Chapter 2. Prehension

126 THE PHASES OF PREHENSION
A
B
180 1 Ts=1.27 Ts4.32
100:. 1 . 1 . 1 . I . 1 . 1
2 3 4 5 6 7 8
ID (bits)
1 8o
TS=target size-CM
A=amplitude-CM
A=7.62 A=15.24 Aa.48
/ b TS=2.54
2 3 4 5 6 7 8
ID (bits)
Figure 5.5: A. Acceleration time (ms) as a function of ID, for each
of the target sizes. Time to peak speed was primarily a function
of amplitude, not target size. B. Percentage of MT spent in
deceleration as a function of ID, for each of the amplitudes. More
time was spent in the deceleration phase as target size decreased.
Amplitude had no significant effect on the deceleration phase of
the movement (from MacKenzie et al., 1987; adapted by
permission).