Jj. Temprado et Wac. Spijkers, PRESETTING AND PREPROGRAMMING IN DONDERS TYPE-C REACTION TASKS, Cahiers de psychologie cognitive, 14(3), 1995, pp. 269-282
The purpose of the present experiment war to determine what type of pr
eparatory adjustment is used by subjects in a Donders' (1868/1969) typ
e C reaction task. In accordance with Lepine et al.'s (1989) suggestio
n, two preparation mechanisms can be distinguished. The first, called
preprogramming, refers to a structural interpretation of motor prepara
tion. The second, called presetting, refers to a functional interpreta
tion of motor preparation, i.e., to the energy supplied to the informa
tion processing stages. To infer the type of preparatory adjustment th
at subjects use in a Donders' type C task, we analyzed reaction time (
RT) on slow and rapid movements as a function of the probability of re
sponding. In addition, we attempted to determine whether the differenc
e usually observed between the RTs of slow and rapid movements persist
ed or disappeared. Subjects took part in a GO versus NO-GO reaction ti
me task and carried out hitting movements that differed in mean veloci
ty (due to variations in amplitude at a constant duration) and in resp
onse probability (.5,.7,.9, and 1.0). Such a task enables subjects to
preprogram the required movement velocity. Response probability expres
ses the degree of certainty that the preprogrammed response will be pe
rformed. The results showed that increasing response probability decre
ases the RT of both slow and rapid movements. For response probabiliti
es less than 1.0, a persistent difference between slow and rapid movem
ents was also observed. This indicates that subjects increased the ext
ent to which they preset motor programming processes. Despite the fact
that subjects could preprogram the response in all probability condit
ions, they did not do so. In the condition in which the response proba
bility was 1.0, we did not find any difference between the RTs of slow
and rapid movements, showing that subjects fully preprogrammed the re
sponse. These results are consistent with a presetting interpretation
of response preparation when subjects are uncertain about whether a re
sponse should be produced. Response probability seems to be a critical
variable in the subjects' choice of which preparation mechanism to us
e. The basis for this suggestion is our view that subjects do not rely
exclusively on one or the other strategy, but predominantly use one o
f the two.