Gaze cueing as a function of perceived gaze direction

Previous studies have found that attention is automatically oriented in the direction of other people's gaze. This study directly investigated whether the perceiving gaze direction modulates the orienting of observers' attention. Gaze perception was manipulated by changing the face context (head orientation) of the gaze cue: the perceived gaze angle was increased (or decreased) when the head and gaze are congruent (or incongruent), while the local‐feature information of the eye region was preserved for all stimuli. The results showed that gaze‐cueing effects were enhanced when the perceived gaze direction was averted more toward left or right, and reduced when the perceived gaze direction was closer to direct gaze. The results suggest that gaze‐cueing effects are based on mechanisms specialized for gaze perception, and the magnitude of gaze‐cueing effects was probably a function of the perceived gaze direction.     

Does matching of internal and external facial features depend on orientation and viewpoint?

Although it is recognized that external (hair, head and face outline, ears) and internal (eyes, eyebrows, nose, mouth) features contribute differently to face recognition it is unclear whether both feature classes predominately stimulate different sensory pathways. We employed a sequential speed-matching task to study face perception with internal and external features in the context of intact faces, and at two levels of contextual congruency. Both internal and external features were matched faster and more accurately in the context of totally congruent/incongruent facial stimuli compared to just featurally congruent/incongruent faces. Matching of totally congruent/incongruent faces was not affected by the matching criteria, but was strongly modulated by orientation and viewpoint. On the contrary, matching of just featurally congruent/incongruent faces was found to depend on the feature class to be attended, with strong effects of orientation and viewpoint only for matching of internal features, but not of external features. The data support the notion that different processing mechanisms are involved for both feature types, with internal features being handled by configuration sensitive mechanisms whereas featural processing modes dominate when external features are the focus.     

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.     

Talking heads or talking eyes? Effects of head orientation and sudden onset gaze cues on attention capture

The direction of gaze towards or away from an observer has immediate effects on attentional processing in the observer. Previous research indicates that faces with direct gaze are processed more efficiently than faces with averted gaze. We recently reported additional processing advantages for faces that suddenly adopt direct gaze (abruptly shift from averted to direct gaze) relative to static direct gaze (always in direct gaze), sudden averted gaze (abruptly shift from direct to averted gaze), and static averted gaze (always in averted gaze). Because changes in gaze orientation in previous study co-occurred with changes in head orientation, it was not clear if the effect is contingent on face or eye processing, or whether it requires both the eyes and the face to provide consistent information. The present study delineates the impact of head orientation, sudden onset motion cues, and gaze cues. Participants completed a target-detection task in which head position remained in a static averted or direct orientation while sudden onset motion and eye gaze cues were manipulated within each trial. The results indicate a sudden direct gaze advantage that resulted from the additive role of motion and gaze cues. Interestingly, the orientation of the face towards or away from the observer did not influence the sudden direct gaze effect, suggesting that eye gaze cues, not face orientation cues, are critical for the sudden direct gaze effect.     

Straight gaze facilitates face processing but does not cause involuntary attentional capture

This study aimed to investigate the conditions under which eyes with a straight gaze capture attention more than eyes with an averted gaze, a phenomenon called the stare-in-the-crowd effect. In Experiment 1, we measured attentional capture by distractor faces with either straight or averted gaze that were shown among faces with closed eyes. Gaze direction of the distractor face was irrelevant because participants searched for a tilted face and indicated its gender. The presence of the distractor face with open eyes resulted in slower reaction times, but gaze direction had no effect, suggesting that straight gaze does not result in more involuntary attentional capture than averted gaze. In three further experiments with the same stimuli, the gaze direction of the target, and not the distractor, was varied. Better performance with straight than averted gaze of the target face was observed when the gaze direction or gender of the target face had to be discriminated. However, no difference between straight and averted was observed when only the presence of a face with open eyes had to be detected. Thus, the stare-in-the crowd effect is only observed when eye gaze is selected as part of the target and only when features of the face have to be discriminated. Our findings suggest that preference for straight gaze bears on target-related processes rather than on attentional capture per se.     

