Luminance-induced shift in the apparent direction of gaze

Changing the luminance of one side of the sclera induces an apparent shift of the perceived direction of gaze toward the darker side of the sclera. This luminance-induced gaze shift was measured in photographic and schematic images of eyes. The effect was substantial: a moderate darkening of one side of the sclera induced an apparent shift of 8 to 10 deg of gaze; the maximum darkening induced a shift of 15 deg of gaze or more. The effect of scleral darkening was also compared to the gaze shift induced by an actual shift of the iris. The effects of the two cues were measured independently and in combination. When pitted against each other, their effects could be nulled, demonstrating that they act on a common level. Predictions of the relative strengths of the luminance and iris shift cues were developed for two simple luminance-based mechanisms: flux ratio and luminance centroid. The data showed the luminance cue was less effective than the models predicted in determining gaze direction. As an alternative source for the gaze shift, irradiation effects on apparent size could create a perceived shift in the iris position but a direct measure of the irradiation shift showed that this was far too small. The results suggest that at least one important mechanism for gaze judgment is based on low-level analysis of the luminance configuration within the eye.     

Perception of gaze direction based on luminance ratio

Changing the luminance of one side of the sclera induces an apparent shift of the perceived direction of gaze toward the darker side of the sclera (Ando, 2002 Perception 31 657-674). However, when both the sclera and the skin surrounding it were darkened simultaneously as if by a cast shadow, the apparent direction of gaze shifted less than when only the sclera was darkened. The results suggest that one mechanism for gaze judgment is based on a simple analysis of the local luminance ratio between the eye and the surrounding region.     

Spatial Simon effects and compatibility effects induced by observed gaze direction

Preconditions for the processing of observed gaze direction were studied by spatial Simon and compatibility effects. In five experiments, responses in the direction of a gaze were faster than responses in the opposite direction. Gaze direction influenced response speed although its processing was not required (Experiments 1, 2, 4, and 5). The result supports the notion of an inclination to process observed gaze direction in humans. However, the processes underlying the Simon effect of observed gaze direction were relatively time-consuming: Simon effects induced by gaze direction increased with response speed. Focusing of attention seemed to be part of the necessary processes: Simon effects were eliminated if attention was focused away from the eyes (Experiment 2). Further, if the processing of observed gaze direction was required, Simon effects by faces' observer-relative screen positions were absent (Experiment 3). Control conditions revealed that Simon effects by gaze direction can be produced with faces tilted by 90°, but that corresponding Simon effects do not result from numerical stimuli with an analogue spatial structure (Experiment 4), and that Simon effects result from gaze directions of scrambled faces (Experiment 5).     

Subliminal gaze cues increase preference levels for items in the gaze direction

Another individual’s gaze automatically shifts an observer’s attention to a location. This reflexive response occurs even when the gaze is presented subliminally over a short period. Another’s gaze also increases the preference level for items in the gaze direction; however, it was previously unclear if this effect occurs when the gaze is presented subliminally. This study showed that the preference levels for nonsense figures looked at by a subliminal gaze were significantly greater than those for items that were subliminally looked away from (Task 1). Targets that were looked at by a subliminal gaze were detected faster (Task 2); however, the participants were unable to detect the gaze direction (Task 3). These results indicate that another individual’s gaze automatically increases the preference levels for items in the gaze direction without conscious awareness.     

Effects of optical pitch on oculomotor control and the perception of target elevation

In two experiments, we used an ISCAN infrared video system to examine the influence of a pitched visual array on gaze elevation and on judgments of visually perceived eye level. In Experiment 1, subjects attempted to direct their gaze to arelaxed or to ahorizontal orientation while they were seated in a room whose walls were pitched at various angles with respect to gravity. Gaze elevation was biased in the direction in which the room was pitched. In Experiment 2, subjects looked into a small box that was pitched at various angles while they attempted simply to direct their gaze alone, or to direct their gaze and place a visual target at their apparent horizon. Both gaze elevation and target settings varied systematically with the pitch orientation of the box. Our results suggest that under these conditions, an optostatic response, of which the subject is unaware, is responsible for the changes in both gaze elevation and judgments of target elevation.     

Interaction effects of perceived gaze direction and dynamic facial expression: Evidence for appraisal theories of emotion

Appraisal theorists suggest that the face expresses cognitive processes involved both in the orienting of attention (primarily gaze direction) and in the evaluation of emotion-eliciting events. Contrary to the assumption of direct emotion recognition by basic emotions theorists, this implies an interaction effect between “perceived gaze direction” and “perceived facial expression” in inferring emotion from the face. These two theoretical perspectives were comparatively tested by requesting participants to decode dynamic synthetic facial expressions of emotion presented with either an averted or a direct gaze. Confirming the interaction predicted by appraisal theories, the perceived specificity and intensity of fear and anger depended on gaze direction (direct gaze for anger and averted gaze for fear).     

