Motor sources of dual-task interference: Evidence for effector-based prioritization in dual-task control

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Factors

Background:

• Dual tasking, performing two tasks simultaneously, typically results in performance decrements.
• Previous research often attributed these costs to early or central stages of information processing, such as stimulus perception or response selection.

Purpose of the Study:

• To investigate the role of late-stage task processing, specifically effector system interactions, in dual-task performance costs.
• To determine if effector system combinations reveal a predictable prioritization pattern influencing dual-task capacity.

Main Methods:

• Examined dual-task costs using pairwise combinations of oculomotor, manual, vocal, and pedal response tasks.
• Compared dual-task costs across different effector systems while controlling for a 'context effector' (e.g., manual).
• Analyzed reaction times (RTs) in relation to stimulus modality and effector mapping.

Main Results:

• Dual-task cost patterns were strongly dictated by the specific effector system combinations.
• Evidence supported an ordinal effector-based prioritization pattern: oculomotor > pedal > vocal > manual.
• Stimulus modality and mapping influenced RTs but had minimal impact on the overall prioritization scheme.

Conclusions:

• Late-stage output processing, particularly effector system characteristics, plays a crucial role in dual-task capacity scheduling.
• Findings challenge "first-come, first-served" models and necessitate effector system weighting mechanisms in dual-task control models.