Namiko Kubo-Kawai

Elimination of the enhanced Simon effect for older adults in a three-choice situation: Ageing and the Simon effect in a go/no-go Simon task

In a Simon task, participants show better performance when the irrelevant stimulus location corresponds with the response location than when it does not, and this effect is typically greater for older adults than for younger adults. To study the effect of cognitive ageing in the Simon task, we compared young and old adults using two versions of the Simon task: (a) a standard visual Simon task, for which participants respond with left and right key-presses to the red and green colours of stimuli presented in left and right locations; (b) a go/no-go version of the Simon task, which was basically the same, except that the shape of the stimulus in one third of the trials indicates that no response is to be made. In both tasks, both age groups showed the Simon effect. The magnitude of the effect for the standard Simon task was greater for the older adults than for the younger adults. Nevertheless, the two groups showed an equivalent Simon effect in the go/no-go version of the Simon task. Reaction time distribution analyses revealed basically similar functions for both age groups: a decreasing pattern of the Simon effect in the standard task and an increasing pattern of the effect in the go/no-go version of the task. The results suggest that older adults find it more difficult to suppress an automatic activation of the corresponding response, though this automatic activation was reduced in situations where the response was frequently inhibited.

Distinct aging effects for two types of inhibition in older adults: a near-infrared spectroscopy study on the Simon task and the flanker task.

The present study examined age-related changes in inhibitory processes among older and younger adults in the flanker and Simon tasks in terms of behavioral performance and prefrontal brain activity by functional near-infrared spectroscopy. The flanker task requires a quick identification of a central target in the presence of surrounding distracters, whereas the Simon task requires an individual to respond with left and right key presses to nonspatial features of the stimulus presented in the left and right locations. The reaction times of two age groups were longer under incongruent conditions than under congruent conditions in both tasks, indicating that the flanker effect (interference suppression) and the Simon effect (response suppression) were evident. In agreement with previous studies, the magnitude of the effect for the Simon task was greater for the older adults than for the younger adults, whereas the two groups showed equivalent flanker effects. The results suggest that older adults have difficulties in response inhibition, but not in stimulus interference suppression. Enhanced activity was found in different brain regions across the two tasks among the older adults. The older adults showed more activity in the superior and middle frontal gyri of the left hemisphere than younger adults in the flanker task; they showed more activity in the bilateral superior frontal gyri in the Simon task. These results suggest that the underlying mechanisms of the inhibition processes for the two tasks are distinct: they rely on different brain regions and have differential vulnerabilities to aging.

Characteristics of Developmental Dyslexia in Japanese Kana: from the Viewpoint of the Japanese Feature

This study identified the individual differences in the effects of Japanese Dyslexia. The participants consisted of 12 Japanese children who had difficulties in reading and writing Japanese and were suspected of having developmental disorders. A test battery was created on the basis of the characteristics of the Japanese language to examine Kana’s orthography-to-phonology mapping and target four cognitive skills: analysis of phonological structure, letter-to-sound conversion, visual information processing, and eye–hand coordination. An examination of the individual ability levels for these four elements revealed that reading and writing difficulties are not caused by a single disability, but by a combination of factors. Additionally, the combination of individual elements differed among the participants, which indicates that children with learning disabilities may need different types of support even if they have similar reading and writing difficulties. Furthermore, this study demonstrated that words written in Kana, one of the Japanese syllabic, are easy to segment into phonological units, but difficult to interpret when attempting to link each letter to its corresponding sound. These findings can help change the concept of Japanese dyslexia and have a significant impact on education methods and techniques in Japan.