On the displacement of leisure items by food during multiple-stimulus preference assessments.

The team ran a multiple-stimulus preference test with adults who had intellectual disabilities. They put food and leisure items on the same tray. They asked each person to pick once before dinner and once after dinner. They wanted to see if a full stomach would make leisure items more attractive.

Food still won. Participants chose food items almost every time, even right after eating. Leisure toys never moved up the list. The "displacement effect" did not fade with satiation.

Butler et al. (2021) followed the same people for a year and found edible choices stayed on top month after month. Their long view extends the 1999 single-day finding: food preference is not just strong, it is also stable.

Lemons et al. (2015) and Livingston et al. (2018) show a practical upside. Because edibles dominate, you can skip long assessments. Just pick a new snack from the learner’s favorite food group and it will probably work.

Zeleny et al. (2020) add another layer of stability. Kids in feeding therapy kept the same food rankings even after daily exposure to those foods. Together these studies say: food preferences are stubborn, so plan accordingly.

If you need non-edible reinforcers, run a leisure-only array. Mixing cookies and toys will give you another cookie winner and hide the real interest in fidgets or music. Save time and protect your data by splitting the decks.