Response inhibition or evaluation of danger? An event-related potential study regarding the origin of the motor interference effect from dangerous objects

Exploring the 'black box' of anxiety: An ERP study of non-consciously triggered fear generalization

Individuals with anxiety disorders frequently display heightened fear responses, even in situations where there is no imminent danger. We hypothesize that these irrational fear responses are related to automatic processing of fear generalization. The initial automatic detection of stimuli often operates at a non-conscious level. However, whether fear generalization can occur when the cues are not perceived consciously remains unclear. The current study investigated the neurocognitive mechanisms underlying fear conditioning and its non-conscious and conscious generalization using a backward masking paradigm, combined with analysis of event-related potentials from electroencephalographic recordings. Behaviorally, participants showed heightened shock expectancy in response to non-conscious perceived generalization stimuli compared to those perceived consciously. Nonetheless, participants could not consciously distinguish between danger and safe cues in non-conscious trials. Physiologically, danger cues evoked larger frontal N1 amplitudes than safety cues in non-conscious trials, suggesting enhanced attention vigilance towards danger cues in the early sensory processing stage. Meanwhile, when fear generalization was conscious, it was accompanied by a larger P2 amplitude, indicating attention orientation or stimulus evaluation. In addition, fear conditioning was associated with sustained discrimination on P2, P3, and LPP. These findings collectively suggest that non-conscious fear generalization occurs at the neural level, yet additional control conditions are required to confirm this phenomenon on the US expectancy. Thus, non-consciously fear generalization may represent a mechanism that could trigger automatic irrational fear, highlighting the need for further research to explore therapeutic targets in anxiety disorders.

Motor inhibition impacts the motor interference effect of dangerous objects based on a prime-target grasping consistency judgment task

Whether motor inhibition impacts the motor interference effect of dangerous objects is controversial. Previous studies have manipulated task type and found that dangerous objects elicited increased motor inhibition compared to safe objects in the reachability judgment task but not in the categorization task. However, it was still unclear why motor inhibition was reduced for dangerous objects in the categorization task. We speculated that the activation strength of object affordance might modulate the occurrence of motor inhibition. To test this hypothesis, the present study designed a prime-target grasping consistency judgment task and manipulated target grips (power grip vs. precision grip), target dangerousness (dangerous vs. safe), and Go/NoGo (Go vs. NoGo). The results showed that under the condition of high activation strength of the target affordance (i.e., power grip targets), processing dangerous targets evoked increased motor inhibition (reflected by a more negative frontal N2 component) compared to safe targets and produced a motor interference effect in reaction time (RT). In contrast, under the condition of low target affordance activation strength (i.e., precision grip targets), processing dangerous targets facilitated RT compared to safe targets, with no difference found between the dangerous and safe conditions in the frontal N2 component. Furthermore, compared to safe objects, dangerous objects attracted more attention and recruited more cognitive resources to select appropriate responses to them. This study extended the findings of previous studies on the motor interference effect by highlighting the importance of activation strength for eliciting motor inhibition based on the prime-target consistency judgment task.

Imitation of Touching Dangerous Animals Triggers Motor Inhibition in a Primed Target Grasping-Categorization Task

The present study adopted a primed target grasping-categorization task and selected pictures of animals as target stimuli to investigate whether motor inhibition influences the motor interference effect of dangerous animals. The results identified more positive P2 and P3 amplitudes accompanied by larger delta event-related synchronization in the dangerous condition than in the neutral condition, suggesting that compared to neutral animal targets, dangerous animal targets attracted increased attentional resources in early processing and that subjects recruited more cognitive resources to process dangerous animal targets than neutral animal targets. Moreover, the results identified larger theta event-related synchronization (reflecting motor inhibition) in the dangerous condition than in the neutral condition. Thus, the results suggested that prepared motor responses were inhibited to avoid touching dangerous animal targets in the current task, supporting that motor inhibition influences the motor interference effect of dangerous animals based on a primed target grasping-categorization task.

Motor Inhibition to Dangerous Objects: Electrophysiological Evidence for Task-dependent Aversive Affordances

Previous work suggests that perception of an object automatically facilitates actions related to object grasping and manipulation. Recently, the notion of automaticity has been challenged by behavioral studies suggesting that dangerous objects elicit aversive affordances that interfere with encoding of an object's motor properties; however, related EEG studies have provided little support for these claims. We sought EEG evidence that would support the operation of an inhibitory mechanism that interferes with the motor encoding of dangerous objects, and we investigated whether such mechanism would be modulated by the perceived distance of an object and the goal of a given task. EEGs were recorded by 24 participants who passively perceived dangerous and neutral objects in their peripersonal, boundary, or extrapersonal space and performed either a reachability judgment task or a categorization task. Our results showed that greater attention, reflected in the visual P1 potential, was drawn by dangerous and reachable objects. Crucially, a frontal N2 potential, associated with motor inhibition, was larger for dangerous objects only when participants performed a reachability judgment task. Furthermore, a larger parietal P3b potential for dangerous objects indicated the greater difficulty in linking a dangerous object to the appropriate response, especially when it was located in the participants' extrapersonal space. Taken together, our results show that perception of dangerous objects elicits aversive affordances in a task-dependent way and provides evidence for the operation of a neural mechanism that does not code affordances of dangerous objects automatically, but rather on the basis of contextual information.

