Which aspect of user experience design emphasizes human understanding of product functionality?

The emphasis on human understanding of product functionality is best represented by the concept of affordances. Affordances refer to the perceived and actual properties of an object that suggest how it can be used. They indicate the possible interactions that a user can have with a product or interface, allowing users to understand functionality intuitively. For instance, a button that looks like it can be pressed gives users an immediate understanding of its purpose, promoting a seamless interaction.

In contrast, other concepts such as micro rules, feedback, and design patterns focus on different aspects of user experience. Micro rules generally pertain to small, specific guidelines that assist in achieving consistency in design but do not directly communicate functionality. Feedback involves the responses or reactions a system provides in response to user actions, which helps users understand the result of their interactions but does not specify how the interface suggests its use. Design patterns represent common solutions to recurring design problems and can aid in usability, but they are not solely focused on how users perceive the functionality of a product. Therefore, affordances are the most relevant concept when discussing how users comprehend what a product does and how to interact with it.