Mapping of non-numerical domains on space: a systematic review and meta-analysis

Abstract

The spatial numerical association of response code (SNARC) effect is characterized by low numbers mapped to the left side of space and high numbers mapped to the right side of space. In addition to numbers, SNARC-like effects have been found in non-numerical magnitude domains such as time, size, letters, luminance, and more, whereby the smaller/earlier and larger/later magnitudes are typically mapped to the left and right of space, respectively. The purpose of this systematic and meta-analytic review was to identify and summarise all empirical papers that have investigated horizontal (left-right) SNARC-like mappings using non-numerical stimuli. A systematic search was conducted using EMBASE, Medline, and PsycINFO, where 2216 publications were identified, with 57 papers meeting the inclusion criteria (representing 112 experiments). Ninety-five of these experiments were included in a meta-analysis, resulting in an overall effect size of d = .488 for a SNARC-like effect. Additional analyses revealed a significant effect size advantage for explicit instruction tasks compared with implicit instructions, yet yielded no difference for the role of expertise on SNARC-like effects. There was clear evidence for a publication bias in the field, but the impact of this bias is likely to be modest, and it is unlikely that the SNARC-like effect is a pure artefact of this bias. The similarities in the response properties for the spatial mappings of numerical and non-numerical domains support the concept of a general higher order magnitude system. Yet, further research will need to be conducted to identify all the factors modulating the strength of the spatial associations.

The Relational SNARC: Spatial Representation of Nonsymbolic Ratios

“…Thus, the SNARC effect should prove to be a SQUARC (Spatial Quantity Association of Response Codes) effect. The nonsymbolic aspects of the current experiments parallel other research demonstrating that the basic operation of the SNARC effect does apply to nonsymbolic magnitudes, such as physical size, luminance, angle magnitude, and loudness (see Macnamara, Keage, & Loetscher, for a review). However, the use of ratio magnitudes in this study represents a major departure from previous nonsymbolic studies involving associations of space and magnitude.…”

Moved by Emotions: Affective Concepts Representing Personal Life Events Induce Freely Performed Steps in Line With Combined Sagittal and Lateral Space-Valence Associations

“…Similarly, space-reward associations across laterality have been found when processing reward-related words, showing faster responses under congruent conditions (monetary gain -dominant right hand; monetary loss -non-dominant left hand) than under incongruent ones (monetary gain -non-dominant left hand; monetary lossdominant right hand; Vicario and Rumiati, 2014). For further spatial-associations across laterality (e.g., luminance, size, letters) see also a review by Macnamara et al (2018).…”

The Faulty Magnitude Detector: Why SNARC‐Like Tasks Cannot Support a Generalized Magnitude System

“…In a typical SNARC effect, people respond faster to smaller numbers with the left hand and to larger numbers with the right, indexing a left-to-right mental number line. Beyond number, SNARC-like tasks have been used to test spatial mappings of many non-spatial domains, including size, brightness, auditory intensity, and even highly abstract domains like emotional intensity (Holmes, Alcat, & Lourenco, 2019;Macnamara, Keage, & Loetscher, 2018). These results have been widely interpreted as evidence of a "generalized magnitude system" (GMS; Walsh, 2003, p. 484).…”

“…In his initial proposal for a GMS, Walsh (2003) suggested that one of the "strong predictions" (p. 487) was that the numerical SNARC effect should generalize to other quantitative domains. Accordingly, SNARC and SNARC-like effects have been highlighted as an especially important source of evidence for the putative GMS (Bueti & Walsh, 2009;Macnamara et al, 2018;Walsh, 2015).…”