Psychonomic Bulletin & Review

, Volume 25, Issue 1, pp 472–481 | Cite as

A critical reexamination of doing arithmetic nonconsciously

Article

Abstract

A recent study claimed to have obtained evidence that participants can solve invisible multistep arithmetic equations (Sklar et al., 2012). The authors used a priming paradigm in which reaction times to targets congruent with the equation’s solution were responded to faster compared with incongruent ones. We critically reanalyzed the data set of Sklar et al. and show that the claims being made in the article are not fully supported by the alternative analyses that we applied. A Bayesian reanalysis of the data accounting for the random variability of the target stimuli in addition to the subjects shows that the evidence for priming effects is less strong than initially claimed. That is, although Bayes factors revealed evidence for the presence of a priming effect, it was generally weak. Second, the claim that unconscious arithmetic occurs for subtraction but not for addition is not supported when the critical interaction is tested. Third, the data do not show well-established features of numerosity priming as derived from V-shaped response time curves for prime-target distances. Fourth, we show that it is impossible to classify reaction times as resulting from congruent or incongruent prime-target relationships, which should be expected if their results imply that participants genuinely solve the equations on each trial. We conclude that the claims being made in the original article are not fully supported by the analyses that we apply. Together with a recent failure to replicate the original results and a critique of the analysis based on regression to the mean, we argue that the current evidence for unconscious arithmetic is inconclusive. We argue that strong claims require strong evidence and stress that cumulative research strategies are needed to provide such evidence.

Keywords

Interocular suppression Unconscious processing Reproducibility 

Notes

Acknowledgements

P.M. was supported by the Research Fund Flanders (FWO Vlaanderen) through a doctoral fellowship. GH is supported by the German Research Foundation (grant HE 6244/1-2).

Author contributions

P.M. and G.H. designed research; P.M. analyzed data; P.M. and G.H. wrote the paper.

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Copyright information

© Psychonomic Society, Inc. 2017

Authors and Affiliations

  1. 1.Laboratory of Experimental Psychology, Department of Brain & CognitionUniversity of Leuven (KU Leuven)LeuvenBelgium
  2. 2.Visual Perception Laboratory, Department of Psychiatry and PsychotherapyCharité-UniversitätsmedizinBerlinGermany

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