The Dual Mechanisms of Cognitive Control (DMCC) project: Validation of an on-line behavioral task battery

Cognitive control serves a crucial role in human higher mental functions. The Dual Mechanisms of Control (DMC) account provides a unifying theoretical framework that decomposes cognitive control into two qualitatively distinct mechanisms – proactive control and reactive control. While prior behavioral and neuroimaging work has demonstrated the validity of individual tasks in isolating these two mechanisms of control, there has not been a comprehensive, theoretically-guided task battery specifically designed to tap into proactive and reactive control across different domains of cognition. To address this critical limitation and provide useful methodological tools for future investigations, the Dual Mechanisms of Cognitive Control (DMCC) task battery was developed to probe these two control modes, as well as their intra-individual and inter-individual differences, across four prototypical domains of cognition: selective attention, context processing, multi-tasking, and working memory. We present this task battery, along with detailed descriptions of the experimental manipulations used to encourage shifts to proactive or reactive control in each of the four task domains. We rigorously evaluate the group effects of these manipulations in primary indices of proactive and reactive control, establishing the validity of the DMCC task battery in providing dissociable yet convergent measures of the two cognitive control modes.

Cognitive Control in Young and Older Adults: Does Mood Matter?

The dual mechanisms of control framework (DMC) proposes two modes of cognitive control: proactive and reactive control. In anticipation of an interference event, young adults primarily use a more proactive control mode, whereas older adults tend to use a more reactive one during the event, due to age-related deficits in working memory. The current study aimed to examine the effects of mood induction on cognitive control mode in older (ages 65+) compared to young adults (ages 18–30) with a standard letter-cue (Experiment 1) and a modified face-cue AX-CPT (Experiment 2). Mood induction into negative and/or positive mood versus neutral mood was conducted prior to the cognitive control task. Experiment 1 replicated the typical pattern of proactive control use in young adults and reactive control use in older adults. In Experiment 2, older adults showed comparable proactive control to young adults in their response time (RT). Mood induction showed little effect on cognitive control across the two experiments. These results did not reveal consistent effects of mood (negative or positive) on cognitive control mode in young and older adults, but discovered (or demonstrated) that older adults can engage proactive control when dichotomous face cues (female or male) are used in AX-CPT.

Learning to Expect the Predictable: The Role of Expectation in the Cognitive Control of Attention

<p>Some of the visual world is relevant to our goals and needs. Much more is not. A problem we face frequently in day-to-day living is that we are distracted by what is not relevant to our goals at the cost of attention towards what is. Emotional stimuli in particular have been shown to be very effective distractors, out-competing task-relevant stimuli for our attentional resources (Carretié, 2014; Pessoa, 2005; Pourtois et al., 2013). How often emotional distractors occur can alter our ability to ignore them and remain task focussed (Grimshaw et al., 2018; Schmidts et al., 2020). The Dual Mechanisms of Control framework (Braver et al., 2007; Braver, 2012) suggests that, because we can expect upcoming distractors when they occur frequently, we can effectively avoid distraction through proactive control; the use of effortful preparatory cognitive control strategies. That said, when distractors are frequent, we also become more experienced with them, and resolving the attentional conflict they create. The present investigation spanned two experiments assessing whether expectation of upcoming distractors would elicit proactive control while holding the experience of previous distractors constant. In Experiment 1 participants performed a simple perceptual task at fixation while neutral or negative task irrelevant images appeared peripherally on 25% of trials, either predictably in sequence (every fourth trial) or randomly. Expectation of distraction did not improve participants’ ability to avoid emotional distraction. A paradoxical expectation effect was also found wherein distraction was increased rather than decreased when distractors occurred predictably. In Experiment 2 distractors appeared either predictably (every fourth trial), on a random 25% of trials, or on a random 75% of trials. However, neutral and emotional images were now presented at fixation with the perceptual task presented above and below. Greater distractor frequency led to lower distraction and expectation of upcoming distractors again did not improve control, although a paradoxical increase in distraction was not replicated. Findings indicate that expectation of upcoming distractors alone is not sufficient to drive individuals to implement proactive control. Rather, distractor frequency is suggested to drive proactive control through implicit changes in top-down control settings based on experience. While the processes behind experience-driven proactive control are unclear, conflict adaptation and selection history are discussed as possible mechanisms of experience driven proactive control. Critically, present findings also indicate that emotional stimuli may present a unique challenge to our ability to control our attention.</p>

