'Your Eyes are Bigger than your Mouth': Over Estimations of Oral Cavity Volume are Improved by Experience

Affordances emerge from relations between the environment and the capabilities of an actor. It is unclear if affordances can emerge for body parts which cannot be seen. The present study was designed to determine: 1) how well people can estimate the size of their oral cavity/mouth by predicting how much water they can fit into their mouth and 2) if physical experience shapes such estimates. Participants (n=20) completed 2 Estimation tasks (Point and Pour) before and after an Execution task in which they physically experienced how much water their mouth could hold. In the Point task, participants were presented with 9 clear glasses of water, ranging from 50-230 ml and then pointed to the 1 glass that they thought held the maximum amount of water their mouth could hold. In the Pour task, participants poured the amount of water into an opaque cup that they thought their mouth could maximally hold. Although estimates in the Point task were more accurate than those in the Pour task prior to the Execution task (p < 0.05), estimates in both tasks converged on the actual volume after the Execution task. These data reveal that physical experience can shape affordances that emerge for body parts that cannot be seen.