title: Order parameter dynamics of body-scaled hysteresis and mode transitions in grasping behavior.
abstract: Several experimental studies have shown that human grasping behavior exhibits a transition from one-handed to two-handed grasping when to-be-grasped objects become larger and larger. The transition point depends on the relative size of objects measured in terms of human body-scales. Most strikingly, the transitions between the two different behavioral 'modes' of grasping exhibit hysteresis. That is, one-to-two hand transitions and two-to-one hand transitions occur at different relative object sizes when objects are scaled up or down in size. In our study we approach body-scaled hysteresis and mode transitions in grasping by exploiting the notion that human behavior in general results from self-organization and satisfies appropriately-defined order parameter equations. To this end, grasping transitions and grasping hysteresis are discussed from a theoretical perspective in analogy to cognitive processes defined by Haken's neural network model for pattern recognition. In doing so, issues such as the exclusivity of grasping modes, biomechanical constraints, mode-mode interactions, single subject behavior and population behavior are explored.
authors: Center for the Ecological Study of Perception and Action, Department of Psychology, University of Connecticut, Storrs, CT 06269, USA. till.frank@uconn.edu
authors: T D
authors: TD
authors: Frank
authors: M J
authors: MJ
authors: Richardson
authors: Stacy M
authors: SM
authors: Lopresti-Goodman
authors: M T
authors: MT
authors: Turvey