How the motor aspect of speaking influences the blink rate

Abstract

The blink rate increases if a person indulges in a conversation compared to quiet rest. Since various factors were suggested to explain this increase, the present series of studies tested the influence of different motor activities, cognitive processes and auditory input on the blink behavior but at the same time minimized visual stimulation as well as social influences. Our results suggest that neither cognitive demands without verbalization, nor isolated lip, jaw or tongue movements, nor auditory input during vocalization or listening influence our blinking behavior. In three experiments, we provide evidence that complex facial movements during unvoiced speaking are the driving factors that increase blinking. If the complexity of the motor output increased such as during the verbalization of speech, the blink rate rose even more. Similarly, complex facial movements without cognitive demands, such as sucking on a lollipop, increased the blink rate. Such purely motor-related influences on blinking advise caution particularly when using blink rates assessed during patient interviews as a neurological indicator.

Motor restrictions impair divergent thinking during walking and during sitting

“…3 ). Furthermore, we corroborated the finding of increased blink rates due to speaking (Brych et al, 2020 ; von Cramon & Schuri, 1980 ) which was clearly associated with the motor activity during speech production (Brych et al, 2020 ). Interestingly, we could show that this increase during speaking was specific to the sitting condition, while blink rates were similarly elevated during the walking condition for all three task phases (baseline, think time and response time).…”

“…When investigating specific movements, it is important to consider that many body movements interact. As shown by us and by others, spontaneous blink rate increases can be linked to movements of the mouth during speech (Brych et al, 2020 ; von Cramon & Schuri, 1980 ). In addition, walking goes hand in hand with an increased blink rate (Cao et al, 2020 ).…”

“…Note that the procedure for a trial with a separate think time and response time was similar to Ueda et al ( 2016 ). The reason for this was because voluntary actions such as speaking is associated with an increase in blinking (Brych et al, 2020 ; von Cramon & Schuri, 1980 ). Participants were allowed breaks between trials and between conditions.…”

“…Although they serve to moisten the eyes, their frequency is much higher than what is required just for that purpose (Kaminer et al, 2011 ). The purpose of these surplus blinks is not completely decoded, but they have been shown to reflect cognitive processes (Brych & Händel, 2020 ; Brych et al, 2020 , 2021 ; Fogarty & Stern, 1989 ; Goldstein et al, 1992 ). One study by Akbari Chermahini and Hommel ( 2010 ) found that participants who had a comparably moderate baseline eye blink rate, as identified as the centre of the distribution of blink rates for this specific study, had higher scores on the AUT compared to subjects showing blink rates at the left and right side of the distribution.…”

Eye blinking, musical processing, and subjective states—A methods account

“…Long periods do not reflect natural blinking, but phases of micro‐sleep (Rodriguez et al, 2018), or instances when participants' gaze is not directed to the recording camera, or other recording failure. A broad range of lower and upper limits have been reported in the literature, with lower limits ranging between 50 and 300 ms (50 ms: Brych et al, 2020, 2021; Caffier et al, 2003; Wang et al, 2011; 100 ms: Aarts et al, 2012; Rodriguez et al, 2018; 200 ms: Jongkees & Colzato, 2016; 300 ms: Nomura et al, 2015) and upper limits between 200 and 1000 ms (200 ms: Naicker et al, 2016; 500 ms: Aarts et al, 2012; Brych et al, 2020; Caffier et al, 2003; Jongkees & Colzato, 2016; Nakano et al, 2013; Rodriguez et al, 2018; Wang et al, 2011; 1000 ms: Brych et al, 2021; Nomura et al, 2015). Note that defining blinks by data loss periods is a simplification, as those do not cover the start and end of the eye‐lid movement (see Caffier et al, 2003).…”