An event-related brain potential study of explicit face recognition

To determine the time course of face recognition and its links to face-sensitive event-related potential (ERP) components, ERPs elicited by faces of famous individuals and ERPs to non-famous control faces were compared in a task that required explicit judgements of facial identity. As expected, the face-selective N170 component was unaffected by the difference between famous and non-famous faces. In contrast, the occipito-temporal N250 component was linked to face recognition, as it was selectively triggered by famous faces. Importantly, this component was present for famous faces that were judged to be definitely known relative to famous faces that just appeared familiar, demonstrating that it is associated with the explicit identification of a particular face. The N250 is likely to reflect early perceptual stages of face recognition where long-term memory traces of familiar faces in ventral visual cortex are activated by matching on-line face representations. Famous faces also triggered a broadly distributed longer-latency positivity (P600f) that showed a left-hemisphere bias and was larger for definitely known faces, suggesting links between this component and name generation. These results show that successful face recognition is predicted by ERP components over face-specific visual areas that emerge within 230 ms after stimulus onset.     

Human brain potential correlates of voice priming and voice recognition

This study investigated repetition priming in the recognition of famous voices, recording reaction times (RTs) and event-related brain potentials (ERPs). In Experiment 1, a facilitation was found in RTs to famous but not to unfamiliar voices when these had been primed by a different voice sample of the same speaker earlier in the experiment. However, ERPs to both famous and unfamiliar voices showed repetition priming in terms of an increased P2 component, which is thought to be generated in the auditory cortex. When the likelihood of conscious retrieval of primes was reduced in Experiment 2, facilitatory priming in RTs was again observed for famous voices, but inhibitory priming was now observed for unfamiliar voices. This is consistent with predictions of a bias model of priming. Moreover, substantial priming was observed even when voice primes were backward speech samples, which were recognised at chance levels. The results suggests that (a) voice priming is mediated to a large extent by frequency characteristics of a particular voice, rather than by articulatory and other 'sequential' features that are eliminated in backward speech; (b) priming affects the processing of voices in auditory cortical areas within 200 ms after voice onset; and (c) explicit recognition of a voice in the priming phase is not a necessary condition for priming to occur.     

Hearing facial identities: brain correlates of face--voice integration in person identification

Audiovisual integration (AVI) is a well-known aspect of speech perception, but integration of facial and vocal information is also important for speaker recognition. We recently demonstrated AVI in the recognition of familiar (but not unfamiliar) speakers. Specifically, systematic behavioural benefits and costs in recognizing a familiar voice occur when the voice is combined with a time-synchronised articulating face of corresponding or noncorresponding speaker identity, respectively (Schweinberger et al., 2007; Robertson and Schweinberger, 2010). Here we report an experiment assessing event-related brain potentials (ERPs) in this novel paradigm, while participants recognized familiar speakers presented in (1) Voice only, (2) voice with identity-corresponding and (3) noncorresponding time-synchronised speaking faces, as well as (4) Face only conditions. Audiovisual speaker identity correspondence influenced only later ERPs around 250–600 msec, with increased negativity for noncorresponding identities at central electrodes. Strikingly, when compared with the ERPs from both unimodal conditions, both audiovisual conditions led to a much earlier onset of frontocentral negativity, with maximal differences around 50–80 msec. Moreover, audiovisual stimuli elicited larger N170 responses than Face only stimuli. These findings suggest that the perception of a voice and a time-synchronised articulating face triggers remarkably early and mandatory mechanisms of audiovisual processing, although the correspondence or discrepancy in audiovisual speaker identity may only be computed ∼200 msec later.     

