注视-西蒙效应的空间编码机制

采用注视-西蒙范式探讨了注视方向知觉的空间编码机制。实验一让被试采用双手交叉的反应方式,发现注视-西蒙效应并不随反应手的交叉而反转,说明它涉及抽象的空间方向编码,而非基于以手为参照系的半侧优势效应。实验二采用纯音音调辨别任务,发现了典型的注视-西蒙效应,结合实验一视觉通道的结果,说明注视-西蒙效应并非特异于视觉通道,它可能发生在晚期的反应选择阶段,而非早期的知觉阶段。结果支持注视线索能够自动诱发观察者形成抽象的方向表征的观点。     

Right hemispheric dominance in gaze-triggered reflexive shift of attention in humans

Recent findings suggest a right hemispheric dominance in gaze-triggered shifts of attention. The aim of this study was to clarify the dominant hemisphere in the gaze processing that mediates attentional shift. A target localization task, with preceding non-predicative gaze cues presented to each visual field, was undertaken by 44 healthy subjects, measuring reaction time (RT). A face identification task was also given to determine hemispheric dominance in face processing for each subject. RT differences between valid and invalid cues were larger when presented in the left rather than the right visual field. This held true regardless of individual hemispheric dominance in face processing. Together, these results indicate right hemispheric dominance in gaze-triggered reflexive shifts of attention in normal healthy subjects.     

Gaze behavior in audiovisual speech perception: the influence of ocular fixations on the McGurk effect

We conducted three experiments in order to examine the influence of gaze behavior and fixation on audiovisual speech perception in a task that required subjects to report the speech sound they perceived during the presentation of congruent and incongruent (McGurk) audiovisual stimuli. Experiment 1 showed that the subjects' natural gaze behavior rarely involved gaze fixations beyond the oral and ocular regions of the talker's face and that these gaze fixations did not predict the likelihood of perceiving the McGurk effect. Experiments 2 and 3 showed that manipulation of the subjects' gaze fixations within the talker's face did not influence audiovisual speech perception substantially and that it was not until the gaze was displaced beyond 10 degrees - 20 degrees from the talker's mouth that the McGurk effect was significantly lessened. Nevertheless, the effect persisted under such eccentric viewing conditions and became negligible only when the subject's gaze was directed 60 degrees eccentrically. These findings demonstrate that the analysis of high spatial frequency information afforded by direct oral foveation is not necessary for the successful processing of visual speech information.     

The eyes have it! Reflexive orienting is triggered by nonpredictive gaze

Normal subjects were presented with a simple line drawing of a face looking left, right, or straight ahead. A target letter F or T then appeared to the left or the right of the face. All subjects participated in target detection, localization, and identification response conditions. Although subjects were told that the line drawing’s gaze direction (the cue) did not predict where the target would occur, response time in all three conditions was reliably faster when gaze was toward versus away from the target. This study provides evidence for covert, reflexive orienting to peripheral locations in response to uninformative gaze shifts presented at fixation. The implications for theories of social attention and visual orienting are discussed, and the brain mechanisms that may underlie this phenomenon are considered.     

眼睛注视线索提示效应: 内源性注意还是外源性注意?

采用改进的Posner视-空间线索提示范式, 对眼睛注视线索提示效应(eyes gaze cueing effect)的加工机制进行了探讨。实验一考察注视提示线索对空间Stroop效应的影响; 实验二考察注视提示线索对特征抽取和特征整合的影响。实验结果显示: 注视线索提示有效时的空间Stroop效应显著大于提示无效的情景; 在单一特征搜索与特征联合搜索任务中, 注视线索提示效应无差别。这说明, 注视线索通过在头脑里形成空间方位表征诱导注意转移; 注视线索通过影响特征抽取、而非特征整合阶段, 对客体加工产生易化。本研究支持注视线索提示效应属于内源性注意的观点。     

Consistent left gaze bias in processing different facial cues

While viewing faces, humans often demonstrate a natural gaze bias towards the left visual field, that is, the right side of the viewee’s face is often inspected first and for longer periods. Previous studies have suggested that this gaze asymmetry is a part of the gaze pattern associated with face exploration, but its relation with perceptual processing of facial cues is unclear. In this study we recorded participants’ saccadic eye movements while exploring face images under different task instructions (free viewing, judging familiarity and judging facial expression). We observed a consistent left gaze bias in face viewing irrespective of task demands. The probability of the first fixation and the proportion of overall fixations directed at the left hemiface were indistinguishable across different task instructions or across different facial expressions. It seems that the left gaze bias is an automatic reflection of hemispheric lateralisation in face processing, and is not necessarily correlated with the perceptual processing of a specific type of facial information.     

