听障和听力正常人群空间主导性和空间参照框架的交互作用

通过要求被试分别在近处空间和远处空间完成空间参照框架的判断任务, 考察了听障和听力正常人群空间主导性和空间参照框架的交互作用。结果表明：(1)相对于听力正常人群, 听障人群完成自我参照框架判断任务的反应时更长, 而在完成环境参照框架判断任务无显著差异; (2)听障人群和听力正常人群空间主导性和空间参照框架交互作用呈现出相反模式。研究表明, 听障人群在听力功能受损后, 其空间主导性和空间参照框架的交互作用也产生了变化。     

Spatial biases in peripersonal space in sighted and blind individuals revealed by a haptic line bisection paradigm

Our representation of peripersonal space does not always accurately reflect the physical world. An example of this is pseudoneglect, a phenomenon in which neurologically normal individuals bisect to the left of the veridical midpoint, reflecting an overrepresentation of the left portion of space compared with the right one. Consistent biases have also been observed in the vertical and radial planes. It is an open question whether these biases depend on normal visual experience for their occurrence. Here we systematically investigated this issue by testing blindfolded sighted and early blind individuals in a haptic line bisection task. Critically, we found a robust leftward bias in all participants. In the vertical and radial planes, sighted participants showed a consistent downward and proximal bias. Conversely, the directional bias in blind participants was dependent on the final movement direction; thus, there was no general bias in either direction. These findings are discussed in terms of different reference frames adopted by sighted and blind participants when encoding space.     

Asymmetries in a unilateral flanker task depend on the direction of the response: the role of attentional shift and perceptual grouping

Four experiments were conducted using a flanker task with 1 distractor appearing either on the left or right side of a central target. Responses were made on a keyboard aligned parallel to the displays. A larger flanker effect was obtained when the distractor was on the same side as the response. Two factors account for this asymmetry. First, when the flanker and target are identical, the 2 form a group that is assigned a spatial tag, creating a form of the Simon effect on the basis of the compatibility between the response keys and the group. Second, preparation of a lateralized response appears to entail a shift of visual attention in the corresponding direction, thus enhancing processing of the flanker on the response side. Consistent with the 2nd hypothesis, participants were more likely to correctly recognize letters that were briefly presented at the distractor position on the same side as the response.     

Near space functioning of the human angular and supramarginal gyri

The posterior parietal cortex (PPC) has been associated with the encoding of events in peripersonal space, but little is known about the precise segregation of parietal areas involved specifically in ‘near‐space’ visuospatial processing. This study applied transcranial magnetic stimulation (TMS) to two parietal areas: the right angular gyrus (ANG) and the right supramarginal gyrus (SMG) in addition to a control site, cortical visual area V5, while subjects performed symmetry judgements on lines presented simultaneously in the left and right visual fields. Eight subjects performed the task with the stimuli presented either in peripersonal or extra personal space. As expected, TMS over the right ANG caused subjects to report lines as being longer ipsilateral to the stimulation site, but only in near space. TMS of the right SMG, however, induced a bias shift in both near and far space, but the change only reached significance in near space. Our findings suggest that, consistent with its role in somatosensory functions, the SMG, like the ANG, is specialised for near space.     

Right visual field advantage for perceived contrast: Correlation with an auditory bias and handedness

Studies have suggested that supramodal attentional resources are biased rightward due to asymmetric spatial fields of the two hemispheres. This bias has been observed especially in right-handed subjects. We presented left and right-handed subjects with brief uniform grey visual stimuli in either the left or right visual hemifield. Consistent with the proposed asymmetry in attentional resources, right-handed subjects estimated right hemifield targets as having a higher contrast than physically identical stimuli presented in the left hemifield. Left-handed participants did not show a systematic rightward or leftward bias. However, the group of left-handed participants also took part in a dichotic listening experiment whose results showed that visual bias score correlated positively with ear-advantage in dichotic listening. Our results are consistent with the view that supramodal processing resources are biased towards the right hemispace, and that this bias is influenced by handedness.     

