Evidence limiting the subtended-angle hypothesis of response-programming delays

Area of Science:

• Human motor control
• Cognitive psychology
• Human-computer interaction

Background:

• Response complexity traditionally affects programming time.
• Sidaway (1991) proposed the "subtended angle" as the key factor, not movement parts.
• Sidaway's experiments used a specific target arrangement (moving away from start).

Purpose of the Study:

• To test Sidaway's subtended-angle hypothesis.
• To investigate if movement complexity influences programming time independently of directional accuracy.
• To examine programming delays in a reversed target-movement paradigm.

Main Methods:

• 30 subjects performed discrete (1-TAP) and serial (3-REVERSE) aiming responses.
• The first target was furthest from the start, with subsequent targets requiring direction reversal.
• The subtended angle was kept constant across conditions.

Main Results:

• Programming time was significantly longer in the 3-REVERSE condition compared to 1-TAP.
• This difference occurred despite identical subtended angles between conditions.
• Number of movement parts demonstrated an effect on programming delays.

Conclusions:

• Results challenge a strict interpretation of the subtended-angle hypothesis.
• Movement complexity, indicated by the number of movement parts, can independently affect response programming delays.
• The findings suggest that both directional accuracy and movement sequencing contribute to programming time.