Processing Of Facial Features Research Articles

Process and Domain Specificity in Regions Engaged for Face Processing: An fMRI Study of Perceptual Differentiation

The degree to which face-specific brain regions are specialized for different kinds of perceptual processing is debated. This study parametrically varied demands on featural, first-order configural, or second-order configural processing of faces and houses in a perceptual matching task to determine the extent to which the process of perceptual differentiation was selective for faces regardless of processing type (domain-specific account), specialized for specific types of perceptual processing regardless of category (process-specific account), engaged in category-optimized processing (i.e., configural face processing or featural house processing), or reflected generalized perceptual differentiation (i.e., differentiation that crosses category and processing type boundaries). ROIs were identified in a separate localizer run or with a similarity regressor in the face-matching runs. The predominant principle accounting for fMRI signal modulation in most regions was generalized perceptual differentiation. Nearly all regions showed perceptual differentiation for both faces and houses for more than one processing type, even if the region was identified as face-preferential in the localizer run. Consistent with process specificity, some regions showed perceptual differentiation for first-order processing of faces and houses (right fusiform face area and occipito-temporal cortex and right lateral occipital complex), but not for featural or second-order processing. Somewhat consistent with domain specificity, the right inferior frontal gyrus showed perceptual differentiation only for faces in the featural matching task. The present findings demonstrate that the majority of regions involved in perceptual differentiation of faces are also involved in differentiation of other visually homogenous categories.

The influence of extrafoveal emotional faces on prosaccade latencies

Across three experiments we sought to determine whether extrafoveally presented emotional faces are processed sufficiently rapidly to influence saccade programming. Two rectangular targets containing a neutral and an emotional face were presented either side of a central fixation cross. Participants made prosaccades towards an abrupt luminosity change to the border of one of the rectangles. The faces appeared 150 ms before or simultaneously with the cue. Saccades were faster towards cued rectangles containing emotional compared to neutral faces even when the rectangles were positioned 12 degrees from the fixation cross. When faces were inverted, the facilitative effect of emotion only emerged in the −150 ms SOA condition, possibly reflecting a shift from configural to featural face processing. Together the results suggest that the human brain is highly specialized for processing emotional information and responds very rapidly to the brief presentation of expressive faces, even when these are located outside foveal vision.

Rigid facial motion influences featural, but not holistic, face processing

We report three experiments in which we investigated the effect of rigid facial motion on face processing. Specifically, we used the face composite effect to examine whether rigid facial motion influences primarily featural or holistic processing of faces. In Experiments 1–3, participants were first familiarized with dynamic displays in which a target face turned from one side to another; then at test, participants judged whether the top half of a composite face (the top half of the target/foil face aligned or misaligned with the bottom half of a foil face) belonged to the target face. We compared performance in the dynamic condition to various static control conditions in Experiments 1–3, which differed from each other in terms of the display order of the multiple static images or the inter-stimulus interval (ISI) between the images. We found that the size of the face composite effect in the dynamic condition was significantly smaller than that in the static conditions. In other words, the dynamic face display influenced participants to process the target faces in a part-based manner and consequently their recognition of the upper portion of the composite face at test became less interfered with by the aligned lower part of the foil face. The findings from the present experiments provide the strongest evidence to date to suggest that the rigid facial motion mainly influences facial featural, but not holistic, processing.

Independent influences of verbalization and race on the configural and featural processing of faces: A behavioral and eye movement study.

Describing a face in words can either hinder or help subsequent face recognition. Here, the authors examined the relationship between the benefit from verbally describing a series of faces and the same-race advantage (SRA) whereby people are better at recognizing unfamiliar faces from their own race as compared with those from other races. Verbalization and the SRA influenced face recognition independently, as evident on both behavioral (Experiment 1) and eye movement measures (Experiment 2). The findings indicate that verbalization and the SRA each recruit different types of configural processing, with verbalization modulating face learning and the SRA modulating both face learning and recognition. Eye movement patterns demonstrated greater feature sampling for describing as compared with not describing faces and for other-race as compared with same-race faces. In both cases, sampling of the eyes, nose, and mouth played a major role in performance. The findings support a single process account whereby verbalization can influence perceptual processing in a flexible and yet fundamental way through shifting one's processing orientation.

Effects of Nicotine on Emotional Reactivity in PTSD and Non-PTSD Smokers: Results of a Pilot fMRI Study.

There is evidence that individuals with posttraumatic stress disorder (PTSD) may smoke in part to regulate negative affect. This pilot fMRI study examined the effects of nicotine on emotional information processing in smokers with and without PTSD. Across groups, nicotine increased brain activation in response to fearful/angry faces (compared to neutral faces) in ventral caudate. Patch x Group interactions were observed in brain regions involved in emotional and facial feature processing. These preliminary findings suggest that nicotine differentially modulates negative information processing in PTSD and non-PTSD smokers.

