Deficits in early-stage face perception in excessive internet users

Excessive Internet use is associated with a limited ability to communicate effectively socially, which depends largely on the capacity for perception of the human face. We used a passive visual detection paradigm to compare the early stages of the processing of face-related information in young excessive Internet users (EIUs) and healthy normal subjects by analyzing event-related potentials (ERPs) elicited by faces and by nonface stimuli (tables), each presented in the upright and inverted position. The P1 and N170 components of the spectrum of ERPs elicited at occipital-temporal sites by the viewing of faces were larger and peaked sooner than the same ERP components elicited by tables, and inverted faces significantly enhanced and delayed the N170 component. EIUs had a generally smaller P1 component than did normal subjects, whether elicited by faces or by tables, and the N170 effect, or difference in amplitude of the N170 component for faces versus tables, was significantly smaller in the EIUs than in normal subjects. However, the N170 inversion effect, or difference in amplitude of the N170 component elicited by upright versus inverted faces, was similar in the EIUs and normal subjects. These data indicate that EIUs have deficits in the early stage of face-perception processing but may have intact holistic/configural processing of faces. Whether some deeper processes of face perception, such as face memory and face identification, are affected in EIUs needs to be investigated further with more specific procedures.     

Atypical updating of face representations with experience in children with autism

Face identity aftereffects are significantly diminished in children with autism relative to typical children, which may reflect reduced perceptual updating with experience. Here, we investigated whether this atypicality also extends to non‐face stimulus categories, which might signal a pervasive visual processing difference in individuals with autism. We used a figural aftereffect task to measure directly perceptual updating following exposure to distorted upright faces, inverted faces and cars, in typical children and children with autism. A size‐change between study and test stimuli limited the likelihood that any processing atypicalities reflected group differences in adaptation to low‐level features of the stimuli. Results indicated that, relative to typical children, figural aftereffects for upright faces, but not inverted faces or cars, were significantly attenuated in children with autism. Moreover, the group difference was amplified when we isolated the ‘face‐selective’ component of the aftereffect, by partialling out the mid‐level shape adaptation common to upright and inverted face stimuli. Notably, the aftereffects of typical children were disproportionately larger for upright faces than for inverted faces and cars, but the magnitude of aftereffects of autistic children was not similarly modulated according to stimulus category. These findings are inconsistent with a pervasive adaptive coding atypicality relative to typical children, and suggest that reduced perceptual updating may constitute a high‐level, and possibly face‐selective, visual processing difference in children with autism.     

Effect of inversion on the recognition of external and internal facial features

The purpose of the present study was to find out whether inversion affects recognition of external and internal facial features. 24 participants matched, under two experimental conditions (pair and multiple-choice matchings), upright target faces with three categories of facial test stimuli: full faces, external features and internal features, which were presented in either upright or inverted orientations. Data analysis showed that matching of facial stimuli was faster, more accurate and more consistent under upright than under inverted orientations for all stimulus categories; mostly for full faces, and least for internal features. As a rule, there were no speed-accuracy trade-offs. Implications of the data for accounts of the inversion effect in face recognition in terms of a shift from configurational to componential processing were discussed.     

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.     

A new look at social attention: Orienting to the eyes is not (entirely) under volitional control

People tend to look at other people's eyes, but whether this bias is automatic or volitional is unclear. To discriminate between these two possibilities, we used a "don't look" (DL) paradigm. Participants looked at a series of upright or inverted faces, and were asked either to freely view the faces or to avoid looking at the eyes, or as a control, the mouth. As previously demonstrated, participants showed a bias to attend to both eyes and mouths during free viewing. In the DL condition, participants told to avoid the eyes of upright faces were unable to fully suppress the tendency to fixate on the faces' eyes, whereas participants told to avoid the mouth of upright faces successfully eliminated their bias to overtly attend to that feature. When faces were inverted, participants were equally able to suppress looks to the eyes and mouth. Together, these results suggest that the tendency to look at the eyes reflects orienting that is both volitional and automatic, and that the engagement of holistic or configural face processing mechanisms during upright face viewing has an influence in guiding gaze automatically to the eyes. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

When feature information comes first! Early processing of inverted faces

We investigated the early stages of face recognition and the role of featural and holistic face information. We exploited the fact that, on inversion, the alienating disorientation of the eyes and mouth in thatcherised faces is hardly detectable. This effect allows featural and holistic information to be dissociated and was used to test specific face-processing hypotheses. In inverted thatcherised faces, the cardinal features are already correctly oriented, whereas in undistorted faces, the whole Gestalt is coherent but all information is disoriented. Experiment 1 and experiment 3 revealed that, for inverted faces, featural information processing precedes holistic information. Moreover, the processing of contextual information is necessary to process local featural information within a short presentation time (26 ms). Furthermore, for upright faces, holistic information seems to be available faster than for inverted faces (experiment 2). These differences in processing inverted and upright faces presumably cause the differential importance of featural and holistic information for inverted and upright faces.     