The effect of gaze on gaze direction while looking at art

In highly controlled cuing experiments, conspecific gaze direction has powerful effects on an observer’s attention. We explored the generality of this effect by using paintings in which the gaze direction of a key character had been carefully manipulated. Our observers looked at these paintings in one of three instructional states (neutral, social, or spatial) while we monitored their eye movements. Overt orienting was much less influenced by the critical gaze direction than what the cuing literature might suggest: An analysis of the direction of saccades following the first fixation of the critical gaze showed that observers were weakly biased to orient in the direction of the gaze. Over longer periods of viewing, however, this effect disappeared for all but the social condition. This restriction of gaze as an attentional cue to a social context is consistent with the idea that the evolution of gaze direction detection is rooted in social communication. The picture stimuli from this experiment can be downloaded from the Psychonomic Society’s Archive of Norms, Stimuli, and Data, www.psychonomic.org/archive.     

Does facial expression affect attention orienting by gaze direction cues?

In 6 experiments, the authors investigated whether attention orienting by gaze direction is modulated by the emotional expression (neutral, happy, angry, or fearful) on the face. The results showed a clear spatial cuing effect by gaze direction but no effect by facial expression. In addition, it was shown that the cuing effect was stronger with schematic faces than with real faces, that gaze cuing could be achieved at very short stimulus onset asynchronies (14 ms), and that there was no evidence for a difference in the strength of cuing triggered by static gaze cues and by cues involving apparent motion of the pupils. In sum, the results suggest that in normal, healthy adults, eye direction processing for attention shifts is independent of facial expression analysis.     

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。     

Detection of emotional faces is modulated by the direction of eye gaze

Emotionally expressive faces have shown enhanced detectability over neutral faces, but little is known about the effect of eye gaze on detecting the presence of emotional faces. Emotional expressions and gaze direction are both cues to the intentions of another person, and gaze direction has been shown to affect recognition accuracy and perceived intensity of emotional faces. The current study showed that fearful faces were detected more frequently with an averted gaze than with a direct gaze in an attentional blink task, whereas angry and happy faces were detected more frequently with a direct gaze than with an averted gaze. The results are in line with the shared signal hypothesis and appraisal theory and suggest that selection for awareness was based on a rapid evaluation of the intentions of another person as conveyed by their facial expression and gaze direction.     

Temporal shifts in eye gaze and facial expressions independently contribute to the perceived attractiveness of unfamiliar faces

ABSTRACT

We investigated whether attractiveness ratings of expressive faces would be affected by gaze shifts towards or away from the observer. In all experiments, effects of facial expression were found, with higher attractiveness ratings to positive over negative expressions, irrespective of effects of gaze-shifts. In the first experiment faces with gaze shifts away from the observer were preferred. However, when the dynamics of the gaze shift was disrupted, by adding an intermediate delay, the effect of direction of gaze shift disappeared. By manipulating the relative duration of each gaze direction during a gaze shift we found higher attractiveness ratings to faces with a longer duration of direct gaze, particularly in the initial exposure to a face. Our findings suggest that although the temporal dynamics of eye gaze and facial expressions influence the aesthetic evaluation of faces, these cues appear to act independently rather than in an integrated manner for social perception.     

头部朝向在社会性注意转移中的作用

注视指向是非常重要的社会性注意线索,但是在日常情境中,注视指向往往伴随着头部朝向信息,而且两者都包含空间指向信息.已有研究发现头部朝向会影响注视指向知觉的速度和准确性,为注视指向提供参照系,进而会影响注视指向诱发的社会性注意.头部朝向和注视指向加工的神经机制也存在着广泛的重合.因此,除眼睛注视以外,头部朝向也是建构和完善基于心理模型的社会性注意机制的一个关键因素.未来的研究应关注头部朝向与眼睛注视指向共同影响注意转移的作用机制,并且从功能整合的角度开展神经机制研究.     

视觉搜索任务中直视探测优势的眼动研究

已有研究发现在视觉搜索任务中对直视的探测比斜视更快且更准确, 该现象被命名为“人群中的凝视效应”。大多数研究者将该效应的产生归因于直视会捕获更多的注意。然而, 直视条件下对搜索项的匹配加工更容易也有可能导致对直视的探测比斜视快。此外,已有研究还发现头的朝向会影响对注视方向的探测, 但对于其产生原因缺乏实验验证。本研究采用视觉搜索范式, 运用眼动技术, 把注视探测的视觉搜索过程分为准备阶段、搜索阶段和反应阶段, 对这两个问题进行了探讨。结果显示：对直视的探测优势主要表现在搜索阶段和反应阶段; 在搜索阶段直视的探测优势获益于搜索路径的变短和分心项数量的变少以及分心项平均注视时间的变短; 头的朝向仅在搜索阶段对注视探测产生影响。该结果表明, 在直视探测中对搜索项的匹配加工比在斜视探测中更容易也是导致“人群中的凝视效应”的原因之一; 头的朝向仅仅影响了对注视方向的搜索并没有影响对其的确认加工。     

What are you looking at? Acuity for triadic eye gaze

The authors measured observers' ability to determine direction of gaze toward an object in space. In Experiment 1, they determined the difference threshold for determining whether a live "looker" was looking to the left or right of a target point. Acuity for eye direction was quite high (approximately 30 s arc). Viewing the movement of the looker's eyes did not improve acuity. When one of the looker's eyes was occluded, the observers' acuity was disrupted and their point of subjective equality was shifted away from the exposed eye. Experiment 2 was a replication of Experiment 1, but digitized gaze displays were used. The results of Experiment 3 showed that the acuity for direction of gaze depended on the position of the looker's target. Overall, the results indicated that humans are highly sensitive to gaze direction and that information from both eyes is used to determine direction of regard.     

