Prime Faces Research Articles

Hemispheric resource availability influences face perception: A multiple resource approach to social perception

Two experiments tested the hypothesis that social perception recruits distinct limited-capacity processing resources that are distinguished by the cerebral hemispheres. To test this hypothesis, social perception efficiency was assessed after relevant hemispheric processing resources were depleted. In Experiment 1 prime faces were unilaterally presented for 30 ms, after which centrally presented target faces were categorised by sex. In Experiment 2 prime faces were unilaterally presented for 80 ms after which centrally presented target faces were categorised by fame. Results showed that sex categorisation was slower after primes were presented in the right versus left visual field, and that fame categorisation was slower after familiar primes were presented in the left versus right visual field. The results support a multiple resource account of social perception in which the availability of resources distributed across the cerebral hemispheres influences social perception.

Understanding the subliminal affective priming effect of facial stimuli: an ERP study

The subliminal affective priming was studied by recording event-related potential (ERP) to ambiguous neutral faces preceded by 20ms positive or negative prime faces. Behavioral results showed that positive and negative prime faces led to valance-consistent biases in affective judgments of ambiguous neutral faces. ERP data showed that subliminal primes differentially influenced N100, N300 and vertex positive potential (VPP), with larger amplitudes in negative priming trials. These results support the conclusion that the early perceptual analysis of targets, as well as evaluation and selection of targets, is affected by subliminal affective information.

Multiple contributions to priming effects for familiar faces: Analyses with backward masking and event‐related potentials

The model of face recognition by Bruce and Young postulates a pool of structural representations for familiar faces in long-term memory, so-called face recognition units (FRUs). Event-related brain potentials show early repetition priming effects for familiar faces around 250-300 ms [N250r or early repetition effect (ERE)], which are thought to reflect the activation of these FRUs. However, small N250r effects are also seen for unfamiliar faces suggesting that priming of perceptual codes (i.e., pictorial and structural codes) also contributes to early repetition effects. Using a face-familiarity task in Experiment 1, we aimed to eliminate these perceptual contributions to face priming by backward masking the prime face with a different, unfamiliar face. As expected, a repetition priming effect appeared only for familiar faces. Experiment 2 used a semantic-decision task and compared the effects of different kinds of masks that interfered with either pictorial codes or with pictorial and structural codes. Our findings indicate that both structural codes and memory representations contribute to the N250r and that unfamiliar-face masks interfere only with structural codes. Face-masks may therefore provide a useful tool to extract the pure contributions of memory representations (i.e., FRUs) to repetition priming.

Effects of unconscious processing on implicit memory for fearful faces.

Emotional stimuli can be processed even when participants perceive them without conscious awareness, but the extent to which unconsciously processed emotional stimuli influence implicit memory after short and long delays is not fully understood. We addressed this issue by measuring a subliminal affective priming effect in Experiment 1 and a long-term priming effect in Experiment 2. In Experiment 1, a flashed fearful or neutral face masked by a scrambled face was presented three times, then a target face (either fearful or neutral) was presented and participants were asked to make a fearful/neutral judgment. We found that, relative to a neutral prime face (neutral–fear face), a fearful prime face speeded up participants' reaction to a fearful target (fear–fear face), when they were not aware of the masked prime face. But this response pattern did not apply to the neutral target. In Experiment 2, participants were first presented with a masked faces six times during encoding. Three minutes later, they were asked to make a fearful/neutral judgment for the same face with congruent expression, the same face with incongruent expression or a new face. Participants showed a significant priming effect for the fearful faces but not for the neutral faces, regardless of their awareness of the masked faces during encoding. These results provided evidence that unconsciously processed stimuli could enhance emotional memory after both short and long delays. It indicates that emotion can enhance memory processing whether the stimuli are encoded consciously or unconsciously.

