Full Frontal View Research Articles

The roles of gaze and head orientation in face categorization during rapid serial visual presentation

Little is known about how perceived gaze direction and head orientation may influence human categorization of visual stimuli as faces. To address this question, a sequence of unsegmented natural images, each containing a random face or a non-face object, was presented in rapid succession (stimulus duration: 91.7 ms per image) during which human observers were instructed to respond immediately to every face presentation. Faces differed in gaze and head orientation in 7 combinations – full-front views with perceived gaze (1) directed to the observer, (2) averted to the left, or (3) averted to the right, left ¾ side views with (4) direct gaze or (5) averted gaze, and right ¾ side views with (6) direct gaze or (7) averted gaze – were presented randomly throughout the sequence. We found highly accurate and rapid behavioural responses to all kinds of faces. Crucially, both perceived gaze direction and head orientation had comparable, non-interactive effects on response times, where direct gaze was responded faster than averted gaze by 48 ms and full-front view faster than ¾ side view also by 48 ms on average. Presentations of full-front faces with direct gaze led to an additive speed advantage of 96 ms to ¾ faces with averted gaze. The results reveal that the effects of perceived gaze direction and head orientation on the speed of face categorization probably depend on the degree of social relevance of the face to the viewer.

The effect of head orientation on face detection in natural images as evidenced by fast periodic visual stimulation

Face detection is typically fast and accurate, but some faces are detected faster and better than others in natural images. While some studies have shown that low-level visual cues contribute to rapid face detection, there is less information concerning the contribution of high-level factors. Here, we tested whether face detection differs for full-front vs. 3/4 head views using fast periodic visual stimulation (FPVS). This approach can isolate cortical responses for the detection of faces – as compared to other object categories – objectively, rapidly and implicitly in natural images, without contribution from low-level visual cues (Rossion et al., 2015). High-density electroencephalogram (EEG) was recorded from 16 observers presented with 40-s sequences containing natural images of objects sinusoidally contrast-modulated at a fixed rate of 12.0 Hz (F). Natural face images were introduced at fixed intervals of F/9 (‘oddballs’, 1.33 Hz). In Condition 1, all faces were posed full-front. In Condition 2, they were at 3/4 views (either left or right, but only in one orientation within a sequence). In Condition 3, the oddball alternated between full-front and 3/4 views throughout the sequence (frequency of each view, F/18 = 0.67 Hz). In all conditions, significant responses were recorded at 1.33 Hz and its harmonics, mainly over the right occipito-temporal region, indicating a high-level face-detection response. Interestingly, Condition 3 also showed significant responses at 0.67 Hz and its harmonics over the same cortical region, implying a differentiable face-detection response to full-front vs. 3/4 views. Analysis in the time domain revealed a sequence of face-selective components, with peak latencies approximately 12 ms earlier for full-front than 3/4 views emerging as early as the first face-selective component (130-150 ms). These findings indicate that a full-front view presents an advantage in face detection, arising in part from a faster high-level brain response. Meeting abstract presented at VSS 2015

A comprehensive review of past and present vision-based techniques for gait recognition

Global security concerns have raised a proliferation of video surveillance devices. Intelligent surveillance systems seek to discover possible threats automatically and raise alerts. Being able to identify the surveyed object can help determine its threat level. The current generation of devices provide digital video data to be analysed for time varying features to assist in the identification process. Commonly, people queue up to access a facility and approach a video camera in full frontal view. In this environment, a variety of biometrics are available - for example, gait which includes temporal features like stride period. Gait can be measured unobtrusively at a distance. The video data will also include face features, which are short-range biometrics. In this way, one can combine biometrics naturally using one set of data. In this paper we survey current techniques of gait recognition and modelling with the environment in which the research was conducted. We also discuss in detail the issues arising from deriving gait data, such as perspective and occlusion effects, together with the associated computer vision challenges of reliable tracking of human movement. Then, after highlighting these issues and challenges related to gait processing, we proceed to discuss the frameworks combining gait with other biometrics. We then provide motivations for a novel paradigm in biometrics-based human recognition, i.e. the use of the fronto-normal view of gait as a far-range biometrics combined with biometrics operating at a near distance.

