Résumé
Objective: Consistent with Uittenhove and Lemaire (2012), we expected that strategy execution would be slower following execution of a difficult strategy than after an easy strategy (strategy sequential difficulty, SSD, effects). Moreover, we expected larger SSD effects in older adults than in young adults, and especially in Alzheimer's disease (AD) patients, a population with marked cognitive impairments. Method: A total of 25 young and older (41 AD and 25 healthy) adults were asked to execute rounding strategies to solve arithmetic problems (e.g., solving 43 + 68 by rounding operands down or up, e.g., 40 + 70 = 110). We measured solution latencies and percentage errors with a strategy as a function of the difficulty of the just-executed strategy. Results: Solution latencies were significantly shorter following the easier rounding-down strategy than following the harder rounding-up strategy, F(2, 156) = 35.8. Moreover, this effect was significantly larger in AD patients, F(1, 78) = 117.4. Conclusions: We found comparable SSD effects in young and healthy older adults but dramatically increased SSD effects in AD patients. This has implications to further our understanding of strategic aspects underlying decreased cognitive functioning in AD patients.