Cited by 112Cognitive Abilities and TestingCognitive and developmental aspects of mathematical skillsCognitive Functions and Memory

The DOI matches its Crossref record; 54 of the 54 references it cites were found in a registry or an index; 6 of the 29 sources its claims cite were checked for support.

Reevaluating the effectiveness of n-back training on transfer through the Bayesian lens: Support for the null

Open access
Dougherty, Michael R., Hamovitz, Toby, Tidwell, Joe W.·2016·Psychonomic Bulletin & Review

Abstract

A recent meta-analysis by Au et al. Psychonomic Bulletin & Review, 22, 366-377, (2015) reviewed the n-back training paradigm for working memory (WM) and evaluated whether (when aggregating across existing studies) there was evidence that gains obtained for training tasks transferred to gains in fluid intelligence (Gf). Their results revealed an overall effect size of g = 0.24 for the effect of n-back training on Gf. We reexamine the data through a Bayesian lens, to evaluate the relative strength of the evidence for the alternative versus null hypotheses, contingent on the type of control condition used. We find that studies using a noncontact (passive) control group strongly favor the alternative hypothesis that training leads to transfer but that studies using active-control groups show modest evidence in favor of the null. We discuss these findings in the context of placebo effects.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

Dougherty et al. reanalyze Au et al.’s (2015) n-back training meta-analysis using Bayesian methods and find that evidence for transfer to fluid intelligence depends heavily on control-group type. Passive-control studies strongly favor transfer, but active-control studies provide modest-to-strong evidence for the null, suggesting the apparent training effect may be a placebo or design artifact.

Key findings

  • Across all 24 comparisons from 20 papers, the meta-analytic Bayes factor ignoring control type was 152:1 in favor of the alternative hypothesis, but this masked a large difference by control condition.
  • Passive-control studies yielded a Bayes factor of 13,241:1 in favor of transfer, whereas active-control studies yielded a Bayes factor of 7.7:1 in favor of the null; with a two-sided test, these were 6,000:1 for the alternative and 11:1 for the null, respectively.
  • Hierarchical Bayesian models showed passive-control studies consistently had positive effect sizes, while active-control studies had effects near zero; the only aggregate effect whose 95% HDI excluded zero was for non-USA passive-control studies, and active-control effects within the USA shrank to essentially zero.
  • Among individual studies, 11 of 12 passive-control effect sizes were positive, but only 6 of 12 active-control effect sizes were positive; the majority of individual studies favored the null, including 6 of 12 passive-control studies.

Methods

  • Bayesian reanalysis of effect sizes from Fig. 3 of Au et al. (2015), using 24 comparisons from 20 papers with healthy adults aged 18–50 and n-back as the only training task; 12 comparisons used passive controls and 12 used active controls.
  • Effect sizes were transformed to t values using \(t = \sqrt{1/n_1 + 1/n_2} \times g\), then default Bayes factors were computed with the BayesFactor package in R (`ttestBF`, `meta.ttestBF`), using a one-sided interval and scale factor \(r = 1\), with sensitivity checks using two-sided tests and different priors.
  • Follow-up hierarchical Bayesian models estimated effect sizes as a function of control type (passive vs. active) and, in additive models, country of origin (USA vs. non-USA), using four prior distributions on population effect size (vague, small, medium, large).

Limitations

  • The paper states that conclusions do not necessarily generalize to other types of training or age groups, because Au et al. limited inclusion to n-back training and healthy adults aged 18–50.
  • The paper states that, without experiments specifically designed to test the placebo explanation, it cannot definitively conclude that the active–passive discrepancy reflects a placebo effect; it also notes causal indeterminacy in comparing placebo controls with no-contact controls across studies.
  • The paper notes that control type covaried with country of origin—most active-control studies were conducted within the USA, while most non-USA studies used passive controls—leaving open the possibility that cultural differences contribute, though the authors doubt this accounts for the 7-fold difference. Evident from the text: active-control studies were heterogeneous in the nature of their control tasks, and the reanalysis depends on the effect sizes and control-type categorization provided by Au et al.

