Attention, spatial integration, and the tail of response time distributions in Stroop task performance

Abstract

A few studies have examined selective attention in Stroop task performance through ex-Gaussian analyses of response time (RT) distributions. It has remained unclear whether the tail of the RT distribution in vocal responding reflects spatial integration of relevant and irrelevant attributes, as suggested by Spieler, Balota, and Faust (2000). Here, two colour–word Stroop experiments with vocal responding are reported in which the spatial relation between colour and word was manipulated. Participants named colours (e.g., green; say “green”) while trying to ignore distractors that were incongruent or congruent words (e.g., red or green), or neutral series of Xs. The vocal RT was measured. Colour words in colour, white words superimposed onto colour rectangles (Experiment 1), and colour rectangles combined with auditory words (Experiment 2) yielded Stroop effects in both the leading edge and the tail of the RT distributions. These results indicate that spatial integration is not necessary for effects in the tail to occur in vocal responding. It is argued that the findings are compatible with an association of the tail effects with task conflict.

Keywords:

• Attention
• Response time distribution
• Spatial integration
• Stroop task
• Vocal responding

Acknowledgments

This research was supported by a Vici grant from the Netherlands Organisation for Scientific Research. The author thanks Marianne Severens for her help in running the experiments and two reviewers and the members of the Attention and Language Performance Lab at the Donders Centre for Cognition for helpful comments.