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.

Previous research into the possibility of learning in paramecium in this laboratory has shown that these organisms can learn to remain in a specific location based on cathode shock reinforcement. The present experiment was designed to assess whether paramecium could learn a discrete action as opposed to remaining in a specific area, using cathode shock as a reinforcer. Results for a sample of 40 indicate that such learning did not take place. It is possible that the learning of discrete actions requires a nervous system.

as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Psychology The University of Toledo May 2012 Response variability may be influenced by multiple factors in the environment as well as an individual's previous experiences. This study was designed to investigate the effect of hunger drive and effortfulness of response on rats' response variability in a two-choice lever press situation. Rats were tested for a total of four weeks, Week 1 was considered to be between-groups and Weeks 1 -4 were combined to test within-subjects data. Variability was measured in three different ways: the number of times the response location changed in a single session, the length of the first group of responses before changing response and the mean length of responses before changing response location. Between-groups data suggest neither hunger nor effort influence response variability in rats. Within-subjects data suggest hunger did not play a role in response variability, however, effort was significant. Variability of response increased when responding required less effort, as illustrated by all three measures of variability: F changes (1, 14) = 10.41, p < .05, d = 2.27, F first run (1, 14) = 11.54, p < .005, d = 1.82, F mean run length (1, 14) = 10.95, p < .005, d = 1.77. iii List of Tables 3.1 Means of measures of response variability for High hunger/Low effort and Low hunger/High effort rats.

Retention of Brightness Discriminationin Paramecia, P. caudatum