How the eyes affect the I: Gaze perception, cognition and the robot-human interface

A good deal of research has shown that humans are particularly sensitive to gaze direction. Indeed we may well have evolved neural mechanisms dedicated to the perception of the eyes and eye-gaze direction. As well as providing a very strong signal to our perceptual systems eye-gaze also produces a number of cognitive effects. This paper reviews a number of studies suggesting that both eye-gaze direction, and head orientation are processed automatically by our cognitive systems interfering with the processing of auditory directional information, triggering reflexive shifts of attention, influencing the information we extract from natural scenes and the performance of certain communicative tasks. Given the potential for social attention cues to influence aspects of cognitive activity, it would seem critical for designers to pay particular attention to the appearance and movement of the eyes and head in the creation of robot-human interfaces

Gaze perception: is seeing influenced by believing?

Gaze perception has been thought to be stimulus-driven. This view is challenged by a new demonstration that a gaze direction aftereffect can be influenced by beliefs about the gazer's ability to see

I don’t see it your way: the dot perspective task does not gauge spontaneous perspective taking

Data from studies employing the dot-perspective task have been used to support the theory that humans are capable of automatically computing the visual perspective of other individuals. Recent work has challenged this interpretation, claiming instead that the results may arise through the automatic reorienting of attention triggered by observed head and gaze cues. The two experiments reported here offer a stronger test of the perspective taking account by replacing the computer generated avatars used in previous research with, respectively, photo-realistic stimuli, and socially co-present individuals in a “live”, face-to-face version of the task. In each study observers were faster to judge the number of dots in a display when either a digitized image depicting a human “gazer” (Experiment 1), or a socially co-present gazer (Experiment 2) could see the same number of dots as the observer, than when the number of dots visible to each was different. However, in both experiments this effect was also obtained in conditions where a barrier clearly occluded the gazers’ view of the target dots so that the perspectives of participants and gazers were always different. These results offer no support for the idea that participants are engaged in spontaneous perspective taking in the dot perspective task. It is argued that, instead, the results are likely caused by a spontaneous redirection of a viewer’s attention by the observed gazes, which is unlikely to involve representations of the gazer’s mental stat

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 use of pigmentation and shading information in recognising the sex and identities of faces

An investigation of what can be learned about representational processes in face recognition from the independent and combined effects of inverting and negating facial image is reported. In experiment 1, independent effects of inversion and negation were observed in a task of identifying famous faces. In experiments 2 through 4 the question of whether effects of negation were still obtained when effects due to the reversal of pigmentation in negative image were eliminated was examined. By the use of images of the 3-D surfaces of faces measured by laser, and displays as smooth surfaces devoid of pigmentation, only effects of inversion were obtained reliably, suggesting that the effects observed in experiment 8 arose largely through the inversion of pigmentation values in normal images of faces. The results of experiment 5 suggested that the difference was not due to the different task demands of experiments 2 - 4 compared with those of experiment 1. When normally pigmented face images were used in a task making similar demands to that of experiment 4, independent effects of inversion and negation were again observed. When a task of sex classification was used in experiment 6 and 7, clear effects of negation as well as inversion were observed on latencies, though not accuracies, of responding. The results are interpreted in terms of the information content of pigmentation relative to shape from shading in different face-classification tasks. Tbe results also reinforce other recent evidence demonstrating the importance of image intensity as well as spatial layout of face 'features'

The Health and Safety in Employment Act 1992 - An Overview

The Health and Safety in Employment Act 1992 (HSE Act or the Act) is a legislative initiative designed to address the problems posed by the previous statutory regimes. In essence this can be reduced to three objectives: a shift in financial responsibility from government to employers, a need for stricter enforcement, and a centralisation of the law

You must see the point: Automatic processing of cues to the direction of social attention