Learning to Expect the Predictable: The Role of Expectation in the Cognitive Control of Attention

<p>Some of the visual world is relevant to our goals and needs. Much more is not. A problem we face frequently in day-to-day living is that we are distracted by what is not relevant to our goals at the cost of attention towards what is. Emotional stimuli in particular have been shown to be very effective distractors, out-competing task-relevant stimuli for our attentional resources (Carretié, 2014; Pessoa, 2005; Pourtois et al., 2013). How often emotional distractors occur can alter our ability to ignore them and remain task focussed (Grimshaw et al., 2018; Schmidts et al., 2020). The Dual Mechanisms of Control framework (Braver et al., 2007; Braver, 2012) suggests that, because we can expect upcoming distractors when they occur frequently, we can effectively avoid distraction through proactive control; the use of effortful preparatory cognitive control strategies. That said, when distractors are frequent, we also become more experienced with them, and resolving the attentional conflict they create. The present investigation spanned two experiments assessing whether expectation of upcoming distractors would elicit proactive control while holding the experience of previous distractors constant. In Experiment 1 participants performed a simple perceptual task at fixation while neutral or negative task irrelevant images appeared peripherally on 25% of trials, either predictably in sequence (every fourth trial) or randomly. Expectation of distraction did not improve participants’ ability to avoid emotional distraction. A paradoxical expectation effect was also found wherein distraction was increased rather than decreased when distractors occurred predictably. In Experiment 2 distractors appeared either predictably (every fourth trial), on a random 25% of trials, or on a random 75% of trials. However, neutral and emotional images were now presented at fixation with the perceptual task presented above and below. Greater distractor frequency led to lower distraction and expectation of upcoming distractors again did not improve control, although a paradoxical increase in distraction was not replicated. Findings indicate that expectation of upcoming distractors alone is not sufficient to drive individuals to implement proactive control. Rather, distractor frequency is suggested to drive proactive control through implicit changes in top-down control settings based on experience. While the processes behind experience-driven proactive control are unclear, conflict adaptation and selection history are discussed as possible mechanisms of experience driven proactive control. Critically, present findings also indicate that emotional stimuli may present a unique challenge to our ability to control our attention.</p>

Motivation reduces positive and negative emotional distractions

<p>Attention is biased toward emotional stimuli, which are often important for our biologically-determined goals of survival and reproduction. But to succeed in our daily tasks we must sometimes ignore emotional stimuli that are not relevant to current goals. In four experiments, I examine the extent to which we can ignore emotional stimuli if we are motivated to do so. I draw on the Dual Mechanisms of Control (DMC) framework which proposes that we use two modes of control to deal with distraction: reactive control, which shifts attention back to a task after distraction has occurred; and proactive control, which allows us to anticipate and control distraction before it occurs. In non-emotional contexts, task motivation encourages use of more effective, but more effortful, proactive control to ignore emotionally-neutral distractions. But, little is known about how we can control our attention to ignore highly distracting emotional stimuli. In all experiments, participants completed a simple visual task while attempting to ignore task-irrelevant negative (mutilation scenes), positive (erotic scenes), and neutral images (scenes of people). Distraction was indexed by slowing on distractor trials relative to a scrambled distractor, or no distractor, baseline. To manipulate motivation, half the participants completed the task with no performance-contingent reward; the other half completed the task with the opportunity to earn points and/or money for fast and accurate performance. In Experiment 1 the images were presented centrally, so attention must be shifted from the distractor location to complete the task. Reward reduced distraction by both positive and negative emotional images. Experiment 2 replicated Experiment 1, and measured pupil dilation to index the timecourse of cognitive effort. The aim of Experiment 2 was to determine whether motivation elicits a shift to proactive control to reduce emotional distraction, as it does in non-emotional contexts. Again, reward reduced positive and negative distraction. Pupil findings indicated that reward dynamically enhanced proactive control prior to stimulus-onset, facilitating rapid disengagement from distractors, regardless of their expected emotional value. In contrast, a sustained proactive strategy was used across blocks in which emotional distractors were expected, relative to blocks in which neutral distractors were expected. In the final two experiments, the distractors were presented peripherally and so must capture attention away from the central targets to impair performance. In Experiment 3, and in Experiment 4 – in which the points did not represent money – reward reduced attentional capture by positive and negative emotional distractors. Together, findings show that motivation can enhance control of positive and negative distractions that appear both centrally, and peripherally. Findings extend the DMC framework to an emotional context; motivation elicits a shift to proactive control, even when distractors are high arousal emotional stimuli. Further, in three out of four experiments, reward reduced emotional to a greater extent than neutral distraction, consistent with reward altering the outcome of goal-driven attentional competition between the targets and distractors. Understanding the complex interactions between motivation, emotion, and cognitive control will help to elucidate how we successfully navigate the world to achieve our goals.</p>

