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Consciousness and Emotional Facial Expression Recognition: Subliminal/Supraliminal Stimulation Effect on N200 and P300 ERPs

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In this study we analyze whether facial expression recognition is marked by specific event-related potential (ERP) correlates and whether conscious and unconscious elaboration of emotional facial stimuli are qualitatively different processes. ERPs elicited by supraliminal and subliminal (10ms) stimuli were recorded when subjects were viewing emotional facial expressions of four emotions or neutral stimuli. Two ERP effects (N2 and P3) were analyzed in terms of their peak amplitude and latency variations. An emotional specificity was observed for the negative deflection N2, whereas P3 was not affected by the content of the stimulus (emotional or neutral). Unaware information processing proved to be quite similar to aware processing in terms of peak morphology but not of latency. A major result of this research was that unconscious stimulation produced a more delayed peak variation than conscious stimulation did. Also, a more posterior distribution of the ERP was found for N2 as a function of emotional content of the stimulus. On the contrary, cortical lateralization (right/left) was not correlated to conscious/unconscious stimulation. The functional significance of our results is underlined in terms of subliminal effect and emotion recognition. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
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... Subliminal perception operates below the subjective threshold and is less susceptible to individual experiences and attitudes, thus minimizing the potential for social desirability bias [12]. Subliminal perception holds particular significance for individual survival, as it can trigger rapid primitive biological responses such as escape or defense [13,14]. Moreover, in line with the findings of previous subliminal priming studies, the congruency effect suggests that participants are expected to exhibit faster and more accurate responses to target stimuli that are congruent with the subliminal prime, compared to those that are incongruent [15]. ...
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Background What is our immediate reaction when we witness someone experiencing pain? The empathy-altruism hypothesis predicts that observers would display empathy and a tendency to approach the person in pain. Alternatively, the threat value of pain hypothesis (TVPH) argues that others' pain serves as a signal of threat and should induce observers’ avoidance response. Methods To examine these two hypotheses, three experiments were conducted. The experiments aimed to investigate the impact of subliminal exposure to others' physical pain on participants' emotional and behavioural responses. Results The results revealed that subliminal pain priming resulted in faster response and attentional bias to fearful faces compared to sad faces (Experiment 1), faster reaction times in recognizing fear-related words compared to anger-related words during a lexical decision task (Experiment 2), and faster avoidance responses towards anger-related words, as opposed to approaching responses towards positive words (Experiment 3). Conclusions The consistent findings across all experiments revealed that subliminal perception of pain scenes elicited fear emotion and immediate avoidance responses. Therefore, the outcomes of our study provide supportive evidence for the TVPH.
... It was founded on empirical outcomes that suggested that different participants required different durations of presentation for attaining unaware presentations during masking ( Pessoa et al., 2002 ;Pessoa, 2005 ;Japee et al., 2009 ;Albrecht et al., 2010 ;Albrecht and Mattler, 2012 ). It was also founded on empirical outcomes that different elicitor types required different durations of presentation for attaining unaware presentations during masking ( Pessoa et al., 2002 ;Pessoa and Ungerleider, 2004 ;Balconi and Lucchiari, 2007 ;Hedger et al., 2015 ;Elgendi et al., 2018 ). ...
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... This is particularly insidious in designs that compare one or more neutral-masked emotional stimuli to neutral-masked neutral faces on the simple grounds of assessing the psychophysiology or participant ratings between perceptible emotional stimuli and marginally imperceptible neutral stimuli. It can result in exaggerated effect sizes between conscious emotional faces compared to marginally unconscious neutral ones (Balconi & Lucchiari, 2007). Several other factors such as age, gender, cultural origin and cultural dialects, racial incongruency and stable emotional predispositions in neutral face-masks can further bias our results when using neutral faces as masks to other masked faces (Kim et al., 2010; see also Adams Garrido, Albohn, Hess & Kleck, 2016). ...
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... As for facial recognition, it has been shown that happy expressions provoked a larger amplitude of P2 in comparison to angry and neutral ones [30]. P300 also has been related to facial emotion recognition [31] and has even been shown as a marker of impairment in schizophrenic patients [32]. ...
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... Frequency analysis can explore responsiveness to emotional stimuli by analyzing synchronous oscillations and uncover small differences in emotion processing (Aftanas et al., 1996). It has been widely used to investigate brain responses to emotional stimuli (Balconi & Lucchiari, 2007). In particular, the alpha (8-12 Hz) and low-beta (12-15 Hz) rhythms are broadly linked to emotional processing (Schubring & Schupp, 2019;Tsang et al., 2001). ...
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... This sequence allowed participants to consciously learn the rule of the experiment in the first half of the study. Researchers studying face perception at different levels of awareness often opt for a randomization of trial presentation across all the conditions, to avoid biasing the outcome that is measured (e.g., Balconi & Lucchiari, 2007;Ihrke & Behrendt, 2011;Liddell et al., 2004;Pegna et al., 2011). Ensuring that the effects are not due to the block structure of the experiment therefore seems necessary. ...