Facial features can induce emotion: Evidence from affective priming tasks

Our previous study found that schematic faces with direct gazes, with mouths, with horizontal oval eyes, or without noses, tend to be perceived as in negative emotion. In this study we further explore these factors by the affective priming task. Faces were taking as prime, and positive or negative words were probe. The task was to judge the valence of the probe. If the faces could induce emotions, a target word with the same emotional valence should be judged faster than with opposite valence (the congruency effect). Experiment 1 used the most positive and negative rated faces in previous study as the primes. The positive faces were with vertical oval eyes and without mouth, while the negative faces were with horizontal eyes and with mouth. Results of 34 participants showed that those faces indeed elicited congruency effects. Experiment 2 manipulated gaze directions (N = 16). After the task the participants were asked to rate the prime faces. According to their rating, faces with direct gaze was perceive as positive, and elicited congruency effect with positive words in affective priming task. Our data thus support the conjecture that shape of eyes, the existence of mouths, and gaze directions could induces emotion.

Self-face enhances processing of immediately preceding invisible faces

The self-face is thought to be an especially salient stimulus. Behavioral evidence suggests that self-face processing advantage is associated with enhanced processing of temporally adjacent subliminal stimuli. However, the neural basis of this self-related processing modulation has not been investigated.We studied self-face induced signal amplification through masked priming and repetition suppression (fMRI adaptation). Subjects performed a gender-categorization task on self- and non-self target faces preceded by subliminal (17ms) prime faces. The relationship between prime and target was varied between task-incongruent (when prime and target belonged to a different gender) and task-congruent (when prime and target belonged to the same gender) pairs.We found that, in the presence of the visible self-face (but not of other non-self faces), a bilateral fronto-parietal network exhibited repetition suppression to subliminal prime faces belonging to the same gender (task-congruent) as the target, consistent with the notion that, in the presence of the self-face, subliminal stimuli access high-level processing systems. These results are in agreement with the notion of self-specific top-down amplification of subliminal task-relevant information, and suggest that the self-face, through its high salience, is particularly efficacious in focusing attention.

Redundancy effects in the perception and memory of visual objects

Is visual representation of an object affected by whether surrounding objects are identical to it, different from it, or absent? To address this question, we tested perceptual priming, visual short-term, and long-term memory for objects presented in isolation or with other objects. Experiment 1 used a priming procedure, where the prime display contained a single face, four identical faces, or four different faces. Subjects identified the gender of a subsequent probe face that either matched or mismatched with one of the prime faces. Priming was stronger when the prime was four identical faces than when it was a single face or four different faces. Experiments 2 and 3 asked subjects to encode four different objects presented on four displays. Holding memory load constant, visual memory was better when each of the four displays contained four duplicates of a single object, than when each display contained a single object. These results suggest that an object's perceptual and memory representations are enhanced when presented with identical objects, revealing redundancy effects in visual processing.

Recognition advantage of happy faces in extrafoveal vision: Featural and affective processing

Happy, surprised, disgusted, angry, sad, fearful, and neutral facial expressions were presented extrafoveally (2.5° away from fixation) for 150 ms, followed by a probe word for recognition (Experiment 1) or a probe scene for affective valence evaluation (Experiment 2). Eye movements were recorded and gaze-contingent masking prevented foveal viewing of the faces. Results showed that (a) happy expressions were recognized faster than others in the absence of fixations on the faces, (b) the same pattern emerged when the faces were presented upright or upside-down, (c) happy prime faces facilitated the affective evaluation of emotionally congruent probe scenes, and (d) such priming effects occurred at 750 but not at 250 ms prime–probe stimulus–onset asynchrony. This reveals an advantage in the recognition of happy faces outside of overt visual attention, and suggests that this recognition advantage relies initially on featural processing and involves processing of positive affect at a later stage.

