Perceptual and decisional factors influencing the discrimination of inversion in the Thatcher illusion

The Thatcher illusion (Thompson, 1980) is considered to be a prototypical illustration of the notion that face perception is dependent on configural processes and representations. We explored this idea by examining the relative contributions of perceptual and decisional processes to the ability of observers to identify the orientation of two classes of forms-faces and churches-and a set of their component features. Observers were presented with upright and inverted images of faces and churches in which the components (eyes, mouth, windows, doors) were presented either upright or inverted. Observers first rated the subjective grotesqueness of all of the images and then performed a complete identification task in which they had to identify the orientation of the overall form and the orientation of each of the interior features. Grotesqueness ratings for both classes of image showed the standard modulation of rated grotesqueness as a function of orientation. The complete identification results revealed violations of both perceptual and decisional separability but failed to reveal any violations of within-stimulus (perceptual) independence. In addition, exploration of a simple bivariate Gaussian signal detection model of the relationship between identification performance and judged grotesqueness suggests that within-stimulus violations of perceptual independence on their own are insufficient for producing the illusion. This lack of evidence for within-stimulus configurality suggests the need for a critical reevaluation of the role of configural processing in the Thatcher illusion. (PsycINFO Database Record (c) 2011 APA, all rights reserved).     

Dissociation of facial attractiveness and distinctiveness processing in congenital prosopagnosia

According to the influential model of Bruce and Young (1986) socially relevant facial information is processed separately from facial information leading to individual face recognition. In recent years functional imaging has identified a network of distinct occipitotemporal cortex areas for the processing of these two kinds of information. Functionally it is not clear at which processing level the “social” and the “recognition” pathways diverge. The study of subjects with a profound face recognition and learning deficit (congenital prosopagnosia—cPA) promises for a better understanding of this issue. We therefore tested the perception of attractiveness (a cue of prime social importance) and distinctiveness (a facial feature related to recognition) in 14 people with cPA. Although attractiveness ratings were highly consistent with controls, cPA subjects' distinctiveness ratings showed random patterns. This dissociation of normal attractiveness processing and impaired distinctiveness processing in cPA helps to specifies the nature of the impairment in this condition while shedding light on the functional architecture of normal face processing.     

Holistic processing impairment can be restricted to faces in acquired prosopagnosia: Evidence from the global/local Navon effect

Previous studies have shown that acquired prosopagnosia is characterized by impairment at holistic/configural processing. However, this view is essentially supported by studies performed with patients whose face recognition difficulties are part of a more general visual (integrative) agnosia. Here, we tested the patient PS, a case of acquired prosopagnosia whose face‐specific recognition difficulties have been related to the inability to process individual faces holistically (absence of inversion, composite, and whole–part effects with faces). Here, we show that in contrast to this impairment, the patient presents with an entirely normal response profile in a Navon hierarchical letter task: she was as fast as normal controls, faster to identify global than local letters, and her sensitivity to global interference during identification of local letters was at least as large as normal observers. These observations indicate that holistic processing as measured with global/local interference in the Navon paradigm is functionally distinct from the ability to perceive an individual face holistically.     

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.     

Understanding the role of configural processing in face emotion recognition in Parkinson’s disease

This investigation examined whether impairment in configural processing could explain deficits in face emotion recognition in people with Parkinson’s disease (PD). Stimuli from the Radboud Faces Database were used to compare recognition of four negative emotion expressions by older adults with PD (n = 16) and matched controls (n = 17). Participants were tasked with categorizing emotional expressions from upright and inverted whole faces and facial composites; it is difficult to derive configural information from these two types of stimuli so featural processing should play a larger than usual role in accurate recognition of emotional expressions. We found that the PD group were impaired relative to controls in recognizing anger, disgust and fearful expressions in upright faces. Then, consistent with a configural processing deficit, participants with PD showed no composite effect when attempting to identify facial expressions of anger, disgust and fear. A face inversion effect, however, was observed in the performance of all participants in both the whole faces and facial composites tasks. These findings can be explained in terms of a configural processing deficit if it is assumed that the disruption caused by facial composites was specific to configural processing, whereas inversion reduced performance by making it difficult to derive both featural and configural information from faces.     

