Developmental change in the nature of attention allocation in a dual task.

Younger children have more difficulty in sharing attention between two concurrent tasks than do older participants, but in addition to this developmental change, we documented changes in the nature of attention sharing. We studied children 6-8 and 10-14 years old and college students (in all, 104 women and 76 men; 3% Hispanic, 3% Black or African American, 3% Asian, 7% multiracial, and 84% White). On each dual-task trial, the participant received an array of colored squares to be retained for a subsequent probe recognition test and then an easy or more difficult signal requiring a quick response (a speeded task, clicking a key on the same side of the screen as the signal or the opposite side).

Retrospective cues based on object features improve visual working memory performance in older adults.

Research with younger adults has shown that retrospective cues can be used to orient top-down attention toward relevant items in working memory. We examined whether older adults could take advantage of these cues to improve memory performance. Younger and older adults were presented with visual arrays of five colored shapes; during maintenance, participants were presented either with an informative cue based on an object feature (here, object shape or color) that would be probed, or with an uninformative, neutral cue.

A two-stage search of visual working memory: investigating speed in the change-detection paradigm.

A popular procedure for investigating working memory processes has been the visual change-detection procedure. Models of performance based on that procedure, however, tend to be based on performance accuracy and treat working memory search as a one-step process, in which memory representations are compared to a test probe to determine if a match is present. To gain a clearer understanding of how search of these representations operate in the change-detection task, we examined reaction time in two experiments, with a single-item probe either located centrally or at the location of an array item.

Age differences in visual working memory capacity: not based on encoding limitations.

Why does visual working memory performance increase with age in childhood? One recent study (Cowan et al., 2010b) ruled out the possibility that the basic cause is a tendency in young children to clutter working memory with less-relevant items (within a concurrent array, colored items presented in one of two shapes). The age differences in memory performance, however, theoretically could result from inadequate encoding of the briefly presented array items by younger children.

Can the focus of attention accommodate multiple, separate items?

Researchers of working memory currently debate capacity limits of the focus of attention, the proposed mental faculty in which items are most easily accessed. Cowan (1999) suggested that its capacity is about 4 chunks, whereas others have suggested that its capacity is only 1 chunk. Recently, Oberauer and Bialkova (2009) found evidence that 2 items could reside in the focus of attention, but only because they were combined into a single chunk.

Seven-year-olds allocate attention like adults unless working memory is overloaded.

Previous studies have indicated that visual working memory performance increases with age in childhood, but it is not clear why. One main hypothesis has been that younger children are less efficient in their attention; specifically, they are less able to exclude irrelevant items from working memory to make room for relevant items. We examined this hypothesis by measuring visual working memory capacity under a continuum of five attention conditions.

Investigating the childhood development of working memory using sentences: new evidence for the growth of chunk capacity.

Child development is accompanied by a robust increase in immediate memory. This may be due to either an increase in the number of items (chunks) that can be maintained in working memory or an increase in the size of those chunks. We tested these hypotheses by presenting younger and older children (7 and 12 years of age) and adults with different types of lists of auditory sentences: four short sentences, eight short sentences, four long sentences, and four random word lists, each read with a sentence-like intonation.

Working memory capacity for spoken sentences decreases with adult ageing: recall of fewer but not smaller chunks in older adults.

Previous studies show that older adults have poorer immediate recall for language but the reason is unknown. Older adults may recall fewer chunks from working memory, or may have difficulty binding words together to form multi-unit chunks. We examined these two hypotheses by presenting four types of spoken sentences for immediate free recall, differing in the number and length of chunks per trial: four short, simple sentences; eight such sentences; four compound sentences, each incorporating two meaningful, short sentences; and four random word lists, each under a sentence-like intonation.

Sources of individual differences in working memory: contributions of strategy to capacity.

Some research on attentional control in working memory has emphasized theoretical capacity differences. However, strategic behavior, which has been relatively unexplored, can also influence attentional control and its relationship to cognitive performance. In two experiments, we examined the relationship between attentional control (measured with operation span) and interference in a part-list cuing paradigm.