Several types of continuous human movements comply with the so-called Two-Thirds Power Law (2/3-PL) stating that velocity (V) is a power function of the radius of curvature (R) of the endpoint trajectory. The origin of the 2/3-PL has been the object of much debate. An experiment investigated further this issue by comparing two-dimensional drawing movements performed in air and water. In both conditions, participants traced continuously quasi-elliptic trajectories (period T = 1.5 s). Other experimental factors were the movement plane (horizontal/vertical), and whether the movement was performed free-hand, or by following the edge of a template. In all cases a power function provided a good approximation to the V-R relation. The main result was that the exponent of the power function in water was significantly smaller than in air. This appears incompatible with the idea that the power relationship depends only on kinematic constraints and suggests a significant contribution of dynamic factors. We argue that a satisfactory explanation of the observed behavior must take into account the interplay between the properties of the central motor commands and the visco-elastic nature of the mechanical plant that implements the commands.

Catavitello, G., Ivanenko, Y., Lacquaniti, F., Viviani, P. (2016). Drawing ellipses in water: evidence for dynamic constraints in the relation between velocity and path curvature. EXPERIMENTAL BRAIN RESEARCH, 234, 1649-1657 [10.1007/s00221-016-4569-9].

Drawing ellipses in water: evidence for dynamic constraints in the relation between velocity and path curvature

LACQUANITI, FRANCESCO;
2016-06-01

Abstract

Several types of continuous human movements comply with the so-called Two-Thirds Power Law (2/3-PL) stating that velocity (V) is a power function of the radius of curvature (R) of the endpoint trajectory. The origin of the 2/3-PL has been the object of much debate. An experiment investigated further this issue by comparing two-dimensional drawing movements performed in air and water. In both conditions, participants traced continuously quasi-elliptic trajectories (period T = 1.5 s). Other experimental factors were the movement plane (horizontal/vertical), and whether the movement was performed free-hand, or by following the edge of a template. In all cases a power function provided a good approximation to the V-R relation. The main result was that the exponent of the power function in water was significantly smaller than in air. This appears incompatible with the idea that the power relationship depends only on kinematic constraints and suggests a significant contribution of dynamic factors. We argue that a satisfactory explanation of the observed behavior must take into account the interplay between the properties of the central motor commands and the visco-elastic nature of the mechanical plant that implements the commands.
giu-2016
Pubblicato
Rilevanza internazionale
Articolo
Esperti anonimi
Settore BIO/09 - FISIOLOGIA
English
Con Impact Factor ISI
Drawing movements; Endpoint trajectory; Kinematic constraints; Two-thirds power law; Visco-elastic forces
Catavitello, G., Ivanenko, Y., Lacquaniti, F., Viviani, P. (2016). Drawing ellipses in water: evidence for dynamic constraints in the relation between velocity and path curvature. EXPERIMENTAL BRAIN RESEARCH, 234, 1649-1657 [10.1007/s00221-016-4569-9].
Catavitello, G; Ivanenko, Y; Lacquaniti, F; Viviani, P
Articolo su rivista
File in questo prodotto:
File Dimensione Formato  
CATAVITELLO_Drawing_2016.pdf

solo utenti autorizzati

Descrizione: Articolo principale
Licenza: Copyright dell'editore
Dimensione 1 MB
Formato Adobe PDF
1 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/141193
Citazioni
  • ???jsp.display-item.citation.pmc??? 3
  • Scopus 11
  • ???jsp.display-item.citation.isi??? 8
social impact