Event-related brain potential correlates of emotional face processing

Results from recent event-related brain potential (ERP) studies investigating brain processes involved in the detection and analysis of emotional facial expression are reviewed. In all experiments, emotional faces were found to trigger an increased ERP positivity relative to neutral faces. The onset of this emotional expression effect was remarkably early, ranging from 120 to 180ms post-stimulus in different experiments where faces were either presented at fixation or laterally, and with or without non-face distractor stimuli. While broadly distributed positive deflections beyond 250ms post-stimulus have been found in previous studies for non-face stimuli, the early frontocentrally distributed phase of this emotional positivity is most likely face-specific. Similar emotional expression effects were found for six basic emotions, suggesting that these effects are not primarily generated within neural structures specialised for the automatic detection of specific emotions. Expression effects were eliminated when attention was directed away from the location of peripherally presented emotional faces, indicating that they are not linked to pre-attentive emotional processing. When foveal faces were unattended, expression effects were attenuated, but not completely eliminated. It is suggested that these ERP correlates of emotional face processing reflect activity within a neocortical system where representations of emotional content are generated in a task-dependent fashion for the adaptive intentional control of behaviour. Given the early onset of the emotion-specific effects reviewed here, it is likely that this system is activated in parallel with the ongoing evaluation of emotional content in the amygdala and related subcortical brain circuits.     

EEG correlates of face recognition in patients with schizophrenia spectrum disorders: A systematic review

ObjectiveTo systematically assess EEG studies and evaluate neuropsychological changes of face recognition in the context of neutral face stimuli in individuals with schizophrenia spectrum disorders.MethodsA literature search was conducted using the PubMed database from inception to March 2018. Studies included in the review measured any event-related potentials, neural oscillations, or phase synchrony.ResultsA total of 113 articles were identified. Twenty-nine studies were included for the review. The majority of the studies focused on the N170 component. Smaller N170 amplitudes were consistently reported in schizophrenia patients compared to the healthy control group. Significant correlations between N170 amplitudes and social functioning scales were reported. Other results were quite inconsistent; however, group differences were more prominent for tasks with specific conditions.ConclusionsOlder patients with longer disease duration show more consistent neuropsychological correlations. Alterations of event-related potentials are likely to be linked to higher severity of symptoms. The N170 component seems to be the most promising event-related potential to be used for evaluation of present status and for dynamic control of cognitive impairments, social functioning, and rehabilitation effectiveness.SignificanceThis systematic review provides evidence of (1) neuropsychological alterations of face processing outside an emotional context, and (2) a potential role of N170 as a diagnostic and treatment monitoring biomarker.     

Event-related potential correlates of repetition priming for ignored faces

An attentional capacity limit was recently suggested for faces, such that only one face can be processed at a time. We measured interference and repetition priming caused by irrelevant distractor faces. Participants initially performed male/female judgments for central faces or symbols flanked by distractor faces. Interference (slower responses for sex-incongruent target-distractor pairs) occurred for central symbols but was absent for central faces. In subsequent fame judgements, previously presented distractor faces had no repetition priming effect on response times. Relative to new faces, event-related brain potentials revealed a right occipitotemporal negativity approximately 400-600 ms for faces previously shown as distractors flanking central symbols (but not distractors flanking faces). These findings support a face-specific attentional capacity limit, showing that event-related brain potential priming effects can reveal covert distractor processing.     

Hemispheric asymmetries in image-specific and abstractive priming of famous faces: evidence from reaction times and event-related brain potentials

We investigated hemispheric differences in image-specific and abstractive immediate repetition priming of famous faces. Participants performed speeded familiarity decisions for centrally presented famous and unfamiliar target faces. Target faces were preceded by lateralized primes (150 ms), presented either in the left or right visual field (LVF or RVF). Primes were either an identical photograph of the famous target face (image-specific priming), a different image of the famous target face (abstractive priming) or a different familiar face (unprimed condition). Reaction times (RTs) revealed significant effects of priming for both image-specific and abstractive priming overall. In addition, image-specific priming was more than twice the magnitude for targets following LVF primes as compared to RVF primes. By contrast, no hemispheric differences emerged for abstractive face priming across different images. Whereas ERPs revealed no evidence that priming affected the N170 component, both image-specific and abstractive priming significantly modulated the amplitudes of a right temporal N250r and a parietal N400 component. Behavioural and electrophysiological evidence for hemispheric differences in image-specific and abstractive face priming are discussed with respect to current theories of how the human left and right ventral temporal cortices represent abstractive and form-specific visual information.     

