Sequential Effects in SNARC

Dinis Gökaydin,Peter Brugger,Tobias Loetscher

doi:10.1038/s41598-018-29337-2

Dinis Gökaydin, Peter Brugger + Show 1 more

Open Access

https://doi.org/10.1038/s41598-018-29337-2

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Abstract

Small and large numbers are typically associated with the left and right side of space, respectively. We conducted an online version of the classical Spatial-Numerical Association of Response Codes (SNARC) paradigm in 604 subjects in order to analyse how previous trials and responses affect SNARC. Our results point to a strong inversion of number-space associations (left/large and right/small) when the last trial was incoherent - i.e. when a response with the left hand was made to a large number or vice-versa. In addition, we demonstrate that the congruency of trials beyond just the last two can influence SNARC, providing empirical support for an important assumption of a working memory account of spatial-numerical associations. Finally, we show that sequential effects in SNARC can be captured by a simple exponential filter, known to underpin sequential effects across a range of stimuli detection and perceptual two-alternative forced choice decision tasks. Our findings point to universal mechanisms responsible for the processing of sequences from perception to cognition.

Highlights

Small and large numbers are typically associated with the left and right side of space, respectively
The Spatial-Numerical Association of Response Codes (SNARC) effect was found to depend on a trial-by-trial basis on the congruency of previous trials, where a congruent trial (C) is defined as one where a response was made with the left hand to a small number or with the right hand to a large number; an incongruent trial (I) is one where a response was made with the right hand to a small number or the left hand to a large number
We will discuss three main types of analysis: in the first we show the slope of the SNARC effect the classical way and how it varies with (1) the congruency of the last trial, (2) whether the current trial is a repetition or alternation and (3) the effect of the congruency of the last trial when restricting to response/stimulus repetitions/alternations

Summary

Introduction

Small and large numbers are typically associated with the left and right side of space, respectively. Several factors are known to influence the SNARC effect such as reading direction[2], working memory demands[3,4], positioning of numbers[5], instructions[6], as well as the participants’ neuropsychological status, especially concerning the presence of deficits in spatial attention[7] These factors influence the magnitude of the SNARC effect but, in some circumstances, can invert it so that subjects respond quicker to small numbers with the right hand and vice-versa.

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