Eyeblink activity as an index of cognitive processing: temporal distribution of eyeblinks as an indicator of expectancy in semantic priming.

Eyeblink activity was examined as a psychophysiological index of cognitive processing during a typical semantic priming task. To examine the expectancy-induced effects, the proportion of semantically related pairs was controlled. 8 undergraduates engaged in a lexical decision task for target words. Each condition differed in target type (Semantically Related with prime vs Unrelated vs Nonword) and proporion of Semantically Related pairs (High vs Low). As a result, the temporal distribution of blinks was clearly influenced by the semantic priming effect. The peak of blink bursts, which is correlated with the end of cognitive processing, occurred the fastest in the semantically Related and High proportion condition. While blink latency showed larger individual differences, the temporal distribution of blinks was suggested as a more efficient index of cognitive processing.