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Integrity signals

Registry

Crossref · 10.3758/s13423-015-0865-9

Cites

54 of 54 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

25 Own interpretation · 11 Sources not found · 9 Own result · 4 No full text of the sources · 4 Own method · 2 Supported so far · 2 Not checked yet · 2 No basis given · 1 Supported · 1 Partly supported · 1 Not supported · accuracy not yet measured

  • Probably not a substantial claim. 15
  • It may state two separate claims as one. 23
35 of 35
  • The authors state this as an assumption.

    The effects observed in passive-control studies reflect something other than a training effect.

    “Because the passivecontrol studies show a substantial positive effect while the active control studies do not, it seems reasonable to assume that the effects observed in the passive-control studies reflects something other than a training effect.”
  • The authors state this as an assumption.

    A one-sided interval placing prior mass on effects greater than zero is reasonable under the hypothesis that training improves Gf.

    “The one-sided test is a reasonable assumption under the hypothesis that training should lead to improvements in Gf.”
  • The paper relies on this without support.

    NHST tends to overstate evidence for the alternative hypothesis and does not allow evaluating the relative probability that the null hypothesis is true.

    “two well-known limitations of the NHST framework are that it tends to overstate evidence for the alternative hypothesis and does not permit one to evaluate the relative probability that the null hypothesis is in fact true.”
  • The authors state this as an assumption.

    Studies that use active controls may also use other procedures that reduce expectancy or placebo effects.

    “it is reasonable to assume that studies that adopt active controls might also adopt other procedures that minimize expectancy or placebo effects.”
4 of 4

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1 of 1

Citations

Cites

Show all 54 references

Research works printed but not linked: 4

  1. Jaeggi, S. M., Buschkuehl, M., & Jonides, J. (2009). Working memory training and transfer. Arlington: Presented at the annual ONR Contractor’s meeting.
  2. Jeffreys, H. (1961). Theory of probability. New York: Oxford University Press.
  3. Katz, B., Jaeggi, S. M., Buschkuehl, M., Shah, P., & Jonides, J. (2015). Money can’t buy you fluid intelligence (but it might not hurt either): The effect of compensation on transfer following a working memory intervention. Manuscript under review.
  4. Schwarb, H. (2012). Optimized cognitive training: Investigating the limits of brain training on generalized cognitive function (Unpublished doctoral dissertation). Atlanta: Georgia Institute of Technology.

Cited by

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Metadata

Authors
Dougherty, M. R., Hamovitz, T., & Tidwell, J. W.
Affiliations
University of Maryland, College Park (US)
Corresponding author
Dougherty, Michael R.
Venue
Psychonomic Bulletin & Review
Published
2015-06-17
Volume
23
Issue
1
Pages
306-316
ISSN
  • 1069-9384 (ISSN-L)
  • 1531-5320
OpenAlex
W808339630
Cited by
112
References
54
Citations by year
2026: 2 · 2025: 1 · 2024: 4 · 2023: 4 · 2022: 7 · 2021: 11 · 2020: 12 · 2019: 17 · 2018: 22 · 2017: 16 · 2016: 13 · 2015: 3
FWCI
16.87
Type
journal article
Language
en
Open access
Locations
  • Psychonomic Bulletin & Review (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Cognitive Abilities and Testing
  • Social Sciences › Psychology › Developmental and Educational Psychology › Cognitive and developmental aspects of mathematical skills
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Cognitive Functions and Memory
Keywords
working memory training, fluid intelligence, transfer of training, Bayesian hypothesis testing, null hypothesis, placebo effect, active control, effect size
MeSH terms
Bayes Theorem, Data Interpretation, Statistical, Humans, Intelligence, Memory, Short-Term, Transfer, Psychology, Meta-Analysis as Topic

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