The influence of color on emotional perception of natural scenes

Is color a critical factor when processing the emotional content of natural scenes? Under challenging perceptual conditions, such as when pictures are briefly presented, color might facilitate scene segmentation and/or function as a semantic cue via association with scene‐relevant concepts (e.g., red and blood/injury). To clarify the influence of color on affective picture perception, we compared the late positive potentials (LPP) to color versus grayscale pictures, presented for very brief (24 ms) and longer (6 s) exposure durations. Results indicated that removing color information had no effect on the affective modulation of the LPP, regardless of exposure duration. These findings imply that the recognition of the emotional content of scenes, even when presented very briefly, does not critically rely on color information.     

Convergence of fMRI and ERP measures of emotional face processing in combat‐exposed U. S. military veterans

The late positive potential (LPP) and fMRI blood‐oxygen‐level dependent (BOLD) activity can provide complementary measures of the processing of affective and social stimuli. Separate lines of research using these measures have often employed the same stimuli, paradigms, and samples; however, there remains relatively little understanding of the way in which individual differences in one of these measures relates to the other, and all prior research has been conducted in psychiatrically healthy samples and using emotional scenes (not faces). Here, 32 combat‐exposed U. S. military veterans with varying levels of posttraumatic stress symptomatology viewed affective social stimuli (angry, fearful, and happy faces) and geometric shapes during separate EEG and fMRI BOLD recordings. Temporospatial principal component analysis was used to quantify the face‐elicited LPP in a data‐driven manner, prior to conducting whole‐brain correlations between resulting positivities and fMRI BOLD elicited by faces. Participants with larger positivities to fearful faces (> shapes) showed increased activation in the amygdala; larger positivities to angry and happy faces (> shapes) were associated with increased BOLD activation in the posterior fusiform gyrus and inferior temporal gyrus, respectively. Across all face types, larger positivities were associated with increased activation in the fusiform “face” area. Correlations using mean area amplitude LPPs showed an association with increased activation in the anterior insula for angry faces (> shapes). LPP‐BOLD associations were not moderated by PTSD. Findings provide the first evidence of correspondence between face‐elicited LPP and BOLD activation across a range of (normal to disordered) psychiatric health.     

Affective modulation of the LPP and α-ERD during picture viewing

Brain responses to engaging stimuli may be reflected both in event-related potentials (ERPs) and in electroencephalogram (EEG) oscillations. Previous studies investigating the effects of top-down factors on stimulus encoding revealed similar modulation of late ERPs and alpha-band desynchronization (α-ERD) by relevant target stimuli. Focusing on the bottom-up effects of emotional content and picture size, the present study aimed to investigate the relationship of the late positive potential (LPP) and α-ERD during the viewing of emotional pictures. Results showed similar affective modulation by picture arousal of the LPP and α-ERD. Moreover, picture size reduction diminished overall magnitude of both responses, but did not dampen affective modulation of either response. These results suggest that, during affective picture viewing, these two brain responses similarly reflect the engagement of motivational systems in order to facilitate perception.     

Personality and emotional processing: A relationship between extraversion and the late positive potential in adolescence

Neuroticism and extraversion are multifaceted affective‐laden personality traits that have been associated with major depressive disorder (MDD). Research and theory have argued that extraversion, and particularly its facet positive emotionality, is specific to MDD, while neuroticism is common across internalizing disorders. Converging evidence has suggested that MDD is associated with reduced engagement with emotional stimuli, but it remains unclear whether either extraversion, neuroticism, or both modulate reactivity to emotional cues. The late positive potential (LPP) is an event‐related brain potential that is uniquely suited to assess engagement with emotional stimuli because it reflects sustained attention toward emotional content. The current study examined the LPP in relation to personality traits that may confer risk for depression by examining the relationship between the LPP and both neuroticism and extraversion in never‐depressed adolescent girls. Specifically, 550 girls aged 13.5–15.5 with no lifetime history of depression completed an emotional picture‐viewing task, and the LPP was measured in response to neutral, pleasant, and unpleasant pictures. Personality traits were gathered via self‐ and informant report. Results indicated that high extraversion was associated with a potentiated LPP to emotional pictures—and this effect was accounted for by positive emotionality in particular. In contrast, there was no association between the LPP and neuroticism or its facets. The present study is one of the first to demonstrate that extraversion is associated with variation in neural indices of emotional picture processing, similar to what has been observed among individuals with depression and at high risk for depression.     

