Optimization in Manual Aiming: Relating Inherent Variability and Target Size, and Its Influence on Tendency

Area of Science:

• Motor control and human movement science.
• Cognitive psychology and decision-making.

Background:

• Manual aiming involves complex motor control strategies.
• Two competing models describe aiming behavior: the optimized submovement model (probabilistic strategy) and the minimization model (play-it-safe strategy).

Purpose of the Study:

• To investigate whether manual aiming strategies shift from target-center aiming to target undershooting as target size decreases relative to inherent movement variability.
• To differentiate between probabilistic and "play-it-safe" aiming strategies in human motor control.

Main Methods:

• Participants performed manual aiming movements towards targets of varying sizes.
• Target sizes were systematically manipulated based on inherent spatial variability of primary movement endpoints.
• Movement endpoints and their variability were analyzed across different target conditions.

Main Results:

• The central tendency of primary movement endpoints consistently neared the target center, irrespective of target size.
• Findings did not support a significant shift towards target undershooting as target size decreased.
• Results align with a probabilistic aiming strategy.

Conclusions:

• Human manual aiming predominantly follows a probabilistic strategy, aiming for the target center.
• Factors potentially influencing a "play-it-safe" strategy warrant further investigation.
• The findings contribute to understanding the adaptive nature of motor control in response to task demands.