The impact of the stimulus features and task instructions on facial processing in social anxiety: An ERP investigation

Social anxiety has been characterized by an attentional bias towards threatening faces. Electrophysiological studies have demonstrated modulations of cognitive processing from 100 ms after stimulus presentation. However, the impact of the stimulus features and task instructions on facial processing remains unclear. Event-related potentials were recorded while high and low socially anxious individuals performed an adapted Stroop paradigm that included a colour-naming task with non-emotional stimuli, an emotion-naming task (the explicit task) and a colour-naming task (the implicit task) on happy, angry and neutral faces. Whereas the impact of task factors was examined by contrasting an explicit and an implicit emotional task, the effects of perceptual changes on facial processing were explored by including upright and inverted faces. The findings showed an enhanced P1 in social anxiety during the three tasks, without a moderating effect of the type of task or stimulus. These results suggest a global modulation of attentional processing in performance situations.     

The temporal dynamics of emotion regulation: an EEG study of distraction and reappraisal

Distraction and reappraisal are two widely used forms of emotion regulation. The process model of emotion regulation (Gross, 1998) holds that they differ (1) in when they act on the emotion-generative process, and (2) in their impact on subsequent responses to regulated stimuli. We tested these two predictions by measuring electrocortical responses to neutral and emotional images during two phases. In the regulation phase, images were watched or regulated using distraction or reappraisal. During the re-exposure phase, the same images were passively watched. As predicted, during regulation, distraction reduced the late positive potential (LPP) earlier than reappraisal. Upon re-exposure, images with a distraction (but not reappraisal) history elicited a larger LPP than images with an attend history. This pattern of results suggests that distraction and reappraisal intervene at separate stages during emotion generation, a feature which may have distinct consequences that extend beyond the regulatory episode.     

Repetitive exposure: Brain and reflex measures of emotion and attention

Effects of massed repetition on the modulation of the late positive potential elicited during affective picture viewing were investigated in two experiments. Despite a difference in the number of repetitions across studies (from 5 to 30), results were quite similar: The late positive potential continued to be enhanced when participants viewed emotional, compared to neutral, pictures. On the other hand, massed repetition did prompt a reduction in the late positive potential that was most pronounced for emotional pictures. Startle probe P3 amplitude generally increased with repetition, suggesting diminished attention allocation to repeated pictures. The blink reflex, however, continued to be modulated by hedonic valence, despite massive massed repetition. Taken together, the data suggest that the amplitude of the late positive potential during picture viewing reflects both motivational significance and attention allocation.     

Electrophysiological evidence of facial inversion with rapid serial visual presentation

Using measurements of event-related potentials (ERPs) during a facial recognition task, we aimed to investigate the facial inversion effect and the role of time-based attention in processing upright and inverted faces. We presented upright and inverted faces at the T2 (target 2) position using a rapid serial visual presentation paradigm. Our results indicate that the N170 component shows the usual face inversion effect (FIE), in which inverted faces elicit larger N170 amplitudes and a longer elicit N170 latency. We also found that upright faces elicit larger P1 amplitudes than inverted faces over the left hemisphere. This study indicates that the N170 and P3, but not the P1, components are modulated by time-based attention. In addition, we found that the N170 amplitude was modulated by an attentional blink (AB) based on behavioral data. These results suggest that the disruption of facial configuration processing caused by inverted faces is relatively independent of attentional resources.     

Dissociating love-related attention from task-related attention: An event-related potential oddball study

The present event-related potential (ERP) study was conducted to investigate the P3 component in response to love-related stimuli while controlling for task-related factors, and to dissociate the influences of both love-related and task-related attention on the P3 amplitude. In an oddball paradigm, photographs of beloved and friends served as target and distractor stimuli. Love-related and task-related attention were separated by varying the target and distractor status of the beloved and friends full factorially. As expected, the P3 amplitude was larger for beloved compared to friends and for targets compared to distractors. Moreover, task-related and love-related attention were unconfounded. These results are in line with findings that the P3 is modulated by both emotion- and task-related factors, supporting the view that the P3 amplitude reflects attention. Furthermore, this study validates the notion that romantic love is accompanied by increased attention for stimuli associated with the beloved, and also shows that this form of attention is different from task-related attention.     

