The Latency of Spontaneous Eye Blinks Marks Relevant Visual and Auditory Information Processing

Eye blinks are influenced by several external sensory and internal cognitive factors. However, neither the precise temporal effects of these factors on blinking nor how their timing compares between modalities is known. Our aim was to understand the influence of sensory input vs task-relevant information on blinks in the visual and auditory domain. Using a visual and an auditory temporal judgement task, we found that blinks were suppressed during stimulus presentation in both domains and the overall input length had a significant positive relationship with blink latency i.e. the end of blink suppression. Indeed, the effect of sensory input duration on blink latency was not significantly different between visual and auditory stimuli. The precise timing of blink latency was further modulated by the duration of the task relevant input, which was independent of the overall length of sensory input. The influence of task related changes embedded in the overall stimulation suggests an additional influence of top-down processes on blink timing. Intriguingly, embedded changes as short as 40 ms in the auditory domain and 100 ms in the visual domain are reflected in blink latency differences. Importantly, we could show that task accuracy and motor response was not the driving factor of blink modulation. Our results show a sensory domain independent modulation of blink latencies introduced by changes in the length of task-relevant information. Therefore, blinks not only mark the time of sensory input but also can act as precise indicator for periods of cognitive processing and attention.