of three sessions of the discrimination training, he showed the amazing performances as shown in Figure 1. The number of pecks during S- period continually decreased, and the discrimination ratio was 0.93 which was the highest among all subjects.DiscussionDiscrimination ratio which were obtained after the three discrimination training were above 0.5 in all subjects. Therefore, it can be said that the doves could discriminate the differences of the luminance and learned what the one or two lights meant. Heinemann and Rudolph (1963) used the three different sizes of stimuli in the discrimination training and found that the smallest stimuli had the greatest efficiency for pigeon*s leaning. The smallest stimuli they used had an inner diameter of 1 inch which was very similar to the stimuli used in this conditioning. Thus, it was one reason of that all doves showed excellent discrimination ratio and even the subject, 4341 which had no previous experience showed the sign of leaning. And also, two red lights had twice the luminosity of one red light, so the overlapped area of the distribution curve of sensation for each light might have been small. These explanations tells about the advantageous conditions for this training.However, the important purpose of this training was to get some ideas about how they learned. Paying attention to the bird, 4557 which had the highest discrimination ratio might give some valuable ideas for that. In the first session, he began to realize that pecking on two red lights did not produce the feeder. He pecked only 5 times in the last S- trial. However, the first S- trial in the second session, he pecked 23 times. It looks like a sign of that he did not learn in the first session, but it does not. In the second session, the procedure called random without replacement was used, so the largest number of pecks required to get food during S+ trials was 25 times. The fact that he pecked 23 times explains that he did...
