The persistence of attention to emotion: brain potentials during and after picture presentation

Emotional stimuli have been shown to elicit increased perceptual processing and attentional allocation. The late positive potential (LPP) is a sustained P300-like component of the event-related potential that is enhanced after the presentation of pleasant and unpleasant pictures as compared with neutral pictures. In this study, the LPP was measured using dense array electroencephalograph both before and after pleasant, neutral, and unpleasant images to examine the time course of attentional allocation toward emotional stimuli. Results from 17 participants confirmed that the LPP was larger after emotional than neutral images and that this effect persisted for 800 ms after pleasant picture offset and at least 1,000 ms after unpleasant picture offset. The persistence of increased attention after unpleasant compared to pleasant stimuli is consistent with the existence of a negativity bias. Overall, these results indicate that attentional capture of emotion continues well beyond picture presentation and that this can be measured with the LPP. Implications and directions for future research are discussed.     

Perceptual processing of natural scenes at rapid rates: Effects of complexity, content, and emotional arousal

During rapid serial visual presentation (RSVP), the perceptual system is confronted with a rapidly changing array of sensory information demanding resolution. At rapid rates of presentation, previous studies have found an early (e.g., 150–280 ms) negativity over occipital sensors that is enhanced when emotional, as compared with neutral, pictures are viewed, suggesting facilitated perception. In the present study, we explored how picture composition and the presence of people in the image affect perceptual processing of pictures of natural scenes. Using RSVP, pictures that differed in perceptual composition (figure–ground or scenes), content (presence of people or not), and emotional content (emotionally arousing or neutral) were presented in a continuous stream for 330 ms each with no intertrial interval. In both subject and picture analyses, all three variables affected the amplitude of occipital negativity, with the greatest enhancement for figure–ground compositions (as compared with scenes), irrespective of content and emotional arousal, supporting an interpretation that ease of perceptual processing is associated with enhanced occipital negativity. Viewing emotional pictures prompted enhanced negativity only for pictures that depicted people, suggesting that specific features of emotionally arousing images are associated with facilitated perceptual processing, rather than all emotional content.     

Here is looking at you: emotional faces predominate in binocular rivalry

Two incompatible pictures compete for perceptual dominance when they are presented to one eye each. This so-called binocular rivalry results in an alternation of dominant and suppressed percepts. In accordance with current theories of emotion processing, the authors' previous research has suggested that emotionally arousing pictures predominate in this perceptual process. Three experiments were run with pictures of emotional facial expressions that are known to induce emotions while being well controlled in terms of physical characteristics. In Experiment 1, photographs of emotional and neutral facial expressions were presented of the same actor to minimize physical differences. In Experiment 2, schematic emotional expressions were presented to further eliminate low-level differences. In Experiment 3, a probe-detection task was conducted to control for possible response-biases. Together, these data clearly demonstrate that emotional facial expressions predominate over neutral expressions; they are more often the first percept and they are perceived for longer durations. This is not caused by physical stimulus properties or by response-biases. This novel approach supports that emotionally significant visual stimuli are preferentially perceived.     

Time course of attentional bias to emotional scenes in anxiety: Gaze direction and duration

Pictures of emotionally neutral, positive, and negative (threat‐ or harm‐related) scenes were presented for 3 seconds, paired with nonemotional control pictures. The eye fixations of high and low trait anxiety participants were monitored. Intensity of stimulus emotionality was varied, with two levels of perceptual salience for each picture (colour vs. greyscale). Regardless of perceptual salience, high anxiety was associated with preferential attention: (a) towards all types of emotional stimuli in initial orienting, as revealed by a higher probability of first fixation on the emotional picture than on the neutral picture of a pair; (b) towards positive and harm stimuli in a subsequent stage of early engagement, as shown by longer viewing times during the first 500 ms following onset of the pictures; and with (c) attention away from (i.e., avoidance) harm stimuli in a later phase, as indicated by shorter viewing times and lower frequency of fixation during the last 1000 ms of picture exposure. This suggests that the nature of the attentional bias varies as a function of the time course in the processing of emotional pictures.     

Time course of attentional bias to emotional scenes in anxiety: Gaze direction and duration

Pictures of emotionally neutral, positive, and negative (threat- or harm-related) scenes were presented for 3 seconds, paired with nonemotional control pictures. The eye fixations of high and low trait anxiety participants were monitored. Intensity of stimulus emotionality was varied, with two levels of perceptual salience for each picture (colour vs. greyscale). Regardless of perceptual salience, high anxiety was associated with preferential attention: (a) towards all types of emotional stimuli in initial orienting, as revealed by a higher probability of first fixation on the emotional picture than on the neutral picture of a pair; (b) towards positive and harm stimuli in a subsequent stage of early engagement, as shown by longer viewing times during the first 500 ms following onset of the pictures; and with (c) attention away from (i.e., avoidance) harm stimuli in a later phase, as indicated by shorter viewing times and lower frequency of fixation during the last 1000 ms of picture exposure. This suggests that the nature of the attentional bias varies as a function of the time course in the processing of emotional pictures.     

