SNARC for numerosities is modulated by comparative instruction (and resembles some non-numerical effects)

Abstract

The spatial-numerical association of response codes (SNARC) effect is observed for both numerical (Arabic digits) and non-numerical stimuli (size, duration, height). However, in a context of comparative judgment, Arabic numbers are mapped onto space differently from sizes and heights: SNARC for Arabic digits is formed consistently in a certain cultural reading direction, whereas SNARC for sizes and heights is additionally modulated by comparative instruction (it reverses when participants choose larger magnitudes). In the present study, we test whether the spatial characteristic of magnitude processing revealed in a context of comparison is determined by a presence or lack of numerical content of the processed information, or it depends on specific directional experience (e.g., left-to-right ordering) associated with the processed magnitude format. We examine the SNARC effect with the pairwise comparison design, by using non-symbolic numerical stimuli (objects' collections), for which the left-to-right spatial structure is not as exceedingly overlearned as for Arabic numbers. We asked participants from two reading cultures (left-to-right vs. mixed reading culture) to compare numerosities of two sets, choosing either a larger or smaller one. SNARC emerged in both groups. Additionally, it was modulated by comparative instruction: It appeared in a left-to-right direction when participants selected a smaller set, but it tended to reverse when participants selected a larger set. We conclude that spatial processing of numerosities is dissociated from spatial processing of Arabic numbers, at least in a context of comparative judgment. This dissociation could reflect differences in spatial ordering experience specific to a certain numerical input.

If John is taller than Jake, where is John? Spatial inference from magnitude comparison.

“…and "The square" the largeness (or smallness) of each item is not immediately apparent and must be accessed indirectly from a representation constructed during processing of the comparative sentence. Such a differential-accessibility account accords with dual-coding models of meaning (e.g., Paivio, 1986) and generates a straightforward prediction: if the response options were identified by verbal labels that explicitly referenced their size (e.g., "The large circle/The small square") we would expect to see a resurgence of the relevance effect.…”

Spatial–numerical associations: Shared symbolic and non-symbolic numerical representations

“…While they did find a traditional left-to-right bias when participants were asked to choose the array with fewer items (from two choices), they observed a right-to-left bias when participants were asked to choose the one with more items. These results were independent from reading direction, which is an important factor for studies using numerals as stimuli, as discussed below (Patro & Shaki, 2016).…”

“…Such a left-to-right bias has also been found for non-symbolic numerical stimuli (Luccio, Fumarola, Tamburini, & Agostini, 2012; Mitchell, Bull, & Cleland, 2012). Patro and Shaki (2016) used arrays of objects in their experiment, verifying this effect for non-symbolic representations of numbers. While they did find a traditional left-to-right bias when participants were asked to choose the array with fewer items (from two choices), they observed a right-to-left bias when participants were asked to choose the one with more items.…”

A gifted SNARC? Directional spatial-numerical associations in gifted children with high level math skills do not differ from controls

“…The SNARC effect can be observed in multiple tasks (e.g., parity judgment, magnitude classification, and phoneme monitoring). It is present irrespective of number presentation format (e.g., Arabic, number words, auditory numbers, dice patterns, nonsymbolic numbers, and numbers presented in a tactile format) and response mode (bi-and unimanual, pointing, bipedal, and eye movements; see Nemeh, Humberstone, Yates, & Reeve, 2018;Patro, & Shaki, 2016 for effects in non-symbolic numbers; Wood, Willmes, Nuerk, & Fischer, 2008 for a meta-analysis; Fischer & Shaki, 2014 for a review).…”