Featural versus configural face processing in a rare genetic disorder: Williams syndrome

Williams syndrome (WMS) is a rare genetic disorder with an estimated prevalence of 1 in 20 000 live births. Among other characteristics, WMS has a distinctive cognitive profile with spared face processing and language skills that contrasts with impairment in the cognitive domains of spatial cognition, problem solving and planning. It remains unclear whether individuals with WMS process faces using a featural strategy that focuses on features or a configural strategy that takes into consideration the contour of a face and spatial relations between features. To investigate face processing in WMS, the tasks specifically probe unfamiliar face matching by using a design that includes manipulations in face presentation (thatcherised and non-thatcherised), face orientation (upright and inverted) and face valence (happy and neutral expression) in a match-to-target face recognition design. The sample consisted of 20 participants with WMS, 10 participants with non-specific developmental delay (IQ-matched) and 10 normal control participants (chronological age-matched). Similar to normal controls, WMS performed best when faces were presented upright. The results show while the WMS group did not perform as well as their typically developing counterparts, they did significantly better than the IQ-matched developmentally delayed group. WMS did not show an accuracy advantage for inverted faces commonly understood as an index for featural face processing, nor did they perform better on thatcherised inverted face conditions whereby featural processing is forced. Furthermore, no accuracy advantage was observed for positively valenced (happy) faces in the WMS group. These results are consistent with previous work showing a configural face processing approach in WMS, a strategy that is also utilised by normal controls.

Dissociating holistic from featural face processing by means of fixation patterns

Dissociating holistic from featural face processing by means of fixation patterns

Training of familiar face recognition and visual scan paths for faces in a child with congenital prosopagnosia

In the current report we describe a successful training study aimed at improving recognition of a set of familiar face photographs in K., a 4-year-old girl with congenital prosopagnosia (CP). A detailed assessment of K.'s face-processing skills showed a deficit in structural encoding, most pronounced in the processing of facial features within the face. In addition, eye movement recordings revealed that K.'s scan paths for faces were characterized by a large percentage of fixations directed to areas outside the internal core features (i.e., eyes, nose, and mouth), in particular by poor attendance to the eye region. Following multiple baseline assessments, training focused on teaching K. to reliably recognize a set of familiar face photographs by directing visual attention to specific characteristics of the internal features of each face. The training significantly improved K.'s ability to recognize the target faces, with her performance being flawless immediately after training as well as at a follow-up assessment 1 month later. In addition, eye movement recordings following training showed a significant change in K.'s scan paths, with a significant increase in the percentage of fixations directed to the internal features, particularly the eye region. Encouragingly, not only was the change in scan paths observed for the set of familiar trained faces, but it generalized to a set of faces that was not presented during training. In addition to documenting significant training effects, our study raises the intriguing question of whether abnormal scan paths for faces may be a common factor underlying face recognition impairments in childhood CP, an issue that has not been explored so far.

Investigation of featural versus configural processing of faces in the middle fusiform gyrus

Investigation of featural versus configural processing of faces in the middle fusiform gyrus

Inversion disrupts both configural and featural face processing equally

Previous studies that used configural vs. featural information manipulations in the investigation of the face inversion effect have reported a confined effect to configural manipulations, widely interpreted as reflecting the dominance of configural information in face processing. We suggest that such hypothesis is based on studies where configural and featural task difficulty were mismatched. Specifically, the featurally altered faces were easier to discriminate than the configurally altered ones when upright. In two experiments we compared the size of the inversion effect between configurally and featurally altered sets of faces when upright performance of both conditions were intentionally matched or mismatched. The magnitude of the inversion effect was comparable for configural and featural conditions when the sets of stimuli were well matched for discriminability, but diverged when the sets were intentionally mismatched. The results provide support against the view that inverted faces are processed in a qualitatively different way.

Processes Underlying the Cross-Race Effect: An Investigation of Holistic, Featural, and Relational Processing of Own-Race versus Other-Race Faces

Adults are often better at recognising own-race than other-race faces. Unlike previous studies that reported an own-race advantage after administering a single test of either holistic processing or of featural and relational processing, we used a cross-over design and multiple tasks to assess differential processing of faces from a familiar race versus a less familiar race. Caucasian and Chinese adults performed four tasks, each with Caucasian and Chinese faces. Two tasks measured holistic processing: the composite face task and the part/whole task. Both tasks indicated holistic processing of own-race and other-race faces that did not differ in degree. Two tasks measured featural and relational processing: the Jane/Ling task, in which same/ different judgments were made about face pairs that differed in features of their spacing, and the scrambled/blurred task, in which test faces were scrambled (isolates memory for components) or blurred (isolates memory for relations). Both tasks provided evidence of an own-race advantage in both featural and relational processing. We conclude that even when adults process other-race faces holistically, other manifestations of an own-race advantage remain.

