Perception Of Affective Pictures Research Articles

Event related beta and gamma oscillatory responses during perception of affective pictures

Several studies reveal that unpleasant pictures elicit higher beta and gamma responses than pleasant and/or neutral pictures; however, the effect of stimulation design (block or random) has not been studied before. The aim of the study is to analyze the common and distinct parameters of affective picture perception in block and random designs by means of analysis of high frequency oscillatory dynamics (beta and gamma). EEG of 22 healthy subjects was recorded at 32 locations. The participants passively viewed 120 emotional pictures (10×4 unpleasant, 10×4 pleasant, 10×4 neutral) in block and random designs. The phase-locking and power of event related beta (14–28Hz) and gamma (29–48Hz) oscillations were analyzed for two different time windows (0–200ms/200–400ms). Statistical analysis showed that in the 0–200ms time window, during the block design, unpleasant stimulation elicited higher beta phase-locking and beta power than the pleasant and neutral stimulation (p<0.05). In the 200–400ms time window, during the block design, over occipital electrodes unpleasant stimulation elicited higher gamma response power than the pleasant stimulation and neutral stimulation (p<0.05). Unpleasant stimulation did not elicit higher beta or gamma responses in the random design. The present study showed that experimental design highly influences the perception of IAPS pictures. Unpleasant stimulation elicited higher event related beta and gamma phase-locking and power only in block design but not in random design. It seems that longer blocks of aversive pictures affect the brain more than the rapid observation of these pictures.

P395: Switching from bimanual to unimanual tapping reveals two distinct post-switching beta synchronization processes

P395: Switching from bimanual to unimanual tapping reveals two distinct post-switching beta synchronization processes

P396: Analysis of event related beta and gamma oscillations in perception of affective pictures

P396: Analysis of event related beta and gamma oscillations in perception of affective pictures

Arousal modulates valence effects on both early and late stages of affective picture processing in a passive viewing task

Valence and arousal are primary dimensions of affective stimuli. An interaction of these two factors on affective processing is largely unknown. In this study, the processing of affective pictures was investigated in an orthogonal valence (positive vs. negative) by arousal (high vs. low) task design. Participants were instructed to passively view each presented picture and did not need to make any responses. The valence by arousal interaction was observed on three event-related potential (ERP) components, including the P2 (160–190 ms), N2 (220–320 ms) and late positive potential (LPP) (400–700 ms). This interaction revealed that negative pictures evoked larger neural responses compared with positive pictures (i.e., negative bias) at the high-arousal level, whereas negative pictures evoked smaller neural responses than positive pictures (i.e., positive offset) at the low-arousal level. The current results suggest that the effect of emotional valence on affective picture perception is modulated by levels of arousal at both early and late stages of processing. Finally, the main effect of valence was evident in the P1 component (90–110 ms) and arousal effect in the N1 component (120–150 ms).

Placebo treatment can alter primary visual cortex activity and connectivity

Placebo treatment can alter brain activation in regions implicated in affective processing and cognitive control of emotions. This functional magnetic resonance imaging (fMRI) study investigated whether a placebo can additionally modulate visual cortex activity and connectivity during affective picture perception. The participants underwent a retest design where they were presented with disgusting, fear-eliciting and neutral pictures both with, and without a placebo (inert pill presented with the suggestion that it can reduce disgust symptoms). The placebo provoked a strong decrease in experienced disgust. This was accompanied by a reduced activation of the primary visual cortex, which showed reduced interaction with the amygdala and the insula. Accordingly, placebos are able to affect basic perceptive processes.

Emotional reactivity during anticipation and perception of affective pictures.

The focus of the present study was on further exploring anticipatory responses to emotional stimuli by measuring the eyeblink startle reflex in a variation of the picture-picture affective learning procedure. Participants (113 undergraduate women) were not explicitly instructed before the experiment began. Instead, they had to learn the specific relations between cues (geometrical shapes) and emotional pictures based on pairings during the first part of the task. Plausible contingency learning effects were tested afterwards, in a parallel sequence of trials including auditory probes during cues and pictures processing during the second part of the task. Results did show the typical affective startle modulation pattern during perception, linear F(1, 200) = 52.67, p < .0001, but unexpected inhibition for both pleasant and unpleasant, compared to neutral cues, during anticipation, quadratic F(1, 200) = 7.07, p < .009. All patterns of startle modulation were independent of cue-picture contingency awareness (all interactions Fs < 1). Skin conductance changes showed the predictable quadratic trend either during picture perception or anticipatory periods (greater activity for emotional vs. neutral; overall quadratic F(1, 224) = 7.04, p < .01), only for participants fully aware of the cue-picture contingency, quadratic F(1, 158) = 5.86, p < .02. Overall, our results during anticipation (cues processing) seem to suggest that more resources were allocated to highly arousing pictures that engage attention. Differences between the present results and prior research may be attributed to procedural variations in the sample, cues, or instructions. Future studies should also explore in more detail the role of the contingency awareness during anticipation.

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.

