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PubMed2005

The effects of face spatial frequencies on cortical processing revealed by magnetoencephalography.

To study the spatial frequency (SF) effects on cortical face processing, we recorded magnetoencephalographic responses in seven healthy subjects to upright and inverted human faces. Four face types were used, including original (broad-band SF, BSF), low SF (LSF, <5 cycles/face), middle SF (MSF, 5-15 cycles/face), and high SF (HSF, >15 cycles/face) face images. Using equivalent current dipole (ECD) modeling, neuromagnetic M170 responses peaking around 160-185 ms were localized in right occipitotemporal region across subjects to BSF faces. M170 responses to LSF faces showed longer latency and smaller amplitude compared with those to BSF faces. We found no significant difference between BSF, MSF, and HSF conditions in M170 amplitude or latency. ECD locations for the four upright face conditions were close to one another, although the mean locations for MSF or HSF seemed more medial than those for BSF or LSF. Longer latencies for inverted than upright faces were observed in BSF (183.4+/-8.5 ms versus 168+/-6.9 ms, P<0.001) and LSF face conditions (223.6+/-13.1 ms versus 207.3+/-16.3 ms, P<0.01). M170 ECDs were located more medial for inverted than upright images in either BSF or LSF condition. In conclusion, the less M170 activation to LSF faces suggests that face parts information is important for early face processing. The cortical representations in right occipitotemporal region for configural and face feature processing are overlapping. Our findings on the face inversion effect suggest that inverted BSF and LSF faces may be processed as objects.

Adult↗
PubMed1986

The effects of distinctiveness in recognising and classifying faces.

In an earlier study it was found that distinctive familiar faces were recognised faster than typical familiar faces in a familiarity decision task. In the first experiment reported here this effect was replicated with the use of celebrities' faces rather than personally familiar faces. In the second and third experiments the effect of distinctiveness was found to reverse if the task was to distinguish between faces and jumbled faces. Subjects took longer to classify distinctive faces as faces than they did to classify typical faces. Thus distinctive faces were recognised faster, but were classified as faces more slowly than were typical faces, both when personally familiar faces and when famous faces were used as stimuli. These results are interpeted as evidence that faces are encoded by reference to a general face prototype.

Decision Making↗
PubMed1999

Evidence for holistic processing of faces viewed as photographic negatives.

Inversion and photographic negation both impair face recognition. Inversion seems to disrupt processing of the spatial relationship between facial features ('relational' processing) which normally occurs with upright faces and which facilitates their recognition. It remains unclear why negation affects recognition. To find out if negation impairs relational processing, we investigated whether negative faces are subject to the 'chimeric-face effect'. Recognition of the top half of a composite face (constructed from top and bottom halves of different faces) is difficult when the face is upright, but not when it is inverted. To perform this task successfully, the bottom half of the face has to be disregarded, but the relational processing which normally occurs with upright faces makes this difficult. Inversion reduces relational processing and thus facilitates performance on this particular task. In our experiments, subjects saw pairs of chimeric faces and had to decide whether or not the top halves were identical. On half the trials the two chimeras had identical tops; on the remaining trials the top halves were different. (The bottom halves were always different.) All permutations of orientation (upright or inverted) and luminance (normal or negative) were used. In experiment 1, each pair of 'identical' top halves were the same in all respects. Experiment 2 used differently oriented views of the same person, to preclude matches being based on incidental features of the images rather than the faces displayed within them. In both experiments, similar chimeric-face effects were obtained with both positive and negative faces, implying that negative faces evoke some form of relational processing. It is argued that there may be more than one kind of relational processing involved in face recognition: the 'chimeric-face effect' may reflect an initial 'holistic' processing which binds facial features into a 'Gestalt', rather than being a demonstration of the configurational processing involved in individual recognition.

Adult↗
PubMed1998

Local and relational aspects of face distinctiveness.

