In the last post, we discussed how vision is structured. According to the Human Information Processing Model proposed by Christopher Wickens, memory and attention — like perception — play a vital role in our response to external stimuli. The model summarizes interdependencies of human systems that heavily influence how we interact with the world. In this post, we will discuss how this knowledge can be applied to build better products.

Memory and attention have limited capacity and highly volatility. Research suggests that the mind can only remember four unrelated items simultaneously. Take, for instance, two-step authentication. Excellent for security; terrible for memory. The volatility in memory forces people to copy and paste access codes to use this feature. Some of us use mental tricks, such as chunking, to ease the burden. Two-step authentication is a not a human-centered solution.

We pay attention to and process information that helps us achieve our goals.

If working memory is limited, then by definition attention must be selective. Humans don’t notice differences in features other than the ones authorized by their goals. When we travel through an airport, we only select visual cues for our flights. Before buying a home, we search for calculators to estimate our mortgage payments. We pay attention to and process information that helps us achieve our goals.

We follow an information scent as suggested by Jeff Johnson in his book, “Designing with the Mind in Mind.” We ignore everything not related to our tasks. A human-centered product knows attention is scarce and overcomes this limitation. For example, Amazon’s Buy Now button is designed to trump the volatility of mental resources to enable a buyer to purchase a product without losing focus.

Johnson also suggests most humans follow a predictable set of patterns caused by limited mental resources. Interactions that support these patterns create elevated experiences. For example, investing app Robinhood displays the total dollar amount on the top of the page in large font because the company correctly predicts that users want to see their overall market position before anything else.

Drawing attention to the most critical piece of information matters. In part two of this week’s post, we’ll examine why finding what your customer deems salient is important and how progressive disclosure reduce mental workload and increases the usability of your product.