Selection history alters attentional filter settings persistently and beyond top‐down control

Visual selective attention is known to be guided by stimulus‐based (bottom‐up) and goal‐oriented (top‐down) control mechanisms. Recent work has pointed out that selection history (i.e., the bias to prioritize items that have been previously attended) can result in a learning experience that also has a substantial impact on subsequent attention guidance. The present study examined to what extent goal‐oriented top‐down control mechanisms interact with an observer's individual selection history in guiding attention. Selection history was manipulated in a categorization task in a between‐subjects design, where participants learned that either color or shape was the response‐relevant dimension. The impact of this experience was assessed in a compound visual search task with an additional color distractor. Top‐down preparation for each search trial was enabled by a pretrial task cue (Experiment 1) or a fixed, predictable trial sequence (Experiment 2). Reaction times and ERPs served as indicators of attention deployment. Results showed that attention was captured by the color distractor when participants had learned that color predicted the correct response in the categorization learning task, suggesting that a bias for predictive stimulus features had developed. The possibility to prepare for the search task reduced the bias, but could not entirely overrule this selection history effect. In Experiment 3, both tasks were performed in separate sessions, and the bias still persisted. These results indicate that selection history considerably shapes selective attention and continues to do so persistently even when the task allowed for high top‐down control.     

Increased neural sensitivity to self‐relevant stimuli in major depressive disorder

The current research examined how individuals with depression process emotional, self‐relevant stimuli. Across two studies, individuals with depression and healthy controls read stimuli that varied in self‐relevance while EEG data were recorded. We examined the late positive potential (LPP), an ERP component that captures the dynamic allocation of attention to motivationally salient stimuli. In Study 1, participants read single words in a passive‐viewing task. Participants viewed negative, positive, or neutral words that were either normative or self‐generated. Exploratory analyses indicated that participants with depression exhibited affective modulation of the LPP for self‐generated stimuli only (both positive and negative) and not for normative stimuli; healthy controls exhibited similar affective modulation of the LPP for both self‐relevant and normative stimuli. In Study 2, using a separate sample and a different task, stimuli were provided within the context of sentence stems referring to the self or other people. Participants with depression were more likely to endorse negative self‐referent sentences and reject positive ones compared to healthy controls. Depressed participants also exhibited an increased LPP to negative stimuli compared to positive or neutral stimuli. Together, these two studies suggest that depression is characterized by relatively increased sensitivity to affective self‐relevant stimuli, perhaps in the context of a broader reduction in emotional reactivity to stimuli that are not self‐relevant. Thus, depression may be characterized by a more nuanced pattern based on the degree of stimulus self‐relevance than either a global decrease or increase in reactivity to affective stimuli.     

Effects of prior mental effort on picture processing: An ERP investigation

The current study examined the aftereffects of mental effort on the processing of picture stimuli using neural measures. Ninety‐seven healthy young adults were randomly assigned to exercise more versus less mental effort on a writing task. Then participants viewed positive, negative, and neutral affective images while P1, N1, P2, N2, P3, and late positive potential (LPP) magnitudes to the images were assessed. We found that performing the more (versus less) effortful writing task caused more negative N2 amplitudes to all images. In addition, and consistent with past research, emotional (versus neutral) images elicited more positive amplitudes on the N2, P3, and LPP components. Thus, prior mental effort appeared to reduce early attentional engagement with visual stimuli but did not diminish later attention modulation by emotional content. These findings suggest novel implications for understanding the behavioral aftereffects of mental effort and self‐control.     

The sound and the fury: Late positive potential is sensitive to sound affect

Emotion is an emergent construct of multiple distinct neural processes. EEG is uniquely sensitive to real‐time neural computations, and thus is a promising tool to study the construction of emotion. This series of studies aimed to probe the mechanistic contribution of the late positive potential (LPP) to multimodal emotion perception. Experiment 1 revealed that LPP amplitudes for visual images, sounds, and visual images paired with sounds were larger for negatively rated stimuli than for neutrally rated stimuli. Experiment 2 manipulated this audiovisual enhancement by altering the valence pairings with congruent (e.g., positive audio + positive visual) or conflicting emotional pairs (e.g., positive audio + negative visual). Negative visual stimuli evoked larger early LPP amplitudes than positive visual stimuli, regardless of sound pairing. However, time frequency analyses revealed significant midfrontal theta‐band power differences for conflicting over congruent stimuli pairs, suggesting very early (∼500 ms) realization of thematic fidelity violations. Interestingly, late LPP modulations were reflective of the opposite pattern of congruency, whereby congruent over conflicting pairs had larger LPP amplitudes. Together, these findings suggest that enhanced parietal activity for affective valence is modality independent and sensitive to complex affective processes. Furthermore, these findings suggest that altered neural activities for affective visual stimuli are enhanced by concurrent affective sounds, paving the way toward an understanding of the construction of multimodal affective experience.     

