tion of the doves. Stimuli were the light produced by one or two red bulbs. The each bulb had approximately 120 cd/uof luminosity. The light produced by two bulbs had approximately 240 cd/uof luminosity. The size of stimuli was the circular switch which was approximately 2 cm in diameter. It was presented at the point of where 7 cm from the floor. The reinforcement was 2 seconds in the discrimination training. The food was mixed grains.The seven chambers were located in the different sound attenuated cubicles. The chambers were operated not by computers but the hands of students. The number of pecks on the key-lights with sufficient force was automatically counted by the machine connected to the chamber. That machine controlled the luminosity of red lights. Basically, pecking the switch with one red light delivered reinforcements (opportunities to eat mixed grains for 2 seconds) to the subjects . No punishment was used in the training.ProcedureFour types of conditionings were conducted in different days. The memory test was done at first. It had two parts. The first part of the test was conducted in order to make the birds remembered that pecking the red key would make food available. The second part was done to make birds remembered that the pecking produces the feeder when the key is red, not when it is dark.The next conditioning was the first session of discrimination training. During this session, the subjects was rewarded with food for pecking only when the key light was illuminated with one red light (S+) and not rewarded when the key is illuminated with two red lights (S-). The subjects were given 60 trials (30 S+ and 30 S- trials). Then, the number of pecking during S- periods (30 seconds) was counted. The key light was turned off between each trial for an inter-trial interval (ITI) of 10 seconds. The second session was the same as the first session of discrimination training except for that the number of S+ and S- trial were 15...
