The role of the head in configural body processing: Behavioural and electrophysiological evidence from the inversion and scrambling effect

The present study aimed to further explore the role of the head for configural body processing by comparing complete bodies with headless bodies and faceless heads (Experiment 1). A second aim was to further explore the role of the eye region in configural face processing (Experiment 2). Due to that, we conducted a second experiment with complete faces, eyeless faces, and eyes. In addition, we used two effects to manipulate configural processing: the effect of stimulus inversion and scrambling. The current data clearly show an inversion effect for intact bodies presented with head and faces including the eye region. Thus, the head and the eye region seem to be central for configural processes that are manipulated by the effect of stimulus inversion. Furthermore, the behavioural and electrophysiological body inversion effect depends on the intact configuration of bodies and is associated with the N170 as the face inversion effect depends on the intact face configuration. Hence, configural body processing depends not only on the presence of the head but rather on a complete representation of human bodies that includes the body and the head. Furthermore, configural face processing relies on intact and complete face representations that include faces and eyes.     

The effects of inversion and familiarity on face versus body cues to person recognition

Extensive research has focused on face recognition, and much is known about this topic. However, much of this work seems to be based on an assumption that faces are the most important aspect of person recognition. Here we test this assumption in two experiments. We show that when viewers are forced to choose, they do use the face more than the body, both for familiar (trained) person recognition and for unfamiliar person matching. However, we also show that headless bodies are recognized and matched with very high accuracy. We further show that processing style may be similar for faces and bodies, with inversion effects found in all cases (bodies with heads, faces alone and bodies alone), and evidence that mismatching bodies and heads causes interference. We suggest that recent findings of no inversion effect when stimuli are headless bodies may have been obtained because the stimuli led viewers to focus on nonbody aspects (e.g., clothes) or because pose and identity tasks led to somewhat different processing. Our results are consistent with holistic processing for bodies as well as faces. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Turning configural processing upside down: part and whole body postures

Like faces, body postures are susceptible to an inversion effect in untrained viewers. The inversion effect may be indicative of configural processing, but what kind of configural processing is used for the recognition of body postures must be specified. The information available in the body stimulus was manipulated. The presence and magnitude of inversion effects were compared for body parts, scrambled bodies, and body halves relative to whole bodies and to corresponding conditions for faces and houses. Results suggest that configural body posture recognition relies on the structural hierarchy of body parts, not the parts themselves or a complete template match. Configural recognition of body postures based on information about the structural hierarchy of parts defines an important point on the configural processing continuum, between recognition based on first-order spatial relations and recognition based on holistic undifferentiated template matching.     

Affective responses to body stimuli: comparing male and female bodies with cropped heads and masked faces

Three studies were conducted to determine whether headless bodies evoke affective responses that might confound neuroimaging and electrophysiological findings. In Experiment 1, 224 participants rated pictures, including bodies with cropped heads and masked faces, for disgust, fear, naturalness, valence and arousal. In Experiment 2, 38 participants viewed the same images during a free word association task, whilst in Experiment 3 galvanic skin responses were measured as 57 participants completed a similar rating task to that in Experiment 1. No differences were found between responses elicited by bodies without heads versus bodies with masked faces, although female bodies were thought of more positively than male bodies. This suggests that headless bodies are not abhorrent and are appropriate stimuli for investigating body-selective perceptual processes as they do not evoke face-processing mechanisms. Our findings also suggest that differences between male and female body viewing should be considered when investigating visual body perception.     

Privileged detection of conspecifics: Evidence from inversion effects during continuous flash suppression

The rapid visual detection of other people in our environment is an important first step in social cognition. Here we provide evidence for selective sensitivity of the human visual system to upright depictions of conspecifics. In a series of seven experiments, we assessed the impact of stimulus inversion on the detection of person silhouettes, headless bodies, faces and other objects from a wide range of animate and inanimate control categories. We used continuous flash suppression (CFS), a variant of binocular rivalry, to render stimuli invisible at the beginning of each trial and measured the time upright and inverted stimuli needed to overcome such interocular suppression. Inversion strongly interfered with access to awareness for human faces, headless human bodies, person silhouettes, and even highly variable body postures, while suppression durations for control objects were not (inanimate objects) or only mildly (animal faces and bodies) affected by inversion. Furthermore, inversion effects were eliminated when the normal body configuration was distorted. The absence of strong inversion effects in a binocular control condition not involving interocular suppression suggests that non-conscious mechanisms mediated the effect of inversion on body and face detection during CFS. These results indicate that perceptual mechanisms that govern access to visual awareness are highly sensitive to the presence of conspecifics.     