Subliminal Affective Priming Effect by Faces With Different Valence: An ERP Study

Subliminal affective priming refers to a phenomenon where subliminal presentation of a prime object shifts subsequent affective evaluation of the supraliminal object in the affective direction of the prime object,but the neural mechanisms underlying this effect is unclear.The emotional significance and neural specificity of facial processing make faces an ideal prime for automatic processing.But the emotional faces differ in two affective dimensions:valence(unpleasant-to-pleasant) and arousal(low-to-high).They may have different effects on ERP component.Most previous studies used only two or three kinds of emotional faces to study subliminal affective priming.In this study,the dimension of arousal was controlled and two groups of priming faces(unpleasant vs.pleasant) were presented for 20ms,followed by a mosaic neutral face for 800ms.We combined behavioral analyses of subliminal affective priming with recordings of event-related potential(ERP) that provide on-line measurements of neural processing with high temporal resolution.We hypothesized that positive and negative prime faces led to valance-consistent biases in affective judgments of ambiguous neutral faces.We reasoned that P1,N1,P2,N2,P3,and late positive potentials(LPP) could provide evidence on early perceptual processing,attention orienting,and late elaborate processing.Seventeen volunteers from University took part in this experiment,they were instructed to judge the affect of the neutral target faces as unpleasant or pleasant,while the response speed was not stressed.The EEG was recorded from 64 scalp sites using Ag/AgCl electrodes.Signals were averaged offline for 1000 ms with an additional 200 ms recorded prior to prime onset to allow for baseline correction.The ERP were averaged separately for unpleasant and pleasant trials.Peak amplitude values were computed for 70-130ms(N1);190-240ms(N2);400-800ms(LPP) time intervals,time locked to prime onset(time 0),these ERP measures were obtained from six electrodes:F5,FZ,F6,C3,CZ,C4.We also computed peak amplitudes from intervals of 70-130ms,130-190ms,240-400ms,400-800ms,corresponding to P1,P2,P3 and LPP.These ERP measures were obtained from eight electrodes:P3,PZ,P4,PO7,POZ,PO8,O1,O2.A repeated measures ANOVA on the peak amplitude of each component was conducted.In addition,the standardized low-resolution brain electromagnetic tomography(sLORETA) technique was conducted to estimate the neural sources of these ERP components which are sensitive to subliminal affective priming.We found that unpleasant and pleasant prime faces led to valence-consistent biases in participants' affective judgments of neutral target faces.ERP results showed that subliminal primes differentially influenced anterior N1 and posterior P2 potentials,with larger amplitudes in negative priming trials.Source analysis revealed that N1 might be generated from brain regions near the precuneus,while P2 was localized to the superior temporal gyrus.These results confirm our hypothesis that the subliminal affective priming effect is related to prime valence,suggesting that the early perceptual analysis of targets is affected by subliminal affective information.The results demonstrate the subliminal affective priming effect.

A Negative compatibility effect in priming of emotional faces

The negative compatibility effect (NCE) is the surprising result that low-visibility prime arrows facilitate responses to opposite-direction target arrows. Here we compare the priming obtained with simple arrows to the priming of emotions when categorizing human faces, which represents a more naturalistic set of stimuli and for which there are no preexisting response biases. When inverted faces with neutral expressions were presented alongside emotional prime and target faces, only strong positive priming occurred. However, when the neutral faces were made to resemble the target faces in geometry (upright orientation), time (flashing briefly), and space (appearing in the same location), positive priming gradually weakened and became negative priming. Implications for theories of the NCE are discussed.