Motivation reduces positive and negative emotional distractions

<p>Attention is biased toward emotional stimuli, which are often important for our biologically-determined goals of survival and reproduction. But to succeed in our daily tasks we must sometimes ignore emotional stimuli that are not relevant to current goals. In four experiments, I examine the extent to which we can ignore emotional stimuli if we are motivated to do so. I draw on the Dual Mechanisms of Control (DMC) framework which proposes that we use two modes of control to deal with distraction: reactive control, which shifts attention back to a task after distraction has occurred; and proactive control, which allows us to anticipate and control distraction before it occurs. In non-emotional contexts, task motivation encourages use of more effective, but more effortful, proactive control to ignore emotionally-neutral distractions. But, little is known about how we can control our attention to ignore highly distracting emotional stimuli. In all experiments, participants completed a simple visual task while attempting to ignore task-irrelevant negative (mutilation scenes), positive (erotic scenes), and neutral images (scenes of people). Distraction was indexed by slowing on distractor trials relative to a scrambled distractor, or no distractor, baseline. To manipulate motivation, half the participants completed the task with no performance-contingent reward; the other half completed the task with the opportunity to earn points and/or money for fast and accurate performance. In Experiment 1 the images were presented centrally, so attention must be shifted from the distractor location to complete the task. Reward reduced distraction by both positive and negative emotional images. Experiment 2 replicated Experiment 1, and measured pupil dilation to index the timecourse of cognitive effort. The aim of Experiment 2 was to determine whether motivation elicits a shift to proactive control to reduce emotional distraction, as it does in non-emotional contexts. Again, reward reduced positive and negative distraction. Pupil findings indicated that reward dynamically enhanced proactive control prior to stimulus-onset, facilitating rapid disengagement from distractors, regardless of their expected emotional value. In contrast, a sustained proactive strategy was used across blocks in which emotional distractors were expected, relative to blocks in which neutral distractors were expected. In the final two experiments, the distractors were presented peripherally and so must capture attention away from the central targets to impair performance. In Experiment 3, and in Experiment 4 – in which the points did not represent money – reward reduced attentional capture by positive and negative emotional distractors. Together, findings show that motivation can enhance control of positive and negative distractions that appear both centrally, and peripherally. Findings extend the DMC framework to an emotional context; motivation elicits a shift to proactive control, even when distractors are high arousal emotional stimuli. Further, in three out of four experiments, reward reduced emotional to a greater extent than neutral distraction, consistent with reward altering the outcome of goal-driven attentional competition between the targets and distractors. Understanding the complex interactions between motivation, emotion, and cognitive control will help to elucidate how we successfully navigate the world to achieve our goals.</p>

EXPRESS: Working Memory Capacity and Dual Mechanisms of Cognitive Control: An Experimental-Correlational Approach

Working memory is thought to be strongly related to cognitive control. Recent studies have sought to understand this relationship under the prism of the dual mechanisms of control (DMC) framework, in which cognitive control is thought to operate in two distinct modes: proactive and reactive. Several authors have concluded that a high working memory capacity is associated with a tendency to engage the more effective mechanism of proactive control. However, the predicted pattern of proactive control use has never been observed; correlational evidence is made difficult to interpret by the overall superiority of participants with a high working memory capacity: they tend to perform better even when proactive control should be detrimental. In two experiments, we used an experimental-correlational approach to experimentally induce the use of reactive or proactive control in the AX-CPT. The relation between working memory capacity and performance was unaffected, incompatible with the hypothesis that the better performance of participants with a high working memory capacity in the task is due to their use of proactive control. It remains unclear how individual differences in working memory capacity relate to cognitive control under the DMC framework.