Modifications of EEG Activity Related to Perception of Emotionally Colored, Erotic, and Neutral Pictures in Women during Different Phases of the Ovulatory (Menstrual) Cycle

We studied modifications of EEG activity related to perception of visual stimuli (pictures) of the International Affective Picture System (IAPS) in women during different phases of the ovulatory (menstrual) cycle. We found that the woman’s brain is most intensely activated by both emotionally negative and positive visual stimuli during the follicular phase of the ovulatory cycle, while such activation is minimum during ovulation per se. Upon the action of neutral stimuli, cerebral activation was the most intense during the lutein phase (compared with that within other phases); manifestations of activation were concentrated in the right hemisphere. Cognitive and emotional components of perception of affective pictures were expressed to a greatest extent in the course of viewing positive stimuli during the follicular phase. Perception of emotionally pleasant stimuli during other phases was accompanied by lateralization of activation of sensory and analytical processes in the left hemisphere during the ovulatory phase and in the right hemisphere within the lutein phase. The viewing of emotionally negative pictures during the follicular phase led to a rise in the power of theta oscillations in the left frontal region and also to depression of the alpha activity in central/parietal parts of the left hemisphere, which can result from aggravation of anxiety and verbally shaped disturbing ideas upon the action of such stimuli. Presentation of erotically colored visual stimuli caused the most intense changes in the EEG, which depended on the phases of the ovulatory cycle, during post-stimulation time interval but not during the viewing of pictures itself.

Affective picture perception: Emotion, context, and the late positive potential

Event-related potentials (ERP) were measured when pleasant, neutral or unpleasant pictures were presented in the context of similarly valenced stimuli, and compared to ERPs elicited when the same pictures were viewed in an intermixed context. An early ERP component (150–300 ms) measured over occipital and fronto-central sensors was specific to viewing pleasant pictures and was not affected by presentation context. Replicating previous studies, emotional pictures prompted a larger late positive potential (LPP, 400–700 ms) and a larger positive slow wave (1–6 s) over centro-parietal sensors that also did not differ by presentation context. On the other hand, ERPs elicited when viewing neutral pictures varied as a function of context, eliciting somewhat larger LPPs when presented in blocks, and prompting smaller slow waves over occipital sensors. Taken together, the data indicate that emotional pictures prompt increased attention and orienting that is unaffected by its context of presentation, whereas neutral pictures are more vulnerable to context manipulations.

Motivational Effects of Success Or Failure Feedback on the Perception of Affective Pictures

A study of perception of affective pictures from the International Affective Photo System, using the Self Assessment Manikin scale, was conducted. It was hypothesized that participants' affective ratings could be moderated by a subjective experience of success or failure. Analysis, based on a sample of 36 university students, showed an approach tendency for women when they were exposed to positive pictures in the success condition. This approach tendency was associated with relatively shorter processing times and high affective ratings. Men showed relatively shorter processing times and high affective ratings when exposed to negative pictures. For memory-related measures, the highest scores were observed in the success condition for exposure to pleasant pictures. The results are discussed in terms of affective-related self-regulatory tendencies moderated by sex.

Repetition and Event-related Potentials: Distinguishing Early and Late Processes in Affective Picture Perception

A repetition paradigm was used to assess the nature of affective modulation of early and late components of the event-related potential (ERP) during picture viewing. High-density ERPs were measured while participants passively viewed affective or neutral pictures that were repeated up to 90 times each. Both ERP components were modulated by emotional arousal, with ERPs elicited when viewing pleasant and unpleasant pictures different than when viewing neutral pictures. On the other hand, repetition had different effects on these two components. The early occipitotemporal component (150-300 msec) primarily showed a decrease in amplitude within a block of repetitions that did not differ as a function of picture content. The late centroparietal component (300-600 msec) showed a decrease both between and within blocks of repetitions, with neutral pictures eliciting no late positive potential in the final block of the study. The data suggest that the early ERP primarily reflects obligatory perceptual processing that is facilitated by active short-term memory representations, whereas the late ERP reflects increased resource allocation due to the motivational relevance of affective cues.

Event-related potentials and visual avoidance in blood phobics: is there any attentional bias?

The possible presence of processing biases for threat-relevant information in blood-injection-injury phobia has been largely neglected in the literature. This issue was addressed by recording the late components (P300 and slow waves) of event-related potentials (ERPs) in the context of affective picture perception, as indicators of processing resources allocation. Blood phobics and healthy controls were shown threat-relevant, emotional threat-irrelevant, and neutral pictures. Free viewing time (VT) was measured as an index of voluntary visual avoidance, along with self-reports of pleasantness and arousal. No group differences as a function of picture content emerged for ERPs. Blood phobics spent less time viewing mutilations than did controls, but they did not show a clear-cut visual avoidance. As expected, individuals with phobias rated blood-related pictures as more unpleasant and arousing relative to controls. ERP results are in line with the limited behavioral data in the literature in demonstrating that blood phobics do not show an attentional bias toward threat-relevant stimuli.