Working memory contains information about the focus of our attention. As the capacity of our working memory is rather small (research shows the capacity can range between 5–7 unrelated concepts), our attention is considerably selective. Our brain is simply not able to process all that is happening around us at once. It is instead narrowing down its focus to the most relevant pieces of information. The relevancy is determined by our own objectives.
Although the design is perceived by our senses (vision, touch, hearing), it is immediately processed by our brain. As designers, we have to understand how to create experiences that go hand in hand with how the human brain evaluates them. While being a designer, you have the power to control the human mind during and even beyond the interaction with the product.