Gaze as depicted in Vermeer's Girl with a Pearl Earring

Ten observers viewed Vermeer's painting Girl With a Pearl Earring and estimated her direction of gaze when her eyes were exposed together and separately. The observers also viewed the painting when her eyes were digitally replaced by those of a real person. The authors found that Vermeer painted the girl's eyes with a precision that was near the limits of visual acuity. Also, Vermeer included 3 gaze illusions, none of which researchers have documented as known in Vermeer's time: (a) when a model whose head is turned to one side gazes at an observer, there is an illusion that she is looking to the side of the observer away from the direction of her head turn; (b) when a model's eyes are viewed separately, they appear to gaze outward relative to each other; and (c) when both of a model's eyes are viewed, the perceived direction of gaze follows that of the nearer eye.     

How the Eyes Tell Lies: Social Gaze During a Preference Task

Social attention is thought to require detecting the eyes of others and following their gaze. To be effective, observers must also be able to infer the person's thoughts and feelings about what he or she is looking at, but this has only rarely been investigated in laboratory studies. In this study, participants' eye movements were recorded while they chose which of four patterns they preferred. New observers were subsequently able to reliably guess the preference response by watching a replay of the fixations. Moreover, when asked to mislead the person guessing, participants changed their looking behavior and guessing success was reduced. In a second experiment, naïve participants could also guess the preference of the original observers but were unable to identify trials which were lies. These results confirm that people can spontaneously use the gaze of others to infer their judgments, but also that these inferences are open to deception.     

Active gaze, visual look-ahead, and locomotor control

The authors examined observers steering through a series of obstacles to determine the role of active gaze in shaping locomotor trajectories. Participants sat on a bicycle trainer integrated with a large field-of-view simulator and steered through a series of slalom gates. Steering behavior was determined by examining the passing distance through gates and the smoothness of trajectory. Gaze monitoring revealed which slalom targets were fixated and for how long. Participants tended to track the most immediate gate until it was about 1.5 s away, at which point gaze switched to the next slalom gate. To probe this gaze pattern, the authors then introduced a number of experimental conditions that placed spatial or temporal constraints on where participants could look and when. These manipulations resulted in systematic steering errors when observers were forced to use unnatural looking patterns, but errors were reduced when peripheral monitoring of obstacles was allowed. A steering model based on active gaze sampling is proposed, informed by the experimental conditions and consistent with observations in free-gaze experiments and with recommendations from real-world high-speed steering.     

The positive and negative of human expertise in gaze perception

Judging where others look is crucial for many social and cognitive functions. Past accounts of gaze perception emphasize geometrical cues from the seen eye. Human eyes have a unique morphology, with a large white surround (sclera) to the dark iris that may have evolved to enhance gaze processing. Here we show that the contrast polarity of seen eyes has a powerful influence on gaze perception. Adult observers are highly inaccurate in judging gaze direction for images of human eyes with negative contrast polarity (regardless of whether the surrounding face is positive or negative), even though negative images of eyes preserve the geometric properties of positives that are judged accurately. The detrimental effect of negative contrast polarity is much larger for gaze perception than for other directional judgements (e.g. judging which way a head is turned). These results suggest an 'expert' system for gaze perception, which always treats the darker region of a seen eye as the part that does the looking.     

Are you looking at me? Measuring the cone of gaze

The processing of gaze cues plays an important role in social interactions, and mutual gaze in particular is relevant for natural as well as video-mediated communications. Mutual gaze occurs when an observer looks at or in the direction of the eyes of another person. The authors chose the metaphor of a cone of gaze to characterize this range of gaze directions that constitutes "looking at" another person. In 4 experiments using either a real person or a virtual head, the authors investigated the influences of observer distance, head orientation, visibility of the eyes, and the presence of a 2nd head on the perceived direction and width of the gaze cone. The direction of the gaze cone was largely affected by all experimental manipulations, whereas its angular width remained comparatively stable.     

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.     

The effects of adults' affective expression and direction of visual gaze on 12‐month‐olds' visual preferences for an object following a 5‐minute, 1‐day,or 1‐month delay

Between 12‐ and 14 months of age infants begin to use another's direction of gaze and affective expression in learning about various objects and events. What is not well understood is how long infants' behaviour towards a previously unfamiliar object continues to be influenced following their participation in circumstances of social referencing. In this experiment, we examined infants' sensitivity to an adult's direction of gaze and their visual preference for one of two objects following a 5‐min, 1‐day, or 1‐month delay. Ninety‐six 12‐month‐olds participated. For half of the infants during habituation (i.e., familiarization), the adults' direction of gaze was directed towards an unfamiliar object (look condition). For the remaining half of the infants during habituation, the adults' direction of gaze was directed away from the unfamiliar object (look‐away condition). All infants were habituated to two events. One event consisted of an adult looking towards (look condition) or away from (look‐away condition) an object while facially and vocally conveying a positive affective expression. The second event consisted of the same adult looking towards or away from a different object while conveying a disgusted affective expression. Following the habituation phase and a 5‐min, 1‐day, or 1‐month delay, infants' visual preference was assessed. During the visual preference phase, infants saw the two objects side by side where the adult conveying the affective expression was not visible. Results of the visual preference phase indicate that infants in the look condition showed a significant preference for object previously paired with the positive affect following a 5‐min and 1‐day delay. No significant visual preference was found in the look condition following a 1‐month delay. No significant preferences were found at any retention interval in the look‐away condition. Results are discussed in terms of early learning, social referencing, and early memory.     