Distinctiveness contributes strongly to the recognition and rejection of faces in memory tasks. In four experiments we examine the role played by local and relational information in the distinctiveness of upright and inverted faces. In all experiments subjects saw one of three versions of a face: original faces, which had been rated as average in distinctiveness in a previous study (Hancock, Burton, & Bruce, 1996), a more distinctive version in which local features had been changed (D-local), and a more distinctive version in which relational features had been changed (D-rel). An increase in distinctiveness was found for D-local and D-rel faces in Experiment 1 (complete faces) and 3 and 4 (face internals only) when the faces had to be rated in upright presentation, but the distinctiveness of the D-rel faces was reduced much more than that of the D-local versions when the ratings were given to the faces presented upside-down (Experiments 1 and 3). Recognition performance showed a similar pattern: presented upright, both D-local and D-rel revealed higher performance compared to the originals, but in upside-down presentation the D-local versions showed a much stronger distinctiveness advantage. When only internal features of faces were used (Experiments 3 and 4), the D-rel faces lost their advantage over the Original versions in inverted presentation. The results suggest that at least two dimensions of facial information contribute to a face's apparent distinctiveness, but that these sources of information are differentially affected by turning the face upside-down. These findings are in accordance with a face processing model in which face inversion effects occur because a specific type of information processing is disrupted, rather than because of a general disruption of performance.

Face↗
PubMed1989

The effect of learning on the face selective responses of neurons in the cortex in the superior temporal sulcus of the monkey.

Neurophysiological studies have shown that some neurons in the cortex in the superior temporal sulcus and the inferior temporal gyrus of macaque monkeys respond to faces. These neurons provided a consistently identifiable substrate with which studies of the storage of visual information were performed. To determine whether face responsive neurons change how much they respond to different novel faces as they become familiar, neurons were tested with two experimental designs. In the first experiment, 22 neurons were tested on their responsiveness to the different members of a large set of novel faces as the set was presented repeatedly until the faces became familiar. 6 neurons altered the relative degree to which they responded to the different members of the set between the first two presentations and subsequent presentations. In a control condition, only 1 out of 17 neurons showed a significant response difference between the first two presentations and subsequent presentations when the experiment started with faces which were already familiar to the monkey. In the second experiment, 26 neurons were tested on their responsiveness to the different members of a set of familiar faces before and after the addition of a novel face to the set. 5 neurons altered the relative degree in which they responded to the different members of the set of familiar faces after addition of a novel face. It is suggested that these changes in neuronal responsiveness to different stimuli reflect the setting up of an ensemble encoded representation of face stimuli. This alteration of neuronal responsiveness as novel faces become familiar suggests that face responsive neurons may store information useful in visual recognition. In addition to this relatively long-term alteration of relative neuronal responsiveness to different stimuli, it was found that a large number of cells showed a higher mean response to the first presentation of a set of novel faces than to subsequent presentations of the faces. However, the response to the first presentation of a set of familiar faces was also higher than to subsequent presentations in that sequence. This pattern indicates a short term recency effect in the response of these neurons to visual stimuli which is similar to that previously reported (Baylis and Rolls 1987).

Animals↗
PubMed2002

Configural processing in face recognition in schizophrenia.

INTRODUCTION: There is currently substantial literature to suggest that patients with schizophrenia are impaired on many face-processing tasks. This study investigated the specific effects of configural changes on face recognition in groups of schizophrenia patients. METHODS: In Experiment 1, participants identified facial expressions in upright faces and in faces inverted from their upright orientation. Experiments 2 and 3 examined recognition memory for faces and other non-face objects presented in upright and inverted orientations. Experiment 4 explored recognition of facial identity in composite images where the top half of one face was fused to the bottom half of another face to form a new face configuration. RESULTS: In each experiment, the configural change had the same effect on face recognition for the schizophenia patients as it did for control participants. Recognising inverted faces was more difficult than recognising upright faces, with a disproportionate effect of inversion on faces relative to other objects. Recognition of facial identity in face-halves was interfered with by the formation of a new face configuration. CONCLUSION: Collectively, these results suggest that people with schizophrenia rely on configural information to recognise photographs of faces.

Journal Article↗
PubMedDate not supplied

Faces scales for the measurement of postoperative pain intensity in children following minor surgery.

