Stimulus generalization to different levels of illumination in Paramecium caudatum

Stimulus generalization to different levels of illumination in Paramecium caudatum" (2008). Theses and Dissertations. Paper 1190. This study was conducted to determine if paramecia (P. caudatum), unicellular organisms, could exhibit stimulus generalization as do mammals and other multicellular organisms. Paramecia were placed in a trough that was divided into two equal portions, one light and one dark, and were trained on a light-dark discrimination. They were rewarded for remaining in the half of the trough that was connected to the cathode of an electrical stimulator, as such cathode stimulation had been shown to be attractive to paramecia. For half of the paramecia, the cathode was connected to the light half of the trough during training. During test, light stimuli which varied in brightness were substituted for the original light stimulus to determine if the paramecia would generalize the training information to the test stimuli. The dark side of the trough remained at a fixed illumination level. For the test phase, the location of the " light side " was switched to the side of the trough opposite to that used during training. The same procedure was carried out for the other half of the subjects, except that, for these iii paramecia, dark side was associated with the cathode during training. During test the " dark side " was varied in brightness and the " light side " remained at a fixed illumination level. The current experiment did not provide strong evidence that paramecia do generalize, at least under the conditions of this study; however it replicated the finding that paramecia prefer the side that was paired with the cathode electrical stimulation.