How dual-task interference on word production is modulated by the timing of the secondary task: evidence from errors in people with aphasia

BackgroundUtterance production is affected under dual-task conditions, but so far studies have shown an impact either on lexical or on phonological processes, but not on both simultaneously.AimsIn the present study, we aimed at investigating how interference on lexical and phonological encoding is modulated by the timing of the concurrent task and by the attentional requirement (divided vs focused attention).MethodsParticipants with aphasia (PWA) underwent a picture naming task and an auditory detection task, with auditory stimuli presented at different stimulus onset asynchronies (SOAs). The dual-task was performed under divided (Experiment 1) and focused attention (Experiment 2).Outcome & ResultsOmission errors increased under dual-task at early SOA only in Experiment 1 while phonological errors increased at later SOAs in both experiments.ConclusionThese patterns of errors indicate that lexical and phonological processes are impacted under dual-task conditions, giving rise to an increase of specific types of errors at specific SOAs. They also show that very mild anomia may be more severe when assessed under dual-task conditions.