The heterogeneity of holistic processing profiles in developmental prosopagnosia: holistic processing is impaired but not absent.

Although it is generally assumed that face recognition relies on holistic processing, whether face recognition deficits observed in Developmental Prosopagnosics (DPs) can be explained by impaired holistic processing is currently under debate. The mixed findings from past studies could be the consequence of DP's heterogeneous deficit nature and the use of different measures of holistic processing-the inversion, part-whole, and composite tasks-which showed a poor association among each other. The present study aimed to gain further insight into the role of holistic processing in DPs. Groups of DPs and neurotypicals completed three tests measuring holistic face processing and non-face objects (i.e., Navon task). At a group level, DPs showed (1) diminished, but not absent, inversion and part-whole effects, (2) comparable magnitudes of the composite face effect and (3) global precedence effect in the Navon task. However, single-case analyses showed that these holistic processing deficits in DPs are heterogeneous.

Opposite size illusions for inverted faces and letters.

Words are the primary means by which we communicate meaning and ideas, while faces provide important social cues. Studying visual illusions involving faces and words can elucidate the hierarchical processing of information as different regions of the brain are specialised for face recognition and word processing. A size illusion has previously been demonstrated for faces, whereby an inverted face is perceived as larger than the same stimulus upright. Here, two experiments replicate the face size illusion, and investigate whether the illusion is also present for individual letters (Experiment 1), and visual words and pseudowords (Experiment 2). Results confirm a robust size Illusion for faces. Letters, words and pseudowords and unfamiliar letters all show a reverse size illusion, as we previously demonstrated for human bodies. Overall, results indicate the illusion occurs in early perceptual stages upstream of semantic processing. Results are consistent with the idea of a general-purpose mechanism that encodes curvilinear shapes found in both scripts and our environment. Word and face perception rely on specialised, independent cognitive processes. The underestimation of the size of upright stimuli is specific to faces. Opposite size illusions may reflect differences in how size information is encoded and represented in stimulus-specialised neural networks, resulting in contrasting perceptual effects. Though words and faces differ visually, there is both symmetry and asymmetry in how the brain 'reads' them.

Converging evidence that left extrastriate body area supports visual sensitivity to social interactions.

Navigating our complex social world requires processing the interactions we observe. Recent psychophysical and neuroimaging studies provide parallel evidence that the human visual system may be attuned to efficiently perceive dyadic interactions. This work implies, but has not yet demonstrated, that activity in body-selective cortical regions causally supports efficient visual perception of interactions. We adopt a multi-method approach to close this important gap. First, using a large fMRI dataset (n = 92), we found that the left hemisphere extrastriate body area (EBA) responds more to face-to-face than non-facing dyads. Second, we replicated a behavioral marker of visual sensitivity to interactions: categorization of facing dyads is more impaired by inversion than non-facing dyads. Third, in a pre-registered experiment, we used fMRI-guided transcranial magnetic stimulation to show that online stimulation of the left EBA, but not a nearby control region, abolishes this selective inversion effect. Activity in left EBA, thus, causally supports the efficient perception of social interactions.

The face inversion effect does not provide a pure measure of holistic face processing.

It is widely held that upright faces are processed more holistically than inverted faces and that this difference is reflected in the face inversion effect. It is not clear, however, how the inversion effect can best be measured, whether it is task specific, or even whether it specifically correlates with processing of upright faces. We examined these questions in a large sample (N = 420) who provided data on processing of upright and inverted stimuli in two different tasks with faces and one with objects. We find that the inversion effects are task dependent, and that they do not correlate better among face processing tasks than they do across face and object processing tasks. These findings were obtained regardless of whether inversion effects were measured by means of difference scores or regression. In comparison, only inversion effects based on regression predicted performance with upright faces in tasks other than those the inversion effects were derived from. Critically, however, inversion effects based on regression also predicted performance with inverted faces to a similar degree as they predicted performance with upright faces. Consequently, and contrary to what is commonly assumed, inversion effects do not seem to capture effects specific to holistic processing of upright faces. While the present findings do not bring us closer to an understanding of which changes in cognitive processing are induced by inversion, they do suggest that inversion effects do not reflect a unitary construct; an implicit assumption that seems to characterize much of the research regarding face processing.

Using transcranial direct current stimulation (tDCS) to selectively modulate the face inversion effect and N170 event-related potentials.