Right visual field advantage for perceived contrast: correlation with an auditory bias and handedness

Studies have suggested that supramodal attentional resources are biased rightward due to asymmetric spatial fields of the two hemispheres. This bias has been observed especially in right-handed subjects. We presented left and right-handed subjects with brief uniform grey visual stimuli in either the left or right visual hemifield. Consistent with the proposed asymmetry in attentional resources, right-handed subjects estimated right hemifield targets as having a higher contrast than physically identical stimuli presented in the left hemifield. Left-handed participants did not show a systematic rightward or leftward bias. However, the group of left-handed participants also took part in a dichotic listening experiment whose results showed that visual bias score correlated positively with ear-advantage in dichotic listening. Our results are consistent with the view that supramodal processing resources are biased towards the right hemispace, and that this bias is influenced by handedness.     

Time does not flow without language: Spatial distance affects temporal duration regardless of movement or direction

Much evidence has suggested that people conceive of time as flowing directionally in transverse space (e.g., from left to right for English speakers). However, this phenomenon has never been tested in a fully nonlinguistic paradigm where neither stimuli nor task use linguistic labels, which raises the possibility that time is directional only when reading/writing direction has been evoked. In the present study, English-speaking participants viewed a video where an actor sang a note while gesturing and reproduced the duration of the sung note by pressing a button. Results showed that the perceived duration of the note was increased by a long-distance gesture, relative to a short-distance gesture. This effect was equally strong for gestures moving from left to right and from right to left and was not dependent on gestures depicting movement through space; a weaker version of the effect emerged with static gestures depicting spatial distance. Since both our gesture stimuli and temporal reproduction task were nonlinguistic, we conclude that the spatial representation of time is nondirectional: Movement contributes, but is not necessary, to the representation of temporal information in a transverse timeline.     

Selective attention, visual laterality, awareness, and perceiving the meaning of parafoveally presented words

Four experiments are reported investigating the effect of selective attention on the semantic encoding of parafoveally presented words. In Experiments 1 and 2 a right visual field (RVF) performance bias was found when subjects attended to words that could appear either left or right of centre (attend-side condition). When subjects attended centrally and ignored lateral distractor words (attendcentre condition) there was an inhibitory effect of word meaning from left visual field (LVF) distractors. Both inhibitory and facilitatory effects of semantic category were observed from unattended words in Experiments 3 and 4. The pattern of effects depended upon the direction of spatial bias in an attend-side condition. Both kinds of effect occurred even for subjects who were unable to make consciously directed semantic category decisions to words at the same eccentricity (4°) and exposure time (15 msec) as ignored distractors in the attend-centre condition. Implications of these findings for theories of selective attention, for the issue of semantic encoding independent of conscious awareness, and for theories of the relationship between lateral performance biases and functional hemispheric asymmetry are discussed.     

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.     

Near, yet so far: the effect of pictorial cues on spatial attention

Distinct cognitive and neural mechanisms underlie perception and action in near (within-reach) and far (outside-reach) space. Objects in far space can be brought into the brain's near-space through tool-use. We determined whether a near object can be pushed into far space by changing the pictorial context in which it occurs. Participants (n = 372) made relative length judgements for lines presented in near space, but superimposed over photographs of near and far objects. The left segment of the line was overestimated in the baseline and near-context conditions whereas the right was overestimated in the far-context. The change from leftward to rightward overestimation is the same when lines are physically shifted from near to far space. Because participants did not have to do anything in relation to the photograph, the results suggest that simply viewing images with a near/far context can cause a shift of attention along the distal/proximal axis, which may reflect differential activation of the ventral/dorsal visual streams.     

