Visual Event-related Potentials Research Articles

Neural correlates of trait anxiety in sensory processing and distractor filtering.

Evidence suggests that trait anxiety relates to cognitive processing and behavior. However, the relationships between trait anxiety and sensory processing, goal-directed performance and sensorimotor function are unclear, particularly in a multimodal context. This study used electroencephalography to evaluate whether trait anxiety influenced visual and tactile event-related potentials (ERPs), as well as behavioral distractor cost, in a bimodal sensorimotor task. Twenty-nine healthy young adults completed the State-Trait Anxiety Inventory. Participants were directed to focus on either tactile or visual stimuli while disregarding the other modality, responding to target stimulus amplitude with a proportional grip. Previous research suggests that somatosensory N70 and visual P2 ERPs serve as markers of attentional relevance, with attention also impacting the visual P3 ERP. It was hypothesized that trait anxiety would modulate the ERPs susceptible to attentional modulation (tactile N70, visual P2 and P3) and not affect behavioral performance. Trait anxiety showed a large, significant interaction with attention for visual P3 latency in response to unimodal visual stimuli, with a positive relationship between P3 latencies and trait anxiety when attending toward the stimulus and negative when attending away. A large, positive main effect of trait anxiety on visual N1 amplitude for bimodal stimuli was also detected. As predicted, trait anxiety related to ERPs but not behavioral distractor cost. These findings suggest that trait anxiety modulates visual but not somatosensory processing correlates based on attention. The absence of overt behavioral performance effects suggests compensatory mechanisms may offset underlying differences in sensory processing.

Distraction impact of concurrent conversation on event-related potential based brain-computer interfaces

Objective.This study investigates the impact of conversation on the performance of visual event-related potential (ERP)-based brain-computer interfaces (BCIs), considering distractions in real life environment. The research aims to understand how cognitive distractions from speaking and listening activities affect ERP-BCI performance.Approach.The experiment employs a dual-task paradigm where participants control a smart light using visual ERP-BCIs while simultaneously conducting speaking or listening tasks.Main results.The findings reveal that speaking notably degrades BCI accuracy and the amplitude of ERP components, while increases the latency variability of ERP components and occipital alpha power. In contrast, listening and simple syllable repetition tasks have a lesser impact on these variables. The results suggest that speaking activity significantly distracts visual attentional processes critical for BCI operationSignificance. This study highlights the need to take distractions by daily conversation into account of the design and implementation of ERP-BCIs.

Effects of daily listening to 6 Hz binaural beats over one month: an event-related potentials study

The aim of the present study was to identify cognitive alterations, as indicated by event-related potentials (ERPs), after one month of daily exposure to theta binaural beats (BBs) for 10 minutes. The recruited healthy subjects (n = 60) were equally divided into experimental and control groups. For a month, the experimental group was required to practice BBs listening daily, while the control group did not. ERPs were assessed at three separate visits over a span of one month, with a two-week interval between each visit. At each visit, ERPs were measured before and after listening. The auditory and visual ERPs significantly increased the auditory and visual P300 amplitudes consistently at each visit. BBs enhanced the auditory N200 amplitude consistently across all visits, but the visual N200 amplitude increased only at the second and third visits. Compared to the healthy controls, daily exposure to BBs for two weeks resulted in increased auditory P300 amplitude. Additionally, four weeks of BBs exposure not only increased auditory P300 amplitude but also reduced P300 latency. These preliminary findings suggest that listening to BBs at 6 Hz for 10 minutes daily may enhance certain aspects of cognitive function. However, further research is needed to confirm these effects and to understand the underlying mechanisms. Identifying the optimal duration and practice of listening to 6 Hz BBs could potentially contribute to cognitive enhancement strategies in healthy individuals.

