Pupil dilation, sex of stimulus, and age and sex of observer

10-yr.-old, 16-yr.-old, and 20-yr.-old male and female observers (ns = 10; N = 60) rated a number of male and female faces for how 'good-looking' they were. Some of these faces were identical save that in one version the pupils were larger. Pupil dilation in the photographs of males produced no significant effects, whereas pupil dilation in the female photographs caused such faces to be rated as more good-looking by the two oldest groups of male observers. The 10-yr.-old boys and the 16- and 20-yr.-old women rated the female faces with enlarged pupils as significantly less 'good-looking' than the same faces with smaller pupils.     

Gaze behavior in face comparison: The roles of sex, task, and symmetry

Knowing where people look on a face provides an objective insight into the information entering the visual system and into cognitive processes involved in face perception. In the present study, we recorded eye movements of human participants while they compared two faces presented simultaneously. Observers’ viewing behavior and performance was examined in two tasks of parametrically varying difficulty, using two types of face stimuli (sex morphs and identity morphs). The frequency, duration, and temporal sequence of fixations on previously defined areas of interest in the faces were analyzed. As was expected, viewing behavior and performance varied with difficulty. Interestingly, observers compared predominantly the inner halves of the face stimuli—a result inconsistent with the general left-hemiface bias reported for single faces. Furthermore, fixation patterns and performance differed between tasks, independently of stimulus type. Moreover, we found differences in male and female participants’ viewing behaviors, but only when the sex of the face stimuli was task relevant.     

Effects of perceived mutual gaze and gender on face processing and recognition memory

Perceived gaze contact in seen faces may convey important social signals. We examined whether gaze perception affects face processing during two tasks: Online gender judgement, and later incidental recognition memory. Individual faces were presented with eyes directed either straight towards the viewer or away, while these faces were seen in either frontal or three-quarters view. Participants were slower to make gender judgements for faces with direct versus averted eye gaze, but this effect was particularly pronounced for faces with opposite gender to the observer, and seen in three-quarters view. During subsequent surprise recognition-memory testing, recognition was better for faces previously seen with direct than averted gaze, again especially for the opposite gender to the observer. The effect of direct gaze was stronger in both tasks when the head was seen in three-quarters rather than in frontal view, consistent with the greater salience of perceived eye contact for deviated faces. However, in the memory test, face recognition was also relatively enhanced for faces of opposite gender in front views when their gaze was averted rather than direct. Together, these results indicate that perceived eye contact can interact with facial processing during gender judgements and recognition memory, even when gaze direction is task-irrelevant, and particularly for faces of opposite gender to the observer (an influence which controls for stimulus factors when considering observers of both genders). These findings appear consistent with recent neuroimaging evidence that social facial cues can modulate visual processing in cortical regions involved in face processing and memory, presumably via interconnections with brain systems specialized for gaze perception and social monitoring.     

Sex differences in unfamiliar face identification: evidence from matching tasks

Research on sex differences in face recognition has reported mixed results, on balance suggesting an advantage for female observers. However, it is not clear whether this advantage is specific to face processing or reflects a more general superiority effect in episodic memory. The current study therefore examined sex differences with a face-matching task that eliminates memory demands. Across two experiments, female but not male observers showed an own-sex advantage on match trials, in which two pictures have to be identified as the same person. This advantage was present for whole faces and when only the internal or external facial features were shown. Female observers were also more accurate in these three conditions on mismatch encounters, in which two photographs have to be identified as different people, but this reflects a more general effect that is present for male and female faces. These findings converge with claims of a female advantage in face recognition and demonstrate that this effect persists when memory demands are eliminated.     

Sex differences for the recognition of direct versus averted gaze faces

Gaze direction plays a central role in face recognition. Previous research suggests that faces with direct gaze are better remembered than faces with averted gaze. We compared recognition of faces with direct versus averted gaze in male versus female participants. A total of 52 adults (23 females, 29 males) and 46 children (25 females, 21 males) completed a computerised task that assessed their recognition of faces with direct gaze and faces with averted gaze. Adult male participants showed superior recognition of faces with direct gaze compared to faces with averted gaze. There was no difference between recognition of direct and averted gaze faces for the adult female participants. Children did not demonstrate this sex difference; rather, both male and female youth participants showed better recognition of faces with direct gaze compared to averted gaze. A large body of previous research has revealed superior recognition of faces with direct, compared to averted gaze. However, relatively few studies have examined sex differences. Our findings suggest that gaze direction has differential effects on face recognition for adult males and females, but not for children. These findings have implications for previous explanations of better recognition for direct versus averted gaze.     

