自動給餌器へのブルーギルの反応レベル

抄録

Six bluegill sunfish were trained in a free operant situation during 90- to 200-day periods including 55 to 86 30-min training sessions to obtain food by thrusting up a bobber (bobber upthrust response: BUR) and thus activating an automatic feeder. Individual variation in the level of the BUR was great, varying between 22.9 and 52.0 responses/session on an average. Enhancement of the level of the BUR with increased numbers of trainings over the experimental period was proved statistically for only 2 fish out of the 6. Within a session, decreasing trends in the level of the BUR were observed for all specimens. The sequential mean levels of the BUR obtained from consecutive 2.5-min blocks of each session fit a negative exponential function (y=ae^bx; y is the mean levels of BUR for xth block, a and b are constant, b<0) well. In contrast to the great variation in the level of the BUR between specimens, the rates of attenuation, expressed by (1-e^b), conform rather well, ranging between 0.06 and 0.13.