Abstract
Tanaka & Yamaoka (1993) reported that the more difficult the task became, the higher was the blink rate, only in a mental arithmetic task, and this relationship was not found in a letter (a cursive Japanese syllabary called “hiragana”)-search task. The two tasks had a different nature in structure of information processing system. And it was not clear which factor of the changes in the task and information processing system was more depended on the relationship between blink activity and task difficulty. So the purpose of this study was to make clear the relationship using another type of letter (hiragana)-search task which had a nature similar to the mental arithmetic task. And this task prepared three levels of difficulty, setting up by memory set size from 2 to 6 with 2 steps, i. e., MSS2, MSS4, MSS6. Analysis showed that blink rate for MSS6, which was the most difficult task, was significantly higher than that for MSS2, which was the easiest one; namely, the relationship between blink rate and task difficulty was the same as that in the mental arithmetic task. This result suggested that changes in a task should have no effect on the relationship between blink rate and task difficulty. The result for blink amplitude indicated that this measure was a valid index of arousal level. Blink duration was not affected by memory set size.