Correcting for ERP latency jitter improves gaze-independent BCI decoding

Objective. Patients suffering from heavy paralysis or Locked-in-Syndrome can regain communication using a Brain–Computer Interface (BCI). Visual event-related potential (ERP) based BCI paradigms exploit visuospatial attention (VSA) to targets laid out on a screen. However, performance drops if the user does not direct their eye gaze at the intended target, harming the utility of this class of BCIs for patients suffering from eye motor deficits. We aim to create an ERP decoder that is less dependent on eye gaze. Approach. ERP component latency jitter plays a role in covert visuospatial attention (VSA) decoding. We introduce a novel decoder which compensates for these latency effects, termed Woody Classifier-based Latency Estimation (WCBLE). We carried out a BCI experiment recording ERP data in overt and covert visuospatial attention (VSA), and introduce a novel special case of covert VSA termed split VSA, simulating the experience of patients with severely impaired eye motor control. We evaluate WCBLE on this dataset and the BNCI2014-009 dataset, within and across VSA conditions to study the dependency on eye gaze and the variation thereof during the experiment. Main results. WCBLE outperforms state-of-the-art methods in the VSA conditions of interest in gaze-independent decoding, without reducing overt VSA performance. Results from across-condition evaluation show that WCBLE is more robust to varying VSA conditions throughout a BCI operation session. Significance. Together, these results point towards a pathway to achieving gaze independence through suited ERP decoding. Our proposed gaze-independent solution enhances decoding performance in those cases where performing overt VSA is not possible.

Motor dominance and movement-outcome congruency influence the electrophysiological correlates of sensory attenuation for self-induced visual stimuli

This study explores the impact of movement-outcome congruency and motor dominance on the action-associated modulations of early visual event-related potentials (ERPs). Employing the contingent paradigm, participants with varying degrees of motor dominance were exposed to stimuli depicting left or right human hands in the corresponding visual hemifields. Stimuli were either passively observed or evoked by voluntary button-presses with the dominant or non-dominant hand, in a manner that was either congruent or incongruent with stimulus laterality and hemifield. Early occipital responses (C1 and P1 components) revealed modulations consistent with sensory attenuation (SA) for self-evoked stimuli. Our findings suggest that sensory attenuation during the initial stages of visual processing (C1 component) is a general phenomenon across all degrees of handedness and stimulus/movement combinations. However, the magnitude of C1 suppression was modulated by handedness and movement-stimulus congruency, reflecting stronger SA in right-handed participants for stimuli depicting the right hand, when elicited by actions of the corresponding hand, and measured above the contralateral occipital lobe. P1 modulation suggested concurrent but opposing influences of attention and sensory prediction, with more pronounced suppression following stimulus-congruent button-presses over the hemisphere contralateral to movement, especially in left-handed individuals. We suggest that effects of motor dominance on the degree of SA may stem from functional/anatomical asymmetries in the processing of body parts (C1) and attention networks (P1). Overall, our results demonstrate the modulating effect of hand dominance and movement-outcome congruency on SA, underscoring the need for deeper exploration of their interplay. Additional empirical evidence in this direction could substantiate a premotor account for action-associated modulation of early sensory processing in the visual domain.

Is Visual Prediction Impaired in Adolescents with Autism spectrum Disorder? Event-Related Potentials in a Cued Visual GO/NOGO Task.

Aim: Deviant visual processing has been observed in autism spectrum disorder (ASD), manifesting as decreased P1 and P2 components of visual event-related potentials (ERPs). Alterations have been attributed to a failure of Bayesian inference, characterized by hypo-activation of top-down predictive abilities. To test this hypothesis, we measured the visual negativity (vN) as an ERP index of visual preparation hypothesized to mirror predictive brain activity. Method: ERPs in a cued visual GO/NOGO task in 63 adolescents with ASD (IQ > 70, attention-deficit hyperactivity disorder excluded) were compared with ERPs in a sex- and age-matched group of 60 typically developing (TD) controls. Results: The behavioral variables (omissions, commissions, reaction time, and reaction time variability), as well as ERP components reflecting, among other processes, cognitive control (contingent negative variation, P3 GO, P3 NOGO, N2 NOGO) did not differ between the groups. There were group differences in visually based ERPs. Besides P1 and P2 differences, the vN component differentiated the 2 groups with the highest effect size (d = 0.74).Conclusion: This ERP study lends support to the hypothesis suggesting that a Bayesian hypo-prediction could underlie unique perceptual experiences in individuals with ASD. This could lead to a predisposition to perceive the world with reduced influence and modulation from contextual cues, prior experiences, and pre-existing expectations.