Peak shift but not range effects in recognition of faces

University students were trained to discriminate between two gray-scale images of faces that varied along a continuum from a unique face to an average face created by morphing. Following training, participants were tested without feedback for their ability to recognize the positive face (S+) within a range of faces along the continuum. In Experiments 1 and 4, the range of stimuli presented during testing was manipulated. In Experiment 2, participants viewed different ranges of faces during an adaptation period that followed training and preceded testing. In all experiments, generalization functions revealed peak shifts or area shifts (fewer “yes” responses to novel faces on the negative side of the S+), but no systematic effects of the test or adaptation range. Peak shift was found both for upright and inverted faces and occurred even if the orientation of the face was reversed between training and test. Using similar methods, either an area shift or range effect (but not both together) was demonstrated for line tilt stimuli (Experiment 3), and the appearance of these effects depended on instructions. It appears that peak shift and area shift are robust across many different kinds of stimuli, but range effects may not readily occur with complex multidimensional stimuli.     

Figural aftereffects in the perception of faces

We examined figural aftereffects in images of human faces, for which changes in configuration are highly discriminable. Observers either matched or rated faces before or after viewing distorted images of faces. Prior adaptation strongly biases face perception by causing the original face to appear distorted in a direction opposite to the adapting distortion. Aftereffects transferred across different faces and were similar for upright or inverted faces, but were weaker when the adapting and test faces had different orientations (e.g., adapt inverted and test upright). Thus the aftereffects depend on which images are distorted, and not simply on the type of distortion introduced. We further show that the aftereffects are asymmetric, for adapting to the original face has little effect on the perception of a distorted face. This asymmetry suggests that adaptation may play an important normalizing role in face perception. Our results suggest that in normal viewing, figural aftereffects may strongly influence form perception and could provide a novel method for probing properties of human face perception.     

Memory conjunction errors for realistic faces are consistent with configural processing

Conjunction faces are formed from feature sets learned across different faces. In previous studies, false alarms (“old” responses) to conjunctions have been very high, approaching hits to old faces; this is surprising, because, perceptually, upright faces are processed configurally, with strong integration of parts into the whole. We test the idea that the atypical reliance on unrelated parts could be due to using unnatural line drawings as stimuli, and to forming conjunctions across external features (e.g., hair) and internal features (e.g., eyes, mouth). We used realistic face stimuli and conjunctions made entirely from internal features. Results were, as expected, consistent with configural processing for upright faces (hits to old faces much greater than FA to conjunctions) and not for inverted faces (hits to old = FA to conjunctions).     

The representations of spacing and part-based information are associated for upright faces but dissociated for objects: Evidence from individual differences

Considerable evidence suggests that qualitatively different processes are involved in the perception of faces and objects. According to a central hypothesis, the extraction of information about the spacing among face parts (e.g., eyes and mouth) is a primary function of face processing mechanisms that is dissociated from the extraction of information about the shape of these parts. Here, we used an individual-differences approach to test whether the shape of face parts and the spacing among them are indeed processed by dissociated mechanisms. To determine whether the pattern of findings that we reveal is unique for upright faces, we also presented similarly manipulated nonface stimuli. Subjects discriminated upright or inverted faces or houses that differed in parts or spacing. Only upright faces yielded a large positive correlation across subjects between performance on the spacing and part discrimination tasks. We found no such correlation for inverted faces or houses. Our findings suggest that face parts and spacing are processed by associated mechanisms, whereas the parts and spacing of nonface objects are processed by distinct mechanisms. These results may be consistent with the idea that faces are special, in that they are processed as nondecomposable wholes.     