Effects of head orientation on gaze perception: How positive congruency effects can be reversed

Several past studies have considered how perceived head orientation may be combined with perceived gaze direction in judging where someone else is attending. In three experiments we tested the impact of different sources of information by examining the role of head orientation in gaze-direction judgements when presenting: (a) the whole face; (b) the face with the nose masked; (c) just the eye region, removing all other head-orientation cues apart from some visible part of the nose; or (d) just the eyes, with all parts of the nose masked and no head orientation cues present other than those within the eyes themselves. We also varied time pressure on gaze direction judgements. The results showed that gaze judgements were not solely driven by the eye region. Gaze perception can also be affected by parts of the head and face, but in a manner that depends on the time constraints for gaze direction judgements. While “positive” congruency effects were found with time pressure (i.e., faster left/right judgements of seen gaze when the seen head deviated towards the same side as that gaze), the opposite applied without time pressure.     

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.     

Perceptibility of schematic face stimuli: Evidence for a perceptual Gestalt

The perceptibility of face, scrambled face, and single-feature stimuli was investigated in three experiments. Stimuli were presented tachistoscopically, followed by a visual noise mask and a forced-choice test of one of three features (eyes, nose, and mouth). In Experiment I, two processing strategies which have been proposed for word perception (involving expectancy and redundancy) were investigated for the stimuli employed here. In Experiments II and III, experimentally induced familiarity was studied for its effect on recognition and perception, and an immediate and delayed perceptual test was employed. Across all three experiments, perception of single-feature and face stimuli were consistently superior to scrambled faces; in Experiment III, differences between single features and faces were eliminated. The effects of perceptual expectancy, internal feature redundancy, familiarity, guessing biases, etc., were shown to be insufficient to account for the superiority of face to scrambled face stimuli. It was argued that the perceptibility of nonredundant features are enhanced when those features are aligned in a well-defined form class. The view that familiarity operates directly on recognitive processes but indirectly on perceptual ones was discussed.     

Effects of head orientation on gaze perception: how positive congruency effects can be reversed

Several past studies have considered how perceived head orientation may be combined with perceived gaze direction in judging where someone else is attending. In three experiments we tested the impact of different sources of information by examining the role of head orientation in gaze-direction judgements when presenting: (a) the whole face; (b) the face with the nose masked; (c) just the eye region, removing all other head-orientation cues apart from some visible part of the nose; or (d) just the eyes, with all parts of the nose masked and no head orientation cues present other than those within the eyes themselves. We also varied time pressure on gaze direction judgements. The results showed that gaze judgements were not solely driven by the eye region. Gaze perception can also be affected by parts of the head and face, but in a manner that depends on the time constraints for gaze direction judgements. While “positive” congruency effects were found with time pressure (i.e., faster left/right judgements of seen gaze when the seen head deviated towards the same side as that gaze), the opposite applied without time pressure.     

Orienting of attention via observed eye gaze is head-centred

Observing averted eye gaze results in the automatic allocation of attention to the gazed-at location. The role of the orientation of the face that produces the gaze cue was investigated. The eyes in the face could look left or right in a head-centred frame, but the face itself could be oriented 90 degrees clockwise or anticlockwise such that the eyes were gazing up or down. Significant cueing effects to targets presented to the left or right of the screen were found in these head orientation conditions. This suggests that attention was directed to the side to which the eyes would have been looking towards, had the face been presented upright. This finding provides evidence that head orientation can affect gaze following, even when the head orientation alone is not a social cue. It also shows that the mechanism responsible for the allocation of attention following a gaze cue can be influenced by intrinsic object-based (i.e. head-centred) properties of the task-irrelevant cue.     

Anticipating intentional actions: The effect of eye gaze direction on the judgment of head rotation

Using a representational momentum paradigm, this study investigated the hypothesis that judgments of how far another agent’s head has rotated are influenced by the perceived gaze direction of the head. Participants observed a video-clip of a face rotating 60° towards them starting from the left or right profile view. The gaze direction of the face was either congruent with, ahead of, or lagging behind the angle of rotation. Following this, two static faces, at varying angles of rotation with respect to the end-point angle of the face in the video-clip, were presented simultaneously. The task of the participants was to decide which of the two heads was at an angle best resembling the angle of the end-point of the moving face. The critical test condition consisted of one test face oriented at 10° before, and the other at 10° after the end-point. The ‘lagging behind’ gaze condition elicited a significant underestimation of the rotation compared to the ‘congruent’ and ‘ahead’ gaze conditions. Participants did not exhibit similar biases when judging the rotation of several non-face control stimuli with visual features that mimicked different aspects of gaze direction. The findings suggest that when the gaze direction of a perceived agent is incongruent with the direction of the agent’s head motion observers automatically utilise this discrepancy to adjust their inferences about the agent’s intended heading direction.     