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>

EEG evidence for the effective proactive control of emotional distraction

<p>Recent behavioural studies using an emotional flanker task have found that task-irrelevent emotional images are more distracting than neutral images under infrequent, but not frequent, distractor conditions.It has been proposed the effective control of distraction in the high distractor frequency condition may be due to a shift to a proactive control strategy, whereby a potential distraction is anticipated and minimised in advance. However, although it is well established that proactive control is effective at reducingneutral distraction, it is not yet clear whether emotional distraction can be effectively proactively controlled. In this thesis, I used EEG to measure pre-stimulus indices of proactive control in order to determine whether proactive control is responsible for the effective control of emotional and neutral distraction in the high distractor frequency condition, as well asto examine whether proactive control differs according whether a neutral or emotional distraction is anticipated.In addition to replicating the previous behavioural findings, posterior EEG alpha was found to be tonically suppressed in the high compared to low distractor frequency condition, strongly supporting the hypothesis that proactive control was engaged in the high distractor frequency condition. By contrast, there was no difference in phasic alpha suppression (i.e., the drop in alpha in response to fixation onset) between conditions, indicating that the more effective control of distraction in the high frequency distractor conditions was due to a sustained proactive control strategy, rather than greater trial-by-trial preparation to attend to the target. In addition, no alpha lateralisation was found, indicating the mechanisms by which distraction was proactively controlled did not include the preparatory suppression of expected distractor locations. Finally, tonic alpha did not differ according to the expected distractor valence, but phasic alpha suppression was more pronounced when negative, compared to neutral or positive, distractors were expected, independent of distractor frequency condition. This suggests proactive control was also used to some extent in the low distractor frequency condition, but more importantly also provides initial evidence that the proactive control of negative distraction may be unique. Taken together, my findings provide compelling evidence that emotional distraction can be effectively proactively controlled. Future research is needed to determine the mechanisms by which this occurs, and whether the proactive control of emotional distraction is particularly effortful.</p>

EEG evidence for the effective proactive control of emotional distraction

<p>Recent behavioural studies using an emotional flanker task have found that task-irrelevent emotional images are more distracting than neutral images under infrequent, but not frequent, distractor conditions.It has been proposed the effective control of distraction in the high distractor frequency condition may be due to a shift to a proactive control strategy, whereby a potential distraction is anticipated and minimised in advance. However, although it is well established that proactive control is effective at reducingneutral distraction, it is not yet clear whether emotional distraction can be effectively proactively controlled. In this thesis, I used EEG to measure pre-stimulus indices of proactive control in order to determine whether proactive control is responsible for the effective control of emotional and neutral distraction in the high distractor frequency condition, as well asto examine whether proactive control differs according whether a neutral or emotional distraction is anticipated.In addition to replicating the previous behavioural findings, posterior EEG alpha was found to be tonically suppressed in the high compared to low distractor frequency condition, strongly supporting the hypothesis that proactive control was engaged in the high distractor frequency condition. By contrast, there was no difference in phasic alpha suppression (i.e., the drop in alpha in response to fixation onset) between conditions, indicating that the more effective control of distraction in the high frequency distractor conditions was due to a sustained proactive control strategy, rather than greater trial-by-trial preparation to attend to the target. In addition, no alpha lateralisation was found, indicating the mechanisms by which distraction was proactively controlled did not include the preparatory suppression of expected distractor locations. Finally, tonic alpha did not differ according to the expected distractor valence, but phasic alpha suppression was more pronounced when negative, compared to neutral or positive, distractors were expected, independent of distractor frequency condition. This suggests proactive control was also used to some extent in the low distractor frequency condition, but more importantly also provides initial evidence that the proactive control of negative distraction may be unique. Taken together, my findings provide compelling evidence that emotional distraction can be effectively proactively controlled. Future research is needed to determine the mechanisms by which this occurs, and whether the proactive control of emotional distraction is particularly effortful.</p>