| Description |
The primary purpose of this experiment was to determine whether hydra, phylum Cnidaria, could be conditioned to associate one stimulus with another in a fashion similar to the planaria. The conditioning procedure consisted of repetition of exposure of the experimental subjects to the light stimulus followed immediately by an electric shock. Signs indicating learning by association w,ere looked. for. Body movement and contraction before the delivery of the electric shock, which were observed in the conditioning experiment of the planaria, were tentatively taken as signs of learning. The frequency of such signs increased from 0% at the beginning to 20% at the end of the 40th training session, went down to Q%, and went back up to 20% at the end of the ,.65th session. The highest frequency exhibited by any specimen was 33%, which was observed on the last day o,f the conditioning. The results of this experiment do not allow one to conclude that hydra. can be conditioned, t it ,does not rule out such a possibility either. Thus, more refined procedures and better controls seem to be necessary to obtain more definitive results. |