Exploring the functional architecture of person recognition system with event-related potentials in a within- and cross-domain self-priming of faces

In this paper, we explored the functional properties of person recognition system by investigating the onset, magnitude, and scalp distribution of within- and cross-domain self-priming effects on event-related potentials (ERPs). Recognition of degraded pictures of famous people was enhanced by a prior exposure to the same person's face (within-domain self-priming) or name (cross-domain self-priming) as compared to those preceded by neutral or unrelated primes. The ERP results showed first that the amplitude of the N170 component to famous face targets was modulated by within- and cross-domain self-priming, suggesting not only that the N170 component can be affected by top–down influences but also that this top–down effect crosses domains. Second, similar to our behavioral data, later ERPs to famous faces showed larger ERP self-priming effects in the within-domain than in the cross-domain condition. In addition, the present data dissociated between two topographically and temporally overlapping priming-sensitive ERP components: the first one, with a strongly posterior distribution arising at an early onset, was modulated more by within-domain priming irrespective whether the repeated face was familiar or not. The second component, with a relatively uniform scalp distribution, was modulated by within- and cross-domain priming of familiar faces. Moreover, there was no evidence for ERP-induced modulations for unfamiliar face targets in the cross-domain condition. Together, our findings suggest that multiple neurocognitive events that are possibly mediated by distinct brain loci contribute to face priming effects.     

Psychophysiological correlates of face processing in social phobia

Social phobia has been associated with abnormal processing of angry faces, which directly signal disapproval--a situation that social phobics fear. This study investigated the electrophysiological correlates of emotional face processing in socially phobic and non-phobic individuals. Subjects identified either the gender (modified emotional Stroop task) or the expression of angry, happy, or neutral faces. Social phobics showed no deviations from controls in reaction times, heart rates, P1, or P2 amplitudes in response to angry faces, although elevated FSS scores were associated with higher P1 amplitudes in social phobic persons. In addition, social phobic persons showed enhanced right temporo-parietal N170 amplitudes in response to angry faces in the emotion identification task. Furthermore, higher scores on the Social Phobia and Anxiety Inventory (SPAI) were associated as a trend with larger N170 amplitudes in response to angry faces in the emotion identification task. Thus, the present results suggest that social phobics show abnormalities in the early visual processing of angry faces, as reflected by the enhanced right-hemispheric N170 when the emotion of the angry face was the focus of attention, while behavioral responses and heart rates showed no evidence for preferred processing of angry facial expressions.     

Human brain potential correlates of face encoding into memory.

ERPs elicited by photographs of unfamiliar faces were shown to be predictive for their later recognition. We established that these ERP differences were unrelated to fluctuations of attention or other non-specific factors during perceptual processing. Therefore they may be interpreted as manifestations of brain processes that correlate with memory encoding. The scalp topography of this ERP difference was bipolar with greater electrical positivity at frontal and greater negativity at parieto-temporal scalp sites. This topography appears to contrast with the more uniformly positive differences reported for verbal stimuli but is in accord with what might be expected for faces and complex visual stimuli.     