视觉空间伪忽视与表征伪忽视神经机制的异同

伪忽视（pseudoneglect）是指个体存在的轻微偏左的不对称空间注意,而视觉空间伪忽视（visuo-spatial pseudoneglect）和表征伪忽视(representational pseudoneglect)是其两种主要表现形式。研究初期,研究者认为两种伪忽视基于相同的注意定向左偏机制,但近年来研究发现,它们仍存在神经机制的差异。本文主要从两种伪忽视神经机制的异同出发,梳理分析近期研究结果,以期增进对伪忽视的理解。未来研究可以从认知时间进程角度或设计更为完善的研究范式进一步探讨这两种伪忽视神经机制的异同。     

Perceptual grouping and visual selective attention

The present study demonstrates that incongruent distractor letters at a constant distance from a target letter produce more response competition and negative priming when they share a target’s color than when they have a different color. Moreover, perceptual grouping by means of color, attenuated the effects of spatial proximity. For example, when all items were presented in the same color, near distractors produced more response competition and negative priming than far distractors (Experiment 3A). However, when near distractors were presented in a different color and far distractors were presented in the same color as the target, the response competition × distractor proximity interaction was eliminated and the proximity × negative priming interaction was reversed (Experiment 3B). A final experiment demonstrated that distractors appearing on the same object as a selected target produced comparable amounts of response competition and negative priming whether they were near or far from the target. This suggests that the inhibitory mechanisms of visual attention can be directed to perceptual groups/objects in the environment and not only to unsegmented regions of visual space.     

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.     

The influence of emotional faces on the spatial allocation of attention

Background objectives: Studies suggest that the right hemisphere is dominant for emotional facial recognition. In addition, whereas some studies suggest the right hemisphere mediates the processing of all emotions (dominance hypothesis), other studies suggest that the left hemisphere mediates positive emotions the right mediates negative emotions (valence hypothesis). Since each hemisphere primarily attends to contralateral space, the goals of this study was to learn if emotional faces would induce a leftward deviation of attention and if the valence of facial emotional stimuli can influence the normal viewer’s spatial direction of attention. Methods: Seventeen normal right handed participants were asked to bisect horizontal lines that had all combinations of sad, happy or neutral faces at ends of these lines. During this task the subjects were never requested to look at these faces and there were no task demands that depended on viewing these faces. Results: Presentation of emotional faces induced a greater leftward deviation compared to neutral faces, independent of where (spatial position) these faces were presented. However, faces portraying negative emotions tended to induce a greater leftward bias than positive emotions. Conclusions: Independent of location, the presence of emotional faces influenced the spatial allocation of attention, such that normal subjects shift the direction of their attention toward left hemispace and this attentional shift appears to be greater for negative (sad) than positive faces (happy).     

Coding left and right

The present study compared the processing of direction for up and down arrows and for left and right arrows in visual displays. Experiment 1 demonstrated that it is more difficult to deal with left and right than with up and down when the two directions must be discriminated but not when they must simply be oriented to. Experiments 2 and 3 showed that telling left from right is harder regardless of whether the responses are manual or verbal. Experiment 4 showed that left-right discriminations take longer than up-down discriminations for judgments of position as well as direction. In Experiment 5 it was found that position information can intrude on direction judgments both within a dimension (e.g., a left arrow to the left of fixation is judged faster than a left arrow to the right of fixation) and across dimensions (e.g., judging vertically positioned left and right arrows is more difficult than judging horizontally positioned left and right arrows). There was indirect evidence in these experiments that although the spatial codes for up and down are symmetrical, the codes for left and right may be less so; this in turn could account for the greater difficulty of discriminating left from right.     

The whereabouts of visual attention: Involuntary attentional bias toward the default gaze direction

This study proposed and verified a new hypothesis on the relationship between gaze direction and visual attention: attentional bias by default gaze direction based on eye-head coordination. We conducted a target identification task in which visual stimuli appeared briefly to the left and right of a fixation cross. In Experiment 1, the direction of the participant’s head (aligned with the body) was manipulated to the left, front, or right relative to a central fixation point. In Experiment 2, head direction was manipulated to the left, front, or right relative to the body direction. This manipulation was based on results showing that bias of eye position distribution was highly correlated with head direction. In both experiments, accuracy was greater when the target appeared at a position where the eyes would potentially be directed. Consequently, eye–head coordination influences visual attention. That is, attention can be automatically biased toward the location where the eyes tend to be directed.     