We report a large study (n = 72) using combined transcranial direct current stimulation-electroencephalography (tDCS-EEG) to investigate the modulation of perceptual learning indexed by the face inversion effect. Participants were engaged with an old/new recognition task involving intermixed upright and inverted, normal and Thatcherized faces. The accuracy results showed anodal tDCS delivered at the Fp3 scalp area (cathode/reference electrode placed at Fp2) increased the behavioural inversion effect for normal faces versus sham/control and this covaried with a modulation of the N170 event-related potential component. A reduced inversion effect for normal faces was found on the N170 latency and amplitude versus sham/control, extending recent work that combined tDCS and EEG in circumstances where the behavioural face inversion effect was reduced. Our results advance understanding of the neural mechanisms responsible for perceptual learning by revealing a dissociation between the N170 amplitude and latency in response to the tDCS-induced modulation of the face inversion effect. The behavioural modulation of the inversion effect tracks the modulation of the N170 amplitudes, albeit it is negatively correlated (i.e., reduced inversion effect-larger N170 amplitude inversion effect, increased inversion effect-reduced N170 amplitude inversion effect). For the N170 latencies, the inversion effect is reduced by the tDCS protocol we use irrespective of any modulation of the behavioural inversion effect.

Asynchrony enhances uncanniness in human, android, and virtual dynamic facial expressions.

OBJECTIVE: Uncanniness plays a vital role in interactions with humans and artificial agents. Previous studies have shown that uncanniness is caused by a higher sensitivity to deviation or atypicality in specialized categories, such as faces or facial expressions, marked by configural processing. We hypothesized that asynchrony, understood as a temporal deviation in facial expression, could cause uncanniness in the facial expression. We also hypothesized that the effect of asynchrony could be disrupted through inversion. RESULTS: Sixty-four participants rated the uncanniness of synchronous or asynchronous dynamic face emotion expressions of human, android, or computer-generated (CG) actors, presented either upright or inverted. Asynchrony vs. synchrony expressions increased uncanniness for all upright expressions except for CG angry expressions. Inverted compared with upright presentations produced less evident asynchrony effects for human angry and android happy expressions. These results suggest that asynchrony can cause dynamic expressions to appear uncanny, which is related to configural processing but different across agents.

Is increased activation in the fusiform face area to Greebles a result of appropriate expertise training or caused by Greebles' face likeness?

Background: In 2011, Brants et al. trained eight individuals to become Greeble experts and found neuronal inversion effects [NIEs; i.e., higher fusiform face area (FFA) activity for upright, rather than inverted Greebles]. These effects were also found for faces, both before and after training. By claiming to have replicated the seminal Greeble training study by Gauthier and colleagues in 1999, Brants et al. interpreted these results as participants viewing Greebles as faces throughout training, contrary to the original argument of subjects becoming Greeble experts only after training. However, Brants et al.'s claim presents two issues. First, their behavioral training results did not replicate those of Gauthier and Tarr conducted in 1997 and 1998, raising concerns of whether the right training regime had been adopted. Second, both a literature review and meta-analysis of NIEs in the FFA suggest its impotency as an index of the face(-like) processing. Objectives: To empirically evaluate these issues, the present study compared two documented training paradigms Gauthier and colleagues in 1997 and 1998, and compared their impact on the brain. Methods: Sixteen NCKU undergraduate and graduate students (nine girls) were recruited. Sixty Greeble exemplars were categorized by two genders, five families, and six individual levels. The participants were randomly divided into two groups (one for Greeble classification at all three levels and the other for gender- and individual-level training). Several fMRI tasks were administered at various time points, specifically, before training (1st), during training (2nd), and typically no <24 h after reaching expertise criterion (3rd). Results: The ROI analysis results showed significant increases in the FFA for Greebles, and a clear neural "adaptation," both only in the Gauthier97 group and only after training, reflecting clear modulation of extensive experiences following an "appropriate" training regime. In both groups, no clear NIEs for faces nor Greebles were found, which was also in line with the review of extant studies bearing this comparison. Conclusion: Collectively, these results invalidate the assumptions behind Brants et al.'s findings.

The effect of face orientation on audiovisual speech integration in infancy: An electrophysiological study.

