Effects of vocal demands on pupil dilation

Abstract

Pupil dilation is known to be affected by a variety of factors, including physical (e.g., light) and cognitive sources of influence (e.g., mental load due to working memory demands, stimulus/response competition etc.). In the present experiment, we tested the extent to which vocal demands (speaking) can affect pupil dilation. Based on corresponding preliminary evidence found in a reanalysis of an existing data set from our lab, we setup a new experiment that systematically investigated vocal response‐related effects compared to mere jaw/lip movement and button press responses. Conditions changed on a trial‐by‐trial basis while participants were instructed to keep fixating a central cross on a screen throughout. In line with our prediction (and previous observation), speaking caused the pupils to dilate strongest, followed by nonvocal movements and finally a baseline condition without any vocal or muscular demands. An additional analysis of blink rates showed no difference in blink frequency between vocal and baseline conditions, but different blink dynamics. Finally, simultaneously recorded electromyographic activity showed that muscle activity may contribute to some (but not all) aspects of the observed effects on pupil size. The results are discussed in the context of other recent research indicating effects of perceived (instead of executed) vocal action on pupil dynamics.

Who Are You To Judge? Investigating Narcissism through Pupil Dilation at Witness Testimonials

“…Again, this would be interesting to explore further. Furthermore, this study expands on previous findings by replicating the Brych et al (2020) investigation. Pupillometry responses to voice demands were investigated, which allowed for replication with the present auditory stimuli utilised.…”

“…Furthermore, hormonal changes could affect pupillary reactions and thereby limits research concerning children and adolescents (Laeng & Falkenberg, 2007). Additionally, as exposure to light and auditory stimuli affects pupil changes, it is essential to be extremely cautious and precise when conducting research (Brych et al, 2020).…”

“…However, this has not been tested in a court setting nor with descriptions of criminal activity. Brych et al (2020) investigated the effects of vocal demands on pupil dilation. This was proposed as a consequence of a reanalysis of a previous preexisting data set which suggested vocalisation to have a more significant effect on pupil dilation in contrast to conditions without vocal demands.…”

Substituting facial movements in singers changes the sounds of musical intervals

“…2) aroused our participants more than the more restrained singer (S 2 ). In general, vocal movements dilate observers' pupils more compared to mere jaw and lip movements 42 and for vocal melodies than when played on the piano 43 , possibly because vocal stimuli are both more arousing and information-rich, demanding more attention. We note that none of our participants explicitly www.nature.com/scientificreports/ reported detecting any perceptual conflict in the videos and, in fact, we did not find larger pupillary response to incongruent than congruent conditions.…”

Pupil dynamics: A potential proxy of neural preparation for goal‐directed eye movement

“…Goal‐directed movement‐related pupil response has been reported in many other kinds of action than visually guided saccadic eye movement, for instance, finger flexion (Richer & Beatty, 1985), aiming (Jiang et al, 2015), walking (Saeedpour‐Parizi et al, 2020) and vocalization (Brych et al, 2021). The norepinephrine (NE) (also called noradrenaline) networks in human and non‐human primate's brain are highly distributed having the LC as an area in it (Aston‐Jones & Cohen, 2005; DiNuzzo et al, 2019).…”