Differential interference effects of negative emotional states on subsequent semantic and perceptual processing

Past studies have revealed that encountering negative events interferes with cognitive processing of subsequent stimuli. The present study investigates whether negative events affect semantic and perceptual processing differently. Presentation of negative pictures produced slower reaction times than neutral or positive pictures in tasks that require semantic processing, such as natural or man-made judgments about drawings of objects, commonness judgments about objects, and categorical judgments about pairs of words. In contrast, negative picture presentation did not slow down judgments in subsequent perceptual processing (e.g., color judgments about words, size judgments about objects). The subjective arousal level of negative pictures did not modulate the interference effects on semantic or perceptual processing. These findings indicate that encountering negative emotional events interferes with semantic processing of subsequent stimuli more strongly than perceptual processing, and that not all types of subsequent cognitive processing are impaired by negative events.     

Gaze Patterns When Looking at Emotional Pictures: Motivationally Biased Attention

Pictures of either emotionally neutral, pleasant (affectionate), or unpleasant (threat and injury) scenes were paired with nonemotional control pictures and presented for 3 s, while eye fixations were monitored. Preferential attention to the emotional picture of eah pair occurred at an early processing stage: The probability of placement of the first fixation and the proportion of viewing time during the first 500 ms were higher for both pleasant and unpleasant pictures than for neutral pictures, whereas later fixation location and time were not differentially affected. This suggests that, when emotional and nonemotional stimuli are presented simultaneously, emotional meaning captures initial overt orienting and engages attention early, as measured by gaze direction and duration. The possibility that this effect could be accounted for by perceptual differences—such as luminance and complexity—between emotional and neutral pictures was ruled out.     

Independent manipulation of emotion in an emotional stroop task using classical conditioning

The effects of emotional connotation on emotional Stroop interference in anxiety were examined. First, a classical conditioning paradigm was used in which neutral words and nonwords were paired with either negative or neutral pictures. These conditioned stimuli were then presented in an emotional Stroop paradigm. Finally, participants rated each word and nonword for emotional connotation. The high-anxious group demonstrated significant interference for the nonwords that had been negatively conditioned, and these effects did not dissipate over time. The affective rating data supported the view that nonwords, but not the words had been successfully conditioned in the high-anxious group. This experiment provides evidence for the importance of emotional connotation rather than confounded semantic factors in the emotional Stroop effect.     

Effects of level of processing on emotional memory: gist and details

The object of this study was to investigate whether level of processing (LOP) modulates enhanced memory performance for emotional stimuli, and, if so, whether the LOP effects relate to their gist and details. During the study phase, participants were presented with colourful pictures with negative, neutral and positive valences and encoded the emotional pictures under either a semantic (living/non-living judgement) or a perceptual (left/right position judgement) condition. During the test phase, they judged whether the presented picture was old or new in Experiments 1 and 2, and also judged whether a specific concept, labelled using words, had been studied in Experiment 2. The results showed that under both encoding conditions, the details of both negative and positive pictures were recognised better than those of neutral pictures. Also, the gist of negative pictures was recognised better than that of neutral pictures but only under the semantic condition. These data provide evidence that the LOP differentially modulates enhanced emotional memory for gist and details of pictures.     

Dissociable effects of conscious emotion regulation strategies on explicit and implicit memory

The authors manipulated emotion regulation strategies at encoding and administered explicit and implicit memory tests. In Experiment 1, participants used reappraisal to enhance and decrease the personal relevance of unpleasant and neutral pictures. In Experiment 2, decrease cues were replaced with suppress cues that directed participants to inhibit emotion-expressive behavior. Across experiments, using reappraisal to enhance the personal relevance of pictures improved free recall. By contrast, attempting to suppress emotional displays tended to impair recall, especially compared to the enhance condition. Using reappraisal to decrease the personal relevance of pictures had different effects depending on picture type. Paired with unpleasant pictures, the decrease cue tended to improve recall. Paired with neutral stimuli, the decrease cue tended to impair recall. Emotion regulation did not affect perceptual priming. Results highlight dissociable effects of emotion regulation on explicit and implicit memory, as well as dissociations between regulation strategies with respect to explicit memory.     

Enhanced memory for emotional pictures: A product of increased attention to affective stimuli?

