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The working memory system is assumed to operate with domain-specific (verbal and visuospatial) resources that support cognitive activities. However, in research on visuospatial working memory, an appropriate visual working memory task has not been established. For the present study, a novel task was developed: the picture span test (PST). This test requires memorizing parts of scene images while comprehending various scene situations simultaneously. Results of correlation analyses and a factor analysis among college students (n = 52) validated that PST can predict visuospatial cognitive skills whereas a simple visual storage task and a verbal working memory task cannot. Furthermore, an error analysis indicated that inhibition is important for visuo-spatial working memory. Additionally, PST is considered to reflect individual differences in the visual working memory capacity. These findings suggest that the PST is appropriate for measuring visual working memory capacity and can elucidate its relationship to higher cognition.
Numerous studies of working memory have suggested that the working memory system supports various highlevel cognitive activities, such as reading comprehension, reasoning, language learning, and so on (e.g., Daneman & Carpenter, 1980; Engle, Tuholski, Laughlin, & Conway, 1999; Kyllonen & Christal, 1990; M. Osaka & N. Osaka, 1994). The concept of working memory represents a modification and extension of an earlier concept, short-term memory, which assumed a mere passive storage function. Since the concept of working memory is assumed to involve executive function, working memory tasks require processing and maintaining information. Therefore, tasks measuring the capacity of working memory have higher correlations with cognitive ability measures than those of other traditional short-term memory tasks (for reviews, see Daneman & Merikle, 1996). Studies of working memory frequently use the reading span test (RST), which requires reading several sentences aloud while maintaining a word from each sentence. As a result, the capacity of working memory measured by span tasks (RST and so on) is considered to be predictive of cognitive skills.
However, further problems arise from several findings in research on working memory. In this study, these unsettled problems are examined in more detail.
The Separability in Working Memory Resources
The relation between working memory and cognitive abilities has been proposed to involve domain-specific resources (i.e., verbal and visuospatial; Baddeley, 1986). This is postulated in Baddeley's model of...