Fractal correlation of initial trajectory dynamics vanishes at the movement end point in human rapid goal-directed movements

• Published in: Neuroscience letters 2001-05, Vol.304 (3), p.173-176
• Main Authors: Miyazaki, Makoto, Kadota, Hiroshi, Kudo, Kazutoshi, Masani, Kei, Ohtsuki, Tatsuyuki
• Format: Article
• Language: English
• Subjects: 1/f fluctuation; Acceleration; Adult; Biological and medical sciences; Biomechanical Phenomena; Female; Fractal; Fractals; Fundamental and applied biological sciences. Psychology; Goal-directed movements; Human; Humans; Kinematics; Male; Psychomotor Performance - physiology; Variability; Vertebrates: body movement. Posture. Locomotion. Flight. Swimming. Physical exercise. Rest. Sports
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/S0304-3940(01)01779-7

Many researchers have investigated the variability of discrete goal-directed movements. However, a possible time-dependent property for them has been ignored. We investigated the time-dependent property of the kinematic variability in human rapid goal-directed movements by using fractal analysis. The variability of the peak acceleration had fractal time correlation characterized by a non-negligible frequency-spectral exponent ( β=0.3). This β value was reduced at the peak velocity ( β=0.2) and nearly reached zero at the peak movement amplitude, indicating that the variability became white noise with no time correlation. A similar result was observed in the progress of the positional trajectory. The functional significance of this phenomenon for the goal-directed task demand is discussed.