Proactive Control of Emotional Distraction: An ERP Investigation

<p>According to the Dual Mechanisms of Control (DMC) framework (Braver, 2012) distraction can be controlled either proactively (i.e., before the onset of a distractor) or reactively (i.e., after the onset of a distractor). Research clearly indicates that, when distractors are emotionally neutral, proactive mechanisms are more effective at controlling distraction than reactive mechanisms. However, whether proactive control mechanisms can control irrelevant emotional distractions as effectively as neutral distraction is not known. In the current thesis I examined cognitive control over emotional distraction. In Experiment 1, I tested whether proactive mechanisms can control emotional distraction as effectively as neutral distraction. Participants completed a distraction task. On each trial, they determined whether a centrally presented target letter (embedded amongst a circle of ‘o’s) was an ‘X’ or an ‘N’, while ignoring peripheral distractors (negative, neutral, or positive images). Distractors were presented on either a low proportion (25%) or a high proportion (75%) of trials, to evoke reactive and proactive cognitive control strategies, respectively. Emotional images (both positive and negative) produced more distraction than neutral images in the low distractor frequency (i.e., reactive control) condition. Critically, emotional distraction was almost abolished in the high distractor frequency condition; emotional images were only slightly more distracting than neutral images, suggesting that proactive mechanisms can control emotional distraction almost as effectively as neutral distraction. In Experiment 2, I replicated and extended Experiment 1. ERPs were recorded while participants completed the distraction task. An early index (the early posterior negativity; EPN) and a late index (the late positive potential; LPP) of emotional processing were examined to investigate the mechanisms by which proactive control minimises emotional distraction. The behavioural results of Experiment 2 replicated Experiment 1, providing further support for the hypothesis that proactive mechanisms can control emotional distractions as effectively as neutral distractions. While proactive control was found to eliminate early emotional processing of positive distractors, it paradoxically did not attenuate late emotional processing of positive distractors. On the other hand, proactive control eliminated late emotional processing of negative distractors. However, the early index of emotional processing was not a reliable index of negative distractor processing under either reactive or proactive conditions. Taken together, my findings show that proactive mechanisms can effectively control emotional distraction, but do not clearly establish the mechanisms by which this occurs.</p>

Proactive Control of Emotional Distraction: An ERP Investigation

<p>According to the Dual Mechanisms of Control (DMC) framework (Braver, 2012) distraction can be controlled either proactively (i.e., before the onset of a distractor) or reactively (i.e., after the onset of a distractor). Research clearly indicates that, when distractors are emotionally neutral, proactive mechanisms are more effective at controlling distraction than reactive mechanisms. However, whether proactive control mechanisms can control irrelevant emotional distractions as effectively as neutral distraction is not known. In the current thesis I examined cognitive control over emotional distraction. In Experiment 1, I tested whether proactive mechanisms can control emotional distraction as effectively as neutral distraction. Participants completed a distraction task. On each trial, they determined whether a centrally presented target letter (embedded amongst a circle of ‘o’s) was an ‘X’ or an ‘N’, while ignoring peripheral distractors (negative, neutral, or positive images). Distractors were presented on either a low proportion (25%) or a high proportion (75%) of trials, to evoke reactive and proactive cognitive control strategies, respectively. Emotional images (both positive and negative) produced more distraction than neutral images in the low distractor frequency (i.e., reactive control) condition. Critically, emotional distraction was almost abolished in the high distractor frequency condition; emotional images were only slightly more distracting than neutral images, suggesting that proactive mechanisms can control emotional distraction almost as effectively as neutral distraction. In Experiment 2, I replicated and extended Experiment 1. ERPs were recorded while participants completed the distraction task. An early index (the early posterior negativity; EPN) and a late index (the late positive potential; LPP) of emotional processing were examined to investigate the mechanisms by which proactive control minimises emotional distraction. The behavioural results of Experiment 2 replicated Experiment 1, providing further support for the hypothesis that proactive mechanisms can control emotional distractions as effectively as neutral distractions. While proactive control was found to eliminate early emotional processing of positive distractors, it paradoxically did not attenuate late emotional processing of positive distractors. On the other hand, proactive control eliminated late emotional processing of negative distractors. However, the early index of emotional processing was not a reliable index of negative distractor processing under either reactive or proactive conditions. Taken together, my findings show that proactive mechanisms can effectively control emotional distraction, but do not clearly establish the mechanisms by which this occurs.</p>

