How to withhold or replace a prepotent response: An analysis of the underlying control processes and their temporal dynamics

Influence of flavor information on visual search: Attentional capture by and suppression of flavor-associated colors

Numerous studies have demonstrated the impact of flavor cues on visual search, yet the underlying mechanisms remain elusive. In this experiment, we used event-related potentials (ERPs) to examine whether, and if so, how flavor information could lead to attentional capture by, and suppression of, flavor-associated colors. The participants were asked to taste certain flavored beverages and subsequently complete a shape-based visual search task, while their neural activities were simultaneously recorded. The behavioral results revealed that the participants made slower responses when a distractor in the flavor-associated color (DFAC) was present, suggesting an attentional bias toward the flavor-associated color. The ERP results revealed that the N2pc was detected if the target and the DFAC were shown in the same visual field (e.g. both target and DFCA on the right side of the screen), when the pairings between flavor cues and target colors were incongruent. However, the N2pc was not observed if the target and the DFAC were shown in the opposite visual fields (e.g. target on the right and DFCA on the left side of the screen) for the incongruent color-flavor pairings. Moreover, the distractor positivity (Pd) was observed if the target and the DFAC were shown in the opposite visual field for the congruent color-flavor pairings. These results suggest that both attentional capture and suppression are involved in the influence of flavor information on visual search. Collectively, these findings provide initial electrophysiological evidence on the mechanisms of the crossmodal influence of flavor cues on visual search.

Common and unique neurophysiological signatures for the stopping and revising of actions reveal the temporal dynamics of inhibitory control

Inhibitory control is a crucial cognitive-control ability for behavioral flexibility that has been extensively investigated through action-stopping tasks. Multiple neurophysiological features have been proposed to represent 'signatures' of inhibitory control during action-stopping, though the processes signified by these signatures are still controversially discussed. The present study aimed to disentangle these processes by comparing simple stopping situations with those in which additional action revisions were needed. Three experiments in female and male humans were performed to characterize the neurophysiological dynamics involved in action-stopping and - changing, with hypotheses derived from recently developed two-stage 'pause-then-cancel' models of inhibitory control. Both stopping and revising an action triggered an early broad 'pause'-process, marked by frontal EEG β-bursts and non-selective suppression of corticospinal excitability. However, partial-EMG responses showed that motor activity was only partially inhibited by this 'pause', and that this activity can be further modulated during action-revision. In line with two-stage models of inhibitory control, subsequent frontocentral EEG activity after this initial 'pause' selectively scaled depending on the required action revisions, with more activity observed for more complex revisions. This demonstrates the presence of a selective, effector-specific 'retune' phase as the second process involved in action-stopping and -revision. Together, these findings show that inhibitory control is implemented over an extended period of time and in at least two phases. We are further able to align the most commonly proposed neurophysiological signatures to these phases and show that they are differentially modulated by the complexity of action-revision.

Understanding and Supporting Inhibitory Control: Unique Contributions From Proactive Monitoring and Motoric Stopping to Children's Improvements With Practice

Children struggle to stop inappropriate behaviors. What interventions improve inhibitory control, for whom, and why? Prior work suggested that practice proactively monitoring for relevant signals improved children's inhibitory control more than practice with motoric stopping. However, these processes were not clearly dissociated. This study tested 162 seven- to nine-year-old children (89 female, 72 male, 1 unreported; 82% White) on the stop-signal task, following monitoring or stopping-focused practice. Both methods improved inhibitory control, supported generalization, and interacted ( η p 2  = .20-.73). Practice approaches differentially impacted variability ( η p 2  = .01-.09). Only monitoring benefits showed signs of depending upon proactive control ( η p 2  = .02). These findings highlight unique contributions of attentional and stopping processes to inhibitory control, suggesting possibilities for tailored interventions.

Electrophysiological Evidence for Distinct Proactive Control Mechanisms in a Stop-Signal Task: An Individual Differences Approach

Proactive control reflects a sustained, top-down maintenance of a goal representation prior to task-related events, whereas reactive control reflects a transient, bottom-up goal reactivation in response to them. We designed a manual stop-signal task to isolate electrophysiological signals specifically involved in proactive control. Participants performed a simple choice reaction time task but had to withhold their response to an infrequent stop signal, resulting in go- and stop-signal trials. We manipulated the stop-signal probability (30% vs. 10%) over different blocks of trials so that different proactive control levels were sustained within each block. The behavioral results indicated that most participants proactively changed their behaviors. The reaction times in the go trials increased and the number of response errors in the stop-signal trials decreased. However, those two behavioral measures did not correlate: individuals with an increased delayed reaction did not necessarily manifest a higher decrease in response errors in the stop-signal trials. To isolate the proactive control signal, we obtained event-related potentials (ERPs) locked to an uninformative fixation onset and compared the signals between the two stop-signal probability conditions. We found that the ERPs at the left hemisphere were more negatively shifted with the increasing stop-signal probability. Moreover, ERP differences obtained from a set of electrodes in the left hemisphere accounted for the changes in response errors in the stop-signal trials but did not explain the changes in reaction times of the go trials. Together, the behavioral and electrophysiological results suggest that proactive control mechanisms reducing erroneous responses of the stop-signal trials are different from mechanisms slowing reaction times of the go trials.

