Elsevier

Cognition

Volume 136, March 2015, Pages 150-155
Cognition

Brief article
Language influences number processing – A quadrilingual study

https://doi.org/10.1016/j.cognition.2014.11.003Get rights and content

Abstract

Reading/writing direction or number word formation influence performance even in basic numerical tasks such as magnitude comparison. However, so far the interaction of these language properties has not been evaluated systematically. In this study we tested English, German, Hebrew, and Arab participants realizing a natural 2 × 2 design of reading/writing direction (left-to-right vs. right-to-left) and number word formation (non-inverted vs. inverted, i.e., forty-seven vs. seven-and-forty). Symbolic number magnitude comparison was specifically influenced by the interaction of reading/writing direction and number word formation: participants from cultures where reading direction and the order of tens and units in number words are incongruent (i.e., German and Hebrew) exhibited more pronounced unit interference in place-value integration. A within-group comparison indicated that this effect was not due to differences in education. Thus, basic cultural differences in numerical cognition were driven by natural language variables and their specific combination.

Introduction

In this quadrilingual cross-cultural study, we examined the impact of reading/writing direction and the formation of number words on performance in a number comparison task. We used a 2 × 2 design involving Arabic-, English-, German-, and Hebrew-speaking participants realizing an orthogonal quasi-experimental manipulation of the two factors. These factors were chosen, because both have been observed to influence number processing when investigated in isolation.

First, it is assumed that numbers are represented in ascending order along a so-called mental number line (MNL; e.g., Dehaene et al., 1993, Restle, 1970; but see Santens & Gevers, 2008 for a differing view). Interestingly, the orientation of the MNL seems to depend on the dominant reading/writing direction. In cultures reading/writing from left-to-right numbers increase in size along the MNL accordingly (e.g., Dehaene et al., 1993). In contrast, in cultures with right-to-left reading/writing a less clear or even reversed right-to-left orientation has been observed (e.g., Shaki et al., 2012, Shaki et al., 2009). Importantly, however, influences of reading/writing direction on number processing have so far been investigated primarily for effects with single-digit numbers (e.g., spatial–numerical associations such as the SNARC effect, Dehaene et al., 1993, indicating faster responses to small numbers by the left hand and to larger numbers by the right hand in left-to-right reading cultures). Yet, it has not been examined whether reading/writing direction also influences place-value integration of tens and units in two-digit number processing.

Second, number word formation influences place-value integration in two-digit number processing. Generally, two methods of number word formation can be distinguished. In most Western languages, the order of tens and units in number words follows the sequence of their corresponding digits in digital notation (e.g., English: 47  “forty-seven”). However, there are also languages in which this order is inverted (e.g., German, 47  “siebenundvierzig”, i.e., seven-and-forty). This inversion property influences basic numerical tasks such as magnitude comparison. When separate comparisons of tens and units yield incompatible (e.g., 47_62, 4 > 6 but 7 < 2) rather than compatible decision biases (e.g., 52_67, 5 > 6 and 2 > 7) reaction times are prolonged because the units interfere with the processing of the decision-relevant tens (e.g., Nuerk, Weger, & Willmes, 2001). Interestingly, such unit interference was more pronounced in languages with inversion in which the order of tens and units is incongruent between verbal and digital notation (e.g., Nuerk et al., 2005, Pixner et al., 2011a). Additionally, inversion influences are not limited to magnitude comparison but were also reported for a variety of both verbal and non-verbal numerical tasks such as transcoding (Pixner et al., 2011b; Zuber, Pixner, Moeller, & Nuerk, 2009), number line estimation (Helmreich et al., 2011), and even addition (Brysbaert et al., 1998, Göbel et al., 2014; see Nuerk, Moeller, Klein, Willmes, & Fischer, 2011, for an overview). However, so far, influences of number word inversion were only investigated in left-to-right reading/writing languages.

Thus, to date (main) effects of reading/writing direction and inversion on number processing have only been investigated in isolation. Yet, performance may depend on an interaction of these two cultural factors. This idea has so far never been pursued by comparing appropriate languages. One might hypothesize that the increased unit-decade compatibility effect in a language with inversion is driven by the fact of opposing directions of overall reading habits (from left-to-right) and the sequence of tens and unit in number words (from right-to-left). If this assumption is correct a reversed pattern of results should be found for participants reading from right-to-left. In the current study we realized an orthogonal variation of reading direction (left-to-right vs. right-to-left) and inversion (with vs. without, Fig. 1) by testing four language groups: (i) English participants reading/writing from left-to-right with no inversion for number words, (ii) German participants also reading/writing from left-to-right but tens and units are inverted in number words, (iii) Hebrew participants reading/writing from right-to-left with no inversion in number words and (iv) Arab participants reading/writing from right-to-left but with an inversion of tens and units in number words. Increased unit interference is expected for language groups with spatially opposing directionality of reading/writing and inversion (i.e., German and Hebrew participants see Fig. 1). The main effects of inversion (e.g., Nuerk et al., 2005) and reading direction (Shaki et al., 2009) reported so far may thus only reflect specific sections of the postulated interaction. Note that neither reading direction nor inversion was task-relevant in our study as we studied symbolic number comparison using the same stimulus set of Arabic digits throughout. Interestingly, while text is generally read from right-to-left in Arabic and Hebrew, multi-digit Arabic numbers are nevertheless read from left-to-right because the place-value system is not reversed (i.e., “47” is written as 47, not

). Thus, we only presented Arabic two-digit numbers to participants that are processed following the same place-value coding in all four language groups. Expected differences should be driven by differing reading/writing direction and inversion properties of number words. It is important to note that our hypothesis specifically addresses unit interference as indicated by the unit-decade compatibility effect and not overall differences between the languages per se.

