Inhibitory modulation of speech trajectories: Evidence from a vowel-modified Stroop task.

How does cognitive inhibition influence speaking? The Stroop effect is a classic demonstration of the interference between reading and color naming. We used a novel variant of the Stroop task to measure whether this interference impacts not only the response speed, but also the acoustic properties of speech. Speakers named the color of words in three categories: congruent (e.g., written in red), color-incongruent (e.g., written in red), and vowel-incongruent - those with partial phonological overlap with their color (e.g., written in red, in green, and in blue). Our primary aim was to identify any effect of the distractor vowel on the acoustics of the target vowel. Participants were no slower to respond on vowel-incongruent trials, but formant trajectories tended to show a bias away from the distractor vowel, consistent with a phenomenon of that increases contrast between confusable alternatives.