Dissociation between the behavioural and electrophysiological effects of the face and body composite illusions

Several studies have reported similarities between perceptual processes underlying face and body perception, particularly emphasizing the importance of configural processes. Differences between the perception of faces and the perception of bodies were observed by means of a manipulation targeting a specific subtype of configural processing: the composite illusion. The composite face illusion describes the fact that two identical top halves of a face are perceived as being different if they are presented with different bottom parts. This effect disappears, if both halves are laterally shifted. Crucially, the effect of misalignment is not observed for bodies. This study aimed to further explore differences in the time course of face and body perception by using the composite effect. The present results replicated behavioural effects illustrating that misalignment affects the perception of faces but not bodies. Thus, face but not body perception relies on holistic processing. However, differences in the time course of the processing of both stimulus categories emerged at the N170 and P200. The pattern of the behavioural data seemed to be related to the P200. Thus, the present data indicate that holistic processes associated with the effect of misalignment might occur 200 ms after stimulus onset.     

The inversion effect reveals species differences in face processing

Face recognition is a complex skill that requires the integration of facial features across the whole face, e.g., holistic processing. It is unclear whether, and to what extent, other species process faces in a manner that is similar to humans. Previous studies on the inversion effect, a marker of holistic processing, in nonhuman primates have revealed mixed results in part because many studies have failed to include alternative image categories necessary to understand whether the effects are truly face-specific. The present study re-examined the inversion effect in rhesus monkeys and chimpanzees using comparable testing methods and a variety of high quality stimuli including faces and nonfaces. The data support an inversion effect in chimpanzees only for conspecifics' faces (expert category), suggesting face-specific holistic processing similar to humans. Rhesus monkeys showed inversion effects for conspecifics, but also for heterospecifics' faces (chimpanzees), and nonfaces images (houses), supporting important species differences in this simple test of holistic face processing.     

Impaired configural body processing in anorexia nervosa: Evidence from the body inversion effect

Patients with anorexia nervosa (AN) suffer from severe disturbances of body perception. It is unclear, however, whether such disturbances are linked to specific alterations in the processing of body configurations with respect to the local processing of body part details. Here, we compared a consecutive sample of 12 AN patients with a group of 12 age‐, gender‐ and education‐matched controls using an inversion effect paradigm requiring the visual discrimination of upright and inverted pictures of whole bodies, faces and objects. The AN patients presented selective deficits in the discrimination of upright body stimuli, which requires configural processing. Conversely, patients and controls showed comparable abilities in the discrimination of inverted bodies, which involves only detail‐based processing, and in the discrimination of both upright and inverted faces and objects. Importantly, the body inversion effect negatively correlated with the persistence scores at the Temperament and Character Inventory, which evaluates increased tendency to convert a signal of punishment into a signal of reinforcement. These results suggest that the deficits of configural processing in AN patients may be associated with their obsessive worries about body appearance and to the excessive attention to details that characterizes their general perceptual style.     

Development of body emotion perception in infancy: From discrimination to recognition

Research suggests that infants progress from discrimination to recognition of emotions in faces during the first half year of life. It is unknown whether the perception of emotions from bodies develops in a similar manner. In the current study, when presented with happy and angry body videos and voices, 5-month-olds looked longer at the matching video when they were presented upright but not when they were inverted. In contrast, 3.5-month-olds failed to match even with upright videos. Thus, 5-month-olds but not 3.5-month-olds exhibited evidence of recognition of emotions from bodies by demonstrating intermodal matching. In a subsequent experiment, younger infants did discriminate between body emotion videos but failed to exhibit an inversion effect, suggesting that discrimination may be based on low-level stimulus features. These results document a developmental change from discrimination based on non-emotional information at 3.5 months to recognition of body emotions at 5 months. This pattern of development is similar to face emotion knowledge development and suggests that both the face and body emotion perception systems develop rapidly during the first half year of life.     