Four experiments explored the processing of pointing gestures comprising hand and combined head and gaze cues to direction. The cross-modal interference effect exerted by pointing hand gestures on the processing of spoken directional words, first noted by S. R. H. Langton, C. O'Malley, and V. Bruce (see record 1996-06577-002), was found to be moderated by the orientation of the gesturer's head-gaze (Experiment 1). Hand and head cues also produced bidirectional interference effects in a within-modalities version of the task (Experiment 2). These findings suggest that both head-gaze and hand cues to direction are processed automatically and in parallel up to a stage in processing where a directional decision is computed. In support of this model, head-gaze cues produced no influence on nondirectional decisions to social emblematic gestures in Experiment 3 but exerted significant interference effects on directional responses to arrows in Experiment 4. It is suggested that the automatic analysis of head, gaze, and pointing gestures occurs because these directional signals are processed as cues to the direction of another individual's social attention

Reflexive visual orienting in response to the social attention of others

Four experiments investigate the hypothesis that cues to the direction of another's social attention produce a reflexive orienting of an observer's visual attention. Participants were asked to make a simple detection response to a target letter which could appear at one of four locations on a visual display. Before the presentation of the target, one of these possible locations was cued by the orientation of a digitized head stimulus, which appeared at fixation in the centre of the display. Uninformative and to-be-ignored cueing stimuli produced faster target detection latencies at cued relative to uncued locations, but only when the cues appeared 100 msec before the onset of the target (Experiments 1 and 2). The effect was uninfluenced by the introduction of a to-be-attended and relatively informative cue (Experiment 3), but was disrupted by the inversion of the head cues (Experiment 4). It is argued that these findings are consistent with the operation of a reflexive, stimulus-driven or exogenous orienting mechanism which can be engaged by social attention signals

Working memory load disrupts gaze-cued orienting of attention

A large body of work has shown that a perceived gaze shift produces a shift in a viewer’s spatial attention in the direction of the seen gaze. A controversial issue surrounds the extent to which this gaze-cued orienting effect is stimulus-driven, or is under a degree of top-down control. In two experiments we show that the gaze-cued orienting effect is disrupted by a concurrent task that has been shown to place high demands on executive resources: random number generation. In Experiment 1 participants were faster to locate targets that appeared in gaze-cued locations relative to targets that appeared in locations opposite to those indicated by the gaze shifts, while simultaneously and continuously reciting aloud the digits 1-9 in order; however, this gaze-cueing effect was eliminated when participants continuously recited the same digits in a random order. Random number generation was also found to interfere with gaze-cued orienting in Experiment 2 where participants performed a speeded letter identification response. Together, these data suggest that gaze-cued orienting is actually under top-down control. We argue that top-down signals sustain a goal to shift attention in response to gazes, such that orienting ordinarily occurs when they are perceived; however, the goal cannot always be maintained when concurrent, multiple, competing goals are simultaneously active in working memory

The influence of head contour and nose angle on the perception of eye-gaze direction

We report seven experiments that investigate the influence that head orientation exerts on the perception of eye-gaze direction. In each of these experiments, participants were asked to decide whether the eyes in a brief and masked presentation were looking directly at them or were averted. In each case, the eyes could be presented alone, or in the context of congruent or incongruent stimuli. In Experiment 1A, the congruent and incongruent stimuli were provided by the orientation of face features and head outline. Discrimination of gaze direction was found to be better when face and gaze were congruent than in both of the other conditions, an effect that was not eliminated by inversion of the stimuli (Experiment 1B). In Experiment 2A, the internal face features were removed, but the outline of the head profile was found to produce an identical pattern of effects on gaze discrimination, effects that were again insensitive to inversion (Experiment 2B) and which persisted when lateral displacement of the eyes was controlled (Experiment 2C). Finally, in Experiment 3A, nose angle was also found to influence participants' ability to discriminate direct gaze from averted gaze, but here the effectwas eliminated by inversion of the stimuli (Experiment 3B). We concluded that an image-based mechanism is responsible for the influence of head profile on gaze perception, whereas the analysis of nose angle involves the configural processing of face features