The dual-task paradigm has been widely used to investigate attentional interference in word production, revealing different patterns of errors produced by patients with aphasia (PWA). These findings have led to the proposal of various hypotheses regarding the origins of attentional interference. This thesis aims to investigate how different parameters affect interference in word production and how they contribute to a better understanding of the origin of attentional interference under dual-task conditions.

A series of dual-task paradigms was used, incorporating variations in parameters such as delay between the tasks, attentional demands, and the type of concurrent auditory stimuli. These experiments were conducted with neurotypical individuals and PWA, demonstrating an impact on different word planning processes. An effect on phonological errors was observed in both populations depending on the type of concurrent auditory stimuli, suggesting that phonological processes require more attention than previously assumed in the literature.

The findings indicate that interference in word production during dual-task situations arises from a combination of two attentional sources proposed in the literature: domain specific and domain general source of interference.