Natural selective attention: orienting and emotion

The foundations of orienting and attention are hypothesized to stem from activation of defensive and appetitive motivational systems that evolved to protect and sustain the life of the individual. Motivational activation initiates a cascade of perceptual and motor processes that facilitate the selection of appropriate behavior. Among these are detection of significance, indexed by a late centro-parietal positivity in the event-related potential, enhanced perceptual processing, indexed by a initial cardiac deceleration, and preparation for action, indexed by electrodermal changes. Data exploring the role of stimulus novelty and significance in orienting are presented that indicate different components of the orienting response habituate at different rates. Taken together, it is suggested that orienting is mediated by activation of fundamental motivational systems that have evolved to support survival.     

The neural processing of fearful faces without attention and consciousness: an event-related potential study

To investigate whether the non-conscious processing of fearful faces exist in unattended condition, event-related potentials (ERPs) were recorded in a facial expression detection task. Participants were asked to discriminate the facial expressions (fearful or neutral) at the attended location. Unattended faces were associated with a response that was either congruent or in conflict with the response to the attended face. ERP results showed that the trials with response conflict between attended and unattended faces enhanced the amplitude of the P3 component when the neutral face was presented at attended location and the fearful face was presented at the unattended location. Our findings imply that the non-conscious fearful faces can be processed in the unattended condition.     

Distinct control networks for cognition and emotion in the prefrontal cortex

The activation of dorsolateral prefrontal cortex (dlPFC) has been suggested to reflect the engagement of a control mechanism for top-down biasing of context processing in resource-demanding memory tasks. Here we tested the hypothesis that the dlPFC subserves a similar function also in attention and emotion tasks. 18 healthy young adults were tested in a functional magnetic resonance imaging (fMRI) study where the demands for context processing were manipulated in three different cognitive domains: auditory attention, episodic retrieval, and emotion regulation. We found that the right dlPFC was jointly sensitive to increased cognitive demands in the attention and memory tasks. By contrast, increased demands in the emotion task (reappraisal) were associated with increased activity in ventromedial PFC along with decreased amygdala activity. Our findings of divergent prefrontal control networks for cognitive and emotional control extend previous separations of cognition and emotion in the anterior cingulate cortex.     

Electrophysiological correlates of visually processing subject's own name

We investigated the electrophysiological correlates of the processing of subject's own name (SON) in comparison to familiar and unfamiliar names in the Chinese language. The three types of names were the deviants in an oddball paradigm among lexical and non-lexical phrases. All items consisted of three characters, and the non-lexical items were the targets. All names caused a clear N170 component of identical size which we take as a correlate of structural encoding. Only SON elicited a large N250 component, reflecting attentional capturing of SON. Additionally, SON caused a larger but later peaking P300 than the other two name stimuli which we interpret as a correlate of access to self-reference information.     

The cognitive consequences of emotion regulation: an ERP investigation

Increasing evidence suggests that emotion regulation (ER) strategies modulate encoding of information presented during regulation; however, no studies have assessed the impact of cognitive reappraisal ER strategies on the processing of stimuli presented after the ER period. Participants in the present study regulated emotions to unpleasant pictures and then judged whether a word was negative or neutral. Electromyographic measures (corrugator supercilli) confirmed that individuals increased and decreased negative affect according to ER condition. Event-related potential analyses revealed smallest N400 amplitudes to negative and neutral words presented after decreasing unpleasant emotions and smallest P300 amplitudes to words presented after increasing unpleasant emotions whereas reaction time data failed to show ER modulations. Results are discussed in the context of the developing ER literature, as well as theories of emotional incongruity (N400) and resource allocation (P300).     

