基于合成平均刺激的平均表征机制——来自平均面孔吸引力的证据

人类能够快速提取集合中的统计信息, 形成平均表征。对于平均表征的产生机制, 研究者提出整合集合成员以合成平均刺激, 或计算集合成员特征值的平均值两种观点。以往研究中合成的平均刺激的特征值和计算成员特征值的平均值两种方式的结果相似, 难以区分两种观点。由于多个面孔的吸引力评分的均值与用这些面孔合成的平均面孔的吸引力评分存在差异, 本研究使用经典的平均辨别任务(实验1和2)和吸引力评价任务(实验3和4)为平均表征的产生来源于合成平均刺激的观点提供了支持证据。4个实验分别采用大容量面孔集合和小容量面孔集合探讨平均表征的形成机制, 结果发现大、小集合都形成了平均刺激, 并且平均表征的评定和加工可能更多依赖合成的平均刺激, 而非简单的对成员特征值进行平均; 此外, 集合吸引力出现了高评现象, 但小集合高评现象更少出现, 说明平均刺激的作用受到集合大小的影响。本研究为集合平均表征的形成机制和面孔集合吸引力高评现象的产生机制提供了新证据。     

You can take the eyes out of the doll, but...

The perceived animacy of a face is well-predicted by the perceived animacy of the eyes presented in isolation. This is not true for other facial features (eg having a highly life-like nose does not appear to be crucial), suggesting that the eyes are a critical feature for perceiving life in a face. Here, we asked whether it was therefore possible to 'transplant' animacy into a face by transplanting the eyes into a face image. We conducted digital eye surgery on a series of morphed human/doll faces and found that while doll eyes make a morphed face look less alive, human eyes do not make you look more so. Thus, we cannot so easily transplant animacy into a face, but we can take it away.     

Perceptual awareness and categorical representation of faces: evidence from masked priming

How internal categories influence how we perceive the world is a fundamental question in cognitive sciences. Yet, the relation between perceptual awareness and perceptual categorization has remained largely uncovered so far. Here, we addressed this question by focusing on face perception during subliminal and conscious perception. We used morphed continua between two face identities and we assessed, through a masked priming paradigm, the perceptual processing of these morphed faces under subliminal and supraliminal conditions. We found that priming from subliminal faces followed linearly the information present in the primes, while priming from visible faces revealed a non-linear profile, indicating a categorical processing of face identities. Our results thus point to a special relation between perceptual awareness and categorical processing of faces, and support the dissociation between two modes of information processing: a subliminal mode involving analog treatment of stimuli information, and a supraliminal mode relying on discrete representation.     

中国学生的自我面孔识别

已有研究表明大脑右半球具有自我面孔再认的优势。为了进一步验证这个观点,该研究使用面孔识别任务,以13名右利手的中国大学生为被试,测量被试对morphing面孔的左右手反应差异。给被试呈现第一张面孔向第二张面孔的morphing过程,当被试看到morphing的面孔更像第二张面孔时报告停止。研究有两个morphing过程：一个为由自我面孔向名人面孔morphing,另一个为好朋友面孔（熟悉的）向名人面孔morphing。结果表明当用左手反应时,被试倾向于把morphing的面孔识别为自己,研究中自我面孔再认的左手优势与已有的发现一致。另外,研究还发现在一定trials条件下,熟悉面孔再认也具有左手优势,这一结果与西方被试的结果不一致,但东西方被试对熟悉面孔再认的差异与独立型自我和互倚型自我的观点一致。该文认为神经心理学有关自我的研究可能需要考虑文化和情境的复杂性。     

The tipping point of animacy. How, when, and where we perceive life in a face

Faces capture humans' attention; yet, beyond aesthetic appreciation, it is presumably not the face itself that interests people but the mind behind it. Minds think, feel, and act in ways that have direct consequences for well-being, but despite their importance, how minds are perceived in faces is not well understood. We investigated this mechanism by presenting participants with morphed images created from animate (human) and inanimate (mannequin) faces. Life and mind were perceived to "appear" at a consistent location on the morph continuum, close to the human endpoint. This location constituted a categorical boundary, as evidenced by increased sensitivity to differences in image pairs that straddled this tipping point. Additionally, the impression of life was gleaned from the eyes more than from other facial features. These results suggest that human beings are highly attuned to specific facial cues, carried largely in the eyes, that gate the categorical perception of life.     

