Reaction time and movement duration influence on end point accuracy in a fast reaching task

Area of Science:

• Motor control and biomechanics
• Human physiology and sport science

Background:

• Fitts' paradigm models movement time based on target distance and size, but omits crucial preparation time.
• Limited research exists on temporal and spatial asymmetries in fast, accurate movements.

Purpose of the Study:

• Investigate how preparatory phase duration (reaction time, T(R)) and arm movement time (T(M)) influence movement speed and accuracy.
• Examine individual temporal and accuracy asymmetries in motor performance.

Main Methods:

• Measured reaction time (T(R)), arm movement time (T(M)), and target achievement error (deltaL) during arm movements.
• Participants: 12 healthy, right-handed, untrained females performing discrete movements with each arm.

Main Results:

• Identified five performance models with varying probabilities.
• Optimal speed and precision (model 5) requires long T(R) and short T(M), occurring rarely (2-3%) in untrained subjects.
• Motor asymmetry was evident in accuracy, with the right arm showing fewer errors, particularly at average T(R) and T(M).

Conclusions:

• Reaction time is a critical factor in developing new rapid and precise motor skills.
• Fitts' paradigm may need modification to include reaction time for a more comprehensive model.
• The findings suggest potential for training interventions to enhance the optimal performance model and offer a method for determining handedness.