Elsevier

Cortex

Volume 44, Issue 4, April 2008, Pages 400-405
Cortex

Special issue: Original article
Digits affect actions: The SNARC effect and response selection

https://doi.org/10.1016/j.cortex.2007.12.003Get rights and content

Abstract

The SNARC (spatial-numerical association of response codes) effect refers to the finding that processing digits can modulate response times, with low digits facilitating left responses and high digits facilitating right responses. Recent evidence indicates that the locus of this effect is in the response selection stage. To examine this possibility, we presented participants with low or high digits and then asked them to make one of two keypresses (left or right) – whichever one they felt more comfortable making. The results showed that low digits biased the selection of left keypresses while high digits biased the selection of right keypresses. Thus, the SNARC effect not only affects how fast responses can be initiated but also affects what responses will be selected.

Section snippets

Method

Participants. Eighteen English speaking students (13 females, 5 males) participated in this experiment for course credit. Their ages ranged from 17 to 21 years, and the average age was 18.5 years. One participant was left handed, and all had normal, or corrected-to-normal, vision. All participants were naïve about the SNARC effect prior to debriefing.

Apparatus. Participants were seated before a monitor and keyboard in a dimly lit room. The aid of a chinrest kept the viewing distance at a

Results

The mean percentage of left hand responses for the neutral characters, low digits, and high digits appears in the upper portion of Table 1. Because there may be a predisposition for the participants to respond with one hand more than the other, different scores were calculated by subtracting the mean percentage of left keypresses to both low and high numbers from the mean percentage of left keypresses to the neutral symbol characters for each participant. In this manner we were able to measure

Discussion

The purpose of this experiment was to determine if the SNARC effect plays a role in determining which of two responses will be selected for action. To answer the question, a free-response paradigm was used in which participants were instructed to choose between making either a left or right keypress when a centrally presented stimulus (low digit, high digit, or neutral character) turned from white to green. The answer arising from the paradigm is a clear yes; low digits prompted participants to

Acknowledgement

This research was supported by a grant from the Natural Sciences and Engineering Council of Canada to Jay Pratt.

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