The influence of concurrent load on mouthed and vocalized modality effects.

A visual search task was coupled with the serial recall of words to assess the extent to which modality effects mediated by vocalizing and silent mouthing reflect an automatically activated preattentive process. Overall, serial position functions systematically changed as concurrent task demands increased, but the magnitude of the modality effect associated with both mouthing and vocalizing was not altered, regardless of whether or not subjects simultaneously searched for digits. These results support the notion that modality effects index a preattentive process that can be activated automatically by either spoken input or gestural cues associated with speech.