知觉经验对面孔整体加工的影响

基于经验的整体加工理论认为, 随着知觉经验的增多, 人们加工面孔的专家化能力逐渐增强。其中一种表现形式为, 在知觉面孔时更倾向于整体加工。该理论已经得到了一些实验证据的支持, 但未能解释另外一些研究的发现, 即对他族人群没有长期知觉经验的被试在加工他族面孔时也有强烈的整体加工。本研究旨在考察知觉经验对面孔整体加工的影响, 包括两个实验。实验1a通过组合面孔范式测量了中国被试在辨别本族面孔、他族面孔和种族融合面孔时的组合面孔效应(即面孔整体加工强度)。结果发现, 被试在知觉种族融合面孔时没有表现出组合面孔效应, 在知觉本族面孔和他族面孔时都表现出强烈的组合面孔效应。实验1b以灰阶图重复了实验1a。结果发现, 被试在知觉种族融合面孔时仍然没有表现出组合面孔效应, 在知觉本族面孔和他族面孔时表现出强烈的组合面孔效应。实验2通过操纵种族融合面孔的有或无, 测量5 s的知觉经验对融合面孔的组合效应的影响。结果发现, 在经过短时的知觉经验后, 被试在知觉融合面孔时也表现出强烈的组合面孔效应。上述实验结果表明, 中国被试在加工本族面孔、他族面孔和种族融合面孔时所诱发组合面孔效应有显著的、量的差别, 且这种整体加工的差异不会受到面孔肤色信息的影响。在经过短时的知觉经验后, 中国被试在加工种族融合面孔时表现出强烈的整体加工。该研究的发现提示, 不论是短时知觉经验还是长期知觉经验, 知觉经验的增加是面孔整体加工的一个关键要素。     

Believing is seeing: the effects of racial labels and implicit beliefs on face perception

Two studies tested whether racial category labels and lay beliefs about human traits have a combined effect on people's perception of, and memory for, racially ambiguous faces. Participants saw a morphed target face accompanied by a racial label (Black or White). Later, they were asked to identify the face from a set of two new morphed faces, one more Black and the other more White than the target. As predicted, entity theorists, who believe traits are immutable, perceived and remembered the target face as consistent with the racial label, whereas incremental theorists, who believe traits are malleable, perceived and remembered the face as inconsistent with the racial label. In Study 2, participants also drew the target face more consistently (entity theorists) or less consistently (incremental theorists) with the racial label. Results of both studies confirm that social variables can affect how physical features are seen and remembered.     

The Face-Space Typicality Paradox: Understanding the Face-Space Metaphor

Some recent accounts of human face processing use the idea of 'face space', considered to be a multi-dimensional space whose dimensions correspond to ways in which faces can vary. Within this space, 'typicality' is sometimes taken to reflect the proximity of a face to its local neighbours. Intuitions about the distribution of faces within the space may suggest that the majority of faces will be 'typical' in these terms. However, when typicality measures are taken, researchers very rarely find that faces cluster at the 'typical' end of the scale. In this short note we attempt to resolve this paradox and point out that reasoning about high dimensional distributions requires that some specific assumptions are made explicit.     

Greater visual averaging of face identity for own-gender faces

Recent evidence suggests that observers can rapidly form an average representation based on a set of simultaneously presented faces. Here, we replicate this finding and show that the tendency to process sets of faces in terms of an average representation is greater for own-gender faces. Male and female participants viewed sets of four male or female faces before deciding whether or not a subsequently presented single test face had been present in the set. Incorrect endorsement that it was one of the set members was greater when the test face was a morphed average of the four faces than when it was an actual set member, and this effect was strongest when the gender of the faces was the same as the observer’s. The finding that observers were more likely to incorrectly endorse own-gender (vs. other-gender) faces forms an exception to the often reported own-gender advantage in face recognition.     

Visual adaptation of the perception of “life”: Animacy is a basic perceptual dimension of faces

One critical component of understanding another’s mind is the perception of “life” in a face. However, little is known about the cognitive and neural mechanisms underlying this perception of animacy. Here, using a visual adaptation paradigm, we ask whether face animacy is (1) a basic dimension of face perception and (2) supported by a common neural mechanism across distinct face categories defined by age and species. Observers rated the perceived animacy of adult human faces before and after adaptation to (1) adult faces, (2) child faces, and (3) dog faces. When testing the perception of animacy in human faces, we found significant adaptation to both adult and child faces, but not dog faces. We did, however, find significant adaptation when morphed dog images and dog adaptors were used. Thus, animacy perception in faces appears to be a basic dimension of face perception that is species specific but not constrained by age categories.     