Gaze behavior in analytical and holistic face processing

We conducted two experiments examining children's and adults' gaze behavior when processing faces analytically (focusing on a single feature) or holistically (comparing the overall similarity of the faces). Children 6-8 and 9-10 years of age and adults were instructed to assign schematically drawn faces in Experiment 1 and photos of real faces in Experiment 2 to two categories. The categories were constructed so as to allow either an analytical or holistic categorization of the faces. During all trials, gaze behavior was recorded from stimulus onset until reaction. The location and duration of the fixations used were analyzed. Whereas the holistic processors fixated the whole area of the eyes and nose most and longest independently of age, analytical processors showed a more feature-specific gaze behavior, focusing their fixations upon the particular feature used for subsequent processing. Thus, differences in analytical and holistic face processing can be detected early in gaze behavior-that is, at the visual encoding stage.     

Familiar other-race faces show normal holistic processing and are robust to perceptual stress

Other-race individuals are remembered more poorly and receive less holistic/configural processing than same-race individuals, at least when faces are novel. Here, we examine the amelioration of these effects with familiarity, using distinctiveness-matched Caucasian and Asian stimulus sets. We confirmed a cross-race deficit for upright faces following a single encoding trial, which disappeared rapidly with practice on a small set of other-race 'friends' and did not re-emerge when perceptual processing was put under stress (presentation in the periphery). We also examined holistic/configural processing for familiarised faces using the peripheral inversion effect (McKone, 2004 Journal of Experimental Psychology: Learning, Memory, and Cognition 30 181 - 197). A test for faces and nonface objects (dogs) confirmed the validity of this technique as providing a direct measure of holistic processing; we then showed that, after 1 h of training, holistic processing was as strong for other-race as same-race faces. We conclude that practice with other-race individuals can rapidly engage normal face-processing mechanisms.     

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.     

Making heads turn: the effect of familiarity and stimulus rotation on a gender-classification task

Recent work has demonstrated that facial familiarity can moderate the influence of inversion when completing a configural processing task. Here, we examine whether familiarity interacts with intermediate angles of orientation in the same way that it interacts with inversion. Participants were asked to make a gender classification to familiar and unfamiliar faces shown at seven angles of orientation. Speed and accuracy of performance were assessed for stimuli presented (i) as whole faces and (ii) as internal features. When presented as whole faces, the task was easy, as revealed by ceiling levels of accuracy and no effect of familiarity or angle of rotation on response times. However, when stimuli were presented as internal features, an influence of facial familiarity was evident. Unfamiliar faces showed no increase in difficulty across angle of rotation, whereas familiar faces showed a marked increase in difficulty across angle, which was explained by significant linear and cubic trends in the data. Results were interpreted in terms of the benefit gained from a mental representation when face processing was impaired by stimulus rotation.     

Abnormalities in visual processing amongst students with body image concerns

Individuals with body dysmorphic disorder (BDD) appear to possess abnormalities in the way they observe and discriminate visual information. A pre-occupation with perceived defects in appearance has been attributed to a local visual processing bias. We studied the nature of visual bias in individuals who may be at risk of developing BDD – those with high body image concerns (BICs) – by using inverted stimulus discrimination. Inversion disrupts global, configural information in favor of local, feature-based processing. 40 individuals with high BIC and 40 low BIC controls performed a discrimination task with upright and inverted faces, bodies, and scenes. Individuals with high BIC discriminated inverted faces and bodies faster than controls, and were also more accurate when discriminating inverted bodies and scenes. This reduction in inversion effect for high BIC individuals may be due to a stimulus-general local, detail-focused processing bias, which may be associated with maladaptive fixation on small features in their appearance.     

