Pup retrieving as a reinforcer in nulliparous mice.

Scientists watched virgin female mice press two bars. One bar gave pups to retrieve. The other only let the mice see and smell pups.

The team flipped the bars halfway through. They wanted to know if the act of retrieving itself would keep the mice pressing.

Every mouse chose the bar that let them fetch pups. When the bars swapped, five of six mice swapped too.

Retrieving pups worked like food or water—it reinforced pressing all by itself.

Corsetti et al. (2025) later used the same idea to save possum lives. They reinforced anti-fox escape behavior before release.

Gover et al. (2022) reviewed fifty years of studies and found most animals, including humans, prefer contingent rewards. The mouse study is an early clean example.

KELLEHEBERRYMAELLIOTT et al. (1962) said neutral cues become reinforcers only if paired with food. This paper shows the consummatory act alone can do the job—no extra pairing needed.

You can use the act of doing as the reward. Let a child earn the chance to line up trains if lining up is what they love. Let a teen run the copier if movement is reinforcing. First, watch what your learner naturally approaches. Then make that action the prize for a target response. You may cut edible use and still see strong responding.