Humans pay special attention to faces and speech from birth, but the interplay of developmental processes leading to specialization is poorly understood. We investigated the effects of face orientation on audiovisual (AV) speech perception in two age groups of infants (younger: 5- to 6.5-month-olds; older: 9- to 10.5-month-olds) and adults. We recorded event-related potentials (ERP) in response to videos of upright and inverted faces producing /ba/ articulation dubbed with auditory syllables that were either matching /ba/ or mismatching /ga/ the mouth movement. We observed an increase in the amplitude of audiovisual mismatch response (AVMMR) to incongruent visual /ba/-auditory /ga/ syllable in comparison to other stimuli in younger infants, while the older group of infants did not show a similar response. AV mismatch response to inverted visual /ba/-auditory /ga/ stimulus relative to congruent stimuli was also detected in the right frontal areas in the younger group and the left and right frontal areas in adults. We show that face configuration affects the neural response to AV mismatch differently across all age groups. The novel finding of the AVMMR in response to inverted incongruent AV speech may potentially imply the featural face processing in younger infants and adults when processing inverted faces articulating incongruent speech. The lack of visible differential responses to upright and inverted incongruent stimuli obtained in the older group of infants suggests a likely functional cortical reorganization in the processing of AV speech.

The inversion effect on the cubic humanness-uncanniness relation in humanlike agents.

The uncanny valley describes the typically nonlinear relation between the esthetic appeal of artificial entities and their human likeness. The effect has been attributed to specialized (configural) processing that increases sensitivity to deviations from human norms. We investigate this effect in computer-generated, humanlike android and human faces using dynamic facial expressions. Angry and happy expressions with varying degrees of synchrony were presented upright and inverted and rated on their eeriness, strangeness, and human likeness. A sigmoidal function of human likeness and uncanniness ("uncanny slope") was found for upright expressions and a linear relation for inverted faces. While the function is not indicative of an uncanny valley, the results support the view that configural processing moderates the effect of human likeness on uncanniness and extend its role to dynamic facial expressions.

Face inversion effect on perceived cuteness of infant faces.

Research has demonstrated that attractiveness evaluations of adult faces were less accurate when faces were inverted than upright. It remains unknown, however, whether a similar effect applies to perceived cuteness of infants, which is assumed to be based on elemental facial features called the "baby schema." In this research, we studied the face inversion effect on perceived cuteness of infant faces in a rating task and a two-alternative forced-choice (2AFC) task. We also examined beauty as a control dimension. Although the rating task revealed no inversion effect, the 2AFC task showed poorer discrimination performance with inverted faces than with upright faces in both evaluations. These results indicate that infant cuteness and beauty dimensions are correlated well with each other, and their perception not only relies on elemental features that are not strongly affected by inversion but is also affected by holistic facial configurations when a detailed comparison is required.

Gauging response time distributions to examine the effect of facial expression inversion.

Introduction: We used images of facial expressions (FEs) of emotion in a speeded Same/Different task to examine (i) distributional characteristics of response times (RTs) in relation to inter-stimulus similarity and (ii) the impact of inversion on FE processing. Methods: Stimuli were seven emotion prototypes, posed by one male and one female, and eight intermediate morphs. Image pairs (N = 225) were presented for 500 ms, upright or inverted, in a block design, each 100 times. Results: For both upright and inverted FEs, RTs were a non-monotonic function: median values were longest for stimulus pairs of intermediate similarity, decreasing for both more-dissimilar and more-similar pairs. RTs of "Same" and "Different" judgments followed ex-Gaussian distributions. The non-monotonicity is interpreted within a dual-process decision model framework as reflecting the infrequency of identical pairs, shifting the balance between the Same and Different processes. The effect of stimulus inversion was gauged by comparing RT-based multidimensional scaling solutions for the two presentation modes. Solutions for upright and inverted FEs showed little difference, with both displaying some evidence of categorical perception. The same features appeared in hierarchical clustering solutions. Discussion: This outcome replicates and reinforces the solutions derived from accuracy of "Different" responses reported in our earlier companion paper. We attribute this lack of inversion effect to the brief exposure time, allowing low-level visual processing to dominate Same/Different decisions while elevating early featural analysis, which is insensitive to face orientation but enables initial positive/negative valence categorization of FEs.

Vertical anisotropy in lightness perception not caused by lighting assumption.

Our recent study found an illusory effect whereby an image of an upward-facing gray panel appears darker than its 180-degree rotated image. We attributed this inversion effect to the observer's implicit assumption that light from above is more intense than light from below. This paper aims to explore the possibility that low-level visual anisotropy also contributes to the effect. In Experiment 1, we investigated whether the effect could be observed even when the position, the contrast polarity, and the existence of the edge were manipulated. In Experiments 2 and 3, the effect was further examined using stimuli that contained no depth cues. Experiment 4 confirmed the effect using stimuli of even simpler configuration. The results of all the experiments demonstrated that brighter edges on the upper side of the target make it appear lighter, indicating that low-level anisotropy contributes to the inversion effect, even without depth orientation information. However, darker edges on the upper side of the target produced ambiguous results. We speculate that the perceived lightness of the target might be affected by two kinds of vertical anisotropy, one of which is dependent on contrast polarity while the other is independent of it. Moreover, the results also replicated the previous finding that the lighting assumption contributes to perceived lightness. Overall, the present study demonstrates that both low-level vertical anisotropy and mid-level lighting assumption influence lightness.

