ERP comparison study of face gender and expression processing in unattended condition

Facial feedback manipulation influences the automatic detection of unexpected emotional body expressions

Unexpected or changing facial expressions are known to be able to engage more automatic processing than frequently occurring facial expressions, thereby inducing a neural differential wave response known as expression mismatch negativity (EMMN). Recent studies have shown that EMMN can be modulated by the observer's facial feedback (i.e., feedback from their own facial movements). A similar EMMN activity has been discovered for body expressions, but thus far only a few emotion types have been investigated. It is unknown whether the EMMNs evoked by body expressions can be influenced by facial feedback. To explore this question, we recorded EEG activity of 29 participants in the reverse oddball paradigm. Here two unexamined categories of body expressions were presented, happy and sad, placed in two paired stimulus sequences: in one the happy body was presented with a probability of 80% (standards) while the sad body was presented with a probability of 20% (deviants), and in the other the probabilities were reversed. The facial feedback was manipulated by different pen holding conditions (i.e., participants holding the pen with the teeth, lips, or nondominant hand). The nonparametric cluster permutation test revealed significant happy and sad body-related EMMN (bEMMN) activities. The happy-bEMMN were more negative than sad-bEMMN within the range of 100-150 ms. Additionally, the bEMMN amplitude of both emotions is modulated by the facial feedback conditions. These results expand the range of emotional types applicable to bEMMN and provide evidence for the validity of the facial feedback hypothesis across emotional carriers.

Belief in biological origin of race (racial essentialism) increases sensitivities to cultural category changes measured by ERP mismatch negativity (MMN)

The dynamic multicultural view explains culture-specific effects on cognition that cultural knowledge is organized in multiple knowledge systems which are specific to each culture and differentially activated when exposed to related objects or scenes. This view predicts automatic categorizations of environmental information according to the culture-specific knowledge systems. This study investigated whether cultural information could be spontaneously categorized, and the modulation of this process by the belief in the biological origin of race (i.e., racial essentialism) with an event-related brain potential, the visual Mismatch Negativity (vMMN). Deviant pictures of Eastern (Western) culture were randomly presented in a stream of standard Western (Eastern) pictures while participants were playing a video game. Participants who endorse racial essentialism (high group) showed vMMNs to the deviants with high relevance to the Eastern or Western culture and the deviant with low Eastern relevance; while participants with low racial essentialism showed vMMN to the deviant with high Eastern relevance only. These results revealed spontaneous cultural categorization with vMMN and the top-down modulation of spontaneous categorization by personal belief. In addition, this is the first demonstration of MMNs to cultural deviance and the potentials in applying MMNs to study psychological essentialism and social categorization.

The automatic detection of unexpected emotion and neutral body postures: A visual mismatch negativity study

The ability to automatically detect emotional changes in the environment is crucial for social interaction. In the visual system, expression-related mismatch negativity (EMMN) reflects the automatic processing of emotional changes in facial expression. However, body postures also carry visual emotional information that can be recognized effectively and processed automatically, although their processing mechanism remains unknown. In this study, the reverse oddball paradigm was used to investigate the mismatch responses of unexpected fear and neutral body postures. The nonparametric cluster permutation test revealed significant fear and neutral visual mismatch negativity (vMMN) activities, and the fear-related vMMN was enhanced prior (130-230 ms) to the neutral vMMN (180-230 ms). The body-sensitive N190 component may partially account for the vMMN obtained in this study. The fearful body posture evoked a greater N190 response over the neutral body, and amplitudes of N190 were more negative in the deviant condition than the standard condition. Additionally, the body-related visual mismatch oscillatory responses were associated with enhancement of the alpha band oscillation, especially for the fearful body posture. These results expanded the applicable scope of body posture cues corresponding to mismatch signals, objectively defined the electrophysiological activities evoked, and revealed the processing bias toward negative emotion.

Early detection of language categories in face perception

Does language categorization influence face identification? The present study addressed this question by means of two experiments. First, to establish language categorization of faces, the memory confusion paradigm was used to create two language categories of faces, Spanish and English. Subsequently, participants underwent an oddball paradigm, in which faces that had been previously paired with one of the two languages (Spanish or English), were presented. We measured EEG perceptual differences (vMMN) between standard and two types of deviant faces: within-language category (faces sharing language with standards) or between-language category (faces paired with the other language). Participants were more likely to confuse faces within the language category than between categories, an index that faces were categorized by language. At the neural level, early vMMN were obtained for between-language category faces, but not for within-language category faces. At a later stage, however, larger vMMNs were obtained for those faces from the same language category. Our results showed that language is a relevant social cue that individuals used to categorize others and this categorization subsequently affects face perception.