Radial bisection of words and lines in right‐brain‐damaged patients with spatial neglect

The bisection of lines positioned radially (with the two ends of the line close and far, with respect to the participant's body) has been less investigated than that of lines placed horizontally (with their two ends left and right, with respect to the body's midsagittal plane). In horizontal bisection, patients with left neglect typically show a rightward bias for both lines and words, greater with longer stimuli. As for radial bisection, available data indicate that neurologically unimpaired participants make a distal error, while results from right‐brain‐damaged patients with left spatial neglect are contradictory. We investigated the bisection of radially oriented words, with the prediction that, during bisection, linguistic material would be recoded to its canonical left‐to‐right format in reading, with the performance of neglect patients being similar to that for horizontal words. Thirteen right‐brain‐damaged patients (seven with left spatial neglect) and fourteen healthy controls were asked to manually bisect 40 radial and 40 horizontal words (5–10 letters), and 80 lines, 40 radial and 40 horizontal, of comparable length. Right‐brain‐damaged patients with spatial neglect exhibited a proximal bias in the bisection of short radial words, with the proximal part corresponding to the final right part of horizontally oriented words. This proximal error was not found in patients without neglect and healthy controls. For bisection, short radial words may be recoded to the canonical orthographic horizontal format, unveiling the impact of left neglect on radially oriented stimuli.     

Retinal location and its effect on the spatial distribution of visual attention

A series of studies tested for distractor compatibility effects across wide target/distractor distances (0.6 degree to 20 degrees of visual angle). The effects of precue condition, constant/varied target location, horizontal/vertical distractor distance, and foveal/peripheral presentation were studied. Results show strong compatibility effects across wide distances when distractors are at peripheral retinal locations. When both stimuli were presented at the same peripheral location in opposite hemifields, compatibility effects were evident within an area of at least 2.5 degrees of visual angle. In contrast, when foveally placed distractors were used, compatibility effects were found primarily with target letters positioned near. The findings suggest that distance effects are not homogeneous across retinal location.     

Experience-guided attention: Uniform and implicit

Frequently finding a visual search target in one region of space induces a spatial attentional bias toward that region. Past studies on this effect typically tested fewer than 20 participants. The small sample prevents an investigation of two properties of learning: visual field uniformity and role of explicit awareness. Pooling data from multiple studies, here we examined location probability learning from ~120,000 visual search trials across 420 participants. Participants performed a serial search task. Unbeknownst to them, the target was disproportionately likely to appear in one visual quadrant. Location probability learning (LPL) was measured as the difference in reaction time to targets in the high-probability “rich” quadrant and the low-probability “sparse” quadrants. Results showed a lack of visual field effect. LPL was equivalent for “rich” quadrant in the upper left, upper right, lower left, and lower right. Learning did not induce a hotspot diagonal to the “rich” quadrant. To the contrary, RT was the longest in the diagonal quadrant. Recognition rate of the “rich” quadrant was above chance. However, recognition accuracy was unrelated to the size of LPL. Implicit learning induces visual-field-independent changes in spatial attention.     

Tool-use changes multimodal spatial interactions between vision and touch in normal humans

In a visual-tactile interference paradigm, subjects judged whether tactile vibrations arose on a finger or thumb (upper vs. lower locations), while ignoring distant visual distractor lights that also appeared in upper or lower locations. Incongruent visual distractors (e.g. a lower light combined with upper touch) disrupt such tactile judgements, particularly when appearing near the tactile stimulus (e.g. on the same side of space as the stimulated hand). Here we show that actively wielding tools can change this pattern of crossmodal interference. When such tools were held in crossed positions (connecting the left hand to the right visual field, and vice-versa), the spatial constraints on crossmodal interference reversed, so that visual distractors in the other visual field now disrupted tactile judgements most for a particular hand. This phenomenon depended on active tool-use, developing with increased experience in using the tool. We relate these results to recent physiological and neuropsychological findings.