Emotion and attention in visual word processing: an ERP study

Emotional words are preferentially processed during silent reading. Here, we investigate to what extent different components of the visual evoked potential, namely the P1, N1, the early posterior negativity (EPN, around 250 ms after word onset) as well as the late positive complex (LPC, around 500 ms) respond differentially to emotional words and whether this response depends on the availability of attentional resources. Subjects viewed random sequences of pleasant, neutral and unpleasant adjectives and nouns. They were first instructed to simply read the words and then to count either adjectives or nouns. No consistent effects emerged for the P1 and N1. However, during both reading and counting the EPN was enhanced for emotionally arousing words (pleasant and unpleasant), regardless of whether the word belonged to a target or a non-target category. A task effect on the EPN was restricted to adjectives, but the effect did not interact with emotional content. The later centro-parietal LPC (450-650 ms) showed a large enhancement for the attended word class. A small and topographically distinct emotion-LPC effect was found specifically in response to pleasant words, both during silent reading and the active task. Thus, emotional word content is processed effortlessly and automatically and is not subject to interference from a primary grammatical decision task. The results are in line with other reports of early automatic semantic processing as reflected by posterior negativities in the ERP around 250 ms after word onset. Implications for models of emotion-attention interactions in the brain are discussed.     

Theta EEG activity and memory processes in rats

Rodent EEG theta activity recorded in the 30 min period after ECS treatment has previously been correlated with passive avoidance retention. In the present experiment rats were trained and tested in an appetitive maze, thereby avoiding the possible confounding of footshock-produced EEG arousal. Our results produced the same relationship between theta and retention, but since ECS was given 7 days after training, we conclude that theta activity is not related only to memory consolidation. Patterns of theta during reinstatement were also found to be more similar to the pattern recorded late in learning when the reinstatment took place in the original start box. The data support the notion of cue-dependent amnesia, and the hypothesis that ECS acts by inhibiting the memory which is active at the time of ECS.     

Cortical potential imaging of episodic memory encoding

Previous findings suggest that episodic memory encoding is subserved by different brain structures that interplay and transform experience into memories. The present study aims to identify topographic location of the underlying neural generators, and correlate their activities with the subsequent memory effect, using electrophysiological neuroimaging of the event-related potentials (ERPs) recorded from 11 healthy subjects participating in word encoding tasks. Cortical potentials were imaged noninvasively from scalp ERPs. Different levels of brain activation were found in the left inferior prefrontal, left temporal and left parietal lobes with different latencies after onset of event. It is concluded that these regions work jointly across both spatial and temporal domains to promote verbal memory formation.     

The topographical N170: Electrophysiological evidence of a neural mechanism for human spatial navigation

We recently demonstrated that the latency of a component of the event-related brain potential, the topographical N170 (NT170), is sensitive to the spatial location of reward-related stimuli in a virtual maze environment, occurring earlier for rewards found following rightward turns compared to leftward turns. We suggested that this NT170 latency effect may result from phase reset of an ongoing theta rhythm by a parahippocampal system for spatial navigation. Here we tested several predictions that follow from this proposal, namely, that the effect is observed only when the rewards are presented in a spatial environment, that it is sensitive to individual differences in spatial ability, that it is localizable to the right parahippocampal region, and that it is consistent with partial phase resetting of an ongoing theta rhythm. These results hold promise for integrating ERP measures of spatial navigation with extensive animal, human, and computational literatures on parahippocampal function.     

The allocation of attention in displays with simultaneously presented singletons

In an ERP experiment, we investigated whether a ‘permanent’ salient distractor changes the deployment of attention to target and nontarget singletons. Observers searched for a color target in a search array that mainly consisted of black vertical lines, but also always contained a line in a task-irrelevant color. Together with this distractor, a target or nontarget singleton was presented. Nontargets could be salient on the task-relevant dimension (color), or on a neutral dimension (line orientation). N2pc amplitude was maximal for targets, no N2pc was elicited by color nontargets, and orientation nontargets elicited an inverse N2pc. Targets and color nontargets elicited larger N2 amplitude than orientation singletons. P3 amplitude was high for relevant and low for irrelevant singletons. Targets also elicited higher reaction times and more errors. Attention seemed thus driven by the target feature, and by its feature dimension, even when constant distraction on that dimension had to be suppressed.     

