Concurrent performance of two working memory tasks: potential mechanisms of interference

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• Simultaneous task performance often leads to decreased efficiency, marked by slower reaction times and more errors.
• Potential causes include increased cognitive load, competition for neural resources, and cross-modal inhibition.

Purpose of the Study:

• To investigate the neurophysiological mechanisms underlying performance decline during dual-tasking.
• To differentiate between task-specific activation, overlapping resource demands, and potential inhibitory effects.

Main Methods:

• Utilized positron emission tomography (PET) to measure regional cerebral blood flow (rCBF).
• Compared brain activity during single auditory working memory (WM), single visual WM, dual WM, and control tasks.

Main Results:

• Both auditory and visual WM tasks activated distinct sensory areas (temporal gyrus, occipital pole) and overlapping non-sensory areas (prefrontal, parietal, cingulate cortex).
• No unique brain regions were activated solely during dual-task performance, suggesting no specific 'dual-task' processing area.
• Reduced rCBF in sensory areas during dual-tasking, compared to single-tasking, suggests interference, though a purely inhibitory mechanism was not definitively proven.

Conclusions:

• Working memory relies on largely non-sensory specific cortical networks.
• Task interference during simultaneous performance appears to stem from competition for shared neural resources in overlapping cortical regions.
• The findings support the hypothesis that concurrent tasks interfere when they require activation of the same brain areas.