Spatial Frequency Tuning of Body Inversion Effects.

Body inversion effects (BIEs) reflect the deployment of the configural processing of body stimuli. BIE modulates the activity of body-selective areas within both the dorsal and the ventral streams, which are tuned to low (LSF) or high spatial frequencies (HSF), respectively. The specific contribution of different bands to the configural processing of bodies along gender and posture dimensions, however, is still unclear. Seventy-two participants performed a delayed matching-to-sample paradigm in which upright and inverted bodies, differing for gender or posture, could be presented in their original intact form or in the LSF- or HSF-filtered version. In the gender discrimination task, participants' performance was enhanced by the presentation of HSF images. Conversely, for the posture discrimination task, a better performance was shown for either HSF or LSF images. Importantly, comparing the amount of BIE across spatial-frequency conditions, we found greater BIEs for HSF than LSF images in both tasks, indicating that configural body processing may be better supported by HSF information, which will bias processing in the ventral stream areas. Finally, the exploitation of HSF information for the configural processing of body postures was lower in individuals with higher autistic traits, likely reflecting a stronger reliance on the local processing of body-part details.

Emotional response evoked by viewing facial expression pictures leads to higher temporal resolution.

We examined the effects of emotional response, with different levels of valence and arousal, on the temporal resolution of visual processing by using photos of various facial expressions. As an index of the temporal resolution of visual processing, we measured the minimum lengths of the noticeable durations for desaturated photographs using the method of constant stimuli by switching colorful facial expression photographs to desaturated versions of the same photographs. Experiments 1 and 2 used facial photographs that evoke various degrees of arousal and valence. Those photographs were prepared not only in an upright orientation but also in an inverted orientation to reduce emotional response without changing the photographs' image properties. Results showed that the minimum duration to notice monochrome photographs for anger, fear, and joy was shorter than that for a neutral face when viewing upright face photographs but not when viewing inverted face photographs. For Experiment 3, we used facial expression photographs to evoke various degrees of arousal. Results showed that the temporal resolution of visual processing increased with the degree of arousal. These results suggest that the arousal of emotional responses evoked by viewing facial expressions might increase the temporal resolution of visual processing.

Are social interactions preferentially attended in real-world scenes? Evidence from change blindness.

In change detection paradigms, changes to social or animate aspects of a scene are detected better and faster compared with non-social or inanimate aspects. While previous studies have focused on how changes to individual faces/bodies are detected, it is possible that individuals presented within a social interaction may be further prioritised, as the accurate interpretation of social interactions may convey a competitive advantage. Over three experiments, we explored change detection to complex real-world scenes, in which changes either occurred by the removal of (a) an individual on their own, (b) an individual who was interacting with others, or (c) an object. In Experiment 1 (N = 50), we measured change detection for non-interacting individuals versus objects. In Experiment 2 (N = 49), we measured change detection for interacting individuals versus objects. Finally, in Experiment 3 (N = 85), we measured change detection for non-interacting versus interacting individuals. We also ran an inverted version of each task to determine whether differences were driven by low-level visual features. In Experiments 1 and 2, we found that changes to non-interacting and interacting individuals were detected better and more quickly than changes to objects. We also found inversion effects for both non-interaction and interaction changes, whereby they were detected more quickly when upright compared with inverted. No such inversion effect was seen for objects. This suggests that the high-level, social content of the images was driving the faster change detection for social versus object targets. Finally, we found that changes to individuals in non-interactions were detected faster than those presented within an interaction. Our results replicate the social advantage often found in change detection paradigms. However, we find that changes to individuals presented within social interaction configurations do not appear to be more quickly and easily detected than those in non-interacting configurations.

Face race and sex impact visual fixation strategies for upright and inverted faces in 3- to 6-year-old children.