Does eye gaze indicate implicit knowledge of false belief? Charting transitions in knowledge

Three-year-olds sometimes look to the correct location but give an incorrect verbal answer in a false belief task. We examined whether correct eye gaze among 3- to 5-year-old children indexed unconscious knowledge or low confidence conscious knowledge. Children "bet" counters on where they thought a story character would go. If children were conscious of the knowledge conveyed by their eye gaze then they should have bet modestly on their explicit answer (i.e., been unsure whether this answer or the answer conveyed through eye direction was correct). We found that children bet very highly on the location consistent with their explicit answer, suggesting that they were not aware of the knowledge conveyed through their eye gaze. This result was supported by a number of conditions that showed that betting was a sensitive measure of even small degrees of uncertainty. The results shed light on false-belief understanding, the implicit-explicit distinction, and transitional knowledge. We argue that the transition to a full understanding of false belief is marked by periods of implicit knowledge and explicit understanding with low confidence.     

Human gaze behaviour during action execution and observation

Gaze shifts and fixations appear to be proactive in both action execution and observation. We investigated a dependency of anticipatory gaze behaviour by using a block stacking task. Blocks were rectangles depicted on a computer screen and the stacking movements were controlled via computer mouse. Subjects either had to execute the task or had to observe it made by the experimenter, or by the computer. The dependency of gaze behaviour on the visibility of a virtual effector, the visibility of the actor, and the nature of the actor was tested by measuring eye movements. Anticipatory eye movements were predominant when the subjects themselves executed the task. During action observation, gaze behaviour did neither depend on the visibility nor depend on the nature of the actor. However, big variability was found between the subjects suggesting the use of two different strategies in action observation: some subjects were mainly tracking the blocks during stacking movements; others were strongly anticipating. We suggest that gaze behaviour during action observation is not predetermined by rigid neural circuitry, but strongly depends on the context. The possibility to explain the causal mechanism, as well as the ownership of the action may be crucial preconditions for anticipatory gaze behaviour.     

The reproduction of vertical and oblique orientations in the visual, haptic, and somatovestibular systems

This study investigates whether the vertical orientation may be predominantly used as an amodal reference norm by the visual, haptic, and somato-vestibular perceptual systems to define oblique orientations. We examined this question by asking the same sighted adult subjects to reproduce, in the frontal (roll) plane, the vertical (0°) and six oblique orientations in three tasks involving different perceptual systems. In the visual task, the subjects adjusted a moveable rod so that it reproduced the orientation of a visual rod seen previously in a dark room. In the haptic task, the blindfolded sighted subjects scanned an oriented rod with one hand and reproduced its orientation, with the same hand, on a moveable response rod. In the somato-vestibular task, the blindfolded sighted subjects, sitting in a rotating chair, adjusted this chair in order to reproduce the tested orientation of their own body. The results showed that similar oblique effects (unsigned angular error difference between six oblique orientations and vertical orientation) were observed across the three tasks. However, there were no positive correlations between the visual, haptic,     

Position of the egocentric reference and performance in line bisection and subjective vertical estimation tasks

Egocentric body coordinates such as the sagittal midline have been proposed to act as a reference for ballistic movements in extracorporeal space. Symmetrical functioning of the multiple neural structures processing sensory information would account for the normal sagittal position of the egocentric reference. According to this hypothesis a unilateral parietal lesion would induce a ipsilesional deviation which would prevent neglect patients from responding to stimuli that occur on that side. In this line of reasoning, an experimental manipulation of the position of the egocentric reference by way of a postural perturbation should have an effect on visuospatial tasks performance in normal subjects. Seventeen right-handed subjects were submitted in the dark to two visuomotor tasks: the adjustment of a luminescent rod to the vertical and the bisection of a luminescent line, either with the trunk and the head aligned at 0 degrees or with a 30 degrees trunk rotation to the right or to the left. Results revealed no significant effect of trunk rotation on the performance in both tasks. We discuss these findings and their implication for the understanding of the neglect syndrome.     