Section snippets

Participants and design

24 English-speaking (7 males, mean age 23.1 years), 18 Arabic-speaking (13 males, mean age 24.4 years), 24 German-speaking (8 males, mean age 23.6 years), and 30 Hebrew-speaking participants (5 males, mean age 22.7 years) were tested in the UK, Palestine, Germany, and Israel, respectively. All participants were native speakers of the respective language, had received the majority of their mathematics education in their native language and were assessed in their native language.

Task and stimuli

All participants

Compatibility effects in the four language groups

In each group the majority of participants showed the expected compatibility effect with faster responses to compatible than incompatible number pairs (English: 23 out of 24 participants, Arab: 16/18, German: 24/24, Hebrew: 28/30). Additionally, t-tests indicated that the compatibility effect was significant for each language group [all: ts > 7.43, all ps < .001; MEnglish = 39 ms; MArabic = 39 ms; MGerman = 46 ms; MHebrew = 49 ms, see Fig. 2].

Differences between compatibility effects across language groups

The ANOVA revealed a reliable effect of reading direction,

Discussion

The current study investigated influences of reading/writing direction and the formation of number words on basic numerical cognition employing a quadrilingual (i.e., Arab, English, German, and Hebrew) 2 × 2 design realizing an orthogonal variation of these two factors. Unit-decade integration was differentially affected in the four language groups depending on the combinations of reading/writing direction and inversion: The unit-decade compatibility effect was significantly larger when the

Acknowledgements

Korbinian Moeller and Hans-Christoph Nuerk are members of the Leibniz-ScienceCampus Tuebingen, the LEAD Graduate School of the University of Tuebingen funded within the framework of the Excellence Initiative via the German Research Foundation as well as the “Cooperative Research Training Group” of the University of Education, Ludwigsburg, and the University of Tuebingen supported by the Ministry of Science, Research and the Arts in Baden-Württemberg.

References (33)

  • S. Santens et al.

    The SNARC effect does not imply a mental number line

    Cognition

    (2008)
  • S. Shaki et al.

    Direction counts: A comparative study of spatially directional counting biases in cultures with different reading directions

    Journal of Experimental Child Psychology

    (2012)
  • J. Zuber et al.

    On the language-specificity of basic number processing: Transcoding in a language with inversion and its relation to working memory capacity

    Journal of Experimental Child Psychology

    (2009)
  • D. Ansari

    Effects of development and enculturation on number representation in the brain

    Nature Reviews Neuroscience

    (2008)
  • S. Dehaene

    Origins of mathematical intuitions: the case of arithmetic

    Annals of the New York Academy of Science

    (2009)
  • S. Dehaene et al.

    The mental representation of parity and numerical magnitude

    Journal of Experimental Psychology: General

    (1993)
  • Cited by (34)

    • Twenty-four or four-and-twenty: Language modulates cross-modal matching for multidigit numbers in children and adults

      2021, Journal of Experimental Child Psychology
      Citation Excerpt :

      Interestingly, slower responses in inverted German than in noninverted French for simultaneous and tens-first conditions could still be observed among fourth-graders but not among adults. Indirect evidence of an impact of inversion even in adults was only reported in a comparison task with double digits (Moeller, Shaki, Göbel, & Nuerk, 2015; Nuerk, Weger, & Willmes, 2005). For number pairs in which the magnitude decision for units only was incompatible with the magnitude decision for decades (and therefore the full number; e.g., 46_72 for which 4 < 7 but 6 > 2), RTs were higher for German speakers than for English speakers, perhaps because the unit is more prominent (it comes first) in number words.

    • The scope of linguistic relativity in graphic and lexical numeration

      2021, Language and Communication
      Citation Excerpt :

      But of course, it can hardly be causal on its own, or else unit-before-tens processing would have long ago disappeared everywhere. Moeller et al. (2015) take this analysis one step further, using a four-case comparison of English, German, Hebrew, and Arabic speakers to separate out inverted vs. non-inverted numerals (where English patterns with Hebrew and German with Arabic) from direction of reading (where English and German contrast with Hebrew and Arabic). Both directionality and inversion were shown to have effects on the speed with which literate speakers selected the larger of two two-digit numbers.

    • Numbers and Language: What's New in the Past 25 Years?

      2018, Heterogeneity of Function in Numerical Cognition
    • Mental arithmetic in the bilingual brain: Language matters

      2017, Neuropsychologia
      Citation Excerpt :

      While it is largely accepted that humans possess non-verbal core numerical abilities and basic arithmetic intuitions (Wynn, 1992; Feigenson et al., 2002), it is also becoming increasingly clear that language plays a critical role in numerical and mathematical thinking (Moeller et al., 2015; Van Rinsveld et al., 2016).

    View all citing articles on Scopus
    View full text