The effect of inversion on the encoding of normal and “thatcherized” faces

In the “Thatcher illusion” a face, in which the eyes and mouth are inverted relative to the rest of the face, looks grotesque when shown upright but not when inverted. In four experiments we investigated the contribution of local and global processing to this illusion in normal observers. We examined inversion effects (i.e., better performance for upright than for inverted faces) in a task requiring discrimination of whether faces were or were not “thatcherized”. Observers made same/different judgements to isolated face parts (Experiments 1-2) and to whole faces (Experiments 3-4). Face pairs had the same or different identity, allowing for different process- ing strategies using feature-based or configural information, respectively. In Experiment 1, feature-based matching of same-person face parts yielded only a small inversion effect for normal face parts. However, when feature-based matching was prevented by using the face parts of different people on all trials (Experiment 2) an inversion effect occurred for normal but not for thatcherized parts. In Experiments 3 and 4, inversion effects occurred with normal but not with thatcherized whole faces, on both same- and different-person matching tasks. This suggests that a common configural strategy was used with whole (normal) faces. Face context facilitated attention to misoriented parts in same-person but not in different-person matching. The results indicate that (1) face inversion disrupts local configural processing, but not the processing of image features, and (2) thatcherization disrupts local configural processing in upright faces.     

A unique look at face processing: the impact of masked faces on the processing of facial features

This experiment utilized a masked priming paradigm to explore the early processes involved in face recognition. The first experiment investigated implicit processing of the eyes and mouth in an upright face, using prime durations of 33 and 50 ms. The results demonstrate implicit processing of both the eyes and mouth, and support the configural processing theory of face processing. The second experiment used the same method with inverted faces and the third experiment was a combination of Experiments 1 and 2. The fourth experiment utilized misaligned faces as the primes. Based on the pattern of results from these experiments, we suggest that, when a face is inverted, the eyes and mouth are initially processed individually and are not linked until a later stage of processing. An upright face is proposed to be processed by analysis of its configuration, whereas an inverted face is initially processed using first-order relational information, and then converted to an upright representation and transferred to face specific regions for configural analysis.     

Perceptual specialization and configural face processing in infancy

Adults’ face processing expertise includes sensitivity to second-order configural information (spatial relations among features such as distance between eyes). Prior research indicates that infants process this information in female faces. In the current experiments, 9-month-olds discriminated spacing changes in upright human male and monkey faces but not in inverted faces. However, they failed to process matching changes in upright house stimuli. A similar pattern of performance was exhibited by 5-month-olds. Thus, 5- and 9-month-olds exhibited specialization by processing configural information in upright primate faces but not in houses or inverted faces. This finding suggests that, even early in life, infants treat faces in a special manner by responding to changes in configural information more readily in faces than in non-face stimuli. However, previously reported differences in infants’ processing of human versus monkey faces at 9 months of age (but not at younger ages), which have been associated with perceptual narrowing, were not evident in the current study. Thus, perceptual narrowing is not absolute in the sense of loss of the ability to process information from other species’ faces at older ages.     

Effects of repetition and configural changes on the development of face recognition processes

We investigated the effect of repetition on recognition of upright, inverted and contrast-reversed target faces in children from 8 to 15 years when engaged in a learning phase/test phase paradigm with target and distractor faces. Early (P1, N170) and late ERP components were analysed Children across age groups performed equally well, and were better at recognizing upright faces. However, teenagers and adults were equally accurate for all three face types. The neurophysiological responses to upright, inverted and negative faces matured until adulthood and showed different effects at different ages. P1 and N170 components were affected by face type at all ages, suggesting early configural disruption on encoding processes regardless of age. Frontal ERPs reflected the difficulty of processing these stimuli. Distinct repetition effects were seen at frontal, temporal frontal and parietal sites, suggesting differential involvement of these brain regions underlying working memory and recognition processes. Thus, a learning phase was sufficient (a) for 8-year-olds to perform as accurately as 15-year-olds and (b) to eliminate face type effects in teenagers and adults, but not in younger children.     

Normal perception of Mooney faces in developmental prosopagnosia: Evidence from the N170 component and rapid neural adaptation

Individuals with developmental prosopagnosia (DP) have a severe difficulty recognizing the faces of known individuals in the absence of any history of neurological damage. These recognition problems may be linked to selective deficits in the holistic/configural processing of faces. We used two‐tone Mooney images to study the processing of faces versus non‐face objects in DP when it is based on holistic information (or the facial gestalt) in the absence of obvious local cues about facial features. A rapid adaptation procedure was employed for a group of 16 DPs. Naturalistic photographs of upright faces were preceded by upright or inverted Mooney faces or by Mooney houses. DPs showed face‐sensitive N170 components in response to Mooney faces versus houses, and N170 amplitude reductions for inverted as compared to upright Mooney faces. They also showed the typical pattern of N170 adaptation effects, with reduced N170 components when upright naturalistic test faces were preceded by upright Mooney faces, demonstrating that the perception of Mooney and naturalistic faces recruits shared neural populations. Our findings demonstrate that individuals with DP can utilize global information about face configurations for categorical discriminations between faces and non‐face objects, and suggest that face processing deficits emerge primarily at more fine‐grained higher level stages of face perception.     