Covert recognition and the neural system for face processing

In this viewpoint, we discuss the new evidence on covert face recognition in prosopagnosia presented by Bobes et al. (2003, this issue) and by Sperber and Spinnler (2003, this issue). Contrary to earlier hypotheses, both papers agree that covert and overt face recognition are based on the same mechanism. In line with this suggestion, an analysis of reported cases with prosopagnosia indicates that a degree of successful encoding of facial representations is a prerequisite for covert recognition to occur. While we agree with this general conclusion as far as Bobes et al.'s and Sperber and Spinnler's data are concerned, we also discuss evidence for a dissociation between different measures of covert recognition. Specifically, studies in patients with Capgras delusion and patients with prosopagnosia suggest that skin conductance and behavioural indexes of covert face recognition are mediated by partially different mechanisms. We also discuss implications of the new data for models of normal face recognition that have been successful in simulating covert recognition phenomena (e.g., Young and Burton, 1999, and O'Reilly et al., 1999). Finally, in reviewing recent neurophysiological and brain imaging evidence concerning the neural system for face processing, we argue that the relationship between ERP components (specifically, N170, N250r, and N400) and different cognitive processes in face recognition is beginning to emerge.     

A comparative case study of face recognition: The contribution of configural and part-based recognition systems, and their interaction

Understanding the interaction between the configural and part-based systems in face recognition is the major aim of this study. Specifically, we established whether configural representation of faces contribute to aspects of face recognition that depend on part-based processes, such as identifying inverted or fractured faces. Using face recognition tasks that require part-based or configural processing, we compared the results of CK—a man who has object agnosia and alexia [Moscovitch, M., Winocur, G., & Behrmann, M. (1997). What is special about face recognition? Nineteen experiments on a person with visual object agnosia and dyslexia but normal face recognition. Journal of Cognitive Neuroscience, 9(5), 555–604] but normal upright face recognition, to those of DC—a man who has prosopagnosia but normal object recognition. CK was normal at recognizing faces if configural processing was sufficient, but poor at recognizing faces that were modified so as to alter their gestalt, and require part-based processing (Moscovitch et al.). DC was impaired at recognizing upright faces and his performance declined in all tasks involving recognition of modified faces, including those that depend on part-based and on configural processing. Nevertheless, DC was normal on tasks involving perception of generic faces and face imagery. These results show that although configural face perception can proceed without part-based processing, the reverse is not the case. Our results suggest that the configural system is always necessary for face recognition, and appears to support what remains of face identification even in prosopagnosic people who have an intact part-based system.     

Telling one face from another: electrocortical correlates of facial characteristics among individual female faces

Research investigating the neural correlates of face processing has emphasized differences in neural activity when participants view faces versus other stimulus categories (e.g., houses). Much less is known about the neural mechanisms underlying the discrimination among individual faces. Using a large number of female faces, here we show that the amplitude of the face-sensitive N170 electrocortical component is related to a range of facial characteristics. The right N170 amplitude was related to eye color and face width. The left N170 amplitude was related to eye shape and face proportions, suggesting a functional dissociation between hemispheres. In contrast, the amplitude of the P100 and N250 components was largely unaffected by these facial characteristics. Consistent with recent findings in non-human primates, we identify for the first time evidence of human electrocortical brain potentials that are sensitive to variations in specific facial characteristics, a prerequisite for recognizing the identity of individual faces.     

Lexical-semantic representation in bilingual aphasia: Findings from semantic priming and cognate repetition priming

Background: While many studies have investigated the nature of language organisation in monolingual speakers with aphasia, our understanding of bilingual aphasia lags far behind. Only a handful of studies have employed on-line psycholinguistic experimental methods to explore the nature of language representation and processing in bilingual speakers with aphasia. Improving our understanding of how language is organised and processed in bilingual speakers with aphasia is central to the development of effective impairment-level language treatments. Cognate/noncognate representation and semantic representation are two key aspects of bilingual language organisation that are yet to be explored in depth in bilingual speakers with aphasia.

Aims: The present study aimed to investigate (1) whether semantic representation was shared across the two languages of a bilingual speaker with aphasia and (2) whether cognate words would produce a processing advantage relative to noncognate words (as has been found in neurologically-normal younger bilingual adults).

Methods & Procedures: A 70-year-old bilingual Italian/English speaker, who presented with nonfluent aphasia and apraxia of speech, completed two priming experiments: a semantic priming experiment and a cognate repetition priming experiment.

