Eyeblink, evoked potentials and visual attention

Effects of background lighting and retinal illuminance on spontaneous eyeblink activity of human subjects in primary eye gaze

PURPOSE

To further evaluate possible effects of lighting conditions on the spontaneous eyeblink rate (SEBR) of normal young adult human subjects.

METHODS

A baseline 5 min video recording was made followed by a second recording under test conditions in 7 different groups of 10 subjects. These test conditions were a simple repeat recording under reference conditions (subjects maintaining silence, with gaze directed towards a target on a 2 m distant whiteboard with the luminance of the reflected light of 35 cd/m, recording under lower (5 cd/m), higher (75 cd/m) and floodlit (150 cd/m) levels, after pupil dilation with phenylephrine 2.5 %, after sudden increase with floodlights (to 200 cd/m), as compared subjects engaged in conversation.

RESULTS

The overall SEBR values ranged from 8.4 to 15.8 eyeblinks per minute (mean 12.3 ± 2.8 eyeblinks per minute). These did not significantly change with repeated assessments, no significant changes were seen comparing lower or higher illumination levels or after pupil dilation, but an increase to 20.0 ± 4.6 eyeblinks per minute was seen with a sudden increase in illumination. Conversation increased SEBR to 22.2 ± 6.4 eyeblinks per minute.

CONCLUSIONS

Spontaneous eyeblink activity in silence may be slightly affected by background lighting conditions, but such effects are notably less than SEBR changes that can occur when there is a sudden increase in lighting levels (as a glare stimulus) or when assessments are made during conversation.

Endogenous eye blinks in preadolescents: relationship to information processing and performance

Endogenous blinks--those occurring without apparent provocation--are regulated in adults with respect to the presentation, cognitive loading, and response demands of stimuli. This investigation determined the extent to which similar regulatory and response-related relationships were evident in preadolescents during a visual continuous performance task (CPT). As in adults, increased blink incidence on task, longer blink deferral following stimuli with greater cognitive loading, and blink-facilitated motor responses to imperative stimuli were observed. Reaction times significantly decreased when the button press (BP) occurred near (+/- 200 ms) blink onset and increased across the task period on blink-free but not blink-associated trials. More blinks occurred before motor responses in females, and a reaction time (RT) advantage for males on blink-free trials was maintained across blink-associated conditions. From these results, an interpretation is developed arguing that endogenous blinks are a meaningful and integral component of sensory-motor processing, indexing times of facilitated attentional and motor response capability.