Direct gaze captures visuospatial attention

This study investigated whether the direct gaze of others influences attentional disengagement from faces in an experimental situation. Participants were required to fixate on a centrally presented face with varying gaze directions and to detect the appearance of a peripheral target as quickly as possible. Results revealed that target detection was delayed when the preceding face was directly gazing at the subject (direct gaze), as compared with an averted gaze (averted gaze) or with closed eyes (closed eyes). This effect disappeared when a temporal gap was inserted between the offset of the centrally presented face and the onset of a peripheral target, suggesting that attentional disengagement contributed to the delayed response in the direct gaze condition. The response delay to direct gaze was not found when the contrast polarity of eyes in the facial stimuli was reversed, reinforcing the importance of gaze perception in delayed disengagement from direct gaze.     

I thought you were looking at me: direction-specific aftereffects in gaze perception

Gaze direction is an important social signal in humans and other primates. In this study, we used an adaptation paradigm to investigate the functional organization of gaze perception in humans. Adaptation to consistent leftward or rightward gaze produced a powerful illusion that virtually eliminated observers' perception of gaze in the adapted direction; gaze to that side was seen as pointing straight ahead, though perception of gaze to the opposite side was unimpaired. This striking dissociation held even when retinotopic mapping between adaptation and test stimuli was disrupted by changes in size or head orientation, suggesting that our findings do not reflect adaptation to low-level visual properties. Moreover, adaptation to averted gaze did not affect judgments of line bisection, illustrating that our findings do not reflect a general spatial bias. Our findings provide evidence that humans have distinct populations of neurons that are selectively responsive to particular directions of seen gaze.     

The neural fate of individual item representations in visual working memory

Previous research has demonstrated an interaction between eye gaze and selected facial emotional expressions, whereby the perception of anger and happiness is impaired when the eyes are horizontally averted within a face, but the perception of fear and sadness is enhanced under the same conditions. The current study reexamined these claims over six experiments. In the first three experiments, the categorization of happy and sad expressions (Experiments 1 and 2) and angry and fearful expressions (Experiment 3) was impaired when eye gaze was averted, in comparison to direct gaze conditions. Experiment 4 replicated these findings in a rating task, which combined all four expressions within the same design. Experiments 5 and 6 then showed that previous findings, that the perception of selected expressions is enhanced under averted gaze, are stimulus and task-bound. The results are discussed in relation to research on facial expression processing and visual attention.     

Visual search for object orientation can be modulated by canonical orientation

The authors studied the influence of canonical orientation on visual search for object orientation. Displays consisted of pictures of animals whose axis of elongation was either vertical or tilted in their canonical orientation. Target orientation could be either congruent or incongruent with the object's canonical orientation. In Experiment 1, vertical canonical targets were detected faster when they were tilted (incongruent) than when they were vertical (congruent). This search asymmetry was reversed for tilted canonical targets. The effect of canonical orientation was partially preserved when objects were high-pass filtered, but it was eliminated when they were low-pass filtered, rendering them as unfamiliar shapes (Experiment 2). The effect of canonical orientation was also eliminated by inverting the objects (Experiment 3) and in a patient with visual agnosia (Experiment 4). These results indicate that orientation search with familiar objects can be modulated by canonical orientation, and they indicate a top-down influence on orientation processing.     

Determining the influence of Gaussian blurring on inversion effects with talking faces

Perception of visual speech and the influence of visual speech on auditory speech perception is affected by the orientation of a talker's face, but the nature of the visual information underlying this effect has yet to be established. Here, we examine the contributions of visually coarse (configural) and fine (featural) facial movement information to inversion effects in the perception of visual and audiovisual speech. We describe two experiments in which we disrupted perception of fine facial detail by decreasing spatial frequency (blurring) and disrupted perception of coarse configural information by facial inversion. For normal, unblurred talking faces, facial inversion had no influence on visual speech identification or on the effects of congruent or incongruent visual speech movements on perception of auditory speech. However, for blurred faces, facial inversion reduced identification of unimodal visual speech and effects of visual speech on perception of congruent and incongruent auditory speech. These effects were more pronounced for words whose appearance may be defined by fine featural detail. Implications for the nature of inversion effects in visual and audiovisual speech are discussed.     