The current experiment addressed the question, is enhanced memory for emotional pictures due to increased attention to affective stimuli? Participants viewed pairs of pictures (emotional-neutral or neutral-neutral) whilst their eye movements were recorded; participants had to decide which picture out of each pair they preferred. There was increased attention to positive pictures and decreased attention to negative images during picture viewing. Despite this, when a recognition test was given 1 week later, memory enhancements were found for negative pictures only. Moreover, although there was a general correlation between total inspection time and memory performance, this reliability was clear only for neutral pictures, and not for emotional images. The results suggest that memory advantages for emotional pictures can occur without increased attention to such images.     

独乐乐与众乐乐？社会与非社会正性情绪刺激的加工差异：一个ERP研究

个体情绪加工具有其生物基础,也受到文化因素的影响。社会性和非社会性情绪刺激加工可能存在不同的机制。然而,以往大多数研究主要关注负性情绪的加工差异。因此,本研究选取大学生被试20名采用图片感知范式（Picture Perception Paradigm）探讨个体在加工社会性和非社会性正性情绪刺激的脑电位活动差异。研究发现：（1）在P1成分上,情绪图片诱发的波幅要显著大于中性图片。（2）在N2成分上,正性社会情绪图片诱发的波幅要显著大于正性非社会情绪图片（3）在早期时间窗中,由正性社会情绪图片与非社会情绪图片诱发的LPP波幅差异不显著。在中期时间窗中,正性社会情绪图片与非社会情绪图片的LPP波幅差异显著。晚期时间窗中,正性社会情绪图片诱发的LPP波幅显著大于正性非社会情绪图片。由此,相对于非社会性请刺激来说,正性社会情绪刺激在加工上可能占据优势地位。     

No emotional "pop-out" effect in natural scene viewing

It has been shown that attention is drawn toward emotional stimuli. In particular, eye movement research suggests that gaze is attracted toward emotional stimuli in an unconscious, automated manner. We addressed whether this effect remains when emotional targets are embedded within complex real-world scenes. Eye movements were recorded while participants memorized natural images. Each image contained an item that was either neutral, such as a bag, or emotional, such as a snake or a couple hugging. We found no latency difference for the first target fixation between the emotional and neutral conditions, suggesting no extrafoveal "pop-out" effect of emotional targets. However, once detected, emotional targets held attention for a longer time than neutral targets. The failure of emotional items to attract attention seems to contradict previous eye-movement research using emotional stimuli. However, our results are consistent with studies examining semantic drive of overt attention in natural scenes. Interpretations of the results in terms of perceptual and attentional load are provided.     

Incidental retrieval of emotional contexts in post-traumatic stress disorder and depression: an fMRI study

In the present study, we used fMRI to assess patients suffering from post-traumatic stress disorder (PTSD) or depression, and trauma-exposed controls, during an episodic memory retrieval task that included non-trauma-related emotional information. In the study phase of the task neutral pictures were presented in emotional or neutral contexts. Participants were scanned during the test phase, when they were presented with old and new neutral images in a yes/no recognition memory task. fMRI results for the contrast between old and new items revealed activation in a predominantly left-sided network of cortical regions including the left middle temporal, bilateral posterior cingulate, and left prefrontal cortices. Activity common to all three groups when correctly judging pictures encoded in emotional contexts was much more limited. Relative to the control and depressed groups the PTSD group exhibited greater sensitivity to correctly recognised stimuli in the left amygdala/ventral striatum and right occipital cortex, and more specific sensitivity to items encoded in emotional contexts in the right precuneus, left superior frontal gyrus, and bilateral insula. These results are consistent with a substantially intact neural system supporting episodic retrieval in patients suffering from PTSD. Moreover, there was little indication that PTSD is associated with a marked change in the way negatively valenced information, not of personal significance, is processed.     

Auditory emotional cues enhance visual perception

Recent studies show that emotional stimuli impair performance to subsequently presented neutral stimuli. Here we show a cross-modal perceptual enhancement caused by emotional cues. Auditory cue words were followed by a visually presented neutral target word. Two-alternative forced-choice identification of the visual target was improved by emotional cues as compared to neutral cues. When the cue was presented visually we replicated the emotion-induced impairment found in other studies. Our results suggest emotional stimuli have a twofold effect on perception. They impair perception by reflexively attracting attention at the expense of competing stimuli. However, emotional stimuli also induce a nonspecific perceptual enhancement that carries over onto other stimuli when competition is reduced, for example, by presenting stimuli in different modalities.     