OBJECTIVES: Faces scales are commonly used to obtain self-reports of pain intensity from children. Previous research using hypothetical vignettes and pain following venepuncture has found differences in children's pain ratings as a function of the type of faces scale used. The purpose of the present study was to determine whether scales beginning with a smiling rather than neutral "no pain" face would produce higher ratings in the assessment of postoperative pain intensity in children and to compare ratings using different faces scales to those reported with an additional independent measure of pain intensity. METHODS: Participants were 78 children between the ages of 5 and 13 years undergoing surgery, one of their parents, and their postoperative care nurse. Following surgery, children were asked to provide a rating of their current pain intensity using a set of 5 successively administered faces scales and the Colored Analog Scale (CAS). Parents and nurses provided independent ratings using the same measures. RESULTS: Results showed that parents and nurses rated significantly more pain when using scales with a smiling rather than a neutral "no pain" face. This pattern was not as clear for the children's ratings, although their highest ratings were provided when using a smiling "no pain" faces scale. Children's and nurses' ratings on the CAS were generally more similar to their ratings using scales with neutral "no pain" faces, whereas parents' CAS ratings tended to fall in between ratings provided on the smiling and neutral "no pain" faces scales. Scale preference, age and sex differences in pain ratings, and child-parent-nurse agreement in pain ratings are also examined. DISCUSSION: Children's and parents' ratings of postoperative pain intensity are influenced by the presence of a smiling "no pain" face at the beginning of faces scales, with such scales producing significantly higher ratings than scales with neutral "no pain" faces. Ratings on the independent CAS measure were more comparable to those provided on faces scales with neutral "no pain" faces. Nurses are also susceptible to the influencing effect of a smiling face at the beginning of a faces scale.

Adolescent↗
PubMed2002

Decreased arousals in infants who sleep with the face covered by bedclothes.

OBJECTIVE: The risk of becoming a victim of sudden infant death syndrome is increased in infants who sleep with their face under bedding items. The present study was designed to evaluate auditory arousal thresholds of infants who sleep with their face covered by bedclothes. METHODS: Twenty healthy infants with a median age of 11.5 weeks (range: 4-22 weeks) were recorded polygraphically for 1 night. Although they slept in their usual supine position, a bed sheet was placed over their face for 60 minutes. Fifteen of the 20 infants were chosen at random and were exposed to white noises of increasing intensities to determine their auditory arousal thresholds. All infants were challenged with the face covered and with the face free during both rapid eye movement (REM) and non-REM (NREM) sleep. Seven infants were first challenged with the face covered, and 8 were challenged with the face free. The following variables were recorded simultaneously: electroencephalogram, breathing and heart rates, and rectal and pericephalic temperatures. In 5 infants who were not exposed to the auditory challenges, end tidal CO2 was recorded for 30 minutes while sleeping with the face covered. RESULTS: During REM sleep, arousals occurred for significantly more intense auditory stimuli when the infant's face was covered than when free. No significant difference was seen in NREM sleep. Compared with the face-free periods, the face-covered sleep periods were characterized by greater rectal and pericephalic temperatures, a greater density of body movements, and a decrease in NREM sleep. Respiratory frequency was increased during the face-covered periods in both REM and NREM sleep. No differences were seen in the frequency or duration of apnea. There was a tendency for heart rate to increase during both sleep stages when the face was covered, compared with the face-free periods, but the changes were not statistically significant. A positive correlation was found between pericephalic temperatures and arousal thresholds (r = 0.60) during REM sleep. End tidal CO2 values increased when the face was covered, reaching a maximum value during the first 5 minutes of the experiment. No fall in oxygen saturation was seen. CONCLUSIONS: Covering the infant's face with a bed sheet was associated with a significant increase in auditory arousal threshold. The finding could be related to an elevation in temperatures within the infant's microenvironment.

Bedding and Linens↗
PubMed2001

Soldier acceptability of a camouflage face paint combined with DEET insect repellent.

