Four experiments were performed to examine the facilitation effect and interference effect of mediated assciation with the paradigm A-B, B-C, A-C. (Exp. I and II for facilitation effect, Exp. IV for interference effect and Exp. III for both.) The stimulus list consisted of pairs of standard nonsense syllables prepared by Umemoto and his co-workers and having 30%-70% non-association values. Exp. I used 4 lists of 8 pairs (Table 1), Exp. II, lists of 4 pairs (Table 3), Exp. III, 7 lists of 6 pairs (Table 5) and Exp. IV, 5 lists of 4 pairs (Table 10). Each list contained two or three subsets for different experimental purposes, that is, for facilitation, interference and control. The Ss were 10 college students in Exp. I, 10 students in Exp. II, 15 students in Exp. III, and 10 students in Exp. IV. In Exp. I, II and IV, the Ss were divided into two groups; in Exp. III, into three groups at random. The Ss learned three lists successively, at 24hr. intervals in Exp. I and at 1-min. intervals in Exp. II, III and IV. Each pair was presented to the Ss for 2sec., until 5 successive correct responses were attained. Two kinds of measures were used; number of trials for each pair and its rank order in learning. The main findings are as follows: 1. In Exp. I, the facilitation effect of mediated association was observed not in terms of the number of trials, but in terms of the rank order of learning, which was statistically significant (Table 2). 2. In Exp. II, the facilitation effect was significant in terms of both measures (Table 4). It can be said, therefore, that if the number of pairs in a list and the length of list intervals are both appropriate, the facilitation effect can be unfailingly observed in such experiment as this. 3. In Exp. III, the facilitation effect was observed in both measures but the interference effect did not appear in either measure (Tables 7, 8, 9). 4. In Exp. IV, in which the interference effect alone was examined, the effect was not observed in terms of either measure (Table 11). Consequently, the interference effect must be examined in a different context from this experiment.
Hull and Leeper questioned whether animals are capable of acquiring differential reactions based solely on internal cues and it was found that, while their rats took one path way to food when hungry, their rats were led to water when thirsty. And, Kendler contributed to the drive discrimination studies, with his experiments on the drive interaction. Our interests are on the aversive aspect of motivation, such as pain, fear and anxiety. Our hypothesis is that, while rats can take one path way to non-shock side when pain is presented, rats can be led to non-buzzer side when fear is presented. Kendler found the drive interaction by the simultaneous presentation of two drives, but in our case, two drives of pain and fear were presented by rapid alternation. Sixteen albino rats were used. The procedure for fear drive conditioning was given in a shuttle box with buzzer and shock pairing. And the procedure for drive discrimination was given in a T-discrimination box. The experimental design is shown on Table 1. Subgroup 1 and 2 were given additional fear conditioning in the starting point in the T-discrimination box for making difference on the fear drive level. Thirty trials were made in each session. Inter-trial interval was 30sec. The second session was reversal learning situation. Table 2 shows the results of the drive discrimination by fear only and the ones by fear and pain drives occurred alternately. The table is a statistical analysis on order of occurrence of successive correct responses. Comparisons between pain and fear on error scores and running speeds are shown on Table 3 and 4. Pain discrimination is much superior to fear. On Fig. 4, the top curve shows error scores produced by fear drive which accompanies pain drive and the second one shows scores produced by fear only. This is interpreted as the drive interaction. Higher level of aversive motivation is worse in discrimination and gives more fixation effect to performance. The effect of the reversal learning gave influence only to the performance produced by weaker level of drive. Fig. 7 shows learning effects in fear discrimination training. There are theoretical and experimental difficulties when we take the problem of drive discrimination by pain and fear, in comparison with the internal stumuli such as hunger and thirst. Pain and fear are considered as exteroceptive drive and always accompany the external stimulations. This experiment depends upon the conceptualization of the aversive motivation by Miller, Mowrer and Spence. Pain and fear occur very rapidly and impel response very strongly. Such rapidness and strongness are characteristics of the aversive motivation. And from an additional experiment, we found out two types of adaptable response, that is, the first type is the discrimination between pain and fear, and the second type is the discrimination between pain and pain-fear-chain responses. The problems mentioned above were discussed in the article.