Everyday face experience tends to be biased, such that infants and young children interact more often with own-race and female faces leading to differential processing of faces within these groups relative to others. In the present study, visual fixation strategies were recorded using eye tracking to determine the extent to which face race and sex/gender impact a key index of face processing in 3- to 6-year-old children (n = 47). Children viewed male and female upright and inverted White and Asian faces while visual fixations were recorded. Face orientation was found to have robust effects on children's visual fixations, such that children exhibited shorter first fixation and average fixation durations and a greater number of fixations for inverted compared to upright face trials. First fixations to the eye region were also greater for upright compared to inverted faces. Fewer fixations and longer duration fixations were found for trials with male compared to female faces and for upright compared to inverted unfamiliar-race faces, but not familiar-race faces. These findings demonstrate evidence of differential fixation strategies toward different types of faces in 3- to 6-year-old children, illustrating the importance of experience in the development of visual attention to faces.

A language compatibility effect in fraction processing.

A language compatibility effect occurs when there is a match between what a language provides and what a mathematical task demands. Here, we investigated whether such an effect exists for fraction processing in English, which names the numerator first, versus Korean, which names the denominator first. We developed two new tasks: a fraction span task where participants view and then recall four fractions and a fraction identification task where they view one fraction and then another and judge whether the two fractions are the same or not. We generally found that English speakers were advantaged when the numerator drove task performance and Korean speakers were advantaged when the denominator was critical. These findings, particularly from the fraction identification task, were inconsistent with the attentional focus hypothesis, which proposes that the serialisation bias of a language guides which fraction component is attended to first. Rather, they were better explained by the verbal encoding hypothesis, which states that a necessary condition for observing language compatibility effects may be that the fraction components must be encoded in verbal working memory and rehearsed there.

The face inversion effect or the face upright effect?

The face inversion effect (FIE) refers to the observation that presenting stimuli upside-down impairs the processing of faces disproportionally more than other mono-oriented objects. This has been taken as evidence that processing of faces and objects differ qualitatively. However, nearly all FIE studies are based on comparing individuation of upright faces, which most people are rather good at, with individuation of objects most people are much less familiar with individuating (e.g., radios and airplanes). Consequently, the FIE may mainly reflect differences between categories in how they are processed prior to inversion, with within-category discrimination of upright faces being a much more familiar task than within-category discrimination among members belonging to other object classes. We tested this hypothesis by comparing inversion effects for faces and objects using object recognition tasks that do not require within-category discrimination (object decision and old/new recognition memory tasks). In all tasks (seven with objects and two with faces) we find credible inversion effects, but in no instance were these effects significantly larger for faces than for objects. This suggests that the FIE can be a product of familiarity with the type of identification process required in the upright conditions rather than some process that is selectively affected for faces when stimuli are inverted.

Face inversion does not affect the reversed congruency effect of gaze.

In a spatial Stroop task, the eye-gaze target produces the reversed congruency effect-responses become shorter when the gaze direction and its location are incongruent than when they are congruent. The present study examined the face inversion effect on the gaze spatial Stroop task to clarify whether the holistic face processing or part-based processing of the eyes is responsible for the reversed congruency effect. In Experiment 1, participants judged the gaze direction of the upright or inverted face with a neutral expression presented either in the left or right visual field. In Experiment 2, we examined whether face inversion interacted with facial expressions (i.e., angry, happy, neutral, and sad). Face inversion disrupted holistic face processing, slowing down the overall performance relative to the performance with upright faces. However, face inversion did not affect the reversed congruency effect. These results further support the parts-based processing account and suggest that while faces are processed holistically, the reversed congruency effect, relying on the extracted local features (i.e., eyes), may be processed in a part-based manner.

Spotting lesions in thorax X-rays at a glance: holistic processing in radiology.

Radiologists often need only a glance to grasp the essence of complex medical images. Here, we use paradigms and manipulations from perceptual learning and expertise fields to elicit mechanisms and limits of holistic processing in radiological expertise. In the first experiment, radiologists were significantly better at categorizing thorax X-rays when they were presented for 200 ms in an upright orientation than when they were presented upside-down. Medical students, in contrast, were guessing in both situations. When the presentation time was increased to 500 ms, allowing for a couple more glances, the radiologists improved their performance on the upright stimuli, but remained at the same level on the inverted presentation. The second experiment circumvented the holistic processing by immediately cueing a tissue within the X-rays, which may or may not contain a nodule. Radiologists were again better than medical students at recognizing whether the cued tissue was a nodule, but this time neither the inverted presentation nor additional time affected their performance. Our study demonstrates that holistic processing is most likely a continuous recurring process which is just as susceptible to the inversion effect as in other expertise domains. More importantly, our study also indicates that holistic-like processing readily occurs in complex stimuli (e.g., whole thorax X-rays) but is more difficult to find in uniform single parts of such stimuli (e.g., nodules).