The Homunculus is described by psychologists as a depiction of what we would look like if each of our body parts grew in proportion to how much we sense with them. For example, our hands would be massive compared our elbows because we use them so much more.
The Homunculus is a very good model for interpreting how our bodies interact with the environment, such as responding to a sound, taste, smell and touch and just how important the ability to sense and perceive these things really is. It has helped psychologists make connections between external stimuli and behavioral responses.
From Crash Course: Psychology on YouTube presented by Hank Green