No evidence of intelligence improvement after working memory training: A randomized, placebo-controlled study.
DOI: 10.1037/a0029082
archive: archived pipeline: cataloged verified
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Summary
This study investigates whether working memory (WM) training leads to improvements in general intelligence, addressing a contentious debate in cognitive psychology. While some prior research, notably Jaeggi et al. (2008), claimed that adaptive dual n-back training significantly enhances fluid intelligence, other reviews highlighted methodological flaws in such studies, including the use of no-contact control groups and single-task measures. The authors aimed to determine if repeated practice on an adaptive dual n-back task causes genuine transfer to intelligence, multitasking, and WM capacity, using a rigorous experimental design to rule out alternative explanations for observed gains. The researchers conducted a randomized, placebo-controlled study involving young adults assigned to one of three groups: a working memory training group practicing an adaptive dual n-back task, an active placebo-control group practicing an adaptive visual search task, and a no-contact control group receiving no practice. All participants completed 20 sessions of training or control activities. To comprehensively assess cognitive changes, subjects underwent pretest, midtest, and posttest sessions featuring multiple measures of fluid intelligence, multitasking, working memory capacity, crystallized intelligence, and perceptual speed. This design addressed previous limitations by employing an active control group to account for practice effects and using multiple tasks to ensure robust measurement of cognitive constructs. Despite significant improvements in performance on the specific training tasks (both dual n-back and visual search) across the 20 sessions, the study found no evidence of positive transfer to any of the cognitive ability tests. The high statistical power of the study confirmed that the lack of transfer was not due to insufficient sample size. Participants in the training group did not show greater gains in fluid intelligence, multitasking, or other cognitive domains compared to the active placebo or no-contact control groups. These results directly contradict earlier claims that dual n-back training improves intelligence, suggesting that previous findings may have been artifacts of methodological weaknesses, such as collapsing data across studies with different procedural conditions or relying on no-contact controls. The findings imply that brief, inexpensive cognitive training interventions do not necessarily enhance general intellectual abilities, challenging the optimistic views held by some researchers and the marketing claims of commercial brain-training programs. The study underscores the importance of rigorous experimental designs, including active control groups and multiple measures, in evaluating cognitive training efficacy. It suggests that while individuals can improve at specific trained tasks, these gains do not generalize to broader cognitive functions like fluid intelligence. Consequently, the field should approach claims of intelligence improvement through WM training with skepticism and prioritize methodological rigor in future research to accurately identify any potential mechanisms of transfer.
Key finding
Working memory training using an adaptive dual n-back task did not produce any transfer effects to measures of fluid intelligence, multitasking, or working memory capacity.
Methodology
lab_experiment
Provenance
The full processing record for this entry. Every stage of this paper's journey through the pipeline is logged — what ran, with which tool and model, how many attempts it took, and when it last completed. Discovered via openalex_abstract on 2026-05-08 (3 acquisition events logged).
| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.
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