International Journal of Comparative Psychology

Previous research into the possibility of learning in paramecia in this laboratory has shown that these organisms can learn to go to and remain in a specific location based on cathode shock reinforcement. The present experiment was designed to determine whether paramecia could retain (remember) the learned brightness discrimination task. The results indicate that the retention interval for this task in paramecia is shorter than 1 minute. It is possible that paramecia can remember this task for longer than a second but shorter than the 1-minute interval that was used during test. It is also possible that remembering for more than a few seconds requires a nervous system, which paramecia do not have.