Answer:
Computional model, used to study an outbreak of an infectious disease called influenza.
A psychological disorder or a mental disorder is compose of behavioral and psychological symptoms impacting on areas of one's life causing further problems. When a psychiatrist like Dylan works on the causes of the disorder such as chemical imbalances, he is now working on the Biological perspective of the treatment.
Mastication is just a fancy way to say chewing. Since nothing chemical is going on and the food is just being chewed, the answer is physical.