Effects of perceptual quality on the processing of human faces presented to the left and right cerebral hemispheres

Three experiments examined the effects of stimulus duration, retinal eccentricity, and visual noise on the processing of human faces presented to the left visual field/right hemisphere (LVF-RH) and right visual field/left hemisphere (RVF-LH). In Experiment 1 observers identified which of 10 similar male faces was presented on a screen. The single face was presented for 10, 55, or 100 ms at 1 degree, 4 degrees, or 9 degrees of visual angle to the left or right of fixation. Decreasing stimulus duration and increasing retinal eccentricity lowered face recognition. The effect of duration was the same for LVF-RH and RVF-LH trials, but the detrimental effect of increasing retinal eccentricity was larger on LVF-RH trials than on RVF-LH trials. In Experiment 2 observers indicated whether a single face from this same set was a member of a memorized set of five positive faces. The probe face on each trial was presented alone or embedded in visual noise. Visual noise increased the error rate more on LVF-RH trials than on RVF-LH trials. This effect was replicated in Experiment 3, which also required observers to make a much easier discrimination between male and female faces. In the male/female task visual noise tended to impair performance more on RVF-LH trials than on LVF-RH trials, opposite the effect for the male/male task. These results are discussed in terms of hemispheric asymmetry for global versus local features of faces, the level of feature analysis demanded by a task, and the level of feature analysis most disrupted by perceptual degradation.     

Face processing in humans and new world monkeys: the influence of experiential and ecological factors

This study tests whether the face-processing system of humans and a nonhuman primate species share characteristics that would allow for early and quick processing of socially salient stimuli: a sensitivity toward conspecific faces, a sensitivity toward highly practiced face stimuli, and an ability to generalize changes in the face that do not suggest a new identity, such as a face differently oriented. The look rates by adult tamarins and humans toward conspecific and other primate faces were examined to determine if these characteristics are shared. A visual paired comparison (VPC) task presented subjects with either a human face, chimpanzee face, tamarin face, or an object as a sample, and then a pair containing the previous stimulus and a novel stimulus was presented. The stimuli were either presented all in an upright orientation, or all in an inverted orientation. The novel stimulus in the pair was either an orientation change of the same face/object or a new example of the same type of face/object, and the stimuli were shown either in an upright orientation or in an inverted orientation. Preference to novelty scores revealed that humans attended most to novel individual human faces, and this effect decreased significantly if the stimuli were inverted. Tamarins showed preferential looking toward novel orientations of previously seen tamarin faces in the upright orientation, but not in an inverted orientation. Similarly, their preference to look longer at novel tamarin and human faces within the pair was reduced significantly with inverted stimuli. The results confirmed prior findings in humans that novel human faces generate more attention in the upright than in the inverted orientation. The monkeys also attended more to faces of conspecifics, but showed an inversion effect to orientation change in tamarin faces and to identity changes in tamarin and human faces. The results indicate configural processing restricted to particular kinds of primate faces by a New World monkey species, with configural processing influenced by life experience (human faces and tamarin faces) and specialized to process orientation changes specific to conspecific faces.     

威胁相关面孔表情对眼睛注视方向知觉的影响

以往研究发现眼睛注视方向知觉受面孔表情的影响,愤怒面孔相较于恐惧面孔更倾向被判断为看着观察者。虽然研究者对此提出了不同的解释,但目前尚不清楚愤怒和恐惧表情在注视方向知觉中的这种差异影响到底来自于面孔的结构信息还是物理特征信息。本研究采用注视方向辨别任务,计算直视知觉范围（The Cone of Direct Gaze,CoDG）为因变量,分别以直立,倒置及模糊图片为实验材料,试图通过分离面孔结构信息和物理特征信息,对以上问题进行探讨。结果发现在保留面孔全部信息的情况下（实验1）愤怒面孔的CoDG大于恐惧面孔;在破坏结构信息加工,只保留特征信息加工的情况下（实验2））愤怒和恐惧表情在直视知觉范围上的差异消失了;在削弱物理特征信息加工,保留结构信息加工的情况下（实验3）二者在CoDG上的差异又复现。本研究结果说明不同威胁性面孔表情对眼睛注视知觉的影响主要来自于二者在与情绪意义相关的结构信息加工上的不同,而二者非低级的物理信息上的差异,支持信号共享假说和情绪评价假说对威胁性面孔表情与注视方向整合加工解释的理论基础。     

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.     