The perception of unfamiliar faces and houses by chimpanzees: influence of rotation angle

The inversion effect, or impaired recognition of upside-down faces, is used as evidence supporting the configural processing of faces. Human studies report a linear relationship between face-discrimination performance and orientation, such that recognition is more difficult as faces are rotated away from their typical viewpoint. Previous studies on chimpanzees also support a configural bias for processing faces, particularly faces for which subjects have developed expertise. In the present study, we examined the influence of expertise and rotation angle on the visual perception of faces in chimpanzees. Six subjects were presented with unaltered and blurred conspecific faces and houses in five orientation angles. A computerized paradigm was used to further delineate the nature of configural face processing in this species. The data were consistent with those reported in humans: chimpanzees showed a significant linear impairment when discriminating conspecific faces as they rotated away from their upright orientation. No inversion effect was observed for discriminations involving houses. Thus, chimpanzees, like humans, show a face-specific inversion effect that is linearly affected by angle of orientation, suggesting that their visual processing of faces is strongly influenced by the extraction of configural cues and closely resembles the perceptual strategies of humans.     

Atypically heterogeneous vertical first fixations to faces in a case series of people with developmental prosopagnosia

ABSTRACT

When people recognize faces, they normally move their eyes so that their first fixation is in the optimal location for efficient perceptual processing. This location is found just below the centre-point between the eyes. This type of attentional bias could be partly innate, but also an inevitable developmental process that aids our ability to recognize faces. We investigated whether a group of people with developmental prosopagnosia would also demonstrate neurotypical first fixation locations when recognizing faces during an eye-tracking task. We found evidence that adults with prosopagnosia had atypically heterogeneous first fixations in comparison to controls. However, differences were limited to the vertical, but not horizontal, plane of the face. We interpret these findings by suggesting that subtle changes to face-based eye movement patterns in developmental prosopagnosia may underpin their face recognition impairments, and suggest future work is still needed to address this possibility.     

Neural and genetic foundations of face recognition and prosopagnosia

Faces are of essential importance for human social life. They provide valuable information about the identity, expression, gaze, health, and age of a person. Recent face‐processing models assume highly interconnected neural structures between different temporal, occipital, and frontal brain areas with several feedback loops. A selective deficit in the visual learning and recognition of faces is known as prosopagnosia, which can be found both in acquired and congenital form. Recently, a hereditary sub‐type of congenital prosopagnosia with a very high prevalence rate of 2.5% has been identified. Recent research results show that hereditary prosopagnosia is a clearly circumscribed face‐processing deficit with a characteristic set of clinical symptoms. Comparing face processing of people of prosopagnosia with that of controls can help to develop a more conclusive and integrated model of face processing. Here, we provide a summary of the current state of face processing research. We also describe the different types of prosopagnosia and present the set of typical symptoms found in the hereditary type. Finally, we will discuss the implications for future face recognition research.     

Normal face-based judgements of social characteristics despite severely impaired holistic face processing

Initial evidence indicates that face-based judgements of socially relevant characteristics such as people's trustworthiness or attractiveness are linked to the configural/holistic processing of facial cues. What remains a matter of debate, however, is whether such processing is actually necessary for normal social judgements to occur and whether it resembles the type of integrative processing as required for facial identification. To address these issues, we asked a well-characterized case of acquired prosopagnosia (PS) with a marked deficit in holistic processing for face identity to rate a series of faces on several dimensions of social relevance. PS provided ratings within the normal range for most of the social characteristics probed (i.e., aggression, attractiveness, confidence, intelligence, sociability, trustworthiness). Her evaluations deviated from those of healthy controls only when facial dominance was concerned. Taken together, these data demonstrate that the inability to integrate facial information during face individuation does not necessarily translate into a generalized deficit to evaluate faces on social dimensions.     

