Attention to the periphery attenuates the EPN and LPP

Current research shows that emotions have an important role in guiding attention and cognitions especially when the emotional stimuli are affective. Load theory proposes that when the perceptual load on attention is sufficiently high, irrelevant emotional stimuli is no longer attended to and thus will not produce a distracting effect. In this study 18 participants performed two discrimination tasks where their attention was manipulated spatially. To investigate the effect of spatial attention on ERP components, emotional pictures in 14 different semantic categories were shown while EEG was recorded. The results indicate that a successful perceptual load was achieved, reflected in the behavioral data that show there was a clear difference in performance between tasks. Further the results indicate that a strong effect was achieved in the mean amplitudes of both EPN and LPP corresponding to the semantic categories of pictures. Critically directing the attention to the periphery while emotionally salient pictures were presented attenuated the mean amplitude of both EPN and LPP

The effects of valenced odors on facial perception

We use our senses to navigate in the world. An important property of olfaction, the sense of smell, is to enable us to approach beneficial things, and to avoid what might be toxic or otherwise harmful in our environment. Other peoples’ behaviors are also paramount for our survival. Thus, we use our vision to decode their internal states from their facial expressions. For many modalities, multiple senses are integrated to enhance sensory percepts. In this thesis, I investigated how valenced odors affect the perception of facial expressions. Specifically, using a multi-method approach, I studied the integration of unpleasant and pleasant odor contexts on odor-congruent and incongruent facial expressions, disgusted, and happy faces. The effects I am interested in are those that valenced odors have on face perception, attention to faces, and the cortical processing of faces. To answer these questions, I used questionnaires, ratings, EEG, and behavioral measures such as reaction times. Across studies, ratings of face valence are affected in the direction of the odor valence (e.g., faces are rated more negatively in the context of an unpleasant odor). Also, overall, the results in my studies indicate that faces are perceived as more arousing in valenced odor contexts; however, these effects occur regardless of facial expression. In study 1, I found that valenced odors and facial expressions are integrated at an earlier time-frame than previously thought. Specifically, I found that the N170 event-related potential component (ERP) to disgusted facial expressions was lower in amplitude in the unpleasant odor condition than in the pleasant odor condition. This effect was not present for happy faces in the N170 component. An unpleasant odor might thus facilitate the processing of threat-related information. In study 2, I found evidence that odors, in general, did not affect the recognition speed of facial expressions that changed from neutral to disgusted or happy over 3 seconds. Also, I found robust evidence against congruency effects in facial expression recognition reaction times (RTs). The results indicated that faces overall were recognized faster in the unpleasant odor condition. Further, these results were not qualified by individual differences in body odor disgust. Thus, unpleasant odors might facilitate the recognition of facial expressions regardless of trait body odor disgust. In study 3, I studied whether valenced odors directed spatial attention toward odor-congruent facial expressions in a “dot-probe” task. I found decisive evidence that odors do not affect attention towards disgusted and happy facial expressions, casting doubt on the dot-probe experiment. However, I found that probes were detected faster as a function of time-on-task in the unpleasant odor condition. I hypothesized that this effect might be due to maintained vigilance in the presence of an unpleasant odor and task fluency effects. In summary, the results indicate that valenced odors affect facial perception. Generally, faces are perceived as more valenced and arousing in odor contexts. Further, an unpleasant odor may decrease RTs; however, this effect seems to be irrespective of the target type. Also, odor face integration may happen earlier than thought; yet, evidence in the literature is mixed, and more research is needed. The methods I have used may increase transparency and robustness of published results, and help accelerate knowledge development in this field of research

Gender moderates valence effects on the late positive potential to emotional distracters

Attention is captured more strongly by emotional pictures than by neutral pictures. This allocation of attention to emotional pictures is commonly indexed by the late positive potential (LPP), an event-related potential (ERP) that is larger for negative and positive pictures than for neutral pictures. However, findings are mixed in regards to valence effects, that is, whether the LPP is larger for negative pictures than for positive pictures (negativity bias) or vice versa (positivity bias). Additionally, previous ERP studies have not explicitly considered a moderating effect of gender. In the present study, positive, negative, and neutral pictures were shown at fixation but were always task-irrelevant. Results showed that LPP amplitudes for the positive and negative distracters were moderated by gender. Men showed a positivity bias on the LPP. Women did not show a clear valence bias on the LPP, but they showed a negativity bias on picture ratings. These gender differences for the LPP did not habituate, as they were obtained even for pictures that were repeated 20 times. Because previous studies with other measures suggest a positivity bias for men and a negativity bias for women, the present findings extend these studies suggesting that attention allocation for emotional pictures of different valence is similarly moderated by gender

