Choosing the fastest movement: perceiving speed-accuracy tradeoffs

Area of Science:

• Cognitive Psychology
• Human Motor Control
• Perception-Action

Background:

• Humans possess sophisticated knowledge of prospective motor actions during movement planning.
• Fitts's Law predicts movement time based on target distance and width (Index of Difficulty).

Purpose of the Study:

• To investigate human consistency with Fitts's Law in selecting movements perceived to have minimal time.
• To determine if participants prioritize minimizing perceived movement time or effort.

Main Methods:

• A 2-alternative forced-choice task was employed to assess movement choices.
• Participants selected between two targets, with varying distances and widths.

Main Results:

• Participants accurately chose targets with lower Index of Difficulty when distance or width favored one option.
• A bias towards closer targets was observed when one target was closer and narrower, deviating from Fitts's Law predictions.
• Performance approached perfection when targets differed significantly in distance or width.

Conclusions:

• Human movement selection is influenced by a subjective representation of movement time.
• A preference for less effortful movements, potentially overriding strict Fitts's Law adherence, is indicated.
• The subjective model integrates Fitts's Law with target distance, suggesting a complex decision-making process.