ANALYSIS OF BLINK RATE PATTERNS IN NORMAL SUBJECTS

The present study measured the normal blink rate (BR) variations in re lation to behavioral tasks in 150 healthy volunteers (70 males and 80 females; aged 35.9 +/- 17.9 years, range 5-87 years). The subjects wer e videotaped in a standard setting while performing three different ta sks: resting quietly, reading a short passage, talking freely. The mea n BR was computed during each task; the data were compared by means of analysis of variance and Student's t tests. Mean BR at rest was 17 bl inks/min, during conversation it increased to 26, and it was as low as 4.5 while reading. As compared with rest, BR decreased by -55.08% whi le reading (p < 1 x 10(-15)) and increased by 99.70% during conversati on (p < 1 x 10(-9)). As compared with reading, BR increased during con versation by 577.8% (p < 1 x 10(-17)). The distribution curves were hi ghly reproducible in each task. The best curve fit was represented by a log-normal distribution, with the upper tail of each curve having a normal distribution. Eye color and eyeglass wearing did not influence BR. Women had higher BR than men just while reading. No age-related di fferences were found. The most common BR pattern was conversation > re st > reading, which occurred in 101 subjects (67.3%); 34 subjects (22. 7%) had the pattern rest > conversation > reading; 12 (8.0%) had the p attern conversation > reading 1 rest. This study identified three norm al behavioral BR patterns and showed that BR is more influenced by cog nitive processes than by age, eye color, or local factors. The present findings provide a normal reference for the analysis of BR in movemen t disorders such as dystonia or ties.