Subliminal Emotional Priming and Decision Making in a Simulated Hiring Situation

The present study examines the unconscious influence of emotional information on decision making in a simulated hiring situation. We used a subliminal masked priming paradigm with varying faces as primes, which were presented for a duration of 50 ms and had two levels of emotion: positive emotion (happiness) and negative emotion (anger). These primes were followed by emotionally neutral target faces. Primes were congruent (same faces) or incongruent (different faces). Prime Emotion (positive vs. negative) was crossed with Prime Repetition (repeat vs. unrelated) in a 2 × 2 factorial design. Each participant was tested in all four of the experimental conditions, each of which had 5 different trials. The participants were asked to indicate as rapidly as possible whether they were “favorable” or “unfavorable” toward the selection of the candidate (target face). Two dependent measures were analyzed: number of target faces chosen (i.e., number of “favorable” responses to target faces) and reaction time (RT). Results revealed a strong effect of emotional priming. Participants tended to choose more target faces preceded by positive prime faces than by negative prime faces. Moreover, they reacted faster when presented with target faces preceded by negative primes. Despite its exploratory nature, this study provides further evidence for the role of emotional processing in modulating decision processes and extends the experimental manipulation of subliminal emotion to the case of the masked repetition priming technique.

The fallout from crossing paths with cellular cytidine deaminases

Humans are unique in encoding eleven APOBEC cytidine deaminases that edit single stranded DNA (ssDNA). So far no other species encodes so many. To be exact, prime face evidence has been found for 8, the remaining 3 proving to be recalcitrant. Single stranded DNA is synonymous with replication and transcription and might suggest a role in epigenetic modification. The most widely known member goes by a different name, AID, and is responsible for class switch recombination and somatic hypermutation of rearranged immunoglobulin V region loci. Retroviral cDNA is of course, single stranded and an anti-viral activity possible. In fact the lentiviruses and one of their precursors were so vulnerable to some of the APOBEC3 enzymes that they evolved the vif gene more than 10 M years ago to effectively take them out. By contrast, HTLV-1 and other retroviruses seem not to be bothered. By contrast several human APOBEC3 genes do act as major restriction factors for hepatitis B virus in vivo. Some of the APOBEC3 genes are upregulated by interferon-α, which goes a long with an anti-viral role for certain APOBEC3 members. Finally some of the human genes at least, may also restrict some other human viruses in vivo presumably during replication and/or transcription. Indeed, a rather eclectic ensemble. The role of these deaminases in controlling the replication of retroviruses and endogenous retroviruses (ERVs) doesn't fit well with their phylogeny and gene copy number. For example, the mouse genome encodes only one APOBEC3 gene while humans have seven. The avian and reptile lineages are full of ERVs yet they do not encode any APOBEC3 gene. Similarly, there are no such genes in plant genomes, despite a plethora of retroviruses. Massive retroviral hypermutation can be used as a surrogate marker for elevated expression of these deaminases in vivo. Given that three laws of thermodynamics shows that no machine is perfect, is it possible that over-expression of some of these cytidine deaminases results in a breakdown of the proper stoichiometry associated with APOBEC3 complexes allowing excess enzyme to turn against cellular DNA? In short, can they help push cells down the road to cancer? This is a particularly exciting idea, given that the exploding field of cancer genomics is showing that not only are there far more mutations in a cancer cell than hitherto thought (>103), but also the most frequent mutation is precisely the C->T transition. The presentation will address all aspects of the above.

Resource-dependent effects during sex categorization

The limited capacity of face perception resources in the left cerebral hemisphere was examined using a sex categorization task. One study tested the hypothesis that sex categorization is impeded whenever feature extraction resources in the left hemisphere are simultaneously being utilized by another task. This hypothesis was tested by presenting prime faces for either 32ms or 320ms to either the left or right visual-field just before centrally presented target faces were categorized by sex. Results showed that sex categorization was slower after prime faces were presented for 32ms in the right visual-field compared to the left visual-field. This difference was not found after the 320ms prime length. The results are interpreted in the context of a neurocognitive model of social perception and suggest that efficient sex categorization depends, in part, on the availability of facial feature extraction resources in the left hemisphere.

Examining the hemispheric distribution of semantic information using lateralised priming of familiar faces

The way in which the semantic information associated with people is organised in the brain is still unclear. Most evidence suggests either bilateral or left hemisphere lateralisation. In this paper we use a lateralised semantic priming paradigm to further examine this neuropsychological organisation. A clear semantic priming effect was found with greater priming occurring when semantically related prime faces were presented to the left visual field than when presented to the right visual field. Possible explanations for this finding are discussed in terms of the bilateral distribution of different classes of semantic information, a possible role of associative processes within semantic priming and interhemispheric transfer.