Memory for words and novel visual patterns: Repetition, recognition, and encoding effects in the event-related brain potential

Event-related potentials (ERPs) were recorded during initial study and recognition of words and novel visual patterns. Words and patterns yielded similar recognition results that discriminated correctly recognized old items from correct new items, incorrect old items, and incorrect new items. The study phase data included a number of dissociations between words and patterns. Occasional repeated items yielded faster reaction times for both stimulus types but a late positive ERP repetition effect for words only. The study phase data differentiated words that would later be recognized versus unrecognized, but the patterns did not yield a similar encoding effect. Moreover, the study phase positivity contingent on subsequent recognition was restricted to words that received a positive semantic judgment during study. The functional relationships among the repetition, recognition, and encoding effects are discussed.     

The selective processing of briefly presented affective pictures: an ERP analysis

Recent event-related potential (ERP) studies revealed the selective processing of affective pictures. The present study explored whether the same phenomenon can be observed when pictures are presented only briefly. Toward this end, pleasant, neutral, and unpleasant pictures from the International Affective Pictures Series were presented for 120 ms while event related potentials were measured by dense sensor arrays. As observed for longer picture presentations, brief affective pictures were selectively processed. Specifically, pleasant and unpleasant pictures were associated with an early endogenous negative shift over temporo-occipital sensors compared to neutral images. In addition, affective pictures elicited enlarged late positive potentials over centro-parietal sensor sites relative to neutral images. These data suggest that a quick glimpse of emotionally relevant stimuli appears sufficient to tune the brain for selective perceptual processing.     

Directed attention reduces processing of emotional distracters irrespective of valence and arousal level

Emotional stimuli tend to capture attention, and this so-called motivated attention is commonly measured using the early posterior negativity (EPN) and the late positive potential (LPP). We hypothesized that voluntary, directed attention reduces motivated attention more strongly for highly than moderately arousing pleasant or unpleasant pictures. Participants were instructed to direct their attention to either a picture at fixation or the letters flanking the picture. Pictures varied substantially in arousal and valence. When the pictures were attended to, EPN and LPP increased linearly with arousal. When the letters were attended to, these linear effects decreased in the EPN for pleasant and unpleasant pictures and in the LPP for pleasant pictures. Thus, directed attention decreases processing of emotional distracters more strongly for highly than moderately arousing pleasant and unpleasant pictures. These results are consistent with the view that directed attention decreases emotion effects on sensory gain.     

The influence of stimulus valence on perceptual processing of facial expressions and subsequent response inhibition

The constant interplay between affective processing and cognitive control supports emotion regulation and appropriate social functioning. Even when affective stimuli are processed implicitly, threat-related stimuli are prioritized in the earliest stages of processing; yet, it remains unclear how implicit attention to affect influences subsequent cognitive control functions. The present study evaluated the influence of affective valence on early perceptual processes and subsequent response inhibition in a context where affective properties of the stimuli (facial expressions) were not critical for performing the task. Participants (N = 32) completed an affective stop-signal task (SST) while their scalp EEGs were recorded. The SST assessed response inhibition while participants implicitly attended to happy and afraid facial expressions that were matched for level of arousal. Behavioral performance was measured via response time and accuracy while physiological response was measured via the P100, N170, and N200/P300 ERP components. Decreased gender discrimination accuracy, delayed P100 latency, and more negative N170 amplitude were observed for afraid faces compared to happy faces, suggesting a shift in processing with respect to face valence. However, differences in stopping accuracy or N200/P300 ERP components during response inhibition were not observed, pointing to top-down cognitive processes likely being recruited to override the early automatic response to prioritize threat-related stimuli. Findings highlight that, in this implicit affective attention task, threat-related stimuli are prioritized early during processing, but implicitly attending to differentially valenced stimuli did not modulate subsequent cognitive control functions.