Gender moderates valence effects on the late positive potential to emotional distracters

AbstractAttention is captured more strongly by emotional pictures than by neutral pictures. This allocation of attention to emotional pictures is commonly indexed by the late positive potential (LPP). This event-related potential (ERP) is larger for negative and positive pictures than for neutral pictures. However, findings are mixed in regards to valence effects, that is, whether the LPP is larger for negative pictures than for positive pictures (negativity bias) or vice versa (positivity bias). Additionally, previous ERP studies have not explicitly considered a moderating effect of gender. In the present study, positive, negative, and neutral pictures were shown at fixation but were always task-irrelevant. Results showed that LPP amplitudes for the positive and negative distracters were moderated by gender. Men showed a positivity bias on the LPP (i.e., larger amplitudes for positive pictures than for negative pictures). Women did not show a clear valence bias on the LPP, but they showed a negativity bias on picture ratings. These gender differences for the LPP did not habituate, as they were obtained even for pictures that were repeated 20 times. Because previous studies with other measures suggest a positivity bias for men and a negativity bias for women, the present findings extend these studies suggesting that attention allocation for emotional pictures of different valence is similarly moderated by gender

Background odors affect behavior in a dot-probe task with emotionally expressive faces

Odors affect perception of social cues in visual environments. Although often underestimated, people use their sense of smell to guide approach or avoidance behavior in social contexts. However, underlying psychological mechanisms are not well known. Prior work suggested olfactory effects are due to increased attention or arousal, or depend on the congruency between olfactory and visual cues. Our aim was to assess how odors influence attentional processes using a dot-probe task with odor-congruent and odor-incongruent facial expressions (happy, disgusted and neutral expressions paired with pleasant odor, unpleasant odor and no-odor). In a preregistered analysis plan, we hypothesized either faster reaction times attributed to arousal from odors in general, or to faces that were emotionally congruent with the odors. We also hypothesized time-on-task effects specific to the odor compared to the control condition. Using Bayesian linear models, we found strong evidence that the faces were rated as more arousing and emotional in odor contexts. However, the dot-probe task did in fact not provide an effective cue to selective visual attention, and odors did not modulate overall attention to the faces. However, we found a time-on-task effect such that in the unpleasant odor condition, response times decreased over time, whereas in the no-odor and pleasant condition there was a slight increase in response times. We conclude that time-on-task effects is an interesting venue for odor-visual interaction research, and such effects might explain inconsistent findings in the prior research literature

Attentional biases in affective face odor integration

Odors affect perception of social cues in visual environments. Although often underestimated, people use their sense of smell to guide approach or avoidance behavior in social contexts. However, psychological mechanisms underlying odor effects are not well known. Prior work suggested a role for increased attention or arousal effects, or congruency in the odor-visual environment. In this pre-registered study, the aim was to assess how odors influence attentional processes using a dot-probe task with odor-congruent and incongruent facial expressions. We hypothesized either faster reaction times attributed to arousal from odors in general, or to faces that were emotionally congruent with the odors. We were also interested in time-on-task effects. Using Bayesian linear models, we found strong evidence that the faces were rated as more arousing and emotional in odor contexts. However, the dot-probe task did in fact not provide an effective cue to selective visual attention, and odors did not modulate overall attention to the faces. Instead, we found that in the unpleasant odor condition, response times decreased with time-on-task, whereas, in the no-odor and pleasant condition there was a slight increase in response times. We conclude that time-on-task effects is an interesting venue for odor-visual interaction research, and such effects might explain inconsistent findings in the prior research literature

Attentional biases in affective face odor integration

We use the dot-probe task to investigate the effect of affective odors on attention to emotional face