Under operational conditions, current doctrine requires separate application of the standard military insect repellent and camouflage face paint. Working with an industrial partner, Amon Re, Inc., we developed a combined camouflage face paint and insect repellent that offers excellent protection from arthropod disease vectors. We undertook a study to determine whether the new product was acceptable to soldiers under field conditions. A new formulation of camouflage face paint containing the insect repellent N,N-diethyl-3-methyl-benzamide (DEET) was tested for user acceptability during a joint-service, multinational, military field training exercise (Operation Cobra Gold 1999) in Thailand. Soldiers testing the camouflage face paint were members of one of three companies (A, B, and C) of 1st Battalion, 21st Infantry Regiment, 25th Infantry Division. Soldiers in A company (N = 98) received standard military camouflage face paint and the U.S. military's Extended Duration Topical Insect and Arthropod Repellent containing 33% DEET, soldiers in B company (N = 75) received a new formulation of camouflage face paint without DEET, and soldiers in C company (N = 88) received the new formulation of camouflage face paint containing 30% DEET. Every soldier who volunteered to participate completed the study and submitted responses to the questionnaire. The different treatments were evaluated while soldiers spent 4 days conducting simulated combat exercises in a hot, tropical environment in central Thailand. Soldiers were provided the test materials, given a briefing on the study, and completed an initial questionnaire on May 19, 1999. Soldiers completed a final questionnaire after they returned from the training exercise on May 24, 1999. Results of the study indicated that soldiers found the new formulation of 30% DEET camouflage face paint easier to apply (88% of respondents) and remove (77%) than the current standard issue camouflage face paint. Soldiers liked the new 30% DEET camouflage face paint formulation better (61%) and were more likely to recommend it (67%) than the old camouflage face paint formulation. Although the addition of DEET to the camouflage face paint occasionally caused minor irritation after application for a short period (less than 15 minutes), the new camouflage face paint formulation with 30% DEET was evaluated most often (72%) as either good or excellent. The new 30% DEET camouflage face paint formulation offers significant operational advantages: protection from disease-transmitting arthropods, elimination of the need to carry separate insect repellent and camouflage face paint, and reduction in the time required to apply repellent and camouflage face paint separately.

Adolescent↗
PubMed2005

[Cognitive evoked potentials in face recognition in autism].

INTRODUCTION AND DEVELOPMENT: Face recognition requires a special type of processing that is different to that used to recognise objects. The right medial region of the fusiform gyrus displays a higher degree of activation when dealing with faces, which is why it is known as the fusiform face area, although the integrity of the right occipital face area may be needed to perform this task. Neuroimaging studies point not only to the existence of normal activation of the fusiform face area in response to faces but also of the occipital area. One modulation that supports the existence of a specific pathway is the face inversion effect, which is defined as the process in which greater disability is displayed in the recognition of inverted faces than for other mono-oriented objects. The P1 potential is the initial endogenic component of visual processing, acting as an index of the processing of features that show lower latency and greater amplitude when dealing with a face stimulus than when stimulated by objects. A later response, the negative component N170, also has lower latency in the case of faces than in inversion and objects. Its amplitude increases when the faces are inverted due to the generation of a greater activation in the region where it originates. A later negative potential can be associated to semantic identification in face recognition. The N170 waves in autistic individuals display greater latency with faces that is similar to the response to objects and, in turn, show no differences in the latencies with inverted faces. It remains to be shown whether they have an N400 response to faces. CONCLUSIONS: Cognitive evoked potentials allow us to evaluate face recognition both in normal and autistic individuals by presenting responses to specific stimuli. Further studies will enable us to determine whether an N400 response exists in individuals with autism.

Autistic Disorder↗
PubMed1999

Effect of familiarity on the processing of human faces.

Most brain imaging studies on face perception have investigated the processing of unknown faces and addressed mainly the question of specific face processing in the human brain. The goal of this study was to highlight the effects of familiarity on the visual processing of faces. Using [15O]water 3D Positron Emission Tomography, regional cerebral blood flow distribution was measured in 11 human subjects performing an identical task (gender categorization) on both unknown and known faces. Subjects also performed two control tasks (a face recognition task and a visual pattern discrimination task). They were scanned after a training phase using videotapes during which they had been familiarized with and learned to recognize a set of faces. Two major results were obtained. On the one hand, we found bilateral activations of the fusiform gyri in the three face conditions, including the so-called fusiform-face area, a region in the right fusiform gyrus specifically devoted to face processing. This common activation suggests that different cognitive tasks performed on known and unknown faces require the involvement of this fusiform region. On the other hand, specific regional cerebral blood flow changes were related to the processing of known and unknown faces. The left amygdala, a structure involved in implicit learning of visual representations, was activated by the categorization task on unknown faces. The same task on known faces induced a relative decrease of activity in early visual areas. These differences between the two categorization tasks reveal that the human brain processes known and unknown faces differently.