Opposite effects of visual versus imagined presentation of faces on subsequent sex perception

Viewing faces of one sex changes the perception of subsequently seen ambiguous faces. Here we investigate if the mechanisms responsible for this sex aftereffect are also activated during mental imagery of faces. Participants categorized the sex of ambiguous faces after either viewing images of male or female actors' faces or imagining these same faces. As in previous studies, the ambiguous images were categorized as female more often after viewing male faces than after viewing female faces. The opposite effect was found for imagined faces, however; the ambiguous images were categorized as female more often after imagining female faces than after imagining male faces. Although our results are inconsistent with findings that imagined faces cause either no aftereffects or similar aftereffects to visually presented faces, our results are consistent with recent evidence that visual and imagined presentation of faces cause opposite adaptation effects on an early electrophysiological response associated with face processing.     

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.     

Pupillary Reactions to Sexual,Aggressive, and Other Stimuli as a Function of Personality

This study investigated how well three personality measures, The Dream Incident Technique, the Edwards Personal Preference Schedule, and the Repression-Sensitization Scale, could predict pupillary dilation to a set of experimental stimuli. The stimuli were brief video sequences portraying themes of sex, aggression, achievement, affiliation, nurturance, dominance, and order. The Dream Incident Technique was most predictive of pupillary dilation to these scenes. The Edwards Personal Preference Schedule correlated only with self reports of stimulation. The R-S Scale was unrelated to either pupillary dilation or self report of stimulation.     

Have you got the look? Gaze direction affects judgements of facial attractiveness

Much is known about the attractiveness of physical attributes, such as symmetry and averageness. Here we examine the effect of a social cue, eye-gaze direction, on facial attractiveness. Given that direct gaze signals social engagement, we predicted that faces showing direct gaze would be preferred to faces showing averted gaze. Thirty-two males completed two tasks designed to assess preferences for female faces displaying a neutral expression. Participants were more likely to select the face with direct gaze, when choosing the more attractive face from direct- and averted-gaze versions of the same face. This direct-gaze preference was stronger for high-attractive than low-attractive face sets, but was present for both. Attractiveness ratings were also higher for faces with direct than averted gaze. Interestingly, stimulus inversion weakened the preference for inverted faces, which suggests the preference does not simply reflect a bilateral symmetry bias.     

Facial attractiveness biases the perception of eye contact

Attractive faces are appealing: We like to look at them, and we like to be looked at by them. We presented attractive and unattractive smiling and neutral faces containing identical eye regions with different gaze directions. Participants judged whether or not a face looked directly at them. Overall, attractive faces increased participants' tendency to perceive eye contact, consistent with a self-referential positivity bias. However, attractiveness effects were modulated by facial expression and gender: For female faces, observers more likely perceived eye contact in attractive than unattractive faces, independent of expression. For male faces, attractiveness effects were limited to neutral expressions and were absent in smiling faces. A signal detection analysis elucidated a systematic pattern in which (a) smiling faces, but not highly attractive faces, reduced sensitivity in gaze perception overall, and (b) attractiveness had a more consistent impact on bias than sensitivity measures. We conclude that combined influences of attractiveness, expression, and gender determine the formation of an overall impression when deciding which individual's interest in oneself may be beneficial and should be reciprocated.     

Facial attractiveness biases the perception of eye contact

Attractive faces are appealing: We like to look at them, and we like to be looked at by them. We presented attractive and unattractive smiling and neutral faces containing identical eye regions with different gaze directions. Participants judged whether or not a face looked directly at them. Overall, attractive faces increased participants' tendency to perceive eye contact, consistent with a self-referential positivity bias. However, attractiveness effects were modulated by facial expression and gender: For female faces, observers more likely perceived eye contact in attractive than unattractive faces, independent of expression. For male faces, attractiveness effects were limited to neutral expressions and were absent in smiling faces. A signal detection analysis elucidated a systematic pattern in which (a) smiling faces, but not highly attractive faces, reduced sensitivity in gaze perception overall, and (b) attractiveness had a more consistent impact on bias than sensitivity measures. We conclude that combined influences of attractiveness, expression, and gender determine the formation of an overall impression when deciding which individual's interest in oneself may be beneficial and should be reciprocated.     

