Attentional asymmetries in a visual orienting task are related to temperament

Spatial asymmetries are an intriguing feature of directed attention. Recent observations indicate an influence of temperament upon the direction of these asymmetries. It is unknown whether this influence generalises to visual orienting behaviour. The aim of the current study was therefore to explore the relationship between temperament and measures of spatial orienting as a function of target hemifield. An exogenous cueing task was administered to 92 healthy participants. Temperament was assessed using Carver and White's (1994) Behavioural Inhibition System and Behavioural Activation System (BIS/BAS) scales. Individuals with high sensitivity to punishment and low sensitivity to reward showed a leftward asymmetry of directed attention when there was no informative spatial cue provided. This asymmetry was not present when targets were preceded by spatial cues that were either valid or invalid. The findings support the notion that individual variations in temperament influence spatial asymmetries in visual orienting, but only when lateral targets are preceded by a non-directional (neutral) cue. The results are discussed in terms of hemispheric asymmetries and dopamine activity.     

Vertical representational biases in healthy university students

In line bisection tasks neurologically intact individuals tend to bisect lines slightly left of their midpoint for horizontal lines, and above centre for vertical lines, a phenomenon known as perceptual pseudoneglect (Bowers & Heilman, 1980; Van Vugt, Fransen, Creten, & Paquiner, 2000). Recent investigations have demonstrated the leftward bias to extend to mental imagery, a finding known as representational pseudoneglect (McGeorge, Beschin, Colnaghi, Rusconi, & Della Sala, 2007). This paper examined whether the upward bias found in perceptual tasks extended to mental imagery in healthy individuals. University students studied a diagram depicting a central character and target objects that were located in six positions relative to the person in the diagram (left/right, up/down, and front/back). Following learning, participants recalled the locations of the objects from several imagined orientations. Performance on the recall task revealed faster response latencies for upward targets, providing evidence for vertical representational biases in healthy individuals.     

Differences in paper-and-pencil versus computerized line bisection according to ADHD subtype and hand-use

Two versions of the line bisection task, paper-and-pencil and computerized, were administered to non-medicated children (5-12 years) with and without Attention-Deficit/Hyperactivity Disorder (ADHD). Fifteen children were classified with ADHD-Inattentive type (ADHD-I), 15 were classified with ADHD-Combined or Hyperactive-Impulsive type (ADHD-C), and 15 children served as controls. During the paper-and-pencil task, and irrespective of hand-use, participants with ADHD-C bisected lines with a right bias, whereas participants with ADHD-I showed a leftwards bias. Interestingly, during the computerized version, an opposite pattern of hemineglect was observed with a leftwards bias for participants with ADHD-C and a rightwards bias for participants with ADHD-I. These findings suggest that different task demands are associated with the paper-and-pencil and computerized tasks. The findings also suggest that the two subtypes differ according to their cognitive profile, and possibly differ as to their underlying neural impairment.     

How does reading direction modulate perceptual asymmetry effects?

Left-side bias effects refer to a bias towards the left side of the stimulus/space in perceptual/visuospatial judgments, and are argued to reflect dominance of right hemisphere processing. It remains unclear whether reading direction can also account for the bias effect. Previous studies comparing readers of languages read from left to right with those read from right to left (e.g., French vs. Hebrew) have obtained inconsistent results. As a language that can be read from left to right or from right to left, Chinese provides a unique opportunity for a within-culture examination of reading direction effects. Chinese participants performed a perceptual judgment task (with both face and Chinese character stimuli; Experiment 1) and two visuospatial attention tasks (the greyscales and line bisection tasks; Experiment 2) once before and once after a reading task, in which they read Chinese passages either from left to right or from right to left for about 20 min. After reading from right to left, participants showed significantly reduced left-side bias in Chinese character perceptual judgments but not in the other three tasks. This effect suggests that the role of reading direction on different forms of left-side bias may differ, and its modulation may be stimulus-specific.     

