Abstract: The slowing of processing speed with aging is one of the most influential causes that can explain the age-related decline of cognitive abilities. It’s reasonable to assume that older adults’ cognition might be maintained or promoted through processing speed training. However, whether processing speed can be enhanced or not is still questionable for older people. Thus, the present study aims at examine the plasticity of processing speed in later life.
Overall, 46 community-dwelling older adults, ranging in age from 60 to 79 years, participated in this study. For the baseline test, a kit of primary mental ability tests, the intellectual self-efficacy questionnaire, and two perceptual speed tests were administered to all the participants. There were 25 participants in the experimental condition (cognitive training). For this condition, the baseline test was followed with additional computerized exercises involving pattern comparison. Each participant received five 50-minute sessions of training over a five-week period. There were 21 participants in the control group condition and these participants received no additional training after baseline test. All the participants completed a post-training test using the same measures at baseline. At four months follow-up, 31 participants completed assessments once more.
In this study, the two perceptual speed test, namely number comparison test (NCT) and picture matching test (PMT) were used to examine the training effects. And, the primary mental ability tests, including word fluency, number, reasoning, spatial orientation, and vocabulary, were used to explore the transferring effects of training. Repeated MANOVA analyses, with group (intervention vs. control) and time (pre-training vs. post-training) as independent variables, were conducted for performances on NCT and PMT respectively. A significant group and time interaction was found for PMT (F(1,44)=4.34, p=0.043) but not for NCT. Repeated MANOVA were also conducted for the five primary mental abilities respectively. The results indicated significant group and time interaction effect on the performance of word fluency test, F(1,44)=7.70, p=0.008. MANOVA were employed to analyze effect at four month follow-up, however, no interactions of group and time were found for either PMT or word fluency test.
In conclusion, processing speed, as measured by reaction time, would appear to be improved through a short-term training intervention. However it cannot be discounted that changes in processing speed could be influenced by secondary rather than primary aging processes. Different processing speed indices may exhibit differential training effects. Compared to NCT, PMT would appear to be more reliable to reflect the training effects.

Key words: older adult, processing speed, cognitive intervention, plasticity