Cerebral asymmetry in autonomic conditioning to facial expressions: Sex differences

In the present experiment, sex differences in hemispheric asymmetry during classical conditioning to emotional stimuli are reported. 125 subjects (62 females and 63 males) were shown a slide of a happy face in the right (or left) visual half field (VHF), and simultaneously a slide of an angry face in the left (or right) VHF. Eight groups were formed by the combination of male and female subjects; left and right VHF positions of the angry/happy faces; and the administration/omission of the shock unconditioned stimulus (UCS). Dependent measures were skin conductance responses recorded from both hands. The results during extinction showed a significant larger SCR magnitude to the shock compared to the no-shock groups only for the female subjects. CS position during conditioning was also important in revealing differential responding to either the happy or angry faces. A right hemisphere effect was found for the angry face CS for both the male and female subjects, however with a greater difference for the females.     

Angry faces are more resistant to forgetting than are happy faces: directed forgetting effects on the identity of emotional faces

Using the item-method directed forgetting paradigm (i.e. intentionally forgetting specified information), we examined directed forgetting of facial identity as a function of facial expression and the sex of the expresser and perceiver. Participants were presented with happy and angry male and female faces cued for either forgetting or remembering, and were then asked to recognise previously studied faces from among a series of neutral faces. For each recognised test face, participants also recalled the face’s previously displayed emotional expression. We found that angry faces were more resistant to forgetting than were happy faces. Furthermore, angry expressions on male faces and happy expressions on female faces were recognised and recalled better than vice versa. Signal detection analyses revealed that male faces gave rise to a greater sensitivity than female faces did, and male participants, but not female participants, showed greater sensitivity to male faces than to female faces. Several theoretical implications are discussed.     

Stare in the crowd: frontal face guides overt attention independently of its gaze direction

Whether or not a stare in the midst of many faces can guide visual attention is a controversial issue. Two experiments are reported that investigate the hypothesis that visual attention is guided toward a frontal face in the search for a stare among faces with varied head angles. The participants were required to search for a face with a direct gaze in a context where the target could be at any of various head angles and the target's head angle was unpredictable in one trial. The search performance was better for a frontal-face target than for deviated-face targets. Furthermore, eye-movement analyses revealed that a frontal-face stimulus tended to be initially fixated prior to deviated-face stimuli, and many of the initially fixated frontal-face stimuli had an averted gaze. The findings suggest that a frontal face guides overt attention independently of its gaze direction in the search for a stare in a crowd. The validity of prioritising a frontal face in order to find a direct gaze among faces and the characteristics of a human-face detection system are discussed.     

Does perceived direct gaze boost detection in adults and children with and without autism? The stare-in-the-crowd effect revisited

This study extended that of von Grünau and Anston (1995) and explored whether perceived direct gaze is easily detected by individuals with and without autism, utilizing a visual-search paradigm. Participants detected target faces with either direct gaze or averted gaze. Laterally averted faces were used to eliminate the involvement of lower perceptual characteristics such as symmetry, which were inherent with the “straight gaze” used by von Grünau and Anston. Both typically developed adults and children detected targets with direct gaze more quickly than those with averted gaze, but face inversion distorted this asymmetrical performance, suggesting the contribution of configurative facial processing. In contrast, children with autism were not affected by the gaze direction presented by realistic facial stimuli. They were, however, faster to detect straight gaze defined solely by local features, which suggests that their impairment might be specific to the detection of direct gaze presented within a facial context.     

Gaze direction and facial expressions exert combined but different effects on attentional resources

Gaze direction and facial expressions are critical components of face processing and have been shown to influence attention deployment. We investigated whether gaze direction (direct vs. averted) combined with a neutral or angry expression modulates the deployment of attentional resources over time. In a Rapid Serial Visual Presentation (RSVP) paradigm participants had to decide the gender of a neutral or an angry target face with direct or averted gaze (T1) and then to judge the orientation of a target picture of a landscape (T2), following the face at different time intervals. Results showed no attentional blink effect (i.e., no deterioration in T2 accuracy) when T1 was an angry face with direct gaze, whereas it was present for angry faces with averted gaze or neutral faces with either averted or direct gaze. These findings are consistent with appraisal theories and are discussed against the background of automatic processing of threat stimuli.