Race categorization modulates holistic face encoding

Recent studies have shown that same-race (SR) faces are processed more holistically than other-race (OR) faces, a difference that may underlie the greater difficulty at recognizing OR than SR faces (the "other-race effect"). This article provides original evidence suggesting that the holistic processing of faces may be sensitive to the observers' racial categorization of the face. In Experiment 1, Caucasian participants performed a face-composite task with Caucasian faces, Asian faces, and racially ambiguous morphed face stimuli. Identical morphed face stimuli were processed more holistically when categorized as SR than as OR faces. Experiment 2 further suggests that this finding was not underlain by strategic or training effects. Overall, these results support the view that one's categorization of a face as belonging to the same or another race plays a critical role in the holistic processing of this face.     

Why are average faces attractive? The effect of view and averageness on the attractiveness of female faces

Images of faces manipulated to make their shapes closer to the average are perceived as more attractive. The influences of symmetry and averageness are often confounded in studies based on full-face views of faces. Two experiments are reported that compared the effect of manipulating the averageness of female faces in profile and full-face views. Use of a profile view allows a face to be ”morphed“ toward an average shape without creating an image that becomes more symmetrical. Faces morphed toward the average were perceived as more attractive in both views, but the effect was significantly stronger for full-face views. Both full-face and profile views morphed away from the average shape were perceived as less attractive. It is concluded that the effect of averageness is independent of any effect of symmetry on the perceived attractiveness of female faces.     

Information processing during face recognition: the effects of familiarity, inversion, and morphing on scanning fixations

Where we make ocular fixations when viewing an object likely reflects interactions between 'external' object properties and internal 'top-down' factors, as our perceptual system tests hypotheses and attempts to make decisions about our environment. These scanning fixation patterns can tell us how and where the visual system gathers information critical to specific tasks. We determined the effects of the internal factors of expertise, experience, and ambiguity on scanning during a face-recognition task, in eight subjects. To assess the effects of expertise, we compared upright with inverted faces, since it is hypothesized that inverted faces do not access an orientation-dependent face-expert processor. To assess the effects of experience, we compared famous with novel faces, as famous faces would have stronger internal representations than anonymous ones. Ambiguity in matching seen and remembered faces was manipulated with morphed faces. We measured three classes of variables: (i) total scanning time and fixations; (ii) the spatial distribution of scanning; and (iii) the sequence of scanning, using first-order Markov matrices for local scan structure and string editing for global scan structure. We found that, with inverted faces, subjects redistributed fixations to the mouth and lower face, and their local and global scan structure became more random. With novel or morphed faces, they scanned the eyes and upper face more. Local scan structure was not affected by familiarity, but global scan structure was least random (most stereotyped) for novel upright faces. We conclude that expertise (upright faces) leads to less lower-face scanning and more predictable global patterns of information gathering. Experience (famous faces) leads to less upper-face scanning and more idiosyncratic global scan structures, suggesting a superseding influence of facial memories. With morphed faces, subjects return to the upper face to resolve ambiguity, implying a greater importance of this region in face recognition.     

The eyes know: eye movements as a veridical index of memory

In two experiments, we examined whether observers' eye movements distinguish studied faces from highly similar novel faces. Participants' eye movements were monitored while they viewed three-face displays. Target-present displays contained a studied face and two morphed faces that were visually similar to it; target-absent displays contained three morphed faces that were visually similar to a studied, but not tested, face. On each trial in a test session, participants were instructed to choose the studied face if it was present or a random face if it was not and then to indicate whether the chosen face was studied. Whereas manipulating visual similarity in target-absent displays influenced the rate of false endorsements of nonstudied items as studied, eye movements proved impervious to this manipulation. Studied faces were viewed disproportionately from 1,000 to 2,000 ms after display onset and from 1,000 to 500 ms before explicit identification. Early viewing also distinguished studied faces from faces incorrectly endorsed as studied. Our findings show that eye movements provide a relatively pure index of past experience that is uninfluenced by explicit response strategies, and suggest that eye movement measures may be of practical use in applied settings.     

Bimodal familiarization re-sensitizes 12-month-old infants to other-race faces

Perceptual narrowing in the domain of face perception typically begins to reduce infants’ sensitivity to differences distinguishing other-race faces from approximately 6 months of age. The present study investigated whether it is possible to re-sensitize Caucasian 12-month-old infants to other-race Asian faces through statistical learning by familiarizing them with different statistical distributions of these faces. The familiarization faces were created by generating a morphed continuum from one Asian face identity to another. In the unimodal condition, infants were familiarized with a frequency distribution wherein they saw the midpoint face of the morphed continuum the most frequently. In the bimodal condition, infants were familiarized with a frequency distribution wherein they saw faces closer to the endpoints of the morphed continuum the most frequently. After familiarization, infants were tested on their discrimination of the two original Asian faces. The infants’ looking times during the test indicated that infants in the bimodal condition could discriminate between the two faces, while infants in the unimodal condition could not. These findings therefore suggest that 12-month-old Caucasian infants could be re-sensitized to Asian faces by familiarizing them with a bimodal frequency distribution of such faces.     

