Chen, T.Y. and Han, B.X., Chinese Academic of Sciences, China
Recently, there are mainly two controversies in the research of working memory (WM), fluid intelligence (FI) and aging. First controversy is about whether the performance difference between younger and older adults on WM/ central executive (CE) is attributable to the age difference on general FI. Second controversy is about whether CE can be fractionated. Almost all previous researches considered only one CE function (CEF) in one experiment, so the relationship between those functions has not been clear. In this paper, three CEFs (random generation, selective attention and memory updating) are considered, and each CEF includes two levels. From the experimental results, it can be found that 1) age effect is significant on the more difficult level of random generation and both levels of memory updating (MU). However, there is no age effect on the other tasks of CEF. 2) Age effect was significant on MU even if age deficits in FI are controlled. 3) Although different levels do not interact with age within each CEF (a strong all-or-none effect), different CEFs do interact with age. 4) Without considering of age, the correlation between different CEFs is not significant, no matter how remarkable the correlation between different levels within each CEF is. In addition, 5) the correlation between different levels within each CEF has nothing to do with FI. Taken together, this paper indicates that the deficit in CE should be unique, and at lease partially independent of age differences in general FI (referring to result 2, 5). Moreover, this study suggests that CE is not a unitary system but includes separable functions (referring to result 1, 3, 4). As its unique and separable properties, some CEFs are valuable diagnostic criteria for cognitive impairment. Furthermore, researches on CEF will promote the evaluation of human's cognitive functions.