Enhanced recognition of emotional stimuli in the chimpanzee (<Emphasis Type="Italic">Pan troglodytes</Emphasis>)

Humans often have a better memory of emotional events than neutral events. From the comparative-cognitive perspective, we explored the enhancement of recognition memory by emotion in chimpanzees (Pan troglodytes) using a serial probe recognition task. In this task, we sequentially presented a list of pictures to subjects and then tested their recognition of specific pictures from within the list. We selected pictures of aggressive chimpanzees as emotional stimuli and less tensed, relaxed chimpanzees as neutral stimuli. In Experiment 1, we gave four-item lists to two young chimpanzees; one showed significantly greater recognition of pictures depicting aggressive chimpanzees than neutral ones. In Experiment 2, this chimpanzee was further tested using a recognition task with eight-item lists. The subject again showed better recognition of emotional stimuli than neutral. Furthermore, the presence of an emotional stimulus in the list also facilitated recognition of the neutral item immediately following it. Overall, although only one of the two chimpanzees showed enhanced recognition memory by emotional stimuli, this is the first demonstration of such a response in the chimpanzee. The findings are discussed in comparison with those of human studies.     

Mindful attention predicts greater recovery from negative emotions,but not reduced reactivity

This study investigated the role of dispositional mindful attention in immediate reactivity to, and subsequent recovery from, laboratory-induced negative emotion. One hundred and fourteen undergraduates viewed blocks of negative pictures followed by neutral pictures. Participants’ emotional responses to negative pictures and subsequent neutral pictures were assessed via self-reported ratings. Participants’ emotional response to negative pictures was used to index level of emotional reactivity to unpleasant stimuli; emotional response to neutral pictures presented immediately after the negative pictures was used to index level of emotional recovery from pre-induced negative emotion (residual negativity). Results indicated that mindful attention was not associated with the emotional response to negative pictures, but it was associated with reduced negative emotion in response to the neutral pictures presented immediately after the negative pictures, suggesting better recovery as opposed to reduced reactivity. This effect was especially pronounced in later experimental blocks when the accumulation of negative stimuli produced greater negative emotion from which participants had to recover. The current study extends previous findings on the relationship between dispositional mindfulness and reduced negative emotion by demonstrating that mindful attention may facilitate better recovery from negative emotion, possibly through more effective disengagement from previous stimuli.     

Attending to affect: appraisal strategies modulate the electrocortical response to arousing pictures

Arousing (unpleasant and pleasant) pictures elicit increased neurophysiological measures of perceptual processing. In particular, the electrocortical late positive potential (LPP) is enhanced for arousing, compared with neutral, pictures. To determine whether the magnitude of the LPP is sensitive to the way stimuli are appraised, 16 participants viewed both pleasant and unpleasant pictures and categorized them along an affective or nonaffective dimension. Results indicate that the LPP was reduced for both pleasant and unpleasant pictures when participants made nonaffective, compared with affective, judgments. These results are consistent with previous studies that have used functional neuroimaging to investigate the role of appraisal on emotional processing. The results are further discussed in terms of the utility of using the LPP to study emotion regulation.     

How chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>) perform in a modified emotional Stroop task

The emotional Stroop task is an experimental paradigm developed to study the relationship between emotion and cognition. Human participants required to identify the color of words typically respond more slowly to negative than to neutral words (emotional Stroop effect). Here we investigated whether chimpanzees (Pan troglodytes) would show a comparable effect. Using a touch screen, eight chimpanzees were trained to choose between two simultaneously presented stimuli based on color (two identical images with differently colored frames). In Experiment 1, the images within the color frames were shapes that were either of the same color as the surrounding frame or of the alternative color. Subjects made fewer errors and responded faster when shapes were of the same color as the frame surrounding them than when they were not, evidencing that embedded images affected target selection. Experiment 2, a modified version of the emotional Stroop task, presented subjects with four different categories of novel images: three categories of pictures of humans (veterinarian, caretaker, and stranger), and control stimuli showing a white square. Because visits by the veterinarian that include anaesthetization can be stressful for subjects, we expected impaired performance in trials presenting images of the veterinarian. For the first session, we found correct responses to be indeed slower in trials of this category. This effect was more pronounced for subjects whose last anaesthetization experience was more recent, indicating that emotional valence caused the slowdown. We propose our modified emotional Stroop task as a simple method to explore which emotional stimuli affect cognitive performance in nonhuman primates.     

条件性的关联学习和消退过程的性别差异

采用事件相关电位技术和条件性关联学习模型相结合的方法, 考察在负性背景下男女性对一般事件的关联学习和消退是否存在差异。结果表明：在关联学习阶段, 男性较女性表现出P2潜伏期缩短和N2波幅增大, 而女性比男性表现出更大的P3波幅。在消退阶段, 女性较男性出现更小的P2波幅和更大的P3/LPP波幅。这说明女性可能慢于男性探索到条件刺激和非条件刺激之间的关联, 并且保持时间更久; 男性在相对早期对消退产生更大的反应, 女性则在相对晚期对消退投入更多的资源及努力。