Outcomes & Results: In the semantic priming experiment, the participant demonstrated large priming effects in both within-language conditions and one cross-language condition. The finding of priming in at least one of the cross-language conditions provides some corroboration for shared semantic representation in this bilingual individual with aphasia. In the cognate repetition priming experiment, the participant produced a language-specific cognate advantage in English, for words repeated in the same language. For words repeated in a different language condition (i.e., as their translation equivalent), the participant produced a processing advantage for noncognate words.

Conclusions: The findings of this study provided support for shared semantic representation in bilingual speakers following aphasia; however, the results also suggested that aphasia can disrupt normal lexical access processes. Results in relation to cognate versus noncognate processing suggested that bilingual speakers with aphasia may not, necessarily, always display a cognate advantage. Overall, the present study showed that language processing in bilingual speakers with aphasia is highly complex and is dependent upon the intricate interplay between the speaker’s premorbid language proficiency, inhibitory processing deficits that occur with normal aging and postmorbid language impairment and recovery patterns.     

Long-term information and distributed neural activation are relevant for the “internal features advantage” in face processing: Electrophysiological and source reconstruction evidence

In face processing tasks, prior presentation of internal facial features, when compared with external ones, facilitates the recognition of subsequently displayed familiar faces. In a previous ERP study (Olivares & Iglesias, 2010) we found a visibly larger N400-like effect when identity mismatch familiar faces were preceded by internal features, as compared to prior presentation of external ones. In the present study we contrasted the processing of familiar and unfamiliar faces in the face-feature matching task to assess whether the so-called “internal features advantage” relies mainly on the use of stored face-identity-related information or if it might operate independently from stimulus familiarity. Our participants (N = 24) achieved better performance with internal features as primes and, significantly, with familiar faces. Importantly, ERPs elicited by identity mismatch complete faces displayed a negativity around 300–600 msec which was clearly enhanced for familiar faces primed by internal features when compared with the other experimental conditions. Source reconstruction showed incremented activity elicited by familiar stimuli in both posterior (ventral occipitotemporal) and more anterior (parahippocampal (ParaHIP) and orbitofrontal) brain regions. The activity elicited by unfamiliar stimuli was, in general, located in more posterior regions. Our findings suggest that the activation of multiple neural codes is required for optimal individuation in face-feature matching and that a cortical network related to long-term information for face-identity processing seems to support the internal feature effect.     

A new selective developmental deficit: Impaired object recognition with normal face recognition

Introduction

Studies of developmental deficits in face recognition, or developmental prosopagnosia, have shown that individuals who have not suffered brain damage can show face recognition impairments coupled with normal object recognition ( [Duchaine and Nakayama, 2005] , [Duchaine et?al., 2006] and [Nunn et?al., 2001] ). However, no developmental cases with the opposite dissociation – normal face recognition with impaired object recognition – have been reported. The existence of a case of non-face developmental visual agnosia would indicate that the development of normal face recognition mechanisms does not rely on the development of normal object recognition mechanisms.

Methods

To see whether a developmental variant of non-face visual object agnosia exists, we conducted a series of web-based object and face recognition tests to screen for individuals showing object recognition memory impairments but not face recognition impairments. Through this screening process, we identified AW, an otherwise normal 19-year-old female, who was then tested in the lab on face and object recognition tests.

Results

AW’s performance was impaired in within-class visual recognition memory across six different visual categories (guns, horses, scenes, tools, doors, and cars). In contrast, she scored normally on seven tests of face recognition, tests of memory for two other object categories (houses and glasses), and tests of recall memory for visual shapes. Testing confirmed that her impairment was not related to a general deficit in lower-level perception, object perception, basic-level recognition, or memory.

