(10) The characteristic eye movements in counting the objects by using working memory
S.Murakami, H.Naraki and T.Yamanoi
Neuroscience, 263.17/Y34, 2009-10
When we count objects of the same color, size and shape in a line, we used working memory to memorize the counted ones until the end of the counting and made eye movement for the counting. The aim of this experiment was to study the eye movement for accurate enumeration in counting the objects in a line by using working memory. The subjects were 5 male and 5 female, aged 21 to 78 years, who had normal vision, physical and mental condition. In this experiment, the visual stimuli for counting displayed on the touch panel screen were five to nine same size, color and shape apple figures in a line. While counting, eye movements were observed and recorded by the EMR-8 (NAC) head-mounted system and analyzed after experiment. The subjects were requested to count the displayed apple figures and answer how many apples were presented. Their correct answer rate was about 84%. When they counted the apples, two ways were observed. In the first way, many subjects counted them to shift their gazes on some points in those apples by using saccades and occasionally made incorrect answers. They grouped those apples within 2 or 3 apples for counting easy. In this way, they used saccades to jump over one or two objects for catching the next target apple. So, the subjects were requested to make saccades from the marked apple to next marked apple, bur if it were incorrect saccade, they miscounted the apples. The larger their saccade were, the more their miscount were. These results show that in second way for counting it needed to catch the marked target apple in the presented apples to prevent double counting or miscounting and their saccade amplitudes were less than 3 times of the apple size, and the accurate enumeration was made in smaller amplitude. In younger, they did in second way to count but elder subjects preferred the first way for counting.
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