Sound suppresses earliest visual cortical processing after sight recovery in congenitally blind humans

Neuroscientific research has consistently shown more extensive non-visual activity in the visual cortex of congenitally blind humans compared to sighted controls; a phenomenon known as crossmodal plasticity. Whether or not crossmodal activation of the visual cortex retracts if sight can be restored is still unknown. The present study, involving a rare group of sight-recovery individuals who were born pattern vision blind, employed visual event-related potentials to investigate persisting crossmodal modulation of the initial visual cortical processing stages. Here we report that the earliest, stimulus-driven retinotopic visual cortical activity (<100 ms) was suppressed in a spatially specific manner in sight-recovery individuals when concomitant sounds accompanied visual stimulation. In contrast, sounds did not modulate the earliest visual cortical response in two groups of typically sighted controls, nor in a third control group of sight-recovery individuals who had suffered a transient phase of later (rather than congenital) visual impairment. These results provide strong evidence for persisting crossmodal activity in the visual cortex after sight recovery following a period of congenital visual deprivation. Based on the time course of this modulation, we speculate on a role of exuberant crossmodal thalamic input which may arise during a sensitive phase of brain development.

RTMS reduces delta and increases theta oscillations in Alzheimer's disease: A visual-evoked and event-related potentials study.

Repetitive transcranial magnetic stimulation (rTMS) has emerged as a promising alternative therapy for Alzheimer's disease (AD) due to its ability to modulate neural networks and enhance cognitive function. This treatment offers the unique advantage of enabling real-time monitoring of immediate cognitive effects and dynamic brain changes through electroencephalography (EEG). This study focused on exploring the effects of left parietal rTMS stimulation on visual-evoked potentials (VEP) and visual event-related potentials (VERP) in AD patients. Sixteen AD patients were recruited for this longitudinal study. EEG data were collected within a Faraday cage both pre- and post-rTMS to evaluate its impact on potentials. Significant alterations were found in both VEP and VERP oscillations. Specifically, delta power in VEP decreased, while theta power in VERP increased post-rTMS, indicating a modulation of brain activities. These findings confirm the positive modulatory impact of rTMS on brain activities in AD, evidenced by improved cognitive scores. They align with previous studies highlighting the potential of rTMS in managing hyperexcitability and oscillatory disturbances in the AD cortex. Cognitive improvements post-rTMS endorse its potential as a promising neuromodulatory treatment for cognitive enhancement in AD, thereby providing critical insights into the neurophysiological anomalies in AD and possible therapeutic avenues.

Visual Event-Related Potentials under External Emotional Stimuli as Early Signs for Mild Cognitive Impairment.

Alzheimer's disease (AD) is a neurodegenerative disorder featured by progressive cognitive decline, which manifests in severe impairment of memory, attention, emotional processing and daily activities, leading to significant disability and social burden. Investigation on Mild Cognitive Impairment (MCI), the prodromal and transitional stage between normal aging and AD, serves as a key in diagnosing and slowing down the progression of AD. Numerous effects have been made up to date, however, the attentional mechanisms under different external emotion stimuli in MCI and AD are still unexplored in deep. To further explore the attentional mechanisms under different external emotion stimuli in both MCI and AD patients. In 51 healthy volunteers (Controls, 24 males and 27 females), 52 MCI (19 males and 33 females), and 47 AD (15 males and 32 females) patients, we administered the visual oddball event-related potentials (ERPs) under three types of external emotional stimuli: Neutral, Happiness and Sadness, in which the components N1, P2, N2 and P3 as well as the abnormal cortical activations corresponding to the significant ERP differences in the three groups were observed. Under all three external emotions, in AD patients, N2 and P3 latencies were significantly prolonged compared to both Controls and MCI. In addition, under Happiness, in MCI, P3 latencies were significantly delayed compared to Controls. Meanwhile, under both Happiness and Sadness, in AD patients, P3 amplitudes were significantly decreased compared to Controls and MCI, respectively. During N2 time window, under Neutral emotion, significant hypoactivation in the right superior temporal gyrus was found in AD patients compared to Controls, and under Happiness, the activation of the right inferior frontal gyrus was significantly attenuated in MCI compared to Controls. Under Sadness, in AD patients, the activation of the right superior frontal gyrus was significantly decreased compared to MCI. During P3 time window, under both Happiness and Sadness, when AD patients compared to MCI, the significantly attenuated activations were located in the right fusiform gyrus and the right middle occipital gyrus, respectively. Our results demonstrated visual attentional deficits under external emotional stimuli in both MCI and AD patients, highlighting the function of Happiness for early detecting MCI, in which the P3 latency and the hypoactivation of right inferior frontal gyrus during N2 time window can be early signs. The current study sheds further light of attentional mechanisms in MCI and AD patients, and indicates the value of emotional processing in the early detection of cognitive dysfunction.

Attention modulates early visual processing: An association between subjective contrast perception and early C1 ERP component.

