Abstract
BackgroundIt has been suggested that perceived mental effort reflects changes in arousal during tasks of attention. Such changes in arousal may be tonic or phasic, and may be mediated by the locus-coeruleus norepinephrine (LC-NE) system. We hypothesized that perceived mental effort during attentional tasks would correlate with tonic changes in cortical arousal, as assessed by relative electroencephalogram (EEG) band power and theta/beta ratio, and not with phasic changes in cortical arousal, assessed by P300 amplitude and latency.MethodsForty-six healthy individuals completed tasks that engage the anterior and posterior attention networks (continuous performance task, go/no-go task, and cued target detection task). During completion of the three attentional tasks a continuous record of tonic and phasic arousal was taken. Cortical measures of arousal included frequency band power, theta/beta ratios over frontal and parietal cortices, and P300 amplitude and latency over parietal cortices. Peripheral measures of arousal included skin conductance responses, heart rate and heart rate variance. Participants reported their perceived mental effort during each of the three attentional tasks.ResultsFirst, changes in arousal were seen from rest to completion of the three attentional tasks and between the attentional tasks. Changes seen between the attentional tasks being related to the task design and the attentional network activated. Second, perceived mental effort increased when demands of the task increased and correlated with left parietal beta band power during the three tasks of attention. Third, increased mental effort during the go/no-go task and the cued target detection task was inversely related to theta/beta ratios.ConclusionThese results indicate that perceived mental effort reflects tonic rather than phasic changes in arousal during tasks of attention. We suggest that perceived mental effort may reflect in part tonic activity of the LC-NE system in healthy individuals.
Highlights
It has been suggested that perceived mental effort reflects changes in arousal during tasks of attention
The aims of the present study were to determine: (1) whether changes in physiological levels of arousal increased during the completion of three voluntary attentional tasks and what aspects of the tasks were associated with these changes, (2) whether perceived mental effort reflected these changes in arousal during tasks of attention and what aspects of these tasks were associated with these changes and (3) whether perceived mental effort reflected tonic or phasic changes in arousal as observed in physiological recordings during the three tasks of attention
Right frontal electrode (F4) relative alpha band power was higher during the resting eyes open phase compared to continuous performance task and the cued target detection task
Summary
It has been suggested that perceived mental effort reflects changes in arousal during tasks of attention Such changes in arousal may be tonic or phasic, and may be mediated by the locus-coeruleus norepinephrine (LC-NE) system. We hypothesized that perceived mental effort during attentional tasks would correlate with tonic changes in cortical arousal, as assessed by relative electroencephalogram (EEG) band power and theta/beta ratio, and not with phasic changes in cortical arousal, assessed by P300 amplitude and latency. According to the Yerkes and Dodson [4] theory, an individual who is underaroused or hyperaroused will perform a task poorly. This suggests that tonic levels of arousal need to be maintained within an optimal range in order to achieve successful completion of a task. Attention required for successful completion of a task requires an optimal level of arousal, which in turn requires activation of particular attentional network
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