Real Men Don't Look Down: Direction of Gaze Affects Sex Decisions on Faces

Classifying a face as male or female was shown to be reliably affected by the direction in which the face was looking—a variable apparently unrelated to reported features of the face that show sexual dimorphism. Decisions were slower when gaze was averted downwards. Furthermore, masculinity ratings were lower for men's faces looking down than for the same faces looking ahead. One high-level (configurational) face feature that varies with the sex of the face and with direction of gaze was identified. The vertical upper-lid-to-brow distance is smaller in men than in women and becomes less salient when eyes are averted down. This display feature may have evolved to signal gender quickly and reliably, especially in alert male faces.     

Resolving ambiguous behavioral intentions by means of involuntary prioritization of gaze processing

Anticipation of others' actions is of paramount importance in social interactions. Cues such as gaze direction and facial expressions can be informative, but can also produce ambiguity with respect to others' intentions. We investigated the combined effect of an actor's gaze and expression on judgments made by observers about the end-point of the actor's head rotation toward the observer. Expressions of approach gave rise to an unambiguous intention to move toward the observer, while expressions of avoidance gave rise to an ambiguous behavioral intention (as the expression and motion cues were in conflict). In the ambiguous condition, observers overestimated how far the actor's head had rotated when the actor's gaze was directed ahead of head rotation (compared to congruent or lagging behind). In the unambiguous condition the estimations were not influenced by the gaze manipulation. These results show that social cue integration does not follow simple additive rules, and suggests that the involuntary allocation of attention to another's gaze depends on the perceived ambiguity of the agent's behavioral intentions.     

Detecting and identifying offset gaze

A number of experiments have demonstrated that observers can accurately identify stimuli that they fail to detect (Rollman and Nachmias, 1972; Harris and Fahle, 1995; Allik et al. 1982, 2014). Using a 2x2AFC double judgements procedure, we demonstrated an analogous pattern of performance in making judgements about the direction of eye gaze. Participants were shown two faces in succession: one with direct gaze and one with gaze offset to the left or right. We found that they could identify the direction of gaze offset (left/right) better than they could detect which face contained the offset gaze. A simple Thurstonian model, under which the detection judgement is shown to be more computationally complex, was found to explain the empirical data. A further experiment incorporated metacognitive ratings into the double judgements procedure to measure observers’ metacognitive awareness (Meta-d’) across the two judgements and to assess whether observers were aware of the evidence for offset gaze when detection performance was at and below threshold. Results suggest that metacognitive awareness is tied to performance, with approximately equal Meta-d’ across the two judgements, when sensitivity is taken into account. These results show that both performance and metacognitive awareness rely not only on the strength of sensory evidence but also on the computational complexity of the decision, which determines the relative distance of that evidence from the decision axes.     

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.     

The role of gaze and road edge information during high-speed locomotion

Robust control of skilled actions requires the flexible combination of multiple sources of information. Here we examined the role of gaze during high-speed locomotor steering and in particular the role of feedback from the visible road edges. Participants were required to maintain one of three lateral positions on the road when one or both edges were degraded (either by fading or removing them). Steering became increasingly impaired as road edge information was degraded, with gaze being predominantly directed toward the required road position. When either of the road edges were removed, we observed systematic shifts in steering and gaze direction dependent upon both the required road position and the visible edge. A second experiment required fixation on the road center or beyond the road edges. The results showed that the direction of gaze led to predictable steering biases, which increased as road edge information became degraded. A new steering model demonstrates that the direction of gaze and both road edges influence steering in a manner consistent with the flexible weighted combination of near road feedback information and prospective gaze information.     

Where a person with a squint is actually looking: Gaze-cued orienting in crossed eyes

In this study, we investigated gaze-cued attention orienting when the perceived eyes are not looking in the same direction. This condition occurs in strabismus (squint). Participants were asked to detect laterally presented reaction signals preceded by schematic faces in which the direction (left, straight, or right) of the left and right eye was independently manipulated. Consistent with earlier studies, the results showed a reliable cuing effect by two eyes with parallel gaze direction. Gaze-cued orienting was also shown in a situation when one eye was averted and the other eye was looking straight ahead. The gaze cuing was not significantly stronger in the former than in the latter situation. When both eyes were either nasally or temporally averted, no shifts of visual attention were observed. The results suggest that, if both eyes are visible, the direction of both eyes is computed and integrated for the gaze-cued orienting.     

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.     

