Mental Chronometry: Do Imagined Times Merely Relate to Task Duration?

Area of Science:

• Cognitive Psychology
• Motor Control
• Human Movement Science

Background:

• The mental chronometry effect describes similar prolonged movement times for executed and imagined actions.
• This effect supports functional equivalence theory, suggesting shared internal representations for both movement types.
• Existing research suggests imagined movements take exponentially longer than executed ones, potentially due to task duration.

Purpose of the Study:

• To investigate the relationship between movement duration, task difficulty (Index of Difficulty - ID), and movement modality (execution vs. imagery).
• To test whether the time cost of task difficulty in imagery is influenced by the number of movement cycles.
• To re-evaluate the assumption that imagery duration is positively related to task duration.

Main Methods:

• Fifteen participants performed and imagined reciprocal aiming movements across three levels of Index of Difficulty (4, 5, 6 bits).
• Participants completed either 3 (short-duration) or 5 (long-duration) movement cycles for both execution and imagery conditions.
• Mean movement times and time-ID slope coefficients were analyzed to compare execution and imagery.

Main Results:

• Movement time in imagery was generally comparable to execution, not exponentially longer.
• The increase in movement time with Index of Difficulty was steeper for 3 cycles of imagery compared to 5 cycles.
• This effect of increased time-ID slope in imagery for shorter durations was not observed in executed movements.

Conclusions:

• Findings challenge the notion that imagery duration is always positively related to task duration.
• The heightened impact of task difficulty on imagined movement time in shorter durations warrants further investigation.
• Results suggest a more nuanced understanding of the mental chronometry effect and functional equivalence is needed, particularly concerning duration effects.