Back View of Beauty: A Bias in Attractiveness Judgment

Attractiveness judgment based on visual appearance seems easy and almost automatic. However, it becomes difficult when we need to rely on glances of a person's back view (eg while passing on the street). How is attractiveness judgment from the back view consistent with that from full-front view? In experiment 1 participants rated the attractiveness of human heads photographed from behind and from the front. Attractiveness ratings between the back and front views were weakly but significantly correlated. However, on average, the back-view photographs were rated more attractive than the front-view photographs. The tendency was most conspicuous when the male participants viewed the photographs of women. In experiment 2 participants were explicitly asked to predict the facial attractiveness of each head's front view based on the back view. Again, the predicted attractiveness based on the back view was higher than the actual rating of the front-view photographs, and the difference reached significance when the male participants viewed the women photographs. These biases in attractiveness judgment would be related to attractiveness judgments in everyday situations where straight full-frontal encounters are rare.

Consistency of Likeability of Objects across Views and Time

Subjective impressions of face images (eg personality trait judgments) are consistent across exposure durations and viewpoints. In this study, we investigated whether subjective likeability of common non-face objects would also be consistent. Participants rated the likeability of 32 common objects (eg chair, car, and kettle). Although the rated likeability scores were generally higher for objects shown in three-quarter views than for the same objects shown in full-frontal views, object-wise correlations across the views were significant (experiment 1). The likeability ratings based on brief exposure duration (eg 100 ms) also significantly correlated with those based on unlimited exposure duration (experiment 2). Even when the duration was brief, the consistency across the views was replicated. The findings confirmed that the subjective likeability of common objects is consistent and the process underlying it is efficient, similar to those of faces. However, the mean rated likeability was higher for longer exposure durations, suggesting a negative bias for briefly observed objects. Since this bias is contrary to previously reported findings for faces, the mechanisms for determining subjective likeability of common objects may be partially different from those of faces.

Category-sensitivity in the N170 range: A question of topography and inversion, not one of amplitude

Event-related potential studies have identified the N170 as the key neurophysiological marker of human face processing. This functional association relies on the observation of a larger N170 amplitude to faces than items from all other visual object categories. However, N170 amplitude is modulated by stimulus variations like viewpoint, size and symmetry, and studies comparing similarly sized and symmetric full-front faces and other objects have failed to find amplitude differences. Here we tested whether the effect of inversion – an increase in N170 amplitude seen for faces presented upside down – is similarly observed for full-front views of cars. Participants discriminated pictures of faces and cars, which were presented upright and inverted, and either in full-front view or varying in size, orientation and viewpoint. For upright stimuli, the N170 was stronger for faces than cars at some electrode sites, but of comparable amplitude at others, as shown by topographical differences. The N170 for inverted faces and cars was delayed, with a stronger delay for faces than cars. Inversion increased N170 amplitude for faces, while modulations for full-front view cars were non-significant or N170 amplitude was reduced. These results further limit the widely acknowledged principle of an association between N170 and visual object categorization. Potential face-sensitivity in the N170 range may therefore rely on topographic differences and effects of inversion, rather than amplitude differences.

How Socially Relevant Visual Characteristics of Avatars Influence Impression Formation

Like in the real world, the first impression a person leaves in a computer-mediated environment depends on his or her online appearance. The present study manipulates an avatar’s pupil size, eyeblink frequency, and the viewing angle to investigate whether nonverbal visual characteristics are responsible for the impression made. We assessed how participants (N = 56) evaluate these avatars in terms of different attributes. The findings show that avatars with large pupils and slow eye blink frequency are perceived as more sociable and more attractive. Compared to avatars seen in full frontal view or from above, avatars seen from below were rated as most sociable, self-confident, and attractive. Moreover, avatars’ pupil size and eyeblink frequency escape the viewer’s conscious perception but still influence how people evaluate them. The findings have wide-ranging applied implications for avatar design.

