Even though no food had entered her stomach, the smell and sight of food caused Jane’s stomach to secrete more acid. This is an example of:

This scenario is an example of a conditioned reflex or classical conditioning. In this case, Jane's body has learned to associate the sight and smell of food with the act of eating, which in turn triggers the stomach to prepare for digestion by secreting acid.

Classical conditioning is a learning process where a neutral stimulus (the smell or sight of food) becomes associated with an unconditioned stimulus (the food itself) that naturally elicits a response (acid secretion). Over time, the neutral stimulus alone can evoke that same response, even in the absence of the actual food. This demonstrates the body's ability to anticipate physiological needs based on learned associations.