Task-irrelevant stimuli reliably boost phasic pupil-linked arousal but do not affect decision formation.

Area of Science:

• Neuroscience
• Cognitive Science
• Psychology

Background:

• The brainstem's arousal systems, particularly the locus coeruleus-noradrenaline system, exhibit phasic activity during decision-making.
• These central arousal transients correlate with pupil dilations and are implicated in reducing bias in challenging perceptual decisions.

Purpose of the Study:

• To investigate if non-invasive auditory stimuli can manipulate central arousal and influence cognitive performance.
• To determine if sound-evoked pupil responses mimic those associated with cognitive task engagement.

Main Methods:

• Participants performed challenging visual decisions while task-irrelevant auditory stimuli were presented at varying onset latencies or durations.
• Pupil responses were monitored to assess the impact of auditory stimuli on task-evoked arousal.
• Behavioral performance, specifically decision bias, was analyzed in relation to pupil responses.

Main Results:

• Task-irrelevant sounds reliably elicited pupil responses that superimposed on task-evoked responses.
• A negative correlation between task-evoked pupil responses and decision bias was replicated.
• However, the auditory stimuli did not produce any significant behavioral effects on decision-making.

Conclusions:

• The study found a dissociation between pupil responses evoked by cognitive tasks and those evoked by external auditory stimuli.
• This suggests that task-irrelevant sounds and cognitive engagement may activate distinct neural systems involved in pupil control.
• Non-invasive auditory stimulation is not an effective method for manipulating central arousal to influence cognitive decisions.