The present study investigates how children's better strategy selection and strategy execution on a given problem are influenced by which strategy was used on the immediately preceding problem and by the duration between their answer to the previous problem and current problem display. These goals are pursued in the context of an arithmetic problem solving task. Third and fifth graders were asked to select the better strategy to find estimates to two-digit addition problems like 36 + 78. On each problem, children could choose rounding-down (i.e., rounding both operands down to the closest smaller decades, like doing 40 + 60 to solve 42 + 67) or rounding-up strategies (i.e., rounding both operands up to the closest larger decades, like doing 50 + 70 to solve 42 + 67). Children were tested under a short RSI condition (i.e., the next problem was displayed 900 ms after participants' answer) or under a long RSI condition (i.e., the next problem was displayed 1,900 ms after participants' answer). Results showed that both strategy selection (e.g., children selected the better strategy more often under long RSI condition and after selecting the poorer strategy on the immediately preceding problem) and strategy execution (e.g., children executed strategy more efficiently under long RSI condition and were slower when switching strategy over two consecutive problems) were influenced by RSI and which strategy was used on the immediately preceding problem. Moreover, data showed age-related changes in effects of RSI and strategy sequence on mean percent better strategy selection and on strategy performance. The present findings have important theoretical and empirical implications for our understanding of general and specific processes involved in strategy selection, strategy execution, and strategic development.

The present study investigated how elementary-school children solve two-digit addition problems (e.g., 34+68). To achieve this end, we examined age-related differences in children's strategy use and strategy performance. Results showed that (a) both third and fifth graders used a set of 9 strategies, (b) fifth-grade individuals used more strategies than third-grade individuals, (c) age-related differences in the size of strategy repertoire was partially explained by age-related differences in basic arithmetic fluency, (d) how often children used each available strategy changed with problem difficulty and children's age, as younger children tended to focus more on one or two strategies and older children used a wider range of strategies, (e) increased arithmetic performance with age varied with problem difficulty both when overall performance was analyzed and when analyses of performance was restricted to children's favorite strategy. The present findings have important implications for our understanding of how complex arithmetic performance changes with children's age and change mechanisms underlying improved performance with age in complex arithmetic.

Background: Age-based cognitive deficits are exacerbated by stereotype threat effects (i.e., the threat of being judged as cognitively incapable due to aging). We tested whether age-based stereotype threat effects can occur via impair- ing older adults’ ability to select the best strategy and/or to execute strategies efficiently. Methods: Older adults (age range: 64.3–89.5 years) were randomly assigned to a stereotype threat or control condition before taking an episodic memory task. They encoded pairs of concrete words and of abstract words, with either a repetition or an imagery strategy, and then took a cued-recall task. Whereas participants in experiment 1 could choose between these two strategies, those of experiment 2 were forced to use either the repetition or the imagery strategy. Results: Our findings showed that age-based stereotype threat disrupts both the selection and execution of the most efficient, but also most resource-demanding, imagery strategy, and that these stereotype threat effects were stronger on concrete words. Conclusion: Our findings have important implications to further understand age-based (and other) stereotype threat effects, and how noncognitive factors modulate age-related changes in human cognition.

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