Specificity of face processing without awareness

The recognition memory for inverted faces is especially difficult when compared with that for non-face stimuli. This face inversion effect has often been used as a marker of face-specific holistic processing. However, whether face processing without awareness is still specific remains unknown. The present study addressed this issue by examining the face inversion effect with the technique of binocular rivalry. Results showed that invisible upright faces could break suppression faster than invisible inverted faces. Nevertheless, no difference was found for invisible upright houses and invisible inverted houses. This suggested that face processing without awareness is still specific. Some face-specific information can be processed by high-level brain areas even when that information is invisible.     

Perceptual learning and acquired face familiarity: Evidence from inversion,use of internal features,and generalization between viewpoints

Pairs of similar faces were created from photographs of different people using morphing software. The ability of participants to discriminate between novel pairs of faces and between those to which they had received brief, unsupervised, exposure (5×2 s each) was assessed. In all experiments exposure improved discrimination performance. Overall, discrimination was better when the faces were upright, but exposure produced improved discrimination for both upright and inverted faces (Experiment 1). The improvement produced by exposure was selective to internal face features (Experiment 2) and was evident when there was a change in orientation (three-quarter to full face or vice versa) between exposure and test (Experiment 3). These findings indicate that perceptual learning observed following brief exposure to faces exhibit well-established hallmarks of familiar face processing (i.e., internal feature advantage and insensitivity to a change of viewpoint). Considered in combination with previous studies using the same type of stimuli (Mundy, Honey, & Dwyer, 2007), the current results imply that general perceptual learning mechanisms contribute to the acquisition of face familiarity.     

Attention misplaced: the role of diagnostic features in the face-inversion effect

Inversion disproportionately impairs recognition of face stimuli compared to nonface stimuli arguably due to the holistic manner in which faces are processed. A qualification is put forward in which the first point fixated on is different for upright and inverted faces and this carries some of the face-inversion effect. Three experiments explored this possibility by using fixation crosses to guide attention to the eye or mouth region of the to-be-presented faces in different orientations. Recognition was better when the fixation cross appeared at the eye region than at the mouth region. The face-inversion effect was smaller when the eyes were cued than when the mouth was cued or when there was no cueing. The results suggest that the first facial feature attended to is important for accurate face recognition and this may carry some of the effects of inversion.     

Effects of motion and audio-visual redundancy on upright and inverted face and feature preferences in 4-13-month old pre- and full-term NICU graduates

NICU infants are reported to have diminished social orientation and increased risk of socio-communicative disorders. In this eye tracking study, we used a preference for upright compared to inverted faces as a gauge of social interest in high medical risk full- and pre-term NICU infants. We examined the effects of facial motion and audio-visual redundancy on face and eye/mouth preferences across the first year. Upright and inverted baby faces were simultaneously presented in a paired-preference paradigm with motion and synchronized vocalization varied. NICU risk factors including birth weight, sex, and degree of CNS injury were examined. Overall, infants preferred the more socially salient upright faces, making this the first report, to our knowledge, of an upright compared to inverted face preference among high medical risk NICU infants. Infants with abnormalities on cranial ultrasound displayed lower social interest, i.e. less of a preferential interest in upright faces, when viewing static faces. However, motion selectively increased their upright face looking time to a level equal that of infants in other CNS injury groups. We also observed an age-related sex effect suggesting higher risk in NICU males. Females increased their attention to the mouth in upright faces across the first year, especially between 7–10 months, but males did not. Although vocalization increased diffuse attention toward the screen, contrary to our predictions, there was no evidence that the audio-visual redundancy embodied in a vocalizing face focused additional attention on upright faces or mouths. This unexpected result may suggest a vulnerability in response to talking faces among NICU infants that could potentially affect later verbal and socio-communicative development.     

Neural developmental changes in processing inverted faces

We explored developmental changes in neural substrates for face processing, using fMRI. Children and adults performed a perceptual-matching task with upright and inverted face and animal stimuli. Behaviorally, inversion disrupted face processing more than animal processing for adults and older children. In line with this behavioral pattern, the left middle occipital gyrus showed a stronger face than animal inversion effect in adults. Moreover, a superior aspect of this region showed a greater face inversion effect in older than in younger children, indicating a developmental change in the processing of inverted faces. The visual regions recruited for inverted face processing in adults also overlapped more with brain regions involved in the viewing of upright objects than with regions involved in the viewing of upright faces in an independent localizer task. Hence, when faces are inverted, adults recruit regions normally engaged for recognizing objects, possibly pointing to a role for the featural processing of inverted faces.