Discussion

AW’s results provide the first neuropsychological evidence that recognition memory for non-face visual object categories can be selectively impaired in individuals without brain damage or other memory impairment. These results indicate that the development of recognition memory for faces does not depend on intact object recognition memory and provide further evidence for category-specific dissociations in visual recognition.     

Autistic traits are linked to reduced adaptive coding of face identity and selectively poorer face recognition in men but not women

Our ability to discriminate and recognize thousands of faces despite their similarity as visual patterns relies on adaptive, norm-based, coding mechanisms that are continuously updated by experience. Reduced adaptive coding of face identity has been proposed as a neurocognitive endophenotype for autism, because it is found in autism and in relatives of individuals with autism. Autistic traits can also extend continuously into the general population, raising the possibility that reduced adaptive coding of face identity may be more generally associated with autistic traits. In the present study, we investigated whether adaptive coding of face identity decreases as autistic traits increase in an undergraduate population. Adaptive coding was measured using face identity aftereffects, and autistic traits were measured using the Autism-Spectrum Quotient (AQ) and its subscales. We also measured face and car recognition ability to determine whether autistic traits are selectively related to face recognition difficulties. We found that men who scored higher on levels of autistic traits related to social interaction had reduced adaptive coding of face identity. This result is consistent with the idea that atypical adaptive face-coding mechanisms are an endophenotype for autism. Autistic traits were also linked with face-selective recognition difficulties in men. However, there were some unexpected sex differences. In women, autistic traits were linked positively, rather than negatively, with adaptive coding of identity, and were unrelated to face-selective recognition difficulties. These sex differences indicate that autistic traits can have different neurocognitive correlates in men and women and raise the intriguing possibility that endophenotypes of autism can differ in males and females.     

Rapid response learning in amnesia: delineating associative learning components in repetition priming

Functional brain imaging studies of priming assume that the behavioral facilitation and activity reductions resulting from multiple repetitions reflect the continued tuning of processes engaged during the initial processing of items. Utilizing an object priming paradigm in which participants were asked to make relative size judgments about visually presented common objects, we tested an alternate hypothesis that states that with multiple repetitions participants come to rely on a more efficient response learning mechanism. In experiment 1, the decision cue was inverted such that previous judgments made either once or three times were rendered invalid. Decision inversion resulted in a reduction of all priming, but most critically, led to a reduction of multiple-repetition priming to the level of single-repetition priming. In experiment 2, patients with amnesia failed to show a priming advantage for multiple repetitions, indicating that response learning is dependent on the medial temporal lobes. Taken together, these results suggest that a different process increasingly mediates priming behavior as repetitions increase. With repeated exposure, behavioral facilitation rapidly comes to reflect a more efficient response learning mechanism rather than facilitated access to object knowledge.     

The classification of 'fear' from faces is associated with face recognition skill in women.

Two experiments were conducted to explore the relationship between the discrimination of the facial expression of 'fear' in faces and facial recognition. On the basis of the reported role of the amygdala in both processes in patients, we hypothesised that the two skills would be correlated in normal adults. In Experiment 1, a series of tests of facial expression categorisation, of face matching and of familiar and unfamiliar face recognition was conducted on normal young women, for whom psychometric scores were also obtained (n=23). Accuracy of categorisation of fear from faces predicted variance in face recognition accuracy-especially in tasks of unfamiliar face recognition (immediate old-new discrimination). No other correlations between face processing and expression classification were significant. Experiment 2 repeated the expression classification tests and an unfamiliar face recognition test on a new sample of men (n=13) and women (n=16). While there were no sex differences in face recognition, the correlation between 'fear' and face recognition was replicated only for women. These data indicate that the amygdala supports both the specific apprehension of fear in faces and face recognition in adult human females, but that the association may not hold for men. Sex differences in the structure of the amygdala-hippocampal complex suggest a likely cortical substrate for the observed differences. We speculate that social learning, which involves identifying the faces of potentially salient others, and also their attitude to the observer, engages the amygdala more readily in women than in men.