The number of letters in number words influences the response time in numerical comparison tasks: Evidence using Korean number words

  • Doyeon Kwon
  • Songjoo OhEmail author
Short Report


Here, we report that the number of letters in number words influences the response time in numerical comparison tasks. In this experiment, a pair of single Korean number words consisting of two or three letters was simultaneously presented in an area of the same size, and the participants reported which was semantically larger. The conditions were categorized as congruent, neutral, and incongruent based on the congruency between the meaning indicated by the numeral (i.e., the size of the number or semantic size) and the number of letters in each number word. In the analysis, compared to the neutral (faster) and incongruent (slowest) conditions, the response time was the fastest under the congruent condition. Thus, the congruency effect is explained by the number of letters rather than continuous visual properties (occupied area and length). These results suggest that the semantic representation of number words is automatically influenced by the number of letters they contain.


Size congruency effect Numerical Stroop effect Korean number words Number of letters 



We would like to thank Craig Leth-Steensen, Todd Kahan, and an anonymous reviewer for providing very supportive comments and suggestions regarding earlier drafts of the paper.

This work was supported by the Korea government (2019-0-01367-BabyMind).

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Copyright information

© The Psychonomic Society, Inc. 2019

Authors and Affiliations

  1. 1.Department of Psychology, College of Social SciencesSeoul National UniversitySeoulSouth Korea

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