Chapter 2. Prehension

18 WHAT IS PREHENSION?
in Table 2.13. Some classifications are more anatomical, but most fo-
cus on functionality, particularly for evaluating remaining capabilities
after accidents, disease or surgery. Each taxonomy offers new in-
sights into the complexity of human prehension. Yet, across this di-
verse set, themes are repeated, suggesting the possibility of a unifying
view, as will be seen in this chapter. Selective classifications are con-
sidered in order to develop the important roles of hand, object, and
task characteristics in the selection of an appropriate, efficient grasp
posture. While this book does not address developmental aspects of
human prehension in detail, taxonomies for looking at the develop-
ment of prehension in infants are also summarized in Appendix B4.
CYLINDRICAL
W
PALMAR
TIP k
HOOK or SNAP
SPHERICAL LATERAL
Figure 2.1 Schlesinger’s classification of prehensile postures.
This set was a minimum set of a more comprehensive one he de-
veloped. See text for details (from Taylor and Schwartz, 1955;
adapted by permission).
3A complete analysis of prehensile classifications is provided in Appendix B.
4We allude to some of the developmental issues throughout the book. We refer the
interested reader to excellent papers and reviews (Bower, 1974; Forssberg et al.,
1991, 1992; Halverson, 1931; von Hofsten, 1990; Piaget, 1953; Twitchell, 1970).