Categorical perception of facial gender information: Behavioural evidence and the face-space metaphor

Categorization is a fundamental property of the human brain. We used an imagemorphing procedure to investigate the categorical perception of facial gender information. Three experiments, an identification and two matching tasks, were reported. First, we showed that, even when facial image information changes linearly across unfamiliar male and female faces, gender is perceived categorically. This holds only when faces are presented in an upright orientation. Second, subjects discriminated more easily two unknown morphed faces presenting a gender change as compared to two unknown morphed faces belonging to the same gender, even when the physical distance between the pairs was identical. We discuss the results in terms of how representations of faces are encoded and stored in long-term memory.     

Self-face perception in 12-month-old infants: A study using the morphing technique

The present study investigated self-face perception in 12-month-old infants using the morphing technique. Twenty-four 12-month-old infants participated in both the main and control experiments. In the main experiment, we used the participant’s own face, an unfamiliar infant’s face (age- and gender-matched), and a morphed face comprising 50 % each of the self and unfamiliar faces as stimuli. The control experiment followed the same procedure, except that the self-face was replaced with another unfamiliar face. In both experiments, two of these stimuli were presented side by side on a monitor in each trial, and infants’ fixation duration was measured. Results showed that shorter fixation durations were found for the morphed face compared with the self-face and the unfamiliar face in the main experiment, but there were no significant preferences for any comparisons in the control experiment. The results suggest that 12-month-old infants could detect subtle differences in facial features between the self-face and the other faces, and infants might show less preference for the self-resembling morphed face due to increased processing costs, which can be interpreted using the uncanny valley hypothesis. Overall, representations of the self-face seem to a certain extent to be formed by the end of the first year of life through daily visual experience.     

An application of caricature: How to improve the recognition of facial composites

Facial caricatures exaggerate the distinctive features of a face and may elevate the recognition of a familiar face. We investigate whether the recognition of facial composites, or pictures of criminal faces, could be similarly enhanced. In this study, participants first estimated the degree of caricature necessary to make composites most identifiable. Contrary to expectation, an anticaricature was found to be best, presumably as this tended to reduce the appearance of errors. In support of this explanation, more positive caricature estimates were assigned to morphed composites: representations that tend to contain less overall error. In addition, anticaricaturing reduced identification for morphed composites but enhanced identification for individual composites. Although such improvements were too small to be of value to law enforcement, a sizeable naming benefit was observed when presenting a range of caricature states, which appeared to capitalize on individual differences in the internal representation of familiar faces.     

知觉适应对种族融合面孔的种族分类和知觉辨别的影响

面孔加工的种族效应(the other-race effects)指人们对面孔做个体辨别任务时辨别本族面孔的绩效优于辨别他族面孔的绩效, 而做种族分类任务时分类他族面孔的绩效优于分类本族面孔的绩效。本研究通过知觉适应操纵被试对种族两歧(高加索和亚洲)融合面孔的种族知觉, 进而比较被试在两种条件下对同一张融合面孔进行种族分类和知觉辨别的绩效的差异。结果发现, 知觉适应能使被试产生将两歧融合面孔知觉为与原始面孔所属种族相反种族的知觉偏向, 并且, 伴随着这种知觉偏向, 两歧融合面孔的加工出现了他族分类优势和本族辨别优势, 提示社会认知因素对面孔加工的种族效应有重要作用。     

Ethnic categorisation of faces is not independent of face identity

Is the extraction of a visually derived semantic code from faces (ethnicity) affected by face identity (familiarity) or not? The traditional view considers that this operation is made independently of face identity, and in parallel with the recognition of identity. However, some recent studies cast doubt on this parallel thesis regarding other visually derived semantic codes, namely: facial expression, facial speech, apparent age, and gender. Twenty-eight Caucasian participants were enrolled in an 'ethnic-decision' task on morphed faces made of an Asiatic source face and a Caucasian source face, in the proportion of 70%-30%. Half of the original faces were previously made familiar by a learning procedure (associating the face, surname, occupation, and city of residence of the person displayed), while the remaining half were unfamiliar. The results showed clearly that ethnic decision was affected by face familiarity. This adds support to the thesis according to which the identification of identity and the extraction of visually derived semantic codes are not made independently from each other and that the 'parallel-route' hypothesis becomes weakly supported.