The biasing of figure-ground assignment by shading cues for objects and faces in prosopagnosia

Prosopagnosia is defined by impaired recognition of the identity of specific faces. Whether the perception of faces at the categorical level (recognizing that a face is a face) is also impaired to a lesser degree is unclear. We examined whether prosopagnosia is associated with impaired detection of facial contours in a bistable display, by testing a series of five prosopagnosic patients on a variation of Rubin's vase illusion, in which shading was introduced to bias perception towards either the face or the vase. We also included a control bistable display in which a disc or an aperture were the two possible percepts. With the control disc/aperture test, prosopagnosic patients did not generate a normal sigmoid function, but a U-shaped function, indicating that they perceived the shading but had difficulty in using the shading to make the appropriate figure-ground assignment. While controls still generated a sigmoid function for the vase/face test, prosopagnosic patients showed a severe impairment in using shading to make consistent perceptual assignments. We conclude that prosopagnosic patients have difficulty in using shading to segment figures from background correctly, particularly with complex stimuli like faces. This suggests that a subtler defect in face categorization accompanies their severe defect in face identification, consistent with predictions of computational models and recent data from functional imaging.     

Impaired holistic and analytic face processing in congenital prosopagnosia: Evidence from the eye-contingent mask/window paradigm

There is abundant evidence that face recognition, in comparison to the recognition of other objects, is based on holistic processing rather than analytic processing. One line of research that provides evidence for this hypothesis is based on the study of people who experience pronounced difficulties in visually identifying conspecifics on the basis of their face. Earlier, we developed a behavioural paradigm to directly test analytic vs. holistic face processing. In comparison to a to be remembered reference face stimulus, one of two test stimuli was either presented in full view, with an eye-contingently moving window (only showing the fixated face feature, and therefore only affording analytic processing), or with an eye-contingently moving mask or scotoma (masking the fixated face feature, but still allowing holistic processing). In the present study we use this paradigm (that we used earlier in acquired prosopagnosia) to study face perception in congenital prosopagnosia (people having difficulties recognizing faces from birth on, without demonstrable brain damage). We observe both holistic and analytic face processing deficits in people with congenital prosopagnosia. Implications for a better understanding, both of congenital prosopagnosia and of normal face perception, are 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.     

Discrimination of faces and houses by rhesus monkeys: the role of stimulus expertise and rotation angle

The face inversion effect, or impaired recognition of upside down compared to upright faces, is used as a marker for the configural processing of faces in primates. The inversion effect in humans and chimpanzees is strongest for categories of stimuli for which subjects have considerable expertise, primarily conspecifics’ faces. Moreover, discrimination performance decreases linearly as faces are incrementally rotated from upright to inverted. This suggests that rotated faces must be transformed, or normalized back into their most typical viewpoint before configural processing can ensue, and the greater the required normalization, the greater the likelihood of errors resulting. Previous studies in our lab have demonstrated a general face inversion effect in rhesus monkeys that was not influenced by expertise. Therefore, the present study examined the influence of rotation angle on the visual perception of face and nonface stimuli that varied in their level of expertise to further delineate the processes underlying the inversion effect in rhesus monkeys. Five subjects discriminated images in five orientation angles. Results showed significant linear impairments for all stimulus categories, including houses. However, compared to the upright images, only rhesus faces resulted in worse performance at rotation angles greater than 45°, suggesting stronger configural processing for stimuli for which subjects had the greatest expertise.     

What aspects of face processing are impaired in developmental prosopagnosia?