Neural correlates of impaired emotional discrimination in borderline personality disorder: An fMRI study

A common approach to study neuronal aspects of emotional reactivity of borderline personality disorder (BPD) is to study the brain response to emotional faces with functional magnetic resonance imaging (fMRI). 10 BPD patients and 10 matched controls were submitted to an emotional discrimination task in which subjects had to identify an emotional face from a neutral face while fMRI data was acquired. BPD patients made more mistakes than controls in the discrimination task when negative faces were involved. The emotional discrimination task activated brain areas that are known to participate in processing of emotional faces (fusiform gyrus, insula and amygdala) regardless of the psychiatric condition. Additionally, BPD showed higher activation than controls in the middle and inferior temporal cortical areas, brain areas that participate in the processing of face features that carry emotional value. Furthermore, activity at this site correlated with impulsivity score in the Zuckerman–Kuhlman Personality Questionnaire. Our findings may be related to cognitive impairment that may be characteristic of the disorder.

Learning influences the encoding of static and dynamic faces and their recognition across different spatial frequencies

Studies on face recognition have shown that observers are faster and more accurate at recognizing faces learned from dynamic sequences than those learned from static snapshots. Here, we investigated whether different learning procedures mediate the advantage for dynamic faces across different spatial frequencies. Observers learned two faces—one dynamic and one static—either in depth (Experiment 1) or using a more superficial learning procedure (Experiment 2). They had to search for the target faces in a subsequent visual search task. We used high-spatial frequency (HSF) and low-spatial frequency (LSF) filtered static faces during visual search to investigate whether the behavioural difference is based on encoding of different visual information for dynamically and statically learned faces. Such encoding differences may mediate the recognition of target faces in different spatial frequencies, as HSF may mediate featural face processing whereas LSF mediates configural processing. Our results show that the nature of the learning procedure alters how observers encode dynamic and static faces, and how they recognize those learned faces across different spatial frequencies. That is, these results point to a flexible usage of spatial frequencies tuned to the recognition task.

The Development of Specialized Processing of Own-Race Faces in Infancy.

In this study, we examined developmental changes in infants' processing of own- versus other-race faces. Caucasian American 8-month-olds (Experiment 1) and 4-month-olds (Experiment 2) were tested in a habituation-switch procedure designed to assess holistic (attending to the relationship between internal and external features of the face) versus featural (attending to individual features of the face) processing of faces. Eight-month-olds demonstrated holistic processing of upright own-race (Caucasian) faces, but featural processing of upright other-race (African) faces. Inverted faces were processed featurally, regardless of ethnicity. Four-month-olds, however, demonstrated holistic processing of both Caucasian and African upright faces. These results demonstrate that infants' processing of own- versus other-race faces becomes specialized between 4 and 8 months.

Face inversion effects in autism: a combined looking time and pupillometric study

Previous research has found that in typically developing individuals, behavioral performance declines and electrophysiological brain responses are altered when the face is inverted. Such effects are generally attributed to disruption of configural information. Individuals with autism spectrum disorder (ASD) have been found to show less pronounced inversion effects, a result in line with the view that featural processing of faces is enhanced in ASD. No study has determined if, or how, such local bias is reflected in the eye movements used in face observation. In this eye tracking study, looking time and pupil dilation were investigated during the presentation of upright and inverted faces in preschool children with ASD and typically developing preschoolers. On average, both children with ASD and typically developing children looked less at the face and the eye areas during inverted presentations than during upright presentations. Nevertheless, individuals with ASD had a stronger tendency than typically developing children to look at the same face features during upright and inverted presentations, which is suggestive of a local bias. Pupil dilation, reflecting increased processing load, was larger for inverted than upright faces in the ASD group only, and pupillary inversion effects were stronger in ASD than in typically developing children.