Make a lasting impression: The neural consequences of re‐encountering people who emote inappropriately

We can learn about the affective content of the environment by observing the behavior of others; their responses to stimuli tend to be appropriate to the context. To investigate the impact of observing such appropriate, compared with inappropriate, behaviors, we developed a novel behavioral task where participants observed different faces reacting to emotional scenes. We found that affective categorization of a scene was facilitated when it was presented alongside an appropriate facial expression (Experiment 1). Further, we observed that several brain areas in the right hemisphere—the putamen, insula, orbitofrontal cortex, and dorsal anterior cingulate cortex—were more activate when viewing faces that were previously observed emoting inappropriately (Experiment 2). We contend that these areas form a network that codes for the retrieval of affective conflict information generated by observing individuals producing inappropriate emotions.     

Electrophysiology of blunted emotional bias in psychopathic personality

Diminished emotional capacity is a core characteristic of psychopathic personality. We examined behavioral and electrophysiological differences in attentional bias to emotional material in 34 healthy individuals rated high or low in psychopathic traits using the short form of the Psychopathic Personality Inventory–Revised (18 high‐trait, 16 low‐trait). While performing an emotional Stroop task, high‐trait participants displayed reduced emotional modulation of the late positive potential (LPP, 400–600 ms), and early anterior positivity (EAP, 200–300 ms) amplitudes. Results suggest blunted bias to affective content in psychopathic personality, characterized by diminished early capture to emotional salience (EAP) and dampened cognitive emotional processing (LPP).     

Affective imagery and the startle response: probing mechanisms of modulation during pleasant scenes,personal experiences,and discrete negative emotions

Two experiments addressed the following issues concerning modulation of the acoustic startle reflex during emotional imagery: (1) Is startle inhibited or potentiated during imagery of pleasurable events? (2) Does startle modulation differ for personal versus standard imagery scenes? (3) Is startle modulated differently during anger versus fear? For standard scenes, startle was greater during aversive than pleasant imagery, with both exceeding neutral. Blink potentiation was greater during imagery of personal pleasant than nonpersonal pleasant scenes. Startle potentiation did not differ for anger versus fear material, but differences were found in self‐report, corrugator EMG, and HR response. These results suggest that in addition to the emotional valence of imagined material, startle reactivity is influenced by the degree of engagement or active disengagement from the sensory environment. The findings also indicate that fear and anger are differentiable in terms of affective report, cardiac mobilization, and expressive behavior, but not at the primary motivational level at which reflex priming occurs.     

Neural response to emotional pictures is unaffected by concurrent task difficulty: an event-related potential study

The late positive potential (LPP) is an event-related potential that is enhanced when viewing arousing (pleasant and unpleasant) pictures compared to neutral pictures. The affective modulation of the LPP is believed to reflect the increased attention to, and perceptual processing of, emotional stimuli. The present study examined whether concurrent task difficulty (performing mathematics) would modulate the LPP while participants viewed emotionally arousing stimuli. Results indicated that the LPP was larger following pleasant and unpleasant stimuli than it was following neutral stimuli; moreover, the magnitude of this increase was not influenced by concurrent task difficulty. This finding suggests that the affective modulation of neural activity during picture viewing is relatively automatic and is insusceptible to competing task demands. Results are further discussed in terms of the LPP's role in motivated attention and implications for research on emotion regulation.     

Demonstrating emotional processing differences in psychopathy using affective ERP modulation

Psychopaths exhibit abnormalities processing emotional information, but there is less certainty regarding the role attention plays in these processes. We present data from two affective picture‐viewing tasks comparing event‐related potential (ERP) modulation effects when emotional information is present but not task relevant (Task 1) followed by a condition directing attention to the categorization of emotional content (Task 2). Controls show a robust, persistent ERP positivity (200–900 ms) associated with emotional target photos compared to neutral targets in both tasks. Individuals with psychopathy only showed this differentiation when explicitly attending to the emotional content of the photos (Task 2), and these effects remained smaller than the amplitude differences demonstrated by controls. Although abnormal allocation of attention may play a critical role, this cannot completely account for emotional processing deficits associated with psychopathy.     