Developmental prosopagnosia (DP) is a severe impairment in identifying faces that is present from early in life and that occurs despite no apparent brain damage and intact visual and intellectual function. Here, we investigated what aspects of face processing are impaired/spared in developmental prosopagnosia by examining a relatively large group of individuals with DP (n = 8) using an extensive battery of well-established tasks. The tasks included measures of sensitivity to global motion and to global form, detection that a stimulus is a face, determination of its sex, holistic face processing, processing of face identity based on features, contour, and the spacing of features, and judgments of attractiveness. The DP cases showed normal sensitivity to global motion and global form and performed normally on our tests of face detection and holistic processing. On the other tasks, many DP cases were impaired but there was no systematic pattern. At least half showed deficits in processing of facial identity based on either the outer contour or spacing of the internal features, and/or on judgments of attractiveness. Three of the eight were impaired in processing facial identify based on the shape of internal features. The results show that DP is a heterogeneous condition and that impairment in recognizing faces cannot be predicted by poor performance on any one measure of face processing.     

面孔加工的结构编码阶段异族效应的加工方式： ERPs研究

实验采用事件相关电位（ERPs）技术,以大学生为被试,运用非洲、欧洲、亚洲三个不同种族的面孔照片,探究异族效应与加工方式的关系。行为实验结果显示,被试对非洲面孔的反应时快于欧洲面孔,且两者均快于亚洲面孔。ERP研究结果显示,亚洲面孔的N170波幅显著小于非洲和欧洲面孔的波幅,后两者的N170波幅没有差异,而且亚洲面孔的倒置效应最大。研究结果说明相对于异族面孔,本族面孔更多地使用构型编码的加工方式,且N170成分表现出右半球优势。     

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.     

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.     

The lady's not for turning: rotation of the Thatcher illusion

Inversion is especially detrimental to the processing of faces. This is clearly demonstrated by the Thatcher illusion. It has been suggested that this detriment is due to a loss of holistic or configural processing for inverted faces (Bartlett and Searcy, 1993 Cognitive Psychology 25 281-316). Stürzel and Spillmann (2000 Perception 29 937-942) suggest that this loss of configural processing occurs suddenly as a face is rotated slowly from upright to inverted. This hypothesis is tested in a study of the reaction times taken to indicate that a face has been Thatcherised at various angles of orientation. The results suggest that there is a gradual loss of configural information rather than a rapid switch from one type of processing to another.     

Perceptual integrality of componential and configural information in faces

The relative contribution of componential and configural information to face perception is controversial. We addressed this issue in the present study by examining how componential information and configural information interact during face processing, using Garner’s (1974) speeded classification paradigm. When classifying upright faces varying in components (eyes, nose, and mouth) and configural information (intereyes and nose-mouth spacing), observers could not selectively attend to components without being influenced by irrelevant variation in configural information, and vice versa, indicating that componential information and configural information are integral in upright face processing. Performance with inverted faces showed selective attention to components but not to configural information, implying dominance of componential information in processing inverted faces. When faces varied only in components, selective attention to different components was observed in upright and inverted faces, indicating that facial components are perceptually separable. These results provide strong evidence that integrality of componential and configural information, rather than the relative dominance of either, is the hallmark of upright face perception.     

The role of holistic face processing in acquired prosopagnosia: evidence from the composite face effect

Faces are processed more holistically than other objects, and it has been suggested that the loss of holistic face processing causes acquired prosopagnosia. Support for this hypothesis comes from several cases who failed to show holistic face effects as well as the absence of reports of prosopagnosics with unequivocally normal holistic face perception. The current study examines the relationship between holistic face processing and prosopagnosia by testing seven acquired prosopagnosics with the face composite task, a classic measure of holistic face processing. To enhance the robustness of the findings, each prosopagnosic was tested with two versions of the composite task showing upright faces. We also tested an inverted condition to exclude the possibility that more general factors account for composite effects for upright faces. Four of the seven acquired prosopagnosic participants showed consistent upright face composite effects with minimal inverted face composite effects. We conclude that severe face processing deficits can co-occur with intact holistic face processing and that factors other than a loss of holistic processing contribute to the perceptual and recognition deficits in acquired prosopagnosia.