Adult↗
PubMed2000

Electrophysiological correlates of recollecting faces of known and unknown individuals.

We recorded brain potentials from healthy human subjects during a recognition test in order to monitor neural processing associated with face recollection. Subjects first attempted to memorize 40 faces; half were accompanied by a voice simulating that person speaking (e.g., "I'm Jimmy and I was a roadie for the Grateful Dead") and half were presented in silence. In the test phase, subjects attempted to discriminate both types of old faces (i.e., "named" and "unnamed" faces) from new faces. Recognition averaged 87% correct for named faces, 74% correct for unnamed faces, and 91% correct for new faces. Potentials to old faces were more positive than those to new faces from 300 to 600 ms after face onset. For named faces, the old-new ERP difference was observed at anterior and posterior scalp locations. For unnamed faces, the old-new ERP difference was observed only at posterior scalp locations. Results from a prior experiment suggest that these effects do not reflect perceptual priming of faces. The posterior portion of the old-new ERP difference was thus interpreted as a neural correlate of retrieval of visual face information and the anterior portion as an indication of retrieval of person-specific semantic information.

Adolescent↗
PubMed2003

Olfaction and face encoding in humans: a magnetoencephalographic study.

Magnetic field changes were recorded while 20 healthy young participants performed a deep face encoding task. Some of the faces were randomly associated with a simultaneously presented odor. A recognition test, during which all faces were presented again together with the same number of new faces, followed. The task was to discriminate between repeated and new faces. During the recognition test no odor was presented. The recognition performance was significantly influenced by the simultaneously associated odor during the encoding phase. Faces associated with odor were less accurately recognized. In addition, we found significant physiological differences between 'encoded faces without odor' and 'encoded faces with odor'. In particular, two effects occurred. Between about 200 and 300 ms after stimulus onset 'encoded faces without odor' evoked higher brain activity than 'encoded faces with odor'. Between about 600 and 900 ms after stimulus onset 'encoded faces with odor' evoked higher brain activity than 'encoded faces without odor'. Whereas the latter effect is interpreted as reflecting conscious olfactory information processing, the earlier effect is suggested to reflect an odor influence on face encoding. We suggest that the simultaneous odor association distracted face encoding resulting in a significantly reduced recognition performance. These findings are suggested to represent evidence of multimodal sensoric interactions between visual face processing and olfactory information.

Adult↗
PubMed2006

Is face distinctiveness gender based?

Two experiments were carried out to study the role of gender category in evaluations of face distinctiveness. In Experiment 1, participants had to evaluate the distinctiveness and the femininity-masculinity of real or artificial composite faces. The composite faces were created by blending either faces of the same gender (sexed composite faces, approximating the sexed prototypes) or faces of both genders (nonsexed composite faces, approximating the face prototype). The results show that the distinctiveness ratings decreased as the number of blended faces increased. Distinctiveness and gender ratings did not covary for real faces or sexed composite faces, but they did vary for nonsexed composite faces. In Experiment 2, participants were asked to state which of two composite faces, one sexed and one nonsexed, was more distinctive. Sexed composite faces were selected less often. The results are interpreted as indicating that distinctiveness is based on sexed prototypes. Implications for face recognition models are discussed.

Adult↗
PubMed2004

Demonstrating the acquired familiarity of faces by using a gender-decision task.

We report an experiment in which participants made gender judgments (male or female) to faces. There were three groups of faces: unfamiliar, familiar (celebrities), and a set which had been learned earlier by the participants during the experimental session. The principal purpose of this study was to establish an indirect measure of assessing whether faces have become familiar through learning that does not require overt recognition. Bruce and Young's (1986 British Journal of Psychology 77 305-327) model of face recognition suggests face-processing tasks are independent of one another and so familiarity should have no impact on the time taken to perform gender decisions. However, recent studies have suggested that some face processes are not completely independent. A gender judgment is a simple task which would be useful in face-learning experiments. We examined whether exposure to previously novel faces facilitates a later gender decision to those faces. During a learning stage, participants viewed a set of unfamiliar faces. At test, participants were able to assign gender faster to previously familiar (famous) faces and learned faces than they were to unfamiliar faces. Therefore familiarity can influence the speed at which gender is analysed. We explain our findings with reference to the Burton et al (1990 British Journal of Psychology 81 361-380) interactive activation and competition (IAC) model of face recognition and discuss how the gender judgment might be employed as a means of tracking the acquisition of familiarity in face-learning studies.