Humans reconfigure target and distractor processing to address distinct task demands

When faced with distraction, we can focus more on goal-relevant information (targets) or focus less goal-conflicting information (distractors). How people decide to distribute cognitive control across targets and distractors remains unclear. To help address this question, we developed a parametric attentional control task with a graded manipulation to both target discriminability and distractor interference. We find that participants exert independent control over target and distractor processing. We measured control adjustments through the influence of incentives and previous conflict on target and distractor sensitivity, finding that these have dissociable influences on control. Whereas incentives preferentially led to target enhancement, conflict on the previous trial preferentially led to distractor suppression. These distinct drivers of control altered sensitivity to targets and distractors early in the trial, and were promptly followed by reactive reconfiguration towards task-appropriate feature sensitivity. Finally, we provide a process-level account of these findings by show that these control adjustments are well-captured by an evidence accumulation model with attractor dynamics over feature weights. These results help establish a process-level account of control configuration that provides new insights into how multivariate attentional signals are optimized to achieve task goals.

Drawn to Distraction: Anxiety Impairs Neural Suppression of Known Distractor Features in Visual Search

When searching for a target, it is possible to suppress the features of a known distractor. This suppression may prevent distractor processing altogether or only after the distractor initially captures attention (i.e., search and destroy). However, suppression may be impaired in individuals with attentional control deficits, such as in high anxiety. In this study (n = 48), we used ERPs to examine the time course of attentional enhancement and suppression when participants were given pretrial information about target or distractor features. Consistent with our hypothesis, we found that individuals with higher levels of anxiety had lower neural measures of suppressing the template-matching distractor, instead showing enhanced processing. These findings indicate that individuals with anxiety are more likely to use a search-and-destroy mechanism of negative templates—highlighting the importance of attentional control abilities in distractor-guided search.

The role of perceptual load and sensory degradation on cross-modal selective attention

To understand our sensory environment, our perceptual system must employ selective attention; the ability to attend to target information while ignoring distracting information. In the uni–modal domain the main determinant of selective attention success is capacity limitation, where only when processing capacity is taxed by the target (high load; HL) is distraction eliminated (perceptual load theory; PLT). Conversely, data limits while also increasing task demands, do not benefit selective attention as these limits are often driven by sensory degradation (SD) such that placing additional resources towards the target is not beneficial. Investigations of PLT to the cross–modal domain have produced mixed results, and no study has yet directly contrasted the impact of capacity and data limits in the cross–modal domain. The present dissertation focused on examining the impact of Perceptual Load (PL) and SD on cross–modal selective attention, in addition to examining how these factors would interact with the attended modality and individual differences (ID) in attentional control. Experiment 1 used a go–no–go manipulation of PL to show that distractor effects were not reduced at HL compared to low load (LL) condition and instead displayed trends for increased distraction under HL regardless of the attended modality. Experiment 2 used the addition of noise to create SD, and found that distractor processing increased under SD, again regardless of the attended modality. Experiment 1 and 2 used a uni–modal measure of attentional control, and overall both studies did not find a consistent pattern of correlation with cross–modal selective attention, suggesting important differences between the two. Experiment 3 used a single manipulation to create HL and SD conditions in a single experiment, and also found that both HL and SD showed trends of increased distraction relative to LL conditions. Overall the current dissertation suggests that capacity limitations arise at the modality level, and so do not impact cross–modal selective attention. As such, the findings of the current dissertation suggest there is no difference between capacity and data limited conditions in the cross–modal domain. Results are interpreted within a cross–modal selective attention framework.

