Chapter 2. Prehension

Preface
In the summer of 1985, at a Motor Control conference in
Henniker, New Hampshire, we met and discovered another individual
who shared a fashTination (some might say obsession!) about the
human hand. Together, we marvelled at its versatility and its multi-
purpose functionality, and discussed the control problem for dextrous
hands from biological and computational perspectives. But at the
same time, we were astounded by the lack of a coherent, integrative
framework dealing with the hand’s complexities. A common vocabu-
lary was lacking for workers in different disciplines; pockets of
research existed, without overall context. Immediately we saw the
need for a book to bring together knowledge about the hand from
these diverse perspectives. With complementary backgrounds in
computing science and computer engineering (TI) and kinesiology
(CM), we were challenged to integrate the current works on the hand.
The ultimate goal of this book is to identify the underlying func-
tionality of the human hand in prehension. We address two questions:
the question of what is the nature of the human hand and the question
of what might be involved in the CNS as it controls this marvelous
tool in prehension. Our approach is based on the assumption that a
complete model of grasping must be developed and validated both
empirically and computationally. The approach is three-fold: we use
behavioral evidence, biological data, and computational results to
further develop and validate models of prehensile functions. In
contrast to a reductionist approach, we focus on sensorimotor
integration processes, which are more than the simple sum of the
motor and the sensory components.
The significance of such a book is to provide a study of prehen-
sion that is comprehensible to interdisciplinary and multidisciplinary
researchers. Designers of prosthetic and robotic dextrous hands will
find this study useful for developing versatile end effectors.
Practitioners of hand rehabilitation will also gain insights for improv-
ing functionality in injured hands. To motor psychologists, neuro-
physiologists, and kinesiologists, we offer many testable hypotheses,
which we feel can be verified through experiments. For computational
modellers, we provide suggestions for critical inputs and outputs,
identifying areas for future work. Another use is as a textbook for
senior undergraduate and graduate level seminars in diverse fields,