Lateralised repetition priming for featurally and configurally manipulated familiar faces: Evidence for differentially lateralised processing mechanisms

Although early research suggested that the right hemisphere was dominant for processing faces, more recent studies have provided evidence for both hemispheres being involved, at least to some extent. In this experiment we examined hemispheric specialisations by using a lateralised repetition-priming paradigm with selectively degraded faces. Configurally degraded prime faces produced negative priming when presented to the left visual field (right hemisphere) and positive priming (facilitation) when presented to the right visual field (left hemisphere). Featurally degraded prime faces produced the opposite pattern of effects: positive priming when presented to the left visual field (right hemisphere) and negative priming when presented to the right visual field (left hemisphere). These results support the proposal that each hemisphere is differentially specialised for processing distinct forms of facial information: the right hemisphere for configural information and the left hemisphere for featural information.

N250r and N400 ERP correlates of immediate famous face repetition are independent of perceptual load

It is a matter of considerable debate whether attention to initial stimulus presentations is required for repetition-related neural modulations to occur. Recently, it has been assumed that faces are particularly hard to ignore, and can capture attention in a reflexive manner. In line with this idea, electrophysiological evidence for long-term repetition effects of unattended famous faces has been reported. The present study investigated influences of attention to prime faces on short-term repetition effects in event-related potentials (ERPs). We manipulated attention to short (200 ms) prime presentations (S1) of task-irrelevant famous faces according to Lavie's Perceptual Load Theory. Participants attended to letter strings superimposed on face images, and identified target letters “X” vs. “N” embedded in strings of either 6 different (high load) or 6 identical (low load) letters. Letter identification was followed by probe presentations (S2), which were either repetitions of S1 faces, new famous faces, or infrequent butterflies, to which participants responded. Our ERP data revealed repetition effects in terms of an N250r at occipito-temporal regions, suggesting priming of face identification processes, and in terms of an N400 at the vertex, suggesting semantic priming. Crucially, the magnitude of these effects was unaffected by perceptual load at S1 presentation. This indicates that task-irrelevant face processing is remarkably preserved even in a demanding letter detection task, supporting recent notions of face-specific attentional resources.

Neural and Behavioral Evidence for Affective Priming from Unconsciously Perceived Emotional Facial Expressions and the Influence of Trait Anxiety

Abstract Affective judgments can often be influenced by emotional information people unconsciously perceive, but the neural mechanisms responsible for these effects and how they are modulated by individual differences in sensitivity to threat are unclear. Here we studied subliminal affective priming by recording brain potentials to surprise faces preceded by 30-msec happy or fearful prime faces. Participants showed valence-consistent changes in affective ratings of surprise faces, although they reported no knowledge of prime-face expressions, nor could they discriminate between prime-face expressions in a forced-choice test. In conjunction with the priming effect on affective evaluation, larger occipital P1 potentials at 145-175 msec were found with fearful than with happy primes, and source analyses implicated the bilateral extrastriate cortex in this effect. Later brain potentials at 300-400 msec were enhanced with happy versus fearful primes, which may reflect differential attentional orienting. Personality testing for sensitivity to threat, especially social threat, was also used to evaluate individual differences potentially relevant to subliminal affective priming. Indeed, participants with high trait anxiety demonstrated stronger affective priming and greater P1 differences than did those with low trait anxiety, and these effects were driven by fearful primes. Results thus suggest that unconsciously perceived affective information influences social judgments by altering very early perceptual analyses, and that this influence is accentuated to the extent that people are oversensitive to threat. In this way, perception may be subject to a variety of influences that govern social preferences in the absence of concomitant awareness of such influences.