The question of whether spatial attention can modulate initial afferent activity in area V1, as measured by the earliest visual event-related potential (ERP) component "C1", is still the subject of debate. Because attention always enhances behavioral performance, previous research has focused on finding evidence of attention-related enhancements in visual neural responses. However, recent psychophysical studies revealed a complex picture of attention's influence on visual perception: attention amplifies the perceived contrast of low-contrast stimuli while dampening the perceived contrast of high-contrast stimuli. This evidence suggests that attention may not invariably augment visual neural responses but could instead exert inhibitory effects under certain circumstances. Whether this bi-directional modulation of attention also manifests in C1 and whether the modulation of C1 underpins the attentional influence on contrast perception remain unknown. To address these questions, we conducted two experiments (N = 67 in total) by employing a combination of behavioral and ERP methodologies. Our results did not unveil a uniform attentional enhancement or attenuation effect of C1 across all subjects. However, an intriguing correlation between the attentional effects of C1 and contrast appearance for high-contrast stimuli did emerge, revealing an association between attentional modulation of C1 and the attentional modulation of contrast appearance. This finding offers new insights into the relationship between attention, perceptual experience, and early visual neural processing, suggesting that the attentional effect on subjective visual perception could be mediated by the attentional modulation of the earliest visual cortical response.

Total Sleep Deprivation Triggers a Compensatory Mechanism During Conflict Monitoring Process: Evidence From Event-Related Potentials.

Sleep deprivation impairs cognitive function and is accompanied by a simultaneous compensatory effect, one of the brain's capacities to maintain function in emergency situations. However, the time course of the compensatory effect is unclear. In this study, 22 male participants completed a pronunciation working memory task that included congruent and incongruent stimuli trials with EEG recordings before and after total sleep deprivation (TSD). Behavioral performance analysis showed that after TSD, the participants' reaction time (RT) was shortened, but accuracy was reduced significantly. Analysis of event-related potential (ERP) results showed that the amplitude of N2 (an early visual ERP) was larger (i.e., more negative) after TSD than at baseline. A significant interaction between congruency and sleep condition was seen. Compared to that before TSD, the increase in amplitude of P3 (a stimulus-induced positive deflection component) under an incongruent stimulus was larger than that under a congruent stimulus after TSD. Moreover, a significant negative correlation was found between P3 amplitude and RT. Our results suggest that TSD impairs cognitive function. Meanwhile, the brain activates a compensatory mechanism after TSD, which is comprehensive during the conflict-detection and information-updating stages. This study provides a fresh viewpoint for understanding how TSD affects cognitive function.

Exploiting Information in Event-Related Brain Potentials from Average Temporal Waveform, Time-Frequency Representation, and Phase Dynamics.

Characterizing the brain's dynamic pattern of response to an input in electroencephalography (EEG) is not a trivial task due to the entanglement of the complex spontaneous brain activity. In this context, the brain's response can be defined as (1) the additional neural activity components generated after the input or (2) the changes in the ongoing spontaneous activities induced by the input. Moreover, the response can be manifested in multiple features. Three commonly studied examples of features are (1) transient temporal waveform, (2) time-frequency representation, and (3) phase dynamics. The most extensively used method of average event-related potentials (ERPs) captures the first one, while the latter two and other more complex features are attracting increasing attention. However, there has not been much work providing a systematic illustration and guidance for how to effectively exploit multifaceted features in neural cognitive research. Based on a visual oddball ERPs dataset with 200 participants, this work demonstrates how the information from the above-mentioned features are complementary to each other and how they can be integrated based on stereotypical neural-network-based machine learning approaches to better exploit neural dynamic information in basic and applied cognitive research.

Stimulus expectations do not modulate visual event-related potentials in probabilistic cueing designs

