Abstract
A test pattern consisting of 1 to 15 dots was presented for 50 ms on a computer screen. Each of fifteen college students was asked to report orally the number of dots displayed as quickly as possible. In the experimental condition, the subject was presented short sentences successively via headset during the dot-counting task. Half of the experimental subjects judged the gender of the voice reading each sentence, and the other half judged truth of the sentence. In the control condition, the subject conducted only the dot-counting task. The results showed that the span of attention (the upper limit for 50％ correct numerosity judgment) was not influenced by the concurrent task, but the reaction time to dot-counting under the concurrent task was longer than that under the control condition.