Human-directed behaviour in goats is not affected by short-term positive handling

In addition to domestication, interactions with humans or task-specific training during ontogeny have been proposed to play a key role in explaining differences in human–animal communication across species. In livestock, even short-term positive interactions with caretakers or other reference persons can influence human–animal interaction at different levels and over different periods of time. In this study, we investigated human-directed behaviour in the ‘unsolvable task’ paradigm in two groups of domestic goats (Capra aegagrus hircus). One group was positively handled and habituated to a plastic box by the experimenter to retrieve a food reward, while the other group only received standard husbandry care and was habituated to the box without human assistance. In the unsolvable task, the lid was fixed to the box, with the reward inaccessible to the subjects. The goats were confronted with the unsolvable task three times. We observed no difference between the two groups regarding gaze and contact alternations with the experimenter when confronted with the task they cannot solve by themselves. The goats did not differ in their expression rates of both gaze and contact alternations over three repetitions of the unsolvable task; however, they showed earlier gaze and contact alternations in later trials. The results do not support the hypothesis that short-term positive handling or task-specific training by humans facilitates human-directed behaviour in goats. In contrast, standard husbandry care might be sufficient to establish humans as reference persons for farm animals in challenging situations.     

被试自身人手初始状态对心理旋转加工的影响：眼动研

利用眼动追踪技术,探讨在左右手判断任务条件下人手心理旋转加工是否受到被试自身人手初始状态的影响。两个实验的反应时数据和眼动数据均发现：（1）心理旋转加工受被试自身人手初始状态的影响,表现出一致性效应;（2）显著的内旋效应;（3）被试心理旋转加工时注视点取样存在着不均衡性。这些结果表明：在左右手判断任务中,心理旋转加工的对象是被试自身人手的表象,是自我参照的心理旋转,并且内旋效应是由被试对自身人手表象进行旋转时受到人手生理机制约束所致,而不是被试旋转刺激图片的表象由“生理机制约束知识”影响所致     

Is there an effect of handedness on the position of the egocentric reference?

Forty normal subjects (20 left-handed; 20 right-handed) were submitted to a proprioceptive straight ahead pointing task while blindfolded to study the effect of the hand used and of the hand preference on the estimation of the subjective sagittal middle. Results showed that left-handed and right-handed subjects both deviated to the left of the objective sagittal middle and presented an effect of the hand used and of the starting point affecting their straight ahead performance in a similar way. In all subjects whatever their manual preference, using the left hand and starting 30 degrees to left induced a tendency to deviate to the same side, whereas using the right hand and starting 30 degrees to right induced a tendency to place the subjective middle to the right of the objective middle. These results are interpreted with regard to the hypothesis of a cortical control of the position of the egocentric reference.     

Visual perception and gaze control in judging versus producing phase relations

We studied visual perception and gaze control in nine participants while they judged the relative phase between two oscillating stimuli (Experiment 1), and while they moved their hand--and therewith a concurrent feedback signal--in-phase or in antiphase with an oscillating stimulus (Experiment 2). As in previous studies, the mean relative phase judgements in Experiment 1 corresponded to the presented phase relations (0 degree, 45 degrees, 90 degrees, 135 degrees, and 180 degrees), whereas their standard deviations followed an inverted U-function of relative phase. The relative phase judgements were hardly affected by the degree of visibility (fully visible, inner parts occluded, outer parts occluded) and the amplitude (5 degrees, 10 degrees, and 20 degrees) of the stimuli. Stimulus-gaze coupling decreased as relative phase increased, and its variability correlated with that of the relative phase judgements. Taken together, task performance and gaze behaviour suggested that the judgement of relative phase might be flexibly based on different variables, rather than a single variable like relative direction of motion. In Experiment 2, the production of the antiphase relation was less stable than that of the in-phase relation. Performance deteriorated when the outer parts of the signals were occluded and when their amplitudes were reduced. Stimulus-gaze coupling was stronger during in-phase than during antiphase tracking and weaker when the signals were partially occluded and when their amplitudes were reduced. Stimulus-gaze coupling at 0 degrees and 180 degrees was stronger in Experiment 2 than in Experiment 1, suggesting that the visual perception of relative phase may benefit from its active production. Overall, the results clearly indicated that visual perception of relative phase and the corresponding gaze control are strongly task-dependent.     