Right up there: hemispatial and hand asymmetries of altitudinal pseudoneglect

Background

Pseudoneglect is a normal left sided spatial bias observed with attempted bisections of horizontal lines and a normal upward bias observed with attempted bisections of vertical lines. Horizontal pseudoneglect has been attributed to right hemispheric dominance for the allocation of attention. The goal of this study was to test the hypothesis that the upward bias in vertical line bisection may also relate to right hemispheric dominance for the allocation of attention and/or action-intention.

Methods

Twenty right handed healthy adults were asked to bisect vertical lines presented in the midsagittal plane (center space) and in sagittal planes to the left and right of the midsagittal plane (left and right hemispace) when using a pen held in either the right or left hand.

Results

Vertical line bisections were biased upward in all three sagittal planes and higher in left than right hemispace. However, bisections made with the left hand were lower than those made with the right hand.

Discussion

Whereas these results suggest a left hemispace-right hemispheric visuospatial attentional upward bias and a relative left hemispheric-right hand upward action-intentional bias, further studies are needed to document this intentional versus attentional bias and to understand the brain mechanisms that produce these biases.     

Near space and its relation to claustrophobic fear

It is well established that the near space immediately surrounding the body (also known as peripersonal space) is represented differently than the space farther away. When bisecting horizontal lines, for example, neurologically-healthy adults show a slight leftward bias (known as pseudoneglect) in near space; this attentional bias, however, transitions rightward in far space. Recent research has used the rate at which this shift occurs to quantify the extent (i.e., size) of near space, showing consistent individual differences that relate to arm length. Here we examined whether the size of near space relates to individual differences in claustrophobic fear, as measured by reported anxiety of enclosed spaces and physically restrictive situations. Trait feelings of claustrophobic fear predicted the size of near space, even after accounting for the relation to arm length. Specifically, people with larger near spaces reported higher rates of claustrophobic fear than people with smaller near spaces. These results are consistent with a defensive function of near space representation and suggest that an over-projection of near space may play an important role in the etiology of claustrophobia.     

Biases of spatial attention in vision and audition

Neurologically normal observers misperceive the midpoint of horizontal lines as systematically leftward of veridical center, a phenomenon known as pseudoneglect. Pseudoneglect is attributed to a tonic asymmetry of visuospatial attention favoring left hemispace. Whereas visuospatial attention is biased toward left hemispace, some evidence suggests that audiospatial attention may possess a right hemispatial bias. If spatial attention is supramodal, then the leftward bias observed in visual line bisection should also be expressed in auditory bisection tasks. If spatial attention is modality specific then bisection errors in visual and auditory spatial judgments are potentially dissociable. Subjects performed a bisection task for spatial intervals defined by auditory stimuli, as well as a tachistoscopic visual line bisection task. Subjects showed a significant leftward bias in the visual line bisection task and a significant rightward bias in the auditory interval bisection task. Performance across both tasks was, however, significantly positively correlated. These results imply the existence of both modality specific and supramodal attentional mechanisms where visuospatial attention has a prepotent leftward vector and audiospatial attention has a prepotent rightward vector of attention. In addition, the biases of both visuospatial and audiospatial attention are correlated.     

Horizontal and vertical pseudoneglect in peri- and extrapersonal space

The present study investigates the influence of depth on pseudoneglect in healthy young participants (n = 18) within three-dimensional virtual space, by presenting a variation of the greyscales task and a landmark task, which were specifically matched for stimulus–response compatibility, as well as perceptual factors within and across the tasks. Tasks were presented in different depth locations (peripersonal, extrapersonal) and different orientations (horizontal, vertical) within three-dimensional virtual space, using virtual reality technique. A horizontal leftward bias (pseudoneglect) for both tasks was found, which was stronger in peripersonal than in extrapersonal space. For the vertical condition, an upward bias was observed in the greyscales task, but not in the landmark task. These results support the hypotheses of right hemispheric dominance for visual spatial attention and our study is the first to examine horizontal and vertical orienting biases with the greyscales task in peri- and extrapersonal space. Furthermore, the differences in attentional asymmetries with respect to depth suggest dissociable neural mechanisms for visual attentional processing in near and far space and the lack of significant correlations implies independence of horizontal and vertical stimulus processing.