Foraging in a simulated natural environment: There's a rat loose in the lab.

The team built a tiny foraging field inside a lab cage. Rats could run to two food spots that differed only in how much chow they gave.

First the rats picked the same side again and again. The researchers then swapped the food amounts left-to-right until each rat had tried every layout.

When the side habit was broken, the rats quickly chose the spot that served more food. Their choices matched the amount of food almost perfectly.

The study shows that position bias can hide true preference. Remove the bias and the animals act like smart shoppers.

Johnson et al. (1991) later showed the same rats cared more about grams per minute than simple pile size. Together the papers say: animals track rate, but you must first cancel side habits.

Bland et al. (2018) found pigeons also stick with the locally richer option even when it pays less overall. The bird data echo the rat rule: local rate drives choice until you rearrange the layout.

Clayton et al. (2020) took the free-choice idea out of the lab and used it to pick toys for tigers. Same method, bigger cats.

If a client always picks the left chair or the red cup, the spot or color may be the reinforcer, not the item. Run a quick reversal: swap left-right or change colors while keeping the good stuff in the weaker spot. Once position bias drops, you will see the true preference and can build teaching programs on cleaner data.