Anxiety and sensitivity to gaze direction in emotionally expressive faces

This study investigated the role of neutral, happy, fearful, and angry facial expressions in enhancing orienting to the direction of eye gaze. Photographs of faces with either direct or averted gaze were presented. A target letter (T or L) appeared unpredictably to the left or the right of the face, either 300 ms or 700 ms after gaze direction changed. Response times were faster in congruent conditions (i.e., when the eyes gazed toward the target) relative to incongruent conditions (when the eyes gazed away from the target letter). Facial expression did influence reaction times, but these effects were qualified by individual differences in self-reported anxiety. High trait-anxious participants showed an enhanced orienting to the eye gaze of faces with fearful expressions relative to all other expressions. In contrast, when the eyes stared straight ahead, trait anxiety was associated with slower responding when the facial expressions depicted anger. Thus, in anxiety-prone people attention is more likely to be held by an expression of anger, whereas attention is guided more potently by fearful facial expressions.     

Configural processing in the perception of eye-gaze direction

Traditional accounts of gaze perception emphasise the geometric or configural cues present in the eye; the position of the iris in relation to the corner of the eye, for example. This kind of geometric account has been supported, in part, by findings that gaze judgments are impaired in faces rotated through 180 degrees, a manipulation known to disrupt the processing of relations between facial elements. However, studies involving this manipulation have confounded inversion of the face context with inversion of the eye region. The effects of inversion might therefore have been caused by a disruption of the computation of gaze direction from the eye region itself and/or a disruption of the influence that face context might exert on gaze processing. In the experiment reported here we independently manipulated eye orientation and the orientation of the face context, and measured participants' sensitivity to gaze direction. Performance was severely affected by inversion of the eyes, regardless of the orientation of the face, whereas face inversion had no significant effect on gaze sensitivity. Previous reports of a face-inversion effect on gaze perception can therefore be attributed to inversion of the eye region itself which, we suggest, disrupts some form of configural or relational processing that is normally involved in the computation of eye-gaze direction.     

Watch out! Directional threat-related postures cue attention and the eyes

Previous work indicates that threatening facial expressions with averted eye gaze can act as a signal of imminent danger, enhancing attentional orienting in the gazed-at direction. However, this threat-related gaze-cueing effect is only present in individuals reporting high levels of anxiety. The present study used eye tracking to investigate whether additional directional social cues, such as averted angry and fearful human body postures, not only cue attention, but also the eyes. The data show that although body direction did not predict target location, anxious individuals made faster eye movements when fearful or angry postures were facing towards (congruent condition) rather than away (incongruent condition) from peripheral targets. Our results provide evidence for attentional cueing in response to threat-related directional body postures in those with anxiety. This suggests that for such individuals, attention is guided by threatening social stimuli in ways that can influence and bias eye movement behaviour.     

The role of facial colour and luminance in visual and audiovisual speech perception

We conducted four experiments to investigate the role of colour and luminance information in visual and audiovisual speech perception. In experiments 1a (stimuli presented in quiet conditions) and 1b (stimuli presented in auditory noise), face display types comprised naturalistic colour (NC), grey-scale (GS), and luminance inverted (LI) faces. In experiments 2a (quiet) and 2b (noise), face display types comprised NC, colour inverted (CI), LI, and colour and luminance inverted (CLI) faces. Six syllables and twenty-two words were used to produce auditory and visual speech stimuli. Auditory and visual signals were combined to produce congruent and incongruent audiovisual speech stimuli. Experiments 1a and 1b showed that perception of visual speech, and its influence on identifying the auditory components of congruent and incongruent audiovisual speech, was less for LI than for either NC or GS faces, which produced identical results. Experiments 2a and 2b showed that perception of visual speech, and influences on perception of incongruent auditory speech, was less for LI and CLI faces than for NC and CI faces (which produced identical patterns of performance). Our findings for NC and CI faces suggest that colour is not critical for perception of visual and audiovisual speech. The effect of luminance inversion on performance accuracy was relatively small (5%), which suggests that the luminance information preserved in LI faces is important for the processing of visual and audiovisual speech.