Background Information

You have a ferret at home. Lately, you've been watching him eat, and you notice that he can be very picky about which pieces of food he prefers to eat from his food bowl. You're not really sure which pieces he likes or doesn't like, but he seems to be searching for specific pieces. All the pieces are the same brand of food, but they come in three different shapes.

If you were to conduct an investigation into which pieces he likes to eat most, how would you set it up?