Effects of facial expression and gaze direction on approach-avoidance behaviour

Humans must coordinate approach-avoidance behaviours with the social cues that elicit them, such as facial expressions and gaze direction. We hypothesised that when someone is observed looking in a particular direction with a happy expression, the observer would tend to approach that direction, but that when someone is observed looking in a particular direction with a fearful expression, the observer would tend to avoid that direction. Twenty-eight participants viewed stimulus faces with averted gazes and happy or fearful expressions on a computer screen. Participants were asked to grasp (approach) or withdraw from (avoid) a left- or right-hand button depending on the stimulus face's expression. The results were consistent with our hypotheses about avoidance responses, but not with respect to approach responses. Links between social cues and adaptive behaviour are discussed.     

Perception of pictorial eye gaze by baboons (Papio papio)

Pictorial faces looking left or right were presented to baboons (Papio papio) before the display of a target letter in the left or right hemifield of a monitor screen. Baboons had to provide go or no-go responses taking into account the identity of the target letter. The 1st 6 experiments showed no reliable effect of eye gaze on discrimination speed, using either schematic gazes or pictures of real gazes. Experiment 7 showed that eye gazes facilitated target processing when eye cues were perfect predictors of target location. Findings suggest that baboons do not spontaneously process eye-gaze direction but can learn to do so if the gaze has a predictive value. Implications of these findings on baboons' perspective-taking abilities are discussed.     

Affective evaluations of objects are influenced by observed gaze direction and emotional expression

Gaze direction signals another person's focus of interest. Facial expressions convey information about their mental state. Appropriate responses to these signals should reflect their combined influence, yet current evidence suggests that gaze-cueing effects for objects near an observed face are not modulated by its emotional expression. Here, we extend the investigation of perceived gaze direction and emotional expression by considering their combined influence on affective judgments. While traditional response-time measures revealed equal gaze-cueing effects for happy and disgust faces, affective evaluations critically depended on the combined product of gaze and emotion. Target objects looked at with a happy expression were liked more than objects looked at with a disgust expression. Objects not looked at were rated equally for both expressions. Our results demonstrate that facial expression does modulate the way that observers utilize gaze cues: Objects attended by others are evaluated according to the valence of their facial expression.     

Emotional expression affects the accuracy of gaze perception

Emotional facial expressions are powerful social cues. Here we investigated how emotional expression affects the interpretation of eye gaze direction. Fifty-two observers judged where faces were looking by moving a slider on a measuring bar to the respective position. The faces displayed either an angry, happy, fearful or a neutral expression and were looking either straight at the observer, or were rotated 2°, 4°, 6° or 8° to the left and right. We found that happy faces were interpreted as directed closer to the observer, while fearful and angry faces were interpreted as directed further away. Judgments were most accurate for neutral faces, followed by happy, angry and fearful faces. These findings are discussed on the background of the “self-referential positivity bias”, suggesting that happy faces are preferably interpreted as directed towards the self while negative emotions are interpreted as directed further away.     

Scrutinizing visual images: The role of gaze in mental imagery and memory

Gaze was monitored by use of an infrared remote eye-tracker during perception and imagery of geometric forms and figures of animals. Based on the idea that gaze prioritizes locations where features with high information content are visible, we hypothesized that eye fixations should focus on regions that contain one or more local features that are relevant for object recognition. Most importantly, we predicted that when observers looked at an empty screen and at the same time generated a detailed visual image of what they had previously seen, their gaze would probabilistically dwell within regions corresponding to the original positions of salient features or parts. Correlation analyses showed positive relations between gaze’s dwell time within locations visited during perception and those in which gaze dwelled during the imagery generation task. Moreover, the more faithful an observer’s gaze enactment, the more accurate was the observer’s memory, in a separate test, of the dimension or size in which the forms had been perceived. In another experiment, observers saw a series of pictures of animals and were requested to memorize them. They were then asked later, in a recall phase, to answer a question about a property of one of the encoded forms; it was found that, when retrieving from long-term memory a previously seen picture, gaze returned to the location of the part probed by the question. In another experimental condition, the observers were asked to maintain fixation away from the original location of the shape while thinking about the answer, so as to interfere with the gaze enactment process; such a manipulation resulted in measurable costs in the quality of memory. We conclude that the generation of mental images relies upon a process of enactment of gaze that can be beneficial to visual memory.     

Effects of facial expression and gaze direction on approach–avoidance behaviour

Humans must coordinate approach–avoidance behaviours with the social cues that elicit them, such as facial expressions and gaze direction. We hypothesised that when someone is observed looking in a particular direction with a happy expression, the observer would tend to approach that direction, but that when someone is observed looking in a particular direction with a fearful expression, the observer would tend to avoid that direction. Twenty-eight participants viewed stimulus faces with averted gazes and happy or fearful expressions on a computer screen. Participants were asked to grasp (approach) or withdraw from (avoid) a left- or right-hand button depending on the stimulus face's expression. The results were consistent with our hypotheses about avoidance responses, but not with respect to approach responses. Links between social cues and adaptive behaviour are discussed.