Association for Behavior Analysis International

Four female Phodopus campbelli dwarf hamsters were trained on FI 4-s, FI 8-s, FI 16-s, and FI 32-s schedules of reinforcement. After reaching stable responding, the hamsters were presented with fox urine in their operant chamber for a randomly determined 5 days during a 10 day period. Results indicated that this species responds to FI schedules in the typical scallop pattern that other species do. However, fox urine did not elicit freezing or decrease response rate. On the contrary, a slight but not statistically significant increase in rate of responding was observed in the presence of fox urine.

Reward sensitivity and behaviors related to foraging were compared across Sprague Dawley rats, Long Evans rats and Syrian Hamsters. All three species of rodents were exposed to four concurrent VT VT schedules while foraging as a group of 5 rats or hamsters in an open field foraging paradigm. Data showed that Syrian Hamsters showed the highest reward sensitivity, followed by Long Evans rats, and then Sprague Dawley rats. Long Evans rats showed the most rearing, but the least eating of pellets. Hamsters showed significantly more eating, although this was actually pouching of the reinforcers, compared to long evens and Sprague Dawley rats. Sprague Dawley rats showed the greatest percent of intervals with social interactions, while hamsters showed the highest percentage of walking. Hamsters also showed the greatest bias. IT appears that, for Sprague Dawley rats, social interactions may have also been a potent source of reward, and thus lessened the reward sensitivity to the reinforcer schedules for food pellets. In contrast, hamsters showed the least social interactions and the highest reward sensitivity values. Results suggest significant differences in the topography of behaviors exhibited during open field foraging, which appear to be related to obtained values of reward sensitivity. Thus, the behavioral topography of the species should be considered in social foraging situations, as these behaviors may interact with reward sensitivity.

In a replication of Farmer-Dougan and Dougan, 2005, we exposed 5 Syrian (Golden) hamsters to multiple schedule contrast while all five foraged together in an open field paradigm. Time spent in the feeder, and the number of pellets pouched (in cheek pouches) was obtained, as well as the number of social and aggressive behaviors. Results found that three of the 5 hamsters showed evidence of behavioral contrast, with the remaining 2 hamsters showing little change in their behavior during the contrast phase as compared to baseline. Interestingly, 4 of the 5 hamsters reduced pellet pouching when exposed to the contrast condition, resulting in a significant difference in pellet pouching between baseline and contrast conditions. Four hamsters increased contact with other hamsters during the contrast condition, while 2 hamsters clearly increased aggression, 2 hamsters decreased aggression towards other hamsters, and 1 hamster showed little change in aggression during contrast, compared to the baseline conditions. Thus, it appears that the percentage of pellets pouched were the best measure of behavior change, with time spent in the feeder being less reliable evidence of contrast than pouching. This suggests that pouching behavior is an important response to examine when comparing hamsters to other rodents, such as rats.