The Effect of Visual Suggestion on the Perception of Voluntariness in Confession

Event Abstract Back to Event The Effect of Visual Suggestion on the Perception of Voluntariness in Confession Jimin Pyo1* and Kwang B. Park1 1 Chungbuk National University, Department of Psychology, South Korea Previous research found that video-recorded confessions made with the camera focused on the suspect would lead observers to assess that the suspect's statements were more voluntary and conclude that the suspect was more likely to be guilty than if the camera focused on the interrogator or on both the suspect and interrogator equally. It was hypothesized that an observer may tend to assess the confession of the suspect focused in a video-recorded interrogation as voluntary because the video showing the frontal view of the confessing suspect conveys a suggestion of volunatariness to the viewer. The task for the subjects in the experiment consisted of listening to an audio, as opposed to video, recording of custodial interrogation, evaluating the volunatariness and truthfulness of the confession made by the suspect during the interrogation, and determining the ultimate guilt of the suspect. While instructing the subjects about the experimental task, a still photo showing a typical interrogation room as an example was used to manipulate the suggestion (independent variable); no visual illustration of custodial interrogation for the subjects in the No Suggestion condition; a still photo showing the full frontal view of the suspect for the subjects in the Suspect-Focused Suggestion condition; a still photo showing the full frontal view of the interrogator for the subjects in the Interrogator-Focused Suggestion condition; and a still photo showing the profiles of a suspect and an interrogator sitting face to face to each other for the subjects in the Equally-Focused Suggestion condition. After the instruction was given to the subjects, the still photo was removed from the visual field of the subjects. And the subjects in all conditions listened to an audio recording of a custodial interrogation. At the end of the audio recording which contained the suspect's confession, the subjects rated voluntariness and truthfulness of the confession and the guilt of the suspect in the audio recording. As predicted, the results provided a support for the hypothesis that a subtle suggestion conveyed by a still photo affects the judgments regarding the voluntariness and veracity of the confession, and the determination of the suspect's guilt.

Personality in Perspective: Judgmental Consistency across Orientations of the Face

Though the psychological literature is replete with information about the perception of faces presented at a full-frontal view, we know very little about how faces are perceived-and impressions formed-when viewed from other angles. We tested impressions of faces at full-frontal, three-quarter, and profile views. Judgments of personality (aggressiveness, competence, dominance, likeability, and trustworthiness) and physiognomy (attractiveness and facial maturity) were significantly correlated across full-frontal, three-quarter, and profile views of male faces. When under time pressure, with only a 50 ms exposure to each face, the correlations for profile with full-frontal and three-quarter view judgments of personality (but not physiognomy) dropped considerably. However, judgments of the full-frontal and three-quarter faces were significantly correlated across the self-paced and 50 ms viewing durations. These findings therefore show that perceptions of full faces lead to relatively similar interferences across both viewing angle and time.

Controlling for interstimulus perceptual variance abolishes N170 face selectivity

Establishing when and how the human brain differentiates between object categories is key to understanding visual cognition. Event-related potential (ERP) investigations have led to the consensus that faces selectively elicit a negative wave peaking 170 ms after presentation, the 'N170'. In such experiments, however, faces are nearly always presented from a full front view, whereas other stimuli are more perceptually variable, leading to uncontrolled interstimulus perceptual variance (ISPV). Here, we compared ERPs elicited by faces, cars and butterflies while--for the first time--controlling ISPV (low or high). Surprisingly, the N170 was sensitive, not to object category, but to ISPV. In addition, we found category effects independent of ISPV 70 ms earlier than has been generally reported. These results demonstrate early ERP category effects in the visual domain, call into question the face selectivity of the N170 and establish ISPV as a critical factor to control in experiments relying on multitrial averaging.

Generalization of Mere Exposure to Faces Viewed from Different Horizontal Angles

Evolutionary accounts of the centrality of social interaction for our species might anticipate more efficient affective processing for faces. The current study assessed whether mere exposure to upright faces resulted in greater generalization of liking than mere exposure to inverted faces, as might be predicted by special–process views of face perception. We presented upright and inverted photographs of faces taken from three different horizontal angles (full front–view, 45-degree, and full-profile), then asked participants to rate their liking for front–view photographs of the same faces. For inverted faces, but not upright faces, there was a significant linear trend for liking to decrease as presentation angle increased (from front–view through 45-degree to full-profile). Thus, upright front–view faces that had previously been presented in full– or semi–profile were liked at equivalent levels to upright front–view faces that had previously been presented in front–view. These findings suggest that mere exposure for upright faces presented at any angle may easily generalize to other views of the face, but that generalization is less efficient for perceptually matched inverted faces. These findings are consistent with evolutionary arguments for enhanced affective discrimination.

