Some methodological issues in the assessment of the spontaneous eyeblink frequency in man

Abstract

Previous assessments of spontaneous eyeblink frequency (SEBF) or interblink intervals (IBI) have been made over period of 0.5 to 15 min and average values calculated; the reliability of the methods has not been validated. Video recordings were made of 14 healthy volunteers, aged 20 to 38 years, while silently fixating on a 2 m distant, 35 mm high target under 350 lux illumination and the traces assessed with an event marker. Significant fluctuations in SEBF or IBI were generally observed, but which did not conform to a minute-by-minute periodicity. Time-dependent trends were uncommon, although uncritical pooling or averaging of data can effectively conceal such fluctuations or trends. Correlation's between SEBF and IBI indicate that eyeblink monitoring over at least 3 min is required. Simple averaging calculations are not appropriate because of a high chance of non-Gaussian distribution of data. Modal IBI values correlated well with an adjusted modal calculated SEBF which is thus recommended for further use.

Blink Rate and Incomplete Blinks in Six Different Controlled Hard-Copy and Electronic Reading Conditions

“…30 Videos were examined independently by each examiner and only in case of discrepancies with their individual results were they subjected to further joint frame-by-frame analysis to inspect particular blinking events. Both examiners attended a training session before the start of the analysis to define criteria regarding blink amplitude and to familiarize themselves with the video assessment procedure.…”

Development and manipulation of spontaneous eye blinking in the first year: Relationships to context and positive affect

“…Infants were observed for 5-6 min in each phase because several minutes of data are needed to obtain reliable rates given the low rate of SEB expression (Zaman & Doughty, 1997). Given the dramatic developmental changes between 4 and 12 months, some of the procedures were modified to ensure infants' engagement in the tasks.…”

Systematic temporal variation in the rate of spontaneous eye blinking in human infants

“…The rate of blinking for each phase (e.g., before, during, and after feeding; first and second half) was calculated by taking the average of the number of blinks each minute. Although blink rate is relatively stable for an individual under constant conditions, the rate of blinking is most reliably calculated over several minutes (Zaman & Doughty, 1997).…”

“…Feeding and attending to novel stimuli are conditions that elicit different types of behavior from the infant; however, they are common and highly salient to infants. Blinks were counted for each minute and averaged over several minutes (Zaman & Doughty, 1997) for each phase of each experiment. The rates of blinking (blinks/min) were compared within infants across the phases of each experiment.…”