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Thesis
This thesis examined the effects of higher cognitive mechanisms on the automatic and elaborate elicitation of motivational behaviours by visual material presented in absence (i.e. subliminal stimuli) and presence of visual awareness (i.e. optimal stimuli), respectively. With the aim of teasing apart automatic and elaborate approach and withdrawal behaviours, the first study measured self-pain tolerance, intensity and unpleasantness during the Cold Pressor Test (within-subjects) in healthy participants (N=155) before and after passive viewing of negative or vicarious pain images at subliminal or optimal exposure (between-subjects). As a further step, the second study examined the neural and behavioural effects of right dorsolateral prefrontal cortex (rDLPFC) inhibition on automatic and elaborate negative processing pathways. For this purpose, encephalographic (EEG) neural responses (within-subjects) were recorded while healthy participants (N=38) passively viewed negative and neutral images presented at subliminal and optimal exposure (within-subjects) before and after right dorsolateral prefrontal cortex (rDLPFC) inhibition or sham via repetitive transcranial magnetic stimulation (rTMS) (between-subjects). EEG event-related potentials were analysed for early (80-120ms), mid (120-300ms) and late time-windows (300-600ms). Participants completed behavioural attention and affective tasks after the trial presentation (N=48). Findings showed that both subliminal and optimal negative images as well as optimal vicarious pain elicited increased self-pain sensitivity, reflecting automatic and elaborate withdrawal behaviours, respectively. Conversely, subliminal vicarious pain decreased self-pain sensitivity, reflecting automatic approach responses (Study 1). Furthermore, two networks of automatic negative processing emerged: temporal pathways showing increased early and mid-latency activity specific to subliminal negative images, which remained unaffected by rDLPFC inhibition; and occipito-parietal pathways, showing increased mid- and late latency activity for negative images after rDLPFC inhibition, independent from visual awareness. Moreover, rDLPFC inhibition increased late frontal activity for optimal negative images at elaborate processing stages. This was associated with decreased withdrawal behaviours; specifically, attenuated negative priming and faster attention disengagement (Study 2). These results indicate that in absence of visual awareness, automatic motivational behaviours may be modulated according to whether visual material reflects self-oriented (i.e. negative) or other-oriented threat (i.e. vicarious pain), thereby requiring withdrawal or approach and empathic understanding that enhance individual or group survival, respectively. Automatic negative processing may follow multiple neural pathways, which underpin automatic attention orienting (temporal network) and stimulus encoding (occipito-temporal network). The occipito-temporal network, in particular, may integrate bottom-up and top-down input, thereby permitting disinhibited higher cognitive processes involved in top-down regulation to exert early influence on automatic activation of approach and withdrawal behaviours. In presence of visual awareness, disinhibition of the frontal control network reduced withdrawal responses, confirming its role in the regulation of elaborate motivational behaviours. It seems likely that vicarious pain processing occurs along similar pathways, albeit with different behavioural consequences; however, such speculation requires future investigation. The distinct networks facilitating healthy automatic and elaborate stimulus processing represent a platform for further exploration, including the detection of aberrant neural activity in clinical disorders characterized by dysfunctional approach-withdrawal behaviours. Given the modulatory effects of top-down regulation on both automatic and elaborate processing, it is tentatively suggested that cognitive management strategies that enhance affective and attentional control may decrease excessive withdrawal responses. Future research may use integrative behavioural-neuroimaging methods to determine relevant boundary conditions of automatic and elaborate processing in healthy and clinical populations.
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We addressed the questions whether stimuli presented below the threshold of verbal awareness are nevertheless perceived and whether there are perceptual differences between the two cerebral hemispheres. Pictures of line drawn objects and animals were subliminally presented to each visual half-field for subsequent identification in a form as fragmented as possible. The performance of 40 healthy subjects was compared to that of 63 controls. Whereas identification performance after blank presentation in the experimental group did not differ from that of controls, identification in a significantly more fragmented form was achieved after the presentation of the complete picture. This effect, however, occurred only after subliminal stimulation in the left visual field, i.e., of the right hemisphere. Our results show that (i) pictures presented below the threshold of verbal awareness can be perceived, and (ii) that only the right hemisphere can perceive them and make use of the perception. It remains an open question whether this kind of hemispheric specialization represents a right hemisphere dominance for subliminal perception or reflects an inability of the left hemisphere to access and behaviorally use unaware percepts via fragmented picture identification, for which a right hemisphere advantage is known.
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Event-related potentials were recorded from 20 healthy male Ss in response to a large number of color slides of unfamiliar faces with happy, sad, or no emotional expression. In an initial task, Ss rated the emotional valence of the faces with a joystick. In comparison with neutral faces, both happy and sad faces evoked a larger lateral occipito-temporal negativity from 200 to 400 ms poststimulus onset. Modulation of late positive complex (LPC: 450–600 ms) by emotional expressions was observed at the frontal sites only in this task, when attention to the emotional valence was required. In a second task, Ss detected repeating faces among nonrepeating, novel faces. Emotionally expressive faces evoked more negative potential than neutral faces occipito-temporally between 270 and 540 ms latency. Although repetition had a large effect in decreasing the N4 and increasing the LPC, it did not interact with emotional expression, supporting previously proposed independence between processing of a face identity and emotional expression. These findings imply that emotional expression affects early perceptual stages as well as later cognitive stages of face processing. Nonrepeated male faces in both tasks evoked a larger late negativity than female faces. (PsycINFO Database Record (c) 2012 APA, all rights reserved)