Working memory (WM) is the set of mental processes holding limited information in a temporarily accessible state in service of cognition. We provide a theoretical framework to understand the relation between WM and aptitude measures. The WM measures that have yielded high correlations with aptitudes include separate storage and processing task components, on the assumption that WM involves both storage and processing. We argue that the critical aspect of successful WM measures is that rehearsal and grouping processes are prevented, allowing a clearer estimate of how many separate chunks of information the focus of attention circumscribes at once. Storage-and-processing tasks correlate with aptitudes, according to this view, largely because the processing task prevents rehearsal and grouping of items to be recalled. In a developmental study, we document that several scope-of-attention measures that do not include a separate processing component, but nevertheless prevent efficient rehearsal or grouping, also correlate well with aptitudes and with storage-andprocessing measures. So does digit span in children too young to rehearse. Keywordsworking memory; short-term memory; individual differences; variation in working memory; cholastic abilities; intellectual abilities; attention; capacity; storage capacity Baddeley and Hitch (1974) highlighted a key theoretical construct, working memory (WM), which can be described generally as the set of mechanisms capable of retaining a small amount of information in an active state for use in ongoing cognitive tasks (though it now means Research on WM suggests that the measures used most often to examine individual differences have both strengths and weaknesses. A main type of strength is their strong correlation with intellectual aptitude tests, and a main type of weakness is the difficulty encountered in analyzing and interpreting WM test results. This difficulty stems largely from the reliance on dual tasks in the measurement of WM capacity (which include separate storage and processing task components). We will argue that the research literature provides hints that the strengths can be retained without using storage-and-processing measures. We will offer a theoretical framework for doing so, and for measuring WM in a more meaningful way than is found with current measurement practices. The theoretical framework is based on the notion of an adjustable attentional focus and on measures of the storage capacity of attention or its scope. The predictions tested in the present article pertain to the scope of attention, whereas the adjustable nature of the focus allows consistency with other highly relevant research (e.g., Kane, Bleckley, Conway, & Engle, 2001).We do not judge the success of this endeavor by whether storage-and-processing measures or the proposed alternative, scope-of-attention measures, pick up more variance in aptitude tasks.Rather, success will be judged by whether the variance that is picked up contributes to our understanding of the processes underlyi...

We asked whether the ability to keep in working memory the binding between a visual object and its spatial location changes with development across the life span more than memory for item information. Paired arrays of colored squares were identical or differed in the color of one square and, in the latter case, the changed color was unique on that trial (item change) or was duplicated elsewhere in the array (color-location binding change). Children (8-10 and 11-12 years old) and older adults (65-85 years old) showed deficits relative to young adults. These were only partly simulated by dividing attention in young adults. The older adults had an additional deficiency, specifically in binding information, which was evident only when item-and binding-change trials were mixed together. In that situation, the older adults often overlooked the more subtle, bindingtype changes. Some working-memory processes related to binding undergo life-span development in an inverted U shape, whereas other, bias-and salience-related processes that influence the use of binding information seem to develop monotonically.Older adults have a memory deficiency compared to young adults, specifically in the retention of binding information. When items are presented in pairs, the items can be remembered normally but there is difficulty in remembering which ones were paired with which others. This appreciable decline occurs for the binding of focal items to contextual elements (Bayen, Phelps, & Spaniol, 2000;Chalfonte & Johnson, 1996 Chalfonte & Johnson (1996), suggested an associative deficit hypothesis, which focuses on the distinction between memory for single units and memory for associations among units. The present study examines the generality of the associative deficit hypothesis for children as well as the older adults, and for a task examining working memory rather than long-term memory. In this task, two arrays of colored squares must be compared, with the arrays sometimes identical and sometimes differing in the color of a single square. This task has been extensively researched in young adults (Luck & Vogel, 1997; Morey & Cowan, 2004, in press;Todd & Marois, 2004;Vogel & Machizawa, 2004;Vogel, Woodman, & Luck, 2001) and has been examined in infants (Ross-Sheehy, Oakes, & Luck, 2003) and children (Cowan et al., in press).In our version of the task, haphazardly-placed squares of different colors form a sample array that is soon replaced by a blank interval and then a test array identical to the sample array or differing in the color of a single square. A circle surrounding one square in the test array indicates which square changed color, if any square did, and the required response is a judgment as to whether a color change occurred. Inasmuch as colors are selected for the sample array

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If working memory is limited by central capacity (e.g., the focus of attention; N. Cowan, 2001), then storage limits for information in a single modality should apply also to the simultaneous storage of information from different modalities. The authors investigated this by combining a visual-array comparison task with a novel auditory-array comparison task in 5 experiments. Participants were to remember only the visual, only the auditory (unimodal memory conditions), or both arrays (bimodal memory conditions). Experiments 1 and 2 showed significant dual-task tradeoffs for visual but not for auditory capacity. In Experiments 3-5, the authors eliminated modality-specific memory by using postperceptual masks. Dual-task costs occurred for both modalities, and the number of auditory and visual items remembered together was no more than the higher of the unimodal capacities (visual: 3-4 items). The findings suggest a central capacity supplemented by modality- or code-specific storage and point to avenues for further research on the role of processing in central storage.

Recent experimentation has shown that cognitive aptitude measures are predicted by tests of the scope of an individual's attention or capacity in simple working memory tasks and also by the ability to control attention. However, these experiments do not indicate how separate or related the scope and control of attention are. An experiment with 52 children (10 to 11 years old) and 52 college students included measures of the scope and control of attention, as well as verbal and nonverbal aptitude measures. The children showed little evidence of using sophisticated attentional control, but the scope of attention predicted intelligence in that group. In adults, both the scope and control of attention varied among individuals and accounted for considerable individual variance in intelligence. About one third that variance was shared between scope and control, and the rest was unique to one or the other. Scope and control of attention appear to be related but distinct contributors to intelligence.