Chapter 2. Prehension

254 THE PHASES OF PREHENSION
Z
151 I LIFT , , ,~
,L,l , ,
12
9
6
3
/
0 I I I I 0
- 1 0 1 2 3 4 5 - 1 0 1 2 3 4 5
15
L L 6
.a 3
L
- 1 0 1 2 3 4 5 - 1 0 1 2 3 4 5
15 1 15 1
12
9
6
3
0
-1
Load Force (N)
Figure 6.19 Grip force as a function of lift force during the
loading phase, from dowel contact to dowel lift, for A) the 66g B)
the 155g and C) the 4238 dowels, for lift and place tasks. The
arrow shows the direction of force change. Note at first contact,
as grip force increases, load force decreases slightly, indicating
that subjects are 'pushing' the dowel into the table. Grip force
and grip force rate increased with object weight (from Weir, 1991;
adapted by permission).
are found in only FAII units. Sometimes those having receptive field
areas are distant from the fingertip areas in contact for the precision