Rats (<i>Rattus norvegicus</i>) find occupancy of a restraint tube rewarding
Rats treat tube confinement as a reinforcer, so restraint can reward rather than punish.
01Research in Context
What this study did
Hachiga et al. (2020) let rats choose to enter a tight plastic tube. The team counted how often the animals went back in and how long they stayed.
Next, the rats had to press a lever to open the tube door. The researchers tracked if tube time kept the lever pressing going.
What they found
The rats returned to the tube more than half the time. They also held the lever down longer when the only payoff was tube access.
In other words, the restraint tube worked like candy or water—it acted as a reinforcer.
How this fits with other research
Poling et al. (1977) saw the same thing with a safe shelf. Rats worked harder for timeout when it included a small ledge, showing that snug spaces can reward behavior.
Schulingkamp et al. (2023) found that social time with another rat also reinforces lever pressing, even if the partner is a stranger. Together these studies widen the menu of rat reinforcers beyond food and water.
Wilkie et al. (1981) showed that a tone predicting "no shock" keeps rats responding. Hachiga’s tube data fit this pattern: safety cues—whether a sound or a tight space—can strengthen behavior.
Why it matters
If you run animal studies, remember that confinement can reward, not stress. Swap your "timeout" box for a tube and you may get more reliable data. For clinicians, the lesson is broader: always test whether an item or activity truly repels or attracts your client. What looks like escape might be access, and what feels safe to us might function as a reinforcer for them.
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Try offering a small pop-up tent or body sock as a potential reinforcer during client preference assessments.
02At a glance
03Original abstract
Two experiments evaluated whether rats' occupancy of a restraint tube is reinforcing. In Experiment 1, each rat in the 0-min group moved freely in a chamber where a wall blocked access to a restraint tube. After 10 min the wall was removed, permitting 15 min of chamber access and tube entry. The other 2 groups were locked in the tube for 10 and 20 min respectively before release into the chamber for 15 min. Across sessions, rats locked up for 10 and 20 min entered the tube more frequently than rats in the 0-min group, and during the first 2 sessions rats in the 20-min group stayed in the tube longer than the other groups. Over sessions this difference disappeared. However, for all groups and sessions the mean percentage of session time in the tube exceeded chance expectations. This result suggests tube occupation was reinforcing. In Experiment 2's Phase 1, rats could enter an open tube. On exiting, the tube door closed. A lever press opened the door for the rest of the 1-hr session. In Phase 2, these rats were locked in the tube for 10 min before the door opened. Upon exiting, the door closed. As in Phase 1, a lever press opened the door for the rest of the session. The latency between pressing and tube entry decreased over sessions, indicating that tube entry reinforced lever pressing. These results are difficult to reconcile with accounts of rat empathy based on the thesis that tube restraint distresses occupants.
Journal of the Experimental Analysis of Behavior, 2020 · doi:10.1002/jeab.596