The “parts and wholes” of face recognition: A review of the literature

It has been claimed that faces are recognized as a “whole” rather than by the recognition of individual parts. In a paper published in the Quarterly Journal of Experimental Psychology in 1993, Martha Farah and I attempted to operationalize the holistic claim using the part/whole task. In this task, participants studied a face and then their memory presented in isolation and in the whole face. Consistent with the holistic view, recognition of the part was superior when tested in the whole-face condition compared to when it was tested in isolation. The “whole face” or holistic advantage was not found for faces that were inverted, or scrambled, nor for non-face objects, suggesting that holistic encoding was specific to normal, intact faces. In this paper, we reflect on the part/whole paradigm and how it has contributed to our understanding of what it means to recognize a face as a “whole” stimulus. We describe the value of part/whole task for developing theories of holistic and non-holistic recognition of faces and objects. We discuss the research that has probed the neural substrates of holistic processing in healthy adults and people with prosopagnosia and autism. Finally, we examine how experience shapes holistic face recognition in children and recognition of own- and other-race faces in adults. The goal of this article is to summarize the research on the part/whole task and speculate on how it has informed our understanding of holistic face processing.     

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.     

眼睛区域构型信息与特征信息的跨维共变增益效应及其加工特异性

面孔知觉可能在区域尺度上发生多维信息整合, 但迄今无特异性实验证据。本研究在两个实验中操纵面孔眼睛区域或嘴巴区域的单维构型或特征信息, 测量人们觉察单维变化或跨维共变的敏感度, 以此检测面孔区域尺度上的多维信息整合有何现象与规律, 进而揭示面孔知觉的多维信息整合机制。实验获得3个发现：(1)正立面孔眼睛区域的信息变化觉察呈现出“跨维共变增益效应”, 跨维信息共变觉察的敏感度显著高于任意一种单维信息变化觉察的敏感度; (2)“跨维共变增益效应”只在正立面孔的眼睛区域出现, 在倒置面孔的眼睛区域、正立面孔的嘴巴区域或倒置面孔的嘴巴区域都没有出现, 因此具有面孔区域特异性和面孔朝向特异性; (3)就单维信息变化觉察而言, 眼睛区域的敏感度不会受到面孔倒置的损伤, 但是嘴巴区域的敏感度会受到面孔倒置的显著损伤。综合可知, 面孔知觉确实会发生区域尺度上的信息整合, 它不是普遍性的信息量效应, 而是特异性的眼睛效应(只发生在正立面孔的眼睛区域)。这是面孔整体加工(face holistic processing)在单维信息分辨和多维信息整合之间建立联系的必经环节。这提示我们对全脸多维信息知觉整合的理解需要从传统的面孔整体加工假设升级到以眼睛为中心的层级化多维信息整合算法(a hierarchical algorithm for multi-dimensional information integration)。     

Why does picture-plane inversion sometimes dissociate perception of features and spacing in faces, and sometimes not? Toward a new theory of holistic processing

Classically, it has been presumed that picture-plane inversion primarily reduces sensitivity to spacing/configural information in faces (distance between location of the major features) and has little effect on sensitivity to local feature information (e.g., eye shape or color). Here, we review 22 published studies relevant to this claim. Data show that the feature inversion effect varied substantially across studies as a function of the following factors: whether the feature change was shape only or included color/brightness, the number of faces in the stimulus set, and whether the feature was in facial context. For shape-only changes in facial context, feature inversion effects were as large as typical spacing inversion effects. Small feature inversion effects occurred only when a task could be efficiently solved by visual-processing areas outside whole-face coding. The results argue that holistic/configural processing for upright faces integrates exact feature shape and spacing between blobs. We describe two plausible approaches to this process.     

面孔知觉中特征、结构和整体加工策略的眼动研究

考察面孔知觉中特征加工、结构加工和整体加工三种不同加工方式对应的眼动模式。实验1中, 将以特征信息为主的错乱面孔和以结构信息为主的模糊面孔作为线索刺激, 引发对测试面孔的特征加工和结构加工, 眼动分析表明：特征加工表现为对面孔各特征内更长的凝视时间, 结构加工表现为对面孔各特征间高频的眼跳。实验2采用相同的研究范式, 将完整面孔、轻度错乱面孔和低水平模糊面孔作为线索刺激, 引发对测试面孔除特征加工和结构加工外的另一种加工方式-- 整体加工, 表现为注视点更多地落在测试面孔中央区的鼻子部位以扩大注视范围, 进而把握整张面孔信息。本研究揭示了三种不同面孔加工方式眼动模式的差异。     

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。