Neural and Behavioral Evidence for Affective Priming from Unconsciously Perceived Emotional Facial Expressions and the Influence of Trait Anxiety

Abstract Affective judgments can often be influenced by emotional information people unconsciously perceive, but the neural mechanisms responsible for these effects and how they are modulated by individual differences in sensitivity to threat are unclear. Here we studied subliminal affective priming by recording brain potentials to surprise faces preceded by 30-msec happy or fearful prime faces. Participants showed valence-consistent changes in affective ratings of surprise faces, although they reported no knowledge of prime-face expressions, nor could they discriminate between prime-face expressions in a forced-choice test. In conjunction with the priming effect on affective evaluation, larger occipital P1 potentials at 145-175 msec were found with fearful than with happy primes, and source analyses implicated the bilateral extrastriate cortex in this effect. Later brain potentials at 300-400 msec were enhanced with happy versus fearful primes, which may reflect differential attentional orienting. Personality testing for sensitivity to threat, especially social threat, was also used to evaluate individual differences potentially relevant to subliminal affective priming. Indeed, participants with high trait anxiety demonstrated stronger affective priming and greater P1 differences than did those with low trait anxiety, and these effects were driven by fearful primes. Results thus suggest that unconsciously perceived affective information influences social judgments by altering very early perceptual analyses, and that this influence is accentuated to the extent that people are oversensitive to threat. In this way, perception may be subject to a variety of influences that govern social preferences in the absence of concomitant awareness of such influences.

Facial attractiveness modulates early and late event-related brain potentials

Facial attractiveness is of high importance for human interaction and communication, and everyday experience suggests that the mere aspect of a face elicits spontaneous appraisal of attractiveness. However, little is known about the time course of brain responses related to this process. In the present study, event-related brain potentials were recorded during attractiveness classification of facial portraits that were standardized with respect to facial expression. The faces were either preceded by another face of high or low attractiveness or by an affectively neutral object. Attractive as opposed to non-attractive target faces elicited an early posterior negativity (EPN; ∼250 ms) and a late parietal positivity (LPC; 400–600 ms), which were not modulated by affectively congruent prime faces. Elevated LPC activity had previously been shown in response to attractive versus non-attractive faces, possibly reflecting task-related evaluative processes. An enhanced EPN had been reported for faces with emotional compared to neutral emotional expression, and related to facilitated selection of emotional information. Extending these findings, our study is the first to report an attractiveness-related ERP modulation prior to the LPC, suggesting that appraising facial attractiveness starts already at processing stages associated with stimulus selection.

Lateralized Repetition Priming for Familiar Faces: Evidence for Asymmetric Interhemispheric Cooperation

Repetition priming refers to facilitated recognition of stimuli that have been seen previously. Although a great deal of work has examined the properties of repetition priming for familiar faces, little has examined the neuroanatomical basis of the effect. Two experiments are presented in this paper that combine the repetition priming paradigm with a divided visual field methodology to examine lateralized recognition of familiar faces. In the first experiment participants were presented with prime faces unilaterally to each visual field and target faces foveally. A significant priming effect was found for prime faces presented to the right hemisphere, but not for prime faces presented to the left hemisphere. In Experiment 2, prime and target faces were presented unilaterally, either to the same visual field or to the opposite visual field (i.e., either within hemisphere or across hemispheres). A significant priming effect was found for the within right hemisphere condition, but not for the within left hemisphere condition, replicating the findings of the first experiment. Priming was also found in both of the across hemispheres conditions, suggesting that interhemispheric cooperation occurs to aid recognition. Taken in combination these experiments provide two main findings. First, an asymmetric repetition priming effect was found, possibly as a result of asymmetric levels of activation following recognition of a prime face, with greater priming occurring within the right hemisphere. Second, there is evidence for asymmetric interhemispheric cooperation with transfer of information from the right hemisphere to the left hemisphere to facilitate recognition.