Humans and other animals can learn and exploit repeating patterns that occur within their environments. These learned patterns can be used to form expectations about future sensory events. Several influential predictive coding models have been proposed to explain how learned expectations influence the activity of stimulus-selective neurons in the visual system. These models specify reductions in neural response measures when expectations are fulfilled (termed expectation suppression) and increases following surprising sensory events. However, there is currently scant evidence for expectation suppression in the visual system when confounding factors are taken into account. Effects of surprise have been observed in blood oxygen level dependent (BOLD) signals, but not when using electrophysiological measures. To provide a strong test for expectation suppression and surprise effects we performed a predictive cueing experiment while recording electroencephalographic (EEG) data. Participants (n=48) learned cue-face associations during a training session and were then exposed to these cue-face pairs in a subsequent experiment. Using univariate analyses of face-evoked event-related potentials (ERPs) we did not observe any differences across expected (90% probability), neutral (50%) and surprising (10%) face conditions. Across these comparisons, Bayes factors consistently favoured the null hypothesis throughout the time-course of the stimulus-evoked response. When using multivariate pattern analysis we did not observe above-chance classification of expected and surprising face-evoked ERPs. By contrast, we found robust within- and across-trial stimulus repetition effects. Our findings do not support predictive coding-based accounts that specify reduced prediction error signalling when perceptual expectations are fulfilled. They instead highlight the utility of other types of predictive processing models that describe expectation-related phenomena in the visual system without recourse to prediction error signalling.

Analysis and Classification of Event-Related Potentials During Image Observation.

In the field of cognitive neuroscience, researchers have conducted extensive studies on object categorization using Event-Related Potential (ERP) analysis, specifically by analyzing electroencephalographic (EEG) response signals triggered by visual stimuli. The most common approach for visual ERP analysis is to use a low presentation rate of images and an active task where participants actively discriminate between target and non-target images. However, researchers are also interested in understanding how the human brain processes visual information in real-world scenarios. To simulate real-life object recognition, this study proposes an analysis pipeline of visual ERPs evoked by images presented in a Rapid Serial Visual Presentation (RSVP) paradigm. Such an approach allows for the investigation of recurrent patterns of visual ERP signals across specific categories and subjects. The pipeline includes segmentation of the EEGs in epochs, and the use of the resulting features as inputs for Support Vector Machine (SVM) classification. Results demonstrate common ERP patterns across the selected categories and the ability to obtain discriminant information from single visual stimuli presented in the RSVP paradigm.

Personalized alpha-tACS targeting left posterior parietal cortex modulates visuo-spatial attention and posterior evoked EEG activity

BackgroundCovert visuo-spatial attention is marked by the anticipatory lateralization of neuronal alpha activity in the posterior parietal cortex. Previous applications of transcranial alternating current stimulation (tACS) at the alpha frequency, however, were inconclusive regarding the causal contribution of oscillatory activity during visuo-spatial attention. ObjectiveAttentional shifts of behavior and electroencephalography (EEG) after-effects were assessed in a cued visuo-spatial attention paradigm. We hypothesized that parietal alpha-tACS shifts attention relative to the ipsilateral visual hemifield. Furthermore, we assumed that modulations of behavior and neurophysiology are related to individual electric field simulations. MethodsWe applied personalized tACS at alpha and gamma frequencies to elucidate the role of oscillatory neuronal activity for visuo-spatial attention. Personalized tACS montages were algorithmically optimized to target individual left and right parietal regions that were defined by an EEG localizer. ResultsBehavioral performance in the left hemifield was specifically increased by alpha-tACS compared to gamma-tACS targeting the left parietal cortex. This hemisphere-specific effect was observed despite the symmetry of simulated electric fields. In addition, visual event-related potential (ERP) amplitudes showed a reduced lateralization over posterior sites induced by left alpha-tACS. Neuronal sources of this effect were localized in the left premotor cortex. Interestingly, accuracy modulations induced by left parietal alpha-tACS were directly related to electric field magnitudes in the left premotor cortex. ConclusionOverall, results corroborate the notion that alpha lateralization plays a causal role in covert visuo-spatial attention and indicate an increased susceptibility of parietal and premotor brain regions of the left dorsal attention network to subtle tACS-neuromodulation.

Impact of Long-Term Shaolin Zen Meditation on Emotional Processing in Aging: A Visual ERP Study.

The aging process is always accompanied by a decline in cognitive and emotional functions. Although previous studies have identified the positive effects of different meditative practices on emotional and cognitive functions, few studies have investigated the most primitive Chinese meditation-Shaolin Zen meditation. In particular, data are extremely limited regarding the brain mechanism of the effects of Shaolin Zen meditation on cognitive and emotional functions during aging. The current study aimed to explore the effects of long-term Shaolin Zen meditation practice on event-related potentials (ERPs) during facial emotion recognition in aging. ERPs were recorded from 16 monks with long-term meditation experience and 20 controls without meditation experience. The significant age-related degenerative changes in the early ERP components did not present in the meditators but only in the controls without meditation experience. Additionally, we found no group differences in the late P3 component. These findings suggest that long-term Shaolin Zen meditation practice can counteract the age-related cognitive decline in the "down-top" automatic processing of emotional stimuli.

