The effects of light signal upon the conditioned feeding response of bluegill sunfish Lepomis macrochirus

For the purpose of examining behavioural adaptability of teleosts to changing environments, an attempt was made to discriminate an instrumental feeding response with a light signal by continuing reinforcement in its presence and by discontinuing it in its absence, in 6 bluegill sunfish. Discrimination was eventually formed in all the fish, with a great individual variation. The number of sessions (each including 9 presentations of the signal) required for the formation ranged from 1 to 40 sessions. It was also revealed that the target response was very soon discriminated in the fish which had acquired the response easily in a formation process and also were emitting it at rather low rate in free operant situation, prior to the present conditioning of discrimination. Levels at which the fish emitted the feeding response seemed to relate to the amount of “resistance to extinction”, possibly leading to a difficulty of the discrimination formation in the fish with the higher level.