Prediction errors in surface segmentation are reflected in the visual mismatch negativity, independently of task and surface features

The visual system quickly registers perceptual regularities in the environment and responds to violations in these patterns. Errors of perceptual prediction are associated with electrocortical modulation, including the visual mismatch negativity (vMMN) and P2 event-related potential. One relatively unexplored question is whether these prediction error signals can encode higher-level properties such as surface segmentation, or whether they are limited to lower-level perceptual features. Using a roving standard paradigm, a triangle surface appeared either behind (featuring amodal contours) or in front of (featuring real contours) a second surface with hole-like windows. A surface layout appeared for two to five repetitions before switching to the other "deviant" layout; lighting and orientation of stimuli varied across presentations while remaining isoluminant. Observers responded when they detected a rare "pinched" triangle, which occasionally appeared. Cortical activity-reflected in mismatch responses affecting the P2-N2 and P300 amplitudes-was sensitive to a change in stimulus layout, when surfaces shifted position in depth, following several repetitions. Specifically, layout deviants led to a more negative P2-N2 complex at posterior electrodes, and greater P300 positivity at central sites. Independently of these signals of a deviant surface layout, further modulations of the P2 encoded differences between layouts and detection of the rare target stimulus. Comparison of the effect of preceding layout repetitions on this prediction error signal suggests that it is all or none and not graded with respect to the number of previous repetitions. We show that within the visual domain, unnoticed and task-irrelevant changes in visual surface segmentation leads to observable electrophysiological signals of prediction error that are dissociable from stimulus-specific encoding and lower-level perceptual processing.

Preattentive and Predictive Processing of Visual Motion

Interaction with the environment requires fast and reliable sensory processing. The visual system is confronted with a continuous flow of high-dimensional input (e.g. orientation, color, motion). From a theoretical point of view, it would be advantageous if critical information was processed independent of attentional load, i.e. preattentively. Here, we hypothesized that visual motion is such a critical signal and aimed for a neural signature of its preattentive encoding. Furthermore, we were interested in the neural correlates of predictability of linear motion trajectories based on the presence or absence of preceding motion. We presented a visual oddball paradigm and studied event-related potentials (ERPs). Stimuli were linearly moving Gabor patches that disappeared behind an occluder. The difference between deviant and standard trials was a trajectory change which happened behind the occluder in deviant trials only, inducing a prediction error. As hypothesized, we found a visual mismatch negativity-component over parietal and occipital electrodes. In a further condition, trials without preceding motion were presented in which the patch just appeared from behind the occluder and, hence, was not predictable. We found larger ERP-components for unpredictable stimuli. In summary, our results provide evidence for a preattentive and predictive processing of linear trajectories of visual motion.

Symmetrical and Asymmetrical Interactions between Facial Expressions and Gender Information in Face Perception

To investigate the interaction between facial expressions and facial gender information during face perception, the present study matched the intensities of the two types of information in face images and then adopted the orthogonal condition of the Garner Paradigm to present the images to participants who were required to judge the gender and expression of the faces; the gender and expression presentations were varied orthogonally. Gender and expression processing displayed a mutual interaction. On the one hand, the judgment of angry expressions occurred faster when presented with male facial images; on the other hand, the classification of the female gender occurred faster when presented with a happy facial expression than when presented with an angry facial expression. According to the evoked-related potential results, the expression classification was influenced by gender during the face structural processing stage (as indexed by N170), which indicates the promotion or interference of facial gender with the coding of facial expression features. However, gender processing was affected by facial expressions in more stages, including the early (P1) and late (LPC) stages of perceptual processing, reflecting that emotional expression influences gender processing mainly by directing attention.

Facial Expression Related vMMN: Disentangling Emotional from Neutral Change Detection

Detection of changes in facial emotional expressions is crucial to communicate and to rapidly and automatically process possible threats in the environment. Recent studies suggest that expression-related visual mismatch negativity (vMMN) reflects automatic processing of emotional changes. In the present study we used a controlled paradigm to investigate the specificity of emotional change-detection. In order to disentangle specific responses to emotional deviants from that of neutral deviants, we presented neutral expression as standard stimulus (p = 0.80) and both angry and neutral expressions as deviants (p = 0.10, each). In addition to an oddball sequence, an equiprobable sequence was presented, to control for refractoriness and low-level differences. Our results showed that in an early time window (100–200 ms), the controlled vMMN was greater than the oddball vMMN only for the angry deviant, suggesting the importance of controlling for refractoriness and stimulus physical features in emotion related studies. Within the controlled vMMN, angry and neutral deviants both elicited early and late peaks occurring at 140 and 310 ms, respectively, but only the emotional vMMN presented sustained amplitude after each peak. By directly comparing responses to emotional and neutral deviants, our study provides evidence of specific activity reflecting the automatic detection of emotional change. This differs from broader “visual” change processing, and suggests the involvement of two partially-distinct pre-attentional systems in the detection of changes in facial expressions.

Comparison of affective and semantic priming in different SOA

Researchers have been at odds on whether affective or semantic priming is faster or stronger. The present study selects a series of facial expression photos and words, which have definite emotional meaning or gender meaning, to set up experiment including both affective and semantic priming. The intensity of emotion and gender information in the prime as well as the strength of emotional or semantic (in gender) relationship between the prime and the target is matched. Three groups of participants are employed separately in our experiment varied with stimulus onset asynchrony (SOA) as 50, 250 or 500 ms. The results show that the difference between two types of priming effect is revealed when the SOA is at 50 ms, in which the affective priming effect is presented when the prime has negative emotion. It indicates that SOA can affect the comparison between the affective and semantic priming, and the former takes the priority in the automatic processing level.