Adolescent↗
PubMed2006

Simulating the 'other-race' effect with autoassociative neural networks: further evidence in favor of the face-space model.

Other-race (OR) faces are less accurately recognized than same-race (SR) faces, but faster classified by race. This phenomenon has often been reported as the 'other-race' effect (ORE). Valentine (1991 Quarterly Journal of Experimental Psychology A: Human Experimental Psychology 43 161-204) proposed a theoretical multidimensional face-space model that explained both of these results, in terms of variations in exemplar density between races. According to this model, SR faces are more widely distributed across the dimensions of the space than OR faces. However, this model does not quantify nor state the dimensions coded within this face space. The aim of the present study was to test the face-space explanation of the ORE with neural network simulations by quantifying its dimensions. We found the predicted density properties of Valentine's framework in the face-projection spaces of the autoassociative memories. This was supported by an interaction for exemplar density between the race of the learned face set and the race of the faces. In addition, the elaborated face representations showed optimal responses for SR but not for OR faces within SR face spaces when explored at the individual level, as gender errors occurred significantly more often in OR than in SR face-space representations. Altogether, our results add further evidence in favor of a statistical exemplar density explanation of the ORE as suggested by Valentine, and question the plausibility of such coding for faces in the framework of recent neuroimaging studies.

Asian People↗
PubMed2003

The effect of inversion on the encoding of normal and "thatcherized" faces.

In the "Thatcher illusion" a face, in which the eyes and mouth are inverted relative to the rest of the face, looks grotesque when shown upright but not when inverted. In four experiments we investigated the contribution of local and global processing to this illusion in normal observers. We examined inversion effects (i.e., better performance for upright than for inverted faces) in a task requiring discrimination of whether faces were or were not "thatcherized". Observers made same/different judgements to isolated face parts (Experiments 1-2) and to whole faces (Experiments 3-4). Face pairs had the same or different identity, allowing for different processing strategies using feature-based or configural information, respectively. In Experiment 1, feature-based matching of same-person face parts yielded only a small inversion effect for normal face parts. However, when feature-based matching was prevented by using the face parts of different people on all trials (Experiment 2) an inversion effect occurred for normal but not for thatcherized parts. In Experiments 3 and 4, inversion effects occurred with normal but not with thatcherized whole faces, on both same- and different-person matching tasks. This suggests that a common configural strategy was used with whole (normal) faces. Face context facilitated attention to misoriented parts in same-person but not in different-person matching. The results indicate that (1) face inversion disrupts local configural processing, but not the processing of image features, and (2) thatcherization disrupts local configural processing in upright faces.

Adult↗
PubMed1992

Towards an exemplar model of face processing: the effects of race and distinctiveness.

Valentine (1991a, 1991b) described a theoretical framework for face recognition in which faces are encoded as locations in a multidimensional space. It was argued that this approach could provide a unified account of the effects of distinctiveness, inversion, and race on face recognition. In this paper we evaluate the ability of this theoretical framework to account for the effects of distinctiveness and race in four experiments in which white British and Japanese faces served as stimuli and both white British and Japanese students acted as subjects. In a recognition memory experiment the expected "own-race bias" was observed as a Race of Subject x Race of Face interaction. Distinctive faces were recognized more accurately than typical faces, but the effect of distinctiveness did not interact with the race of face or the race of subject. Typical faces were classified faster than distinctive faces in a task in which intact faces had to be distinguished from jumbled faces, as found in earlier work, and the effect of distinctiveness did not interact with the race of face or race of subject. In contrast, a task in which subjects classified faces according to their race did show a greater effect of distinctiveness for own-race faces. The results are discussed in relation to the two specific models within the multidimensional space framework identified by Valentine (1991a): a purely exemplar-based model and a norm-based coding model. It is argued that these results are more easily accommodated in terms of a purely exemplar-based model. Some conceptual problems in applying the norm-based coding model to the effect of race are discussed.

Adult↗