Information about human memory is very important for interface design. In week 3, we learned how to translate the knowledge to graphic design. However, after two months, I find that I can relate Gestalt theory to the good or bad examples while I never mention visual attention theory or information foraging theory. I should not forget these fundamental principles. So I read again and summarize the fundamental rules of human computer interaction design which can find testimony in human psychology.
Why is clarity so important to interface design? Before I read the article on Blackboard, I will say well, it is human nature. So what nature? Information foraging theory tells us that people always seek and select information they need and get maximum benefit for minimum effort. People are likely to avoid complexity and information overload. Therefore, designers should clearly indentify links and category descriptions in order to help users find the destination. More easily to recognize what it is, where they are and how they do, more successfully people interact with our interface. That’s why explicit navigation bars are necessary. No mystery and cluttered information in our system.
According to visual search paradigm, people search target items among a number of distracting items. Some highly artificial stimuli like brighter color, salient letters will guide attention and help user keep track what was attended. The paradigm has been used extensively, especially in most of Gestalt Laws. As to law of balance/symmetry, a psychological sense of equilibrium is a stimulus directing attention. In law of figure-ground, two different foreground colors is a stimulus to guide attention orienting in foreground or background. In law of focal point, the focal point will draw users’ attention as a stimulus. Highlighting should be used not only for differentiating things, but also for guiding attention.
Put Primary Interaction Per Screen
When opening a homepage, it is annoying to see splash screens. When scanning highlight of the page, it is angry to see many advertisements. Why? According to visual attention theory, our attention is precious and selection is object-based. That means our attention is directed toward the target. Attention is precious. Do not use distractible materials to upset users. Our users are selfish, lazy, and ruthless. They are very unhappy to be interrupted or hard to find what they are looking for. Moreover, object-based deployment of attention is influenced by determine perceptual grouping. As a result, one screen is supported for one primary interaction and you will get credit for that.
Sometimes we want to create a perfect interface so that we add more options, graphics, widgets, buttons to the page which looks like a hodgepodge. One of the interesting things about information foraging is that doing cost-benefit analysis for user behavior. Absolutely, users need food, need calories. But if you give them so many contents and options, it will be time consuming to find their target items. So the best design is that user can manipulate physical objects directly and focus on their tasks. In Cooper and UxBook, the word excise appears many times—navigation excise, visual excise, menu excise, etc. Before designing a page, make tradeoffs and asked yourself what users will gain from the page and what their time and effort cost is. It is pretty the same thing with usability metrics which Dr. V. introduced last week. The performance metric includes task success, time on task, errors and efficiency.
Strong Visual Hierarchies and Smart Organization
Clutter means confusing. Clear view order of elements means user friendly. To achieve strong visual hierarchies and smart organization, we should decide the visual weight of all elements, which are related and above the fold, which are obscure with muted color. Why will we benefit from this principle? Top-down and Bottom-up control of attention can explain this. In visual search, Top-down is goal-driven attention which refers to recognize patterns in a contextual domain. Bottom-up is stimulus-driven attention which means beginning from retina to the visual cortex. How we perceive things is a combination of both bottom-up and top-down mechanisms. The bottom-up process happens so quickly that we may not notice it. The stimuli help us recognize and identify objects when we interact with the system. While the top-down process is contextual, what we know, what we expect, and what we want to do influence what we see. By understanding how this process works, we can understand strong visual hierarchies and smart organization enable user to better remember and understand the message that the webpage conveys.