Alertness and cognitive control: Testing the spatial grouping hypothesis

Alerting effects require the absence of surprise

Ongoing actions are interrupted for a brief period of time whenever salient and expectancy-discrepant stimuli (surprise stimuli) interfere with the present task set. By contrast, salient stimuli (alerting cues) preceding targets can facilitate behaviour by reducing time to initiate actions. Both phenomena seem to be at odds with each other as actions are either impaired or facilitated. Therefore, in the present study, we asked how surprise and alerting effects interact. In two experiments, participants performed choice reaction tasks without any prior knowledge of the impending alerting cue. After a baseline period of trials without an alerting cue, the alerting cue was presented for the first time. It was found that the initial presentation of the alerting cue significantly slowed down reaction times. However, after just a single trial this impairment went away. This reveals that the beneficial effects of alerting for action presuppose that alerting cues are expected and represented in the top-down task set. As such, the present findings challenge the standard view of phasic alerting as a bottom-up and entirely stimulus-driven phenomenon.

Testing the saliency-based account of phasic alertness

As an essential component of the human attention system, the effect of phasic alertness refers to the change of performance with the presence of a preceding warning signal. Weinbach and Henik (Cognition, 133 (2), 414-419, 2014) argued that phasic alertness is an adaptive mechanism that diverts attention to salient events. This mechanism enhances selective attention when the critical event is more salient than others. When selective attention to less salient details is required, phasic alertness can lead to more interference from task-irrelevant information. The experiment on which this saliency-based account of phasic alertness is based has not been replicated. In two experiments, the present study attempted to replicate the alertness-related findings of Weinbach and Henik. Although we used a similar design, the results did not reveal evidence for an interaction between phasic alertness and response congruency in the global/local processing task. Our results do not support the saliency-based account of phasic alertness. We argue that more systematic investigation is needed for this phasic alertness account.

The Effect of Safety Signs on the Monitoring of Conflict and Erroneous Response

The safety sign is important in our daily life and workplace to prevent potential safety issues. However, it remains undetermined whether the safety signs would influence the cognitive control ability of the people, which serves to guide the behaviors in a goal-directed manner. Therefore, this study aimed to examine the effect of safety signs on cognitive control by uncovering the behavioral performance and neural manifestations underlying the monitoring of conflict and error. The participants performed a flanker task after watching low- and high-hazard safety signs with the electroencephalogram (EEG) data recorded continually. The behavioral results indicated a classic congruency effect with higher accuracy rate and faster response time under a congruent condition compared to an incongruent condition. However, no hazard effect on behavioral performances was observed. The results of event-related potentials (ERPs) demonstrated a more negative N2 elicited by the incongruent trials and an increased (error-related negativity) ERN difference between the error and correct responses in the high-hazard condition compared to those in the low-hazard condition, implying that the monitoring of the conflict and error were both enhanced after watching the high-hazard safety signs. This study contributes to the understanding of the relationship between safety signs and cognitive control, and further expand the measurements that can be applied to assess the effectiveness of safety signs design.