Differences Between Autism Spectrum Disorder and Typically Developing Individuals During Visual Information Processing—A Systematic Review and Meta-analysis Focusing on Visual Event-Related Potentials

Differences Between Autism Spectrum Disorder and Typically Developing Individuals During Visual Information Processing—A Systematic Review and Meta-analysis Focusing on Visual Event-Related Potentials

Visual event-related potentials reveal the early whole-word lexical processing of Chinese two-character words

Morphologically complex words are common across different languages, especially in Chinese, because more than 90% of common modern Chinese words are complex words. Many behavioral studies have suggested the whole-word processing of Chinese complex words, but the neural correlates of whole-word processing remain unclear. Previous electrophysiological studies revealed automatic and early (∼250 ms) access to the orthographic forms of monomorphic words in the ventral occipitotemporal area. In this study, we investigated whether there is also automatic and early orthographic recognition of Chinese complex words (as whole units) by recording event-related potentials (ERPs). A total of 150 two-character words and 150 two-character pseudowords composed of the same 300 characters (morphemes) were pseudorandomly presented to proficient Chinese readers. Participants were required to determine the color of each stimulus in the color decision task and to determine whether each stimulus was a word in the lexical decision task. The two constituent characters of each stimulus were horizontally arranged in Experiment 1 and vertically arranged in Experiment 2. The results revealed a significant early ERP difference between words and pseudowords approximately 250–300 ms after stimulus onset in the parieto-occipital scalp region. The early ERP difference was more prominent in the color decision task than in the lexical decision task, more prominent in Experiment 1 than in Experiment 2, and more prominent in the left parieto-occipital scalp region than in the right. Source analysis results showed that the early ERP difference originated from the left ventral occipitotemporal cortex. These results reflected early and automatic access to whole-word orthographic representations of Chinese complex words in the left ventral occipitotemporal cortex.

Effects of Temporal Light Modulation on Cognitive Performance,Eye Movements, and Brain Function

ABSTRACT Temporal light modulation (TLM) describes variations in light output from a light source or lighting system and can be a characteristic of their normal operation. TLM at 100 or 120 Hz can disrupt eye movements and reduce visual performance compared to 40 kHz, but little is known of the effects between those frequencies. Such evidence could provide the basis for lighting product and application standards to support the development of energy-efficient lighting systems. This repeated-measures experiment compared the effects of three stimuli (no TLM [DC], 100 Hz, and 500 Hz [both rectangular-wave, 100% modulation depth, 50% duty cycle]) on state anxiety, eye movements (blinks, saccades, fixations, and pupil size), cognitive performance (Stroop task and sentence reading speed), and visual event-related potentials (ERPs). Post-processing of EEG data included dipole source analysis and estimates of source dipole strength. TLM at 100 Hz was associated with larger pupil sizes and greater ERP dipole strength during 100 Hz exposure than no TLM, particularly in the right hemisphere. Cognitive interference was lower for 500 Hz TLM than 100 Hz. State anxiety was unaffected. The addition of TLM to the light source signal increased arousal and altered brain activity; at the highest frequency tested here this reduced cognitive interference. Arousal theory and stochastic facilitation can provide possible explanations.

Effects of emotion and emotional ambiguity on early visual event-related potentials.

The modulation of early sensory event-related potentials such as the P1, N1, and N170 by emotion and emotional ambiguity is still controversial. Some studies have found a modulation of one or all of these components by one or both of these factors, whereas others have failed to show such results. The objective of this study was to investigate the effects of emotion and ambiguity on the behavioral and electrophysiological responses to a morphed emotion recognition task. Thirty-seven healthy participants (19 men) completed an emotion recognition task where photographs of a male face expressing the six basic emotions morphed with another emotion (in a proportion ranging from 26% to 74%) were randomly presented while electroencephalography was recorded. After each face presentation, participants were asked to identify the facial emotion. We found an emotional effect on the P1, N1, and N170, with greater amplitudes for some emotional facial expressions than for others. However, we found no significant emotional ambiguity effect or interaction between emotion and ambiguity for any of these components. These findings suggest that computation of emotional facial expressions (regardless of their ambiguity) occurs from the early stages of brain processing. (PsycInfo Database Record (c) 2023 APA, all rights reserved).