Midfrontal neural dynamics distinguish between general control and inhibition-specific processes in the stopping of motor actions

Action inhibition, the suppression of action impulses, is crucial for goal-directed behaviour. In order to dissociate neural mechanisms specific to motor stopping from general control processes which are also relevant for other types of conflict adjustments, we compared midfrontal oscillatory activity in human volunteers via EEG between action inhibition and two other types of motor conflicts, unexpected action activation and unexpected action change. Error rates indicated that action activation was significantly easier than the other two equally demanding tasks. Midfrontal brain oscillations were significantly stronger for inhibition than for both other conflict types. This was driven by increases in the delta range (2–3 Hz), which were higher for inhibition than activation and action change. Increases in the theta range (4–7 Hz) were equally high for inhibition and change, but lower for action activation. These findings suggest that inhibition is facilitated by neural mechanisms specific to motor-stopping, with midfrontal delta being a potentially selective marker of motor inhibition.

Does Learning Influence the Detection of Signals in a Response-Inhibition Task?

Learning can modulate various forms of action control, including response inhibition. People may learn associations between specific stimuli and the acts of going or stopping, influencing task performance. The present study tested whether people also learn associations between specific stimuli and features of the stop or no-go signal used in the task. Across two experiments, participants performed a response-inhibition task in which the contingencies between specific stimuli and the spatial locations of the 'go' and 'withhold' signals were manipulated. The contingencies between specific stimuli and either going or withholding were also manipulated, such that a subset of stimuli were associated with responding and another subset with withholding a response. Although there was clear evidence that participants learned to associate specific stimuli with the acts of going or withholding, there was no evidence that participants acquired the spatial signal-location associations. The absence of signal learning was supported by Bayesian analyses. These findings challenge our previous proposals that learning always influences signal-detection processes in response-inhibition tasks where features of the signal remain the same throughout the task.

Reward anticipation changes corticospinal excitability during task preparation depending on response requirements and time pressure

The preparation of an action is accompanied by transient corticospinal (CS) excitability changes. Motivation can modulate these changes. Specifically, when a cue indicates that a reward can be obtained, CS excitability initially increases, followed by a pronounced decrease. This dynamic could reflect processes related to reward expectancy, processes related to action preparation, or a combination of both. Here we set up two experiments to dissociate these accounts. A rewarded choice reaction time task was used in which individuals were cued at the beginning of each trial whether or not a response would be required at target onset and whether or not a reward could be obtained. We used single-pulse transcranial magnetic stimulation (spTMS) over the left primary motor cortex (M1) early (shortly after cue onset) or late (shortly before target onset) preceding target onset to examine CS excitability during motivated action preparation. Electromyography (EMG) was obtained from the right first dorsal interosseous (FDI) muscle. In the first experiment, we used a lenient response deadline, whereas a strict response time-out procedure was employed in the second experiment. Reward modulated CS excitability differentially only in the second experiment: CS excitability was highest during reward anticipation for the early stimulation epoch and was reduced for the late stimulation epoch when individuals were required to prepare a response, while CS excitability remained unchanged during non-reward anticipation. Our findings suggest that the reward effect on CS excitability is dependent on the actual implementation of effort to attain reward (i.e., the preparation of an actual action), as well as on temporal requirements (i.e., time pressure) invoked by the task.

A reaction-time adjusted PSI method for estimating performance in the stop-signal task

A central experimental task in executive control research is the Stop-signal task, which allows measuring the ability to inhibit dominant responses. A crucial aspect of this task consists of varying the delay between the Go- and Stop-signal. Since the time necessary to administer the task can be long, a method of optimal delay choice was recently proposed: the PSI method. In a behavioral experiment, we show a variant of this method, the PSI marginal method, to be unable to deal with the Go-response slowing often observed in the Stop-signal task. We propose the PSI adjusted method, which is able to deal with this response slowing by correcting the estimation process for the current reaction time. In several sets of behavioral simulations, as well as another behavioral experiment, we document and compare the statistical properties of the PSI marginal method, our PSI adjusted method, and the traditional staircase method, both when reaction times are constant and when they are linearly increasing. The results show the PSI adjusted method's performance to be comparable to the PSI marginal method in the case of constant Go-response times, and to outperform the PSI marginal method as well as the staircase methods when there is response slowing. The PSI adjusted method thus offers the possibility of efficient estimation of Stop-signal reaction times in the face of response slowing.

Effects of reward and punishment on the interaction between going and stopping in a selective stop-change task

Inhibition of no-longer relevant go responses supports flexible and goal-directed behavior. The present study explored if the interaction between going and stopping is influenced by monetary incentives. Subjects (N = 108) performed a selective stop-change task, which required them to stop and change a go response if a valid signal occurred, but to execute the planned go response if invalid signals or no signals occurred. There were two incentive groups: the punishment group lost points for unsuccessful valid-signal trials, whereas the reward group gained points for successful valid-signal trials. There was also a control group that could not win or lose points on any trials. We found that, compared with the control group, incentives encouraged subjects to slow down on no-signal trials, suggesting proactive control adjustments. Furthermore, latencies of valid change responses were shorter in the incentive groups than in the control group, suggesting improvements in executing an alternative response. However, incentives did not modulate stop latency or the interaction between going and stopping on valid-signal trials much. Finally, Bayesian analyses indicated that there was no difference between the reward and punishment groups. These findings are inconsistent with the idea that reward and punishment have distinct effects on stop performance.