Look away! Eyes and arrows engage oculomotor responses automatically

The present study investigates how people’s voluntary saccades are influenced by where another person is looking, even when this is counterpredictive of the intended saccade direction. The color of a fixation point instructed participants to make saccades either to the left or right. These saccade directions were either congruent or incongruent with the eye gaze of a centrally presented schematic face. Participants were asked to ignore the eyes, which were congruent only 20% of the time. At short gaze—fixation-cue stimulus onset asynchronies (SOAs; 0 and 100 msec), participants made more directional errors on incongruent than on congruent trials. At a longer SOA (900 msec), the pattern tended to reverse. We demonstrate that a perceived eye gaze results in an automatic saccade following the gaze and that the gaze cue cannot be ignored, even when attending to it is detrimental to the task. Similar results were found for centrally presented arrow cues, suggesting that this interference is not unique to gazes.     

Developmental changes in the control of saccadic eye movements in response to directional eye gaze and arrows

We investigated developmental differences in oculomotor control between 10-year-old children and adults using a central interference task. In this task, the colour of a fixation point instructed participants to saccade either to the left or to the right. These saccade directions were either congruent or incongruent with two types of distractor cue: either the direction of eye gaze of a centrally presented schematic face, or the direction of arrows. Children had greater difficulties inhibiting the distractor cues than did adults, which revealed itself in longer saccade latencies for saccades that were incongruent with the distractor cues as well as more errors on these incongruent trials than on congruent trials. Counter to our prediction, in terms of saccade latencies, both children and adults had greater difficulties inhibiting the arrow than the eye gaze distractors.     

Developmental changes in the control of saccadic eye movements in response to directional eye gaze and arrows

We investigated developmental differences in oculomotor control between 10-year-old children and adults using a central interference task. In this task, the colour of a fixation point instructed participants to saccade either to the left or to the right. These saccade directions were either congruent or incongruent with two types of distractor cue: either the direction of eye gaze of a centrally presented schematic face, or the direction of arrows. Children had greater difficulties inhibiting the distractor cues than did adults, which revealed itself in longer saccade latencies for saccades that were incongruent with the distractor cues as well as more errors on these incongruent trials than on congruent trials. Counter to our prediction, in terms of saccade latencies, both children and adults had greater difficulties inhibiting the arrow than the eye gaze distractors.     

Chimpanzee gaze following in an object-choice task

Many primate species reliably track and follow the visual gaze of conspecifics and humans, even to locations above and behind the subject. However, it is not clear whether primates follow a human’s gaze to find hidden food under one of two containers in an object-choice task. In a series of experiments six adult female chimpanzees followed a human’s gaze (head and eye direction) to a distal location in space above and behind them, and checked back to the human’s face when they did not find anything interesting or unusual. This study also assessed whether these same subjects would also use the human’s gaze in an object-choice task with three types of occluders: barriers, tubes, and bowls. Barriers and tubes permitted the experimenter to see their contents (i.e., food) whereas bowls did not. Chimpanzees used the human’s gaze direction to choose the tube or barrier containing food but they did not use the human’s gaze to decide between bowls. Our findings allowed us to discard both simple orientation and understanding seeing-knowing in others as the explanations for gaze following in chimpanzees. However, they did not allow us to conclusively choose between orientation combined with foraging tendencies and understanding seeing in others. One interesting possibility raised by these results is that studies in which the human cannot see the reward at the time of subject choice may potentially be underestimating chimpanzees’ social knowledge. Received: 16 February 1998 / Accepted after revision: 5 July 1998     

Intimacy in response to direct gaze

Believing that they were participating in a study of encounter groups, male and female subjects were encouraged to deliver a personally revealing monologue to a same-sex listener whose visual behavior had been “programmed” by the experimenter. In the four experimental conditions, designed to explore the role of gaze as a stimulus, as a potential reinforcer, and as a source of feedback, the listener provided (a) continuous direct gaze; (b) direct gaze contingent upon intimate statements; (c) continuous gaze aversion; or (d) gaze aversion contingent upon intimate statements. The intimacy of the speaker's monologue was rated by a “blind” observer, the listener, and the speaker himself. Direct gaze, whether constant or contingent, appeared to promote intimacy between females and reticence between males, while gaze avoidance had the opposite effects. The only raters who disagreed with this assessment were the male speakers, who felt that they had been most intimate in the two direct gaze conditions. Positive feelings including liking for the listener and task satisfaction also were associated both with self-revelation and with direct gaze among females but not among males.