Limitations:
- Perceptual: how many things can we attend to at the same time?
- Central processing/executive: dual task performance and capacity limitations.
Theories:
- Multiple Resource: The success of dual task performance depends on whether the tasks require the same processing resources.
- Central Capacity: this depends on the demands of each task on the limited capacity central processor
Factors influencing the success of dual task performance:
- Task similarity: the participant is more likely to be successful if the task involves different stimulus or response modalities.
- Task difference: this does not necessarily mean the sum of the difficulties, but it also concerns coordination and interference difficulties.
- Practice: The demands placed on attentional resources may be reduced if the task or action is practiced. A development takes place from controlled to automatic processing.
Task Similarity
- Stimulus modality: Stimuli that are presented in the same sense modality produced poorer monitoring performance than when they were presented in different modalities (Treisman & Davies 1973)
- Response Modality: An experimental example of this comes from McLeod, (1977) where a tracking task and a tone-identification task were used, and a manual or vocal response was given. The performance on the tracking task was worse when the mode of response was the same as the task, ie manual, than when it was different ie vocal.
Task Difficulty
- The effectiveness of a dual task performance decreased as a task becomes more difficult
- The difficulty refers not only to the demands of each task, but also of the demands of coordinating the two. This can require additional processing resources.
- D'Esposito et al. (1995): Semantic judgement task AND/OR spatial rotation. In the DUAL task condition, fMRI shows significant activity in the prefrontal cortex and anterior cingulate
