Intra-subject consistency of spontaneous eye blink rate in young women across the menstrual cycle

Abstract

The spontaneous eye blink rate (EBR) has been linked to different cognitive processes and neurobiological factors. It has also been proposed as a putative index for striatal dopaminergic function. While estradiol is well-known to increase dopamine levels through multiple mechanisms, no study up to date has investigated whether the EBR changes across the menstrual cycle. This question is imperative however, as women have sometimes been excluded from studies using the EBR due to potential effects of their hormonal profile. Fifty-four women were tested for spontaneous EBR at rest in three different phases of their menstrual cycle: during menses (low progesterone and estradiol), in the pre-ovulatory phase (when estradiol levels peak and progesterone is still low), and during the luteal phase (high progesterone and estradiol). No significant differences were observed across the menstrual cycle and Bayes factors show strong support for the null hypothesis. Instead, we observed high intra-individual consistency of the EBR in our female sample. Accordingly, we strongly encourage including female participants in EBR studies, regardless of their cycle phase.

Blink rate measuredin situdecreases while reading from printed text or digital devices, regardless of task duration, complexity or working distance

“…Repeatability was better with blink rates ≤ 10 blinks/min (CoR: ±5.4 blinks/min) but less reliable above 10 blinks/min (CoR: ±18.8 blinks/min) (supplementary data Table 3). Previous studies intending to report repeatability of blink rate do not provide a standard repeatability measure to enable comparison with the present findings [6,18,28,29]. These findings suggest that the wearable eye tracker is able to reliably measure blink rate within the normal ranges of spontaneous blinking.…”

“…The repeatability of recent and commonly used blink measurement methods has not been assessed. Repeated measurements of blink rate have been reported for electrophysiology methods (magnetic search coil technique and electro-oculography) [6,18,28], and for manual counting of blinks from eye video recording [29][30][31] conducted in a laboratory setting where participants' head position was fixed. However, none of these studies reported standard measures of repeatability [32].…”

Blink Rate Measured In Situ Decreases While Reading From Printed Text or Digital Devices, Regardless of Task Duration, Difficulty, or Viewing Distance

“…Previous studies intending to report repeatability of blink rate do not provide a standard repeatability measure to enable comparison with the present findings. 6 , 18 , 29 , 30 These findings suggest that blink repeatability may be better during reading than conversation and walking. These results provide a basis on which to estimate sample size in future studies.…”

“…The repeatability of recent and commonly used blink measurement methods has not been assessed. Repeated measurements of blink rate have been reported for electrophysiology methods (magnetic search coil technique and electro-oculography), 6 , 18 , 29 and for manual counting of blinks from eye video recording 30 – 32 conducted in a laboratory setting where participants’ head position was fixed. However, none of these studies reported standard measures of repeatability.…”

Examining the relationship between substance use and exploration–exploitation behavior in young adults.

“…Descriptive analyses were carried out in relation to participants’ demographic, questionnaire, and Crab Foraging Task data. One outlier (3 SD > mean) was detected for EBR and was removed from all analyses (Cook’s D = .20); this outlier threshold of three standard deviation units from the mean has been used in previous EBR studies (Byrne et al, 2016; Doughty, 2019; Hidalgo-Lopez et al, 2020).…”