Arousal modulates the motor interference effect stimulated by pictures of threatening animals

Previous research related to the motor interference effect from dangerous objects indicated that delayed responses to dangerous objects were associated with more positive parietal P3 amplitudes, suggesting that great attentional resources were allocated to evaluate the level of danger (i.e., negative valence). However, arousal covaried with valence in this research. Together with previous studies in which the P3 amplitude was found to be increased along with a higher arousal level in the parietal lobe, we raised the issue that more positive parietal P3 amplitudes might also be affected by a high arousal level. To clarify whether valence or arousal impacted the motor interference effect, this study used a motor priming paradigm mixed with a Go/NoGo task and manipulated the valence (negative, neutral and positive) and arousal (medium and high) of target stimuli. Analysis of the behavioral results identified a significant motor interference effect (longer reaction times (RTs) in the negative valence condition than in the neutral valence condition) at the medium arousal level and an increased effect size (increment of RT difference) at the high arousal level. The results indicated that negative valence stimuli may interfere with the prime elicited motor preparation more strongly at the high arousal level than at the medium arousal level. The ERP results identified larger centroparietal P3 amplitudes for the negative valence condition than for the neutral valence condition at a high arousal level. However, the inverse result, i.e., lower centroparietal P3 amplitudes for the negative valence condition than for the neutral valence condition, was observed at a medium arousal level. The ERP results further indicated that the effect size of the behavioral motor interference effect increased because subjects are more sensitive to the negative valence stimuli at the high arousal level than at the medium arousal level. Furthermore, the motor interference effect is related to the negative valence rather than emotionality of the target stimuli because different result patterns emerged between the positive and negative valence conditions. Detailed processes underlying the interaction between valence and arousal effects are discussed.

Increasing Perceptual Salience Diminishes the Motor Interference Effect From Dangerous Objects

Existing research has indicated that dangerous objects may conflict with an individual’s prepared motor actions and thus slow responses. This phenomenon is called the motor interference effect from dangerous objects. However, its origin remains arguable. The current study aimed to preclude an alternative origin and to investigate whether the efficiency of processing a prepared response toward a dangerous object could benefit from increasing the perceptual salience of the object by painting the object red. The design used a shape categorization task to emphasize the dangerous elements of target objects and manipulated target color (gray versus red), target dangerousness (safe versus dangerous) and prime-target congruency (congruent versus incongruent). The null effect of N2 amplitudes between the dangerous and safe conditions precluded the alternative origin and suggested that the motor interference effect did not originate from response inhibition. Furthermore, the results indicated a modulation effect of the motor interference effect in different colors. The classic motor interference effect was observed in the gray target condition, but it diminished in the red target condition. The underlying cognitive processes were reflected in ERPs. More positive P2 and frontal P3 amplitudes were identified in the red target condition than in the gray target condition, which indicated that deeper feature detection was assigned to and more attentional resources were automatically recruited for the red targets than for the gray targets. Analysis of the parietal P3 amplitudes identified a similar result pattern as the mean RTs. A more positive P3 amplitude was identified in the dangerous condition than in the safe condition when the targets were painted gray. In contrast, the P3 amplitudes were identical between the dangerous condition and the safe condition when the targets were painted red. The results indicated that the increased attentional resources facilitated the evaluation of red target dangerousness and thus accelerated reactions to the red dangerous targets; the reaction speeds to those targets were close to those for the reaction speeds to the red safe targets. Detailed processes that underline these components are discussed.

Embodiment in Virtual Environments: The Role of Working Memory in Experiencing Presence as Revealed via Eye Tracking

Working memory capacity (WMC) is critical in maintaining goal-directed behavior and in inhibiting task irrelevant or conflicting thoughts. Using eye tracking data, the current study developed measures to investigate users' experiences of presence. We investigated the cognitive processing mechanisms of feelings of presence by examining how users of varying WMC coordinate their attention between their actions in using external controllers for computer mediated environments, and the actions produced by their avatars in virtual environments. To rule out the possibility of participants acting out of social pressure, a well-practiced everyday task with minimal social component was used. Participants performed vegetable cutting tasks in a desktop virtual environment by controlling an avatar's arm, with no pressure (Experiment 1) versus while pressured to improve the evenness of their cuts (Experiment 2). The results showed that high WMC participants experienced higher degrees of presence, as indicated by the attention allocated to the avatar's hand and to task planning. Under performance pressure, low WMC participants became more immersed in the tasks. The mechanisms of adaptive and personalized presence in virtual world simulation training environments are discussed in light of our findings on the effects of pressure and individual differences of WMC in experiencing presence.