The role of perceptual load and sensory degradation on cross-modal selective attention

To understand our sensory environment, our perceptual system must employ selective attention; the ability to attend to target information while ignoring distracting information. In the uni–modal domain the main determinant of selective attention success is capacity limitation, where only when processing capacity is taxed by the target (high load; HL) is distraction eliminated (perceptual load theory; PLT). Conversely, data limits while also increasing task demands, do not benefit selective attention as these limits are often driven by sensory degradation (SD) such that placing additional resources towards the target is not beneficial. Investigations of PLT to the cross–modal domain have produced mixed results, and no study has yet directly contrasted the impact of capacity and data limits in the cross–modal domain. The present dissertation focused on examining the impact of Perceptual Load (PL) and SD on cross–modal selective attention, in addition to examining how these factors would interact with the attended modality and individual differences (ID) in attentional control. Experiment 1 used a go–no–go manipulation of PL to show that distractor effects were not reduced at HL compared to low load (LL) condition and instead displayed trends for increased distraction under HL regardless of the attended modality. Experiment 2 used the addition of noise to create SD, and found that distractor processing increased under SD, again regardless of the attended modality. Experiment 1 and 2 used a uni–modal measure of attentional control, and overall both studies did not find a consistent pattern of correlation with cross–modal selective attention, suggesting important differences between the two. Experiment 3 used a single manipulation to create HL and SD conditions in a single experiment, and also found that both HL and SD showed trends of increased distraction relative to LL conditions. Overall the current dissertation suggests that capacity limitations arise at the modality level, and so do not impact cross–modal selective attention. As such, the findings of the current dissertation suggest there is no difference between capacity and data limited conditions in the cross–modal domain. Results are interpreted within a cross–modal selective attention framework.

Differing Time Courses of Reward-Related Attentional Processing: An EEG Source-Space Analysis

Since our environment typically contains more information than can be processed at any one time due to the limited capacity of our visual system, we are bound to differentiate between relevant and irrelevant information. This process, termed attentional selection, is usually categorized into bottom-up and top-down processes. However, recent research suggests reward might also be an important factor in guiding attention. Monetary reward can bias attentional selection in favor of task-relevant targets and reduce the efficiency of visual search when a reward-associated, but task-irrelevant distractor is present. This study is the first to investigate reward-related target and distractor processing in an additional singleton task using neurophysiological measures and source space analysis. Based on previous studies, we hypothesized that source space analysis would find enhanced neural activity in regions of the value-based attention network, such as the visual cortex and the anterior cingulate. Additionally, we went further and explored the time courses of the underlying attentional mechanisms. Our neurophysiological results showed that rewarding distractors led to a stronger attentional capture. In line with this, we found that reward-associated distractors (compared with reward-associated targets) enhanced activation in frontal regions, indicating the involvement of top-down control processes. As hypothesized, source space analysis demonstrated that reward-related targets and reward-related distractors elicited activation in regions of the value-based attention network. However, these activations showed time-dependent differences, indicating that the neural mechanisms underlying reward biasing might be different for task-relevant and task-irrelevant stimuli.

Parallel fast and slow recurrent cortical processing mediates target and distractor selection in visual search

Visual search has been commonly used to study the neural correlates of attentional allocation in space. Recent electrophysiological research has disentangled distractor processing from target processing, showing that these mechanisms appear to operate in parallel and show electric fields of opposite polarity. Nevertheless, the localization and exact nature of this activity is unknown. Here, using MEG in humans, we provide a spatiotemporal characterization of target and distractor processing in visual cortex. We demonstrate that source activity underlying target- and distractor-processing propagates in parallel as fast and slow sweep from higher to lower hierarchical levels in visual cortex. Importantly, the fast propagating target-related source activity bypasses intermediate levels to go directly to V1, and this V1 activity correlates with behavioral performance. These findings suggest that reentrant processing is important for both selection and attenuation of stimuli, and such processing operates in parallel feedback loops.