The accessory stimulus effect is mediated by phasic arousal: A pupillometry study

Abstract

People usually respond faster to a visual stimulus when it is immediately preceded by a task-irrelevant, auditory accessory stimulus (AS). This AS effect occurs even in choice reaction time tasks, despite the fact that the AS carries no information about the correct response. Researchers often assume that the AS effect is mediated by a phasic arousal burst evoked by the AS, but direct evidence for that assumption is lacking. We conducted a pupillometry study to directly test the phasic arousal hypothesis. Participants carried out a demanding choice reaction time task with accessory stimuli occurring on 25% of the trials. Pupil diameter, a common index of arousal, was measured throughout the task. Standard analyses of task performance and pupil diameter showed that participants exhibited the typical AS effect, and that accessory stimuli evoked a reliable early pupil dilation on top of the more protracted dilation associated with the imperative stimulus. Moreover, regression analyses at the single-trial level showed that variation in reaction times on AS trials was selectively associated with pupil dilation during the early time window within which the AS had an effect, such that particularly large AS-evoked dilations were associated with especially fast responses. These results provide the first evidence that the AS effect is mediated by AS-evoked phasic arousal.

No arousal-biased competition in focused visuospatial attention

“…We presented a target of fixed color and intensity, but manipulated the surrounding distractor stimuli to create different levels of competition in visual processing. Arousal level was successfully manipulated in three different ways, as evidenced by ERP modulations in response to emotionally arousing pictures (Experiment 1B), improvements in stimulus processing speed after the presentation of alerting auditory tones that are known to elicit a phasic arousal response (Experiment 2; Hackley & Valle-Inclán, 2003;Jepma et al, 2009;Tona et al, 2016), and by large increases in pupil diameter under white-noise stimulation (Experiment 3B). Two of these manipulations affected trial-to-trial changes in (phasic) arousal, one manipulation affected arousal in a blockwise (tonic) fashion.…”

“…In Experiment 2 we used auditory alerting tones to induce arousal in participants, and compared task performance to a no-tone condition. A loud tone often induces a reflexive phasic arousal response (Hackley & Valle-Inclán, 2003;Tona, Murphy, Brown, & Nieuwenhuis, 2016), and can serve as a temporal cue for the participant to concentrate their efforts in a narrow interval of time.…”

Exteroceptive stimuli override interoceptive state in reaction time control

“…The first type is the energy integration model, in which accessory stimuli facilitate stimulus encoding at early information processing stages (Bernstein, 1970;Stein, London, Wilkinson, & Price, 1996). This view is supported by evidence that the ASE is mediated by phasic arousal, which is indexed by pupil dilation during an early time window (Tona, Murphy, Brown, & Nieuwenhuis, 2016). An additive activation of multisensory neurons in the modality-specific areas serves as the neural mechanism of energy integration (Jepma, Wagenmakers, Band, & Nieuwenhuis, 2008).…”

Triggering Mechanisms for Motor Actions: The Effects of Expectation on Reaction Times to Intense Acoustic Stimuli

“…However, Niemi (1979) showed that foreperiod effects are reduced when the IS is an intense signal in the auditory modality, suggestive of a facilitatory effect of phasic arousal over the neural activity of circuits responsible for the initiation and execution of the voluntary response 81; Tona, Murphy, Brown, & Nieuwenhuis, 2016). This reduction of foreperiod effects when using an intense acoustic go-signal may reflect the activation of a specific physiological mechanism thought to be involved in the StartReact 5 effect (Valls-.…”