Pediatric OCD in the era of RDoC

The NIMH Research Domain Criteria (RDoC) initiative was established with the goal of developing an alternative research classification to further research efforts in mental health. While RDoC acknowledges that constructs should be considered within a developmental framework, developmental considerations have not yet been well integrated within the existing RDoC matrix. In this paper, we consider RDoC in relation to pediatric OCD, a paradigmatic example of a neuropsychiatric disorder that often has onset in childhood but is also present across the lifespan. We discuss three RDoC subdomains with relevance to OCD as exemplars, providing for each construct a brief review of normative developmental changes, the state of construct-relevant research in pediatric OCD, and challenges and limitations related to developmental considerations within each subdomain. Finally, we conclude with a brief discussion of how RDoC may continue to evolve with regard to developmental considerations in order to further research in pediatric OCD.

Emotional arousal elicited by irrelevant stimuli affects event-related potentials (ERPs) during response inhibition

Previous event-related potential (ERP) studies using the Go/Nogo task have indicated that response inhibition is influenced by the arousal elicited by emotional stimuli, when those stimuli are relevant to response selection of Go and Nogo trials. Due to stimulus and task design issues, however, it is uncertain whether response inhibition is affected by emotional valence or arousal, when emotional stimuli are irrelevant to response selection. Therefore, the present study aimed to re-investigate this issue by circumventing limitations of previous research. To address this issue, thirty-one young adults (16 females and 15 males) were required to make motor responses to frequently-presented faces of one sex (Go trials) and to inhibit responses to less-frequently presented faces of the opposite sex (Nogo trials). Crucially, the faces were superimposed onto positive, negative and neutral pictures. The pictures were presented in a randomized order. The arousal values between positive and negative pictures were highly matched. Results showed that Nogo faces elicited smaller N2 but larger P3a amplitudes, when the faces were associated with positive and negative pictures as compared to neutral pictures. These findings suggest that response inhibition is influenced by emotional arousal, when emotional stimuli are irrelevant to response selection. Additionally, for Go faces, results showed smaller N2 but larger P3a amplitudes within negative pictures as compared to neutral and positive pictures, suggesting a role of emotional valence elicited by irrelevant stimuli on response execution.

A sequential trial effect based on the motor interference effect from dangerous objects: An ERP study

INTRODUCTION

This study aims to investigate whether processing a prepared response toward a dangerous object in a previous trial influences subsequent trial processing.

METHODS

The design manipulated the Go/NoGo factor of the current trial, the target dangerousness of the previous trial and that of the current trial.

RESULTS

In current Go trials, the behavioral results revealed a classical motor interference effect in trials that were preceded by a safe trial (a longer reaction time (RT) and a larger error rate for the previous safe and current dangerous (sD) condition than for the previous safe and current safe (sS) condition). However, the motor interference effect diminished in trials that were preceded by a dangerous trial (insignificant differences in the mean RTs and error rates between the previous dangerous and current dangerous (dD) condition and the previous dangerous and current safe (dS) condition). The event-related potential (ERP) results identified more positive P2 and parietal P3 amplitudes (indicating attentional resource allocation) for the dD condition than for the dS condition. However, the P2 and parietal P3 amplitudes of the sD condition did not significantly differ from those of the sS condition.

DISCUSSIONS

These results support the hypothesis that the avoidance motivation elicited by a dangerous target in a previous trial may indicate a dangerous situation, which leads to recruitment of more attentional resources allocated to the subsequent dangerous trial. Therefore, RTs are improved and errors are reduced in the consecutive dangerous condition, subsequently decreasing the motor interference effect in trials preceded by a dangerous trial compared with trials preceded by a safe trial. However, analysis of current NoGo trials revealed that none of the main effects or interactions reached significance in both the behavioral and ERP results, indicating that the hypothesis holds true only if the prepared response needs to be executed.

Time-frequency analysis of event-related potentials associated with the origin of the motor interference effect from dangerous objects

Previous research has suggested that the motor interference effect of dangerous objects may originate from danger evaluations rather than direct response inhibition, as evidenced by a larger parietal P3 amplitude (which represents danger evaluations) under dangerous conditions than under safe conditions and an insignificant difference between dangerous and safe conditions in the frontal P3 component (which represents response inhibition). However, an alternative explanation exists for the null effect of the frontal P3 component. Specifically, this null effect may be attributed to cancellation between the theta and delta band oscillations, and only theta band oscillations represent response inhibition. To clarify this issue, the current study decomposed event-related potential data into different frequency bands using short-time Fourier transform. The results identified an insignificant difference of theta oscillations between dangerous and safe conditions in the mid-frontal area during a 200-500-ms time window. Instead, decreased alpha oscillations were identified in the dangerous compared with the safe condition in Go trials in the right parietal area during a 100-660-ms time window. Regression analyses further indicated that the alpha oscillations significantly contributed to the parietal P3 amplitude in the right parietal area. In summary, the results indicated that when an emergent dangerous object is encountered during the execution of prepared motor actions, an individual may tend to chiefly evaluate the potential dangerousness rather than directly suppress the prepared motor actions toward the dangerous object.