Large‐scale functional brain connectivity during emotional engagement as revealed by beta‐series correlation analysis

It has been hypothesized that the medial prefrontal cortex (mPFC) is a hub in the network that mediates appetitive responses whereas the amygdala is thought to mediate both aversive and appetitive processing. Both structures may facilitate adaptive responses to emotional challenge by linking perception, attention, memory, and motor circuits. We provide an initial exploration of these hypotheses by recording simultaneous EEG‐fMRI in eleven participants viewing affective pictures. MPFC‐ and amygdala‐seeded functional connectivity maps were generated by applying the beta‐series correlation method. The mPFC‐seeded correlation map encompassed visual regions, sensorimotor areas, prefrontal cortex, and medial temporal lobe structures, exclusively for pleasant content. For the amygdala‐seeded correlation map, a similar set of distributed brain areas appeared in the unpleasant‐neutral contrast, with the addition of structures such as the insula and thalamus. A substantially sparser network was recruited for the pleasant‐neutral contrast. Using the late positive potential (LPP) to index the intensity of emotional engagement, functional connectivity was found to be stronger in trials with larger LPP. These results demonstrate that mPFC‐mediated functional interactions are engaged specifically during appetitive processing, whereas the amygdala is coupled to distinct sets of brain regions during both aversive and appetitive processing. The strength of these interactions varies as a function of the intensity of emotional engagement.     

Local context influences memory for emotional stimuli but not electrophysiological markers of emotion‐dependent attention

Emotional enhancement of free recall can be context dependent. It is readily observed when emotional and neutral scenes are encoded and recalled together in a “mixed” list, but diminishes when these scenes are encoded separately in “pure” lists. We examined the hypothesis that this effect is due to differences in allocation of attention to neutral stimuli according to whether they are presented in mixed or pure lists, especially when encoding is intentional. Using picture stimuli that were controlled for semantic relatedness, our results contradicted this hypothesis. The amplitude of well‐known electrophysiological markers of emotion‐related attention—the early posterior negativity (EPN), the late positive potential (LPP), and the slow wave (SW)—was higher for emotional stimuli. Crucially, the emotional modulation of these ERPs was insensitive to list context, observed equally in pure and mixed lists. Although list context did not modulate neural markers of emotion‐related attention, list context did modulate the effect of emotion on free recall. The apparent decoupling of the emotional effects on attention and memory, challenges existing hypotheses accounting for the emotional enhancement of memory. We close by discussing whether findings are more compatible with an alternative hypothesis, where the magnitude of emotional memory enhancement is, at least in part, a consequence of retrieval dynamics.     

Late positive potentials in affective picture processing during adolescence

Recent research in adults has determined that late positive potential (LPP) is modulated by affective pictures. Here we investigated whether affective modulation of LPP reflects developmental changes during adolescence. Event-related potentials were recorded from 50 adolescents (11-17 years old) while they viewed 90 pictures of middle arousal level from the Chinese affective picture system. Consistent with previous studies in adults, affective pictures elicited larger LPP activities than neutral pictures over bilateral centroparietal sensors. Moreover, the LPP amplitudes varied as a function of age, increasing with age regardless of picture valence. These observations imply that adolescents exhibit affective modulation of LPP similar to adults, and undergo developmental changes in automatic attention to affective or non-affective pictures.     

Emotional targets: evaluative categorization as a function of context and content

Event-related potential (ERP) studies of early evaluative categorization have often used variants of an oddball paradigm to assess attention to target stimuli as a function of content (i.e., valence) and context (e.g., presentation among non-targets differing in valence). However, most previous studies have not fully crossed content and context, and have not examined the time-course of these effects. The purpose of the current study was to investigate these two issues in an effort to further clarify the nature of evaluative categorization as reflected in the late positive potential (LPP). Pleasant, neutral, and unpleasant images served as both targets and non-targets in an emotional oddball task. Results indicate additive effects of emotional content and target status on the early portion of the LPP; however, the LPP did not differ between pleasant and unpleasant stimuli. Only target status modulated the later portion of the LPP, suggesting different contributions of cognitive-affective processes over time during evaluative categorization.     

Emotional reactivity and regulation in individuals with psychopathic traits: Evidence for a disconnect between neurophysiology and self‐report

Individuals with psychopathic traits often demonstrate blunted reactivity to negative emotional stimuli. However, it is not yet clear whether these individuals also have difficulty regulating their emotional responses to negative stimuli. To address this question, participants with varying levels of psychopathic traits (indexed by the Triarchic Measure of Psychopathy; Patrick, 2010) completed a task in which they passively viewed, increased, or decreased their emotions to negative picture stimuli while electrocortical activity was recorded. During passive viewing of negative images, higher boldness, but not higher disinhibition or meanness, was associated with reduced amplitude of the late positive potential (LPP), an ERP that indexes reactivity to emotionally relevant stimuli. However, all participants demonstrated expected enhancement of the LPP when asked to increase their emotional response. Participants did not show expected suppression of the LPP when asked to decrease their emotional response. Contrary to the electrophysiological data, individuals with higher boldness did not self‐report experiencing blunted emotional response during passive viewing trials, and they reported experiencing greater emotional reactivity relative to other participants when regulating (e.g., both increasing and decreasing) their emotions. Results suggest inconsistency between physiological and self‐report indices of emotion among high‐bold individuals during both affective processing and regulation.