The mutual influence of gaze and head orientation in the analysis of social attention direction

Three experiments are reported that investigate the hypothesis that head orientation and gaze direction interact in the processing of another individual's direction of social attention. A Stroop-type interference paradigm was adopted, in which gaze and head cues were placed into conflict. In separate blocks of trials, participants were asked to make speeded keypress responses contingent on either the direction of gaze, or the orientation of the head displayed in a digitized photograph of a male face. In Experiments 1 and 2, head and gaze cues showed symmetrical interference effects. Compared with congruent arrangements, incongruent head cues slowed responses to gaze cues, and incongruent gaze cues slowed responses to head cues, suggesting that head and gaze are mutually influential in the analysis of social attention direction. This mutuality was also evident in a cross-modal version of the task (Experiment 3) where participants responded to spoken directional words whilst ignoring the head/gaze images. It is argued that these interference effects arise from the independent influences of gaze and head orientation on decisions concerning social attention direction.     

The effect of facial expression and gaze direction on memory for unfamiliar faces

We report data from an experiment that investigated the influence of gaze direction and facial expression on face memory. Participants were shown a set of unfamiliar faces with either happy or angry facial expressions, which were either gazing straight ahead or had their gaze averted to one side. Memory for faces that were initially shown with angry expressions was found to be poorer when these faces had averted as opposed to direct gaze, whereas memory for individuals shown with happy faces was unaffected by gaze direction. We suggest that memory for another individual's face partly depends on an evaluation of the behavioural intention of that individual.     

The effect of facial expression and gaze direction on memory for unfamiliar faces

We report data from an experiment that investigated the influence of gaze direction and facial expression on face memory. Participants were shown a set of unfamiliar faces with either happy or angry facial expressions, which were either gazing straight ahead or had their gaze averted to one side. Memory for faces that were initially shown with angry expressions was found to be poorer when these faces had averted as opposed to direct gaze, whereas memory for individuals shown with happy faces was unaffected by gaze direction. We suggest that memory for another individual's face partly depends on an evaluation of the behavioural intention of that individual.     

Eye remember you two: gaze direction modulates face recognition in a developmental study

The effects of gaze direction on memory for faces were studied in children from three different age groups (6-7, 8-9, and 10-11 years old) using a computerized version of a task devised by Hood, Macrae, Cole-Davies and Dias (2003). Participants were presented with a sequence of faces in an encoding phase, and were then required to judge which faces they had previously encountered in a surprise two-alternative forced-choice recognition test. In one condition, stimulus eye gaze was either direct or deviated at the viewing phase, and eyes were closed at the test phase. In another condition, stimulus eyes were closed at the viewing phase, with either direct or deviated gaze at the test phase. Modulation of gaze direction affected hit rates, with participants demonstrating greater accuracy for direct gaze targets compared to deviated gaze targets in both conditions. Reaction times (RT) to correctly recognized stimuli were faster for direct gaze stimuli at the viewing phase, but not at the test phase. The age group of participants differentially affected these measures: there was a greater hit rate advantage for direct gaze stimuli in older children, although RTs were less affected by age. These findings suggest that while the facilitation of face recognition by gaze direction is robust across encoding and recognition stages, the efficiency of the process is affected by the stage at which gaze is modulated.     

Affect in the eyes: explicit and implicit evaluations

The present study investigated whether another individual’s gaze direction influences an observer’s affective responses. In Experiment 1, subjective self-ratings and an affective priming paradigm were employed to examine how participants explicitly and implicitly, respectively, evaluated the affective valence of direct gaze, averted gaze, and closed eyes. The explicit self-ratings showed that participants evaluated closed eyes more positively than direct gaze. However, the implicit priming task showed an inverse pattern of results indicating that direct gaze was automatically evaluated more positively than closed eyes were. Experiment 2 confirmed that the opposite patterns of results between the two tasks were not due to differences in presentation times of the gaze stimuli. The results provide evidence for automatic affective reactions to eye gaze and indicate a dissociation between explicit and implicit affective evaluations of eyes and gaze direction.     

Spatial attentional distribution is modulated by head direction during eccentric gaze

Visual perception during eccentric gaze can be facilitated when a visual stimulus appears in front of the head direction. This study investigated the relative effects of gaze location and head direction on visual perception in central and peripheral vision. Participants identified the orientation of a T-shaped figure presented in the centre of a monitor and simultaneously localised a dot appearing in the periphery, while head direction relative to gaze location was to the left, right or centre. Effects of head direction were found only when the dot appeared far from the gaze fixation point, such that dot detection was superior when it appeared to the left (right) of fixation in the left (right) head direction. Experimental results indicated this was not due to a small shift of gaze location. Thus this study suggests that head direction influences visual perception particularly in peripheral vision where visual acuity decreases.