, Perenin, Helft, & Imbert, 1998). An important consideration for the current study, however, is that the direction of scanning eye movements was dissociated from the direction of laser pointer movement in half of the trials.…”

Section: Discussionsupporting

confidence: 91%

Perceptual–attentional and motor-intentional bias in near and far space

Garza

Eslinger

Barrett

2008

Brain and Cognition

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Spatial bias demonstrated in tasks such as line-bisection may stem from perceptual-attentional (PA) "where" and motor-intentional (MI) "aiming" influences. We tested normal participants' line bisection performance in the presence of an asymmetric visual distracter with a video apparatus designed to dissociate PA from MI bias. An experimenter stood as a distractor to the left or right of a video monitor positioned in either near or far space, where participants viewed lines and a laser point they directed under 1) natural and 2) mirror-reversed conditions. Each trial started with the pointer positioned at either the top left or top right corner of the screen, and alternated thereafter. Data analysis indicated that participants made primarily PA leftward errors in near space, but not in far space. Furthermore, PA, but not MI, bias increased bilaterally in the direction of distraction. In contrast, MI, but not PA, bias was shifted bilaterally in the direction of startside. Results support the conclusion that a primarily PA left sided bias in near space is consistent with right hemisphere spatial attentional dominance. A bottom-up visual distractor specifically affected PA "where" spatial bias while top-down motor cuing influenced MI "aiming" bias.

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Section: Discussionsupporting

confidence: 91%

Perceptual–attentional and motor-intentional bias in near and far space

Garza

Eslinger

Barrett

2008

Brain and Cognition

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“…This advantage is proposed to be equivalent to the one enjoyed by left-sided items in a horizontal arrangement of visually or haptically presented stimuli [Bradshaw, Nathan, Nettleton, Wilson, & Pierson (1987): rod centering] and referred to, alternatively, as "initial exploration asymmetry" (Ebersbach et al, 1996;Hättig, 1992), "left-side underestimation" (Bradshaw, Nettleton, Nathan, & Wilson, 1983), "right hemispatial inattention" (Weintraub & Mesulam, 1988) or "pseudoneglect" (Bowers & Heilman, 1980). Pseudoneglect along the mental number line was originally demonstrated in the bisection of numerical intervals (Oliveri et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

Asymmetric prefrontal cortex functions predict asymmetries in number space

Bachmann

Fischer

Landolt

et al. 2010

Brain and Cognition

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Asymmetric prefrontal cortex functions predict asymmetries in number spaceBachmann, V; Fischer, M H; Landolt, H P; Brugger, P Bachmann, V; Fischer, M H; Landolt, H P; Brugger, P (2010 AbstractLittle is known about the neuropsychological factors that contribute to individual differences in the asymmetric orientation along the mental number line. The present study documents healthy subjects' preference for small numbers over large numbers in a random number generation task. This preference, referred to as "small number bias" (SNB), varied with prefrontal functional lateralization: it was larger in participants with over-proportionately better performance in design fluency compared to letter fluency than in participants with overproportionately better performance in letter fluency when compared to design fluency.Asymmetries in learning and memory tasks (verbal vs. non-verbal) were not related to direction or size of the SNB. We conclude that hemispheric asymmetries of specifically prefrontal executive functions are predictive of an individual's lateral orientation bias along the mental number line. Therefore, the focus on parietal contributions to spatial-numerical associations may not be justified. Random number generation may be a helpful method to further explore these associations uncontaminated by the asymmetric involvement of response effectors.

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“…No dierences were found between the left-to-right scan, the right-to-left scan, and a control condition in which subjects bisected lines without ®rst viewing them traced by the experimenter. Bradshaw et al [14] had subjects bisect a line by sliding it in a channel, with the subjects perceived line midpoint indicated by a stationary midpoint marker. In one condition subjects were asked to ®xate on the marker placed at line midpoint, while in the other condition subjects were allowed free visual scanning.…”

Section: Directional Scanningmentioning

confidence: 99%

“…Bradshaw et al [14] varied the salience of the rods which subjects bisected by using black or white rods on either matching backgrounds (i.e., black on black, low salience) or opposite backgrounds (i.e., white on black, high salience). Subjects erred to the left of veridical center across all experimental conditions, although when the left half of a rod was low in salience compared to the right, subjects erred farther to the left of veridical.…”

Section: Line Saliencementioning

confidence: 99%