THE WHALE AVATAR OF THE HINDOOS IN MELVILLE'S MOBY DICK

Herman Melville depicted the great whale Moby Dick as a powerful force of nature, impossible to comprehend fully. He attributes to the whale not only great antiquity, but also divinity. One of the most striking and effective ways in which he does so is by describing the whale as a manifestation (avatar) of the Hindu deity Vishnu, whose mythology he recounts, the Matsya Avatara. These passages are analysed in the context of the novel's other references to India and Hindu religious thought. In an effort to inter pret the significance of India and Hinduism in the novel, aspects of Melville's life and thought are also analysed. We conclude that the structure of the myth of the fish avatar is reflected in the novel's structure, and that the novel presents a concept of the divine at variance with Christian theological orthodoxy. But in the great Sperm Whale, this high and mighty god-like dignity inherent in the brow is so immensely amplified, that gazing on it, in that full front view, you feel the Deity and the dread powers more forcibly than in beholding any other object in living nature.1

Canonical views of faces and the cerebral hemispheres

Evidence is given for a special, canonical, status of one specific view in the identification of familiar faces. In the first experiment, subjects identified by name the fully frontal or profile poses of briefly familiarised individuals less efficiently than an intermediate pose. In addition, in a matching experiment using faces seen in different poses, it was found that one specific intermediate pose (corresponding to 22.5 degrees of angle from the full frontal view) was matched more efficiently in the right visual field (RVF) than in the left visual field (LVF). This finding supports the hypothesis of a superiority of the left hemisphere (LH) over the right hemisphere (RH) in processing a familiar face's canonical view. The other tested "noncanonical" views (i.e., full frontal, 45 degrees, and profile) of these same familiar faces were better matched in the LVF (i.e., the RH); especially at low levels of familiarity. We conclude that, for each familiar face, a viewer-centred representation of the canonical (22.5°) view is stored in the LH's memory system, whereas multiple views of familiar faces are stored in a memory system of the RH. With increasing levels of familiarity other views are increasingly more efficiently encoded by the LH, and in fact for facial self-recognition the full-front view is superior to any of the other tested views. These findings taken together suggest that complementary lateralised memory subsystems in the two cerebral hemispheres store different sets, only partially overlapping, of view-centred face representations.

The perceived attractiveness of preterm infants

It has been argued that human infants (with their relatively large foreheads and eyes) evoke nurturant behaviors from adults. This study empirically tests whether or not conceptional age affects these facial features and adult perceptions of the infants. Pictures (full frontal views of the face) were taken of 29 newborns: 10 born at term, 10 born 1 month early, and 9 born 2 months before term. All facial features were measured proportionally, and three composite drawings (one for each gestational age) were made. Using a 7-point Likert-style scale, college-aged subjects rated the composite drawings on the basis of overall impressions, perceived functional evaluations, and judged behavioral inclinations. Results indicated that full-term infants possessed proportionally wider eyes and rounder heads than did preterm infants. Composite drawings depicting the fullterm characteristics evoked much more favorable responses for all items than did the two composite drawings depicting preterm infants' characteristics. Moreover, the composite drawing depicting an infant born 1 month early elicited more favorable responses than did the composite drawing depicting an infant born 2 months prematurely.

Adults' perception of the cries of high-complications and low-complications infants

It has been argued that human infants (with their relatively large foreheads and eyes) evoke nurturant behaviors from adults. This study empirically tests whether or not conceptional age affects these facial features and adult perceptions of the infants. Pictures (full frontal views of the face) were taken of 29 newborns: 10 born at term, 10 born 1 month early, and 9 born 2 months before term. All facial features were measured proportionally, and three composite drawings (one for each gestational age) were made. Using a 7-point Likert-style scale, college-aged subjects rated the composite drawings on the basis of overall impressions, perceived functional evaluations, and judged behavioral inclinations. Results indicated that full-term infants possessed proportionally wider eyes and rounder heads than did preterm infants. Composite drawings depicting the fullterm characteristics evoked much more favorable responses for all items than did the two composite drawings depicting preterm infants' characteristics. Moreover, the composite drawing depicting an infant born 1 month early elicited more favorable responses than did the composite drawing depicting an infant born 2 months prematurely.