Training of familiar face recognition and visual scan paths for faces in a child with congenital prosopagnosia

In the current report we describe a successful training study aimed at improving recognition of a set of familiar face photographs in K., a 4-year-old girl with congenital prosopagnosia (CP). A detailed assessment of K.'s face-processing skills showed a deficit in structural encoding, most pronounced in the processing of facial features within the face. In addition, eye movement recordings revealed that K.'s scan paths for faces were characterized by a large percentage of fixations directed to areas outside the internal core features (i.e., eyes, nose, and mouth), in particular by poor attendance to the eye region. Following multiple baseline assessments, training focused on teaching K. to reliably recognize a set of familiar face photographs by directing visual attention to specific characteristics of the internal features of each face. The training significantly improved K.'s ability to recognize the target faces, with her performance being flawless immediately after training as well as at a follow-up assessment 1 month later. In addition, eye movement recordings following training showed a significant change in K.'s scan paths, with a significant increase in the percentage of fixations directed to the internal features, particularly the eye region. Encouragingly, not only was the change in scan paths observed for the set of familiar trained faces, but it generalized to a set of faces that was not presented during training. In addition to documenting significant training effects, our study raises the intriguing question of whether abnormal scan paths for faces may be a common factor underlying face recognition impairments in childhood CP, an issue that has not been explored so far.

Do emotionally expressive faces automatically capture attention? Evidence from global–local interference

The present experiments investigated whether perception of a global face gestalt automatically interferes with processing of facial features. Upward- and downward-curved arcs were grouped into triplets to resemble faces with positive or negative expressions. The arcs were presented either in a uniform grey colour to facilitate global face perception or in mixed colours where individual arcs were coloured red to reduce global face perception. Experiments 1 and 2 induced a local processing orientation by requiring participants to count individual arc features. Negative face displays yielded slower and less accurate arc counting performance than positive face displays, but only when all arcs were the same colour. In Experiment 3, a global processing orientation was induced by requiring participants to count the number of arc triplets. This time, negative face displays yielded slower reaction times, regardless of feature colour. These results show that interference from emotional face gestalts is not automatic but can be eliminated and may depend on both attentional control settings and “bottom-up” stimulus attributes.

Neural correlates of processing facial identity based on features versus their spacing

Adults’ expertise in recognizing facial identity involves encoding subtle differences among faces in the shape of individual facial features (featural processing) and in the spacing among features (a type of configural processing called sensitivity to second-order relations). We used fMRI to investigate the neural mechanisms that differentiate these two types of processing. Participants made same/different judgments about pairs of faces that differed only in the shape of the eyes and mouth, with minimal differences in spacing (featural blocks), or pairs of faces that had identical features but differed in the positions of those features (spacing blocks). From a localizer scan with faces, objects, and houses, we identified regions with comparatively more activity for faces, including the fusiform face area (FFA) in the right fusiform gyrus, other extrastriate regions, and prefrontal cortices. Contrasts between the featural and spacing conditions revealed distributed patterns of activity differentiating the two conditions. A region of the right fusiform gyrus (near but not overlapping the localized FFA) showed greater activity during the spacing task, along with multiple areas of right frontal cortex, whereas left prefrontal activity increased for featural processing. These patterns of activity were not related to differences in performance between the two tasks. The results indicate that the processing of facial features is distinct from the processing of second-order relations in faces, and that these functions are mediated by separate and lateralized networks involving the right fusiform gyrus, although the FFA as defined from a localizer scan is not differentially involved.

The Respective Role of Low and High Spatial Frequencies in Supporting Configural and Featural Processing of Faces

One distinctive feature of processing faces, as compared to other categories, is thought to be the large dependence on configural cues such as the metric relations among features. To test the role of low spatial frequencies (LSFs) and high spatial frequencies (HSFs) in configural and featural processing, subjects were presented with triplets of faces that were filtered to preserve either LSFs (below 8 cycles per face width), HSFs (above 32 cycles per face width), or the full frequency spectrum. They were asked to match one of two probe faces to a target face. The distractor probe face differed from the target either configurally, featurally, or both featurally and configurally. When the difference was at the configural level, performance was better with LSF faces than with HSF faces. In contrast, with a featural difference, a strong performance advantage was found for HSF faces as compared to LSF faces. These results support the dominant role that LSFs play in the configural processing of faces, whereas featural processing is largely dependent on HSFs.

Neural correlates of featural versus configural face processing in visually normal adults

Y -! Y Y! ! 10! -! Y -! 9! Y -! Y Y! ! 8! Y -! Y Y! ! 7! Y Y! Y Y! ! 6! -! Y Y! ! 5! Y -! Y Y! ! 4! Y Y! ! Y Y! ! 3! Y Y! ! Y Y! ! 2! Y Y! 1! Neural Correlates of Featural versus Configural Face Processing in Visually Normal Adults! K. O Craven1 R. LeGrand2,3, D. Maurer2, C. Mondloch2, G. Pellicori1, T. Lewis2, C. Grady1 1Rotman Research Institute Toronto, Ontario! 2McMaster University Hamilton, Ontario! 3University of Victoria Victoria, B.C.!