Fitts's Law violation and motor imagery: are imagined movements truthful or lawful?

ABSTRACT

Fitts's Law for the timing of targeted movements states that, when target width is held constant, movement time (MT) will increase as the travelled distance increases. Even imagined movements, mentally simulated actions without actual actions, obey Fitts's Law. Recently, a violation of Fitts's Law has been reported; when targets occur in a structured array, MT to the farthest target is shorter than that predicted by Fitts's Law. We conducted two experiments to determine if the violation also occurs for imagined movements. Results showed a close correspondence between real and imaginary MTs across target locations, including the Fitts's violation for the farthest target. We conclude that the violation of Fitts's Law occurs in motor imagery and that the locus of the violation is in the planning stage of action.