Interaction between space and number representations during motor preparation in manual aiming.

Full Abstract

The existence of a spatial component in the representation of number magnitude has been repeatedly supported by the demonstration that the left hand responds faster to smaller numbers, whereas the right hand responds faster to larger numbers. These results support the view that the 'mental number line' is oriented such that smaller numbers are associated with the left side of space while larger numbers are associated with the right side. We investigated whether the link between spatial and number processing arises from a continuous or categorical mapping between space and number representations. The investigation was designed to study all aspects of the motor act, including both planning and execution phases. For this purpose we measured reaction times (RTs), movement times (MTs), spatial accuracy, and endpoint pressure of manual aiming, while subjects reached with the right hand towards the location of a visual digit target. Five different digits were equiprobably presented at five positions along the horizontal axis. A GO/NO-GO choice task paradigm was used to ensure that digit parity (i.e., odd/even) was being processed. Analyses of MT, accuracy, and pressure data showed no digit effects. However, two number-related effects were observed on RTs. First, shorter RTs were obtained for smaller digits independent of target location, despite the use of the right hand. Second, an interaction was observed between target location and number magnitude whereby relative RTs were shortest when there was a congruity between target magnitude and location. These results imply that motor preparation is contaminated both by the direct activation of number magnitude and by the congruity between the spatial location of a target number and its magnitude. We conclude that continuous mapping intervenes between mental number representation and physical space.

Author information

Author/s: Ishihara, Masami (M); Jacquin-Courtois, Sophie (S); Flory, Vasantha (V); Salemme, Romeo (R); Imanaka, Kuniyasu (K); Rossetti, Yves (Y);

Affiliation: Espace et Action, UMR-S 534 INSERM-UCBL, Institut National de la Santé Et de la Recherche Médicale, 16 Avenue du Doyen Lépine, 69676 Bron, France.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Neuropsychologia (Neuropsychologia), published in England. (Language: eng)

Reference: 2006-; vol 44 (issue 7) : pp 1009-16

Dates: Created 2006/04/25; Completed 2006/10/11; Revised 2006/11/15;

PMID: 16406028, status: MEDLINE (last retrieval date: 2/18/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

External Links for this article
(including full text providers, if available):

Click Electronic Full-text Provider Links to see options for finding the electronic full text links to this article. Note there may be a subscription or fee required for access to the full text. See our FAQ for information on finding FREE full text articles.

This article may also be located in paper journal collections available in many libraries. Use the Journal and Publication Information above to find the full article.

MeSH headings (categories)

This article was linked to the MESH Headings shown below.

This article has not been indexed for related articles as yet, however you can still use the live related article search links below.

See 100+ related articles.

See a large map of 100+ related articles.