The purpose of the present investigation was to examine the effect on the selective reaction time (RT) of the anxiety, which was experimentally controlled by means of an electric shock (ES). The present research included four experiments with essentially the same procedures, except that the numbers of reinforcements varied with the different experiments. Each experiment consisted of three sessions, which were spaced 5min apart.
In the first session (habituation), three light stimuli (red, blue and yellow) used as a RT signal were presented randomly 10 presentations per stimulus, with a 30- to 60-second interval between the stimuli.
Ss were instructed to respond to each signal as rapidly as possible. The RT was measured by the pressing of a key paired in position with each signal. The habituation period served to make comparison of the effects of the subsequent sessions.
In the second session (classical aversive discriminative conditioning), the three light stimuli were presented at random for 20, 5, 10 and 20 presentations per stimuli in Exp. I, Exp. II, Exp. III and Exp. IV respectively. Although the RT was measured in the same way as in habituation treatment, the red signal alone was reinforced by pairing it with the unavoidable and unescapable strong ES, which was delivered immediately after the response to the red signal. But no ES was given to any presentations of RT signals in Exp. I. This session can be regarded as a non-specific anxiety inducing situation.
The third session (extinction) replicated the same procedure as the first session, that is, each stimulus was no longer followed by ES. Here, the specific effects caused by the classical aversive discriminative conditioning should distinguish themselves from the non-specific effect of the anxiety inducing situation in the second period.
Further, GSR was continuously recorded during three sessions in each experiment.
The main results obtained were as follows:
(1) The most striking appearances of spontaneous GSRs were demonstrated during ITI in the conditioning session of each experiment except for Exp. I. This result could be considered to be evidence that this session became a non-specific anxiety inducing situation.
(2) Two opposing patterns of change in the RT to CS
+ and CS
- were observed in this anxiety situation, that is, a marked prolongation of the RT to CS
- was demonstrated throughout the second session; on the contrary, the RT to CS
+ became even shorter at least in early trials of the second session than in the first session.
(3) According to the introspective reports after the experiment,
Ss focused attention on the red signal (CS
+) during conditioning. Therefore it appears that two reverse tendencies on RT were due to a difference in selectivity between CS
+ and CS
-.
(4) But with reference to CS
+, its RT became gradually longer as conditioning trials progressed. This gradual lengthening of the RT should be considered to reflect the progressive development of the conditioned anxiety elicited by CS
+.
(5) In the third session (extinction), the RT to CS
+ was also markedly lengthened as it was later in the course of conditioning session, whereas the RT to CS
- was shorter in early trials of this session than the base-line level of the first session. It is apparent that CS
- came to acquire the capacity of behavioral control, just as CS
+ did, as a result of the discriminative learning. But both the excitatory and the inhibitory effects elicited by CS
+ and CS
- respectively decreased gradually during extinction session.
(6) The aboved-mentioned changes in the RT to CS
+ were scarcely observed in Exp. II, on the contrary, the evoked GSR to CS
+ increased in amplitude most markedly in Exp. II.
(7) The difference between effects of the
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