G. A. Miller and W. J. McGill showed that free recall of verbal material could be analyzed in terms of a probability model. The model assumes that the probability of recalling a word on a given trial is completely determined by the number of its recalls on the preceding trials. Although the model holds only in a limited case of learning, it seems worthy of special mention, because the model describes the data from every aspect we can think of and in almost all aspects the curves derived from the model fit the data very well. As they themselves admitted, however, the two authors' method of estimating parameters, p0 and a, was not satisfactory. Hence, the present author used the maximum likelihood estimates for p0 and a which were obtained from the frequency distribution of the number of non-recalls for the word after it has been recalled k-times on the preceding trials (Equations 7 and 8). The table to be used in the estimation was given in an appendix. That is a supplement to the table already available (2) in the case where both p0 and a are larger than 0.5. Materials in Miller and McGill's experiments were simple English words read aloud to the subject. The order of the words in a list was randomized from trial to trial. In the first experiment of the present study, Japanese nonsense syllables were visually presented to the subject one at a time and results similar to Miller and McGill's were obtained. In other words, our data were well fitted by their model. The maximum likelihood method of estimation of the parameters can be also applied to each word by substituting m=1. In the second experiment, serial learning was done for five lists, each of which consisted of 20 nonsense syllables of 2 Japanese letters. The procedures were almost the same as those in the first experiment except that the word order in each list was fixed throughout the trials. A list was presented repeatedly until it was reproduced without errors, and a and p0 were estimated for each word. Then averages of a's and p0's for the five lists were computed and the a and p0 were expressed as functions of the position in the list. By applying the method of moving averages (span of 3) it became clear that both the initial and final effects appeared primarily in the p0-curve and slightly, if any, in the a-curve (Fig. 4). As trials were repeated, a kind of learning occurred in the skill of remembering and this was apparent in a but not in p0 (Fig. 6). In some cases, learning curves were S-shaped and in others, they had no inflection point. The latter shows only negative acceleration. It is to be noted that from the model under discussion the curve with no inflection point can be derived as well as the S-shaped curve by putting an appropriate set of values into a and p0 (Fig. 7). As to the data which were fitted by Miller and McGill by highly complex equations involving three parameters, it was shown that they could also be successfully explained by simpler equations with two parameters.
Problem Hull has proposed the following hypotheses concerning adient and abient behaviors. 1. The strength of adient reaction potential is a negative growth function of the distance of the organism from the object. 2. The strength of abient reaction potential is a negative growth function of the distance of the organism from the object. 3. The strength of abient reaction potential increases more rapidly with decreasing distance to the object than does that of adient reaction potential. 4. The strength of adient or abient reaction potential varies with the strength of drive. There hypotheses are proposed on the basis of J. S. Brown's experimental work. But his work does not completely verify them at a quantitative level because of the following reasons: a) The strength of pull (used as an index of reaction potential) was measured only at two points, one near the object and the other away from the object. b) Not only the effect of the object, but also those of the motor factor and the starting point, per sec., would act on the strength of pull. c) The effect of the pulling time was not examined. In other words, it was not examined whether the average strength of pull for 5sec. was an optimal time for measuring reaction potential or not. The present writer attempted to examine these problems as well as to find conditions necessary to verify the above mentioned hypotheses. Method Guinea pigs between 3 and 4 months of age at the beginning of the experiment were used. These animals were trained, under 23 hours food deprivation, to approach the end of a straight alley for food. After attainment of a prescribed criterion, the strength of pull was measured at different points in the alley. The pulling time was 3sec. in experiment 1, and 10sec. in experiments 2 and 3. Results 1) The strength of pull could be measured at five points in the alley without evoking experimental extinction. 2) The effects of the motor factor and the starting point, per sec., could be controlled by keeping the distance between a pull point and the starting point constant. 3) Average strengths of pull were used as indices of reaction potential. It was indicated that the average strength of pull for 10sec. was superior to those for 3sec. and for 5sec. (Brown's condition) (Fig. 7, 8). 4) The results verified one of Hull's hypotheses, i.e., the strength of adient reaction potential is a negative growth function of the distance from the object (Fig. 7, 9, 10).
If a cross figure consists of upper and lower black arms, right and left white arms, and a central gray square, we do not perceive the mosaic sum of these five parts. We see, instead, a black vertical bar and a white horizontal bar. In the central part of this figure, we can see simultaneously two colors, white and black, one behind the other. One of these two colors appears transparent and the other appears to be seen through the former (See Fig. 1A). The following investigation is concerned with this apparent transparency. Method: Experimental procedures were nearly the same with those of our previous studies on figure-ground reversal (This journal, 1955, 26, 178-188). Observers were instructed to fixate their eyes upon the center of the figure 60 to 120 seconds, and push the first one of the three electric buttons when the black bar appeared in front of the white bar, push the second button when the white bar appeared nearer, and push the third button during ambiguous appearances. As the measure of relative dominancy of black and white, the formula, Rb=100Tb/(Tb+Tw), was adopted, in which Tb indicates the total pushing time of the first button, and Tw, that of the second. Results: 1) In general, the white bar has a stronger tendency to appear in front of the black bar when the central square is light gray, and the black bar is dominant when the central square is dark gray. It was discovered that the relative dominancy was approximately proportional to the difference between the square root of reflectance of the central part and that of the arms (Table 1, Fig. 2, 3, 4). 2) The lightness of the surrounding field has little effect on the relative dominancy of two bars (Table 2). 3) When the arms are of two of the four chromatic colors, red, yellow, green and blue, instead of white and black, and the central part is the mixture of these two colors produced by the rotating disk, yellow is the most dominant color, red is the second, green the third and blue the last. However, red may be more dominant than yellow if the above mentioned effect of lightness is eliminated (Table 3). 4) When the vertical arms are red, the horizontal arms are green, and the central square is the mixture of red and green in various ratios, the relative dominancy is represented in a S-shaped curve as a function of the mixture ratio, i.e., the angle ratio in color disk (Table 4, Fig. 5, 6). 5) The effect of area of the arms is equivocal. There are large individual differences, and the difference of instructions easily affects the results (Fig. 8, 9, 10, Table 5). The similar results were obtained in the stimulus figures of another type (Fig. 1B, 11).