[MUSIC] Have you ever wondered about how much of your brain you use when you're looking at a design, or how much information your brain can absorb without exploding? Memory and design are more closely related than you might think. Humans are visual creatures. A significant amount of human brain is dedicated to visual processing, resulting in our sight having a sharpness of perception far surpassing our other senses. As you can see from the figure, more information enters our brains at any given time through sight than our other senses, both at the subconscious and conscious level. In fact, roughly 70% the body's sense receptors relate to sight. Visual data brings together all aspects of memory. Let's recall. Visual perception, the act of seeing a visual or an image, is handled by the visual cortex located at the back of the brain. The visual cortex is extremely fast and efficient. Cognition, the act of thinking, of processing information and examining relationships, is handled by the cerebral cortex and is much slower and less efficient. Data visualization shifts the balance between perception and cognition to use our brain's capabilities to its advantage. This means more use of visual perception and less use of cognition. How do we achieve this? Before we answer this question, we need to understand the visual processing model and how our memory works. Memory plays an important role, not only in helping an individual remember a set of learned codes for reading a visualization, but also at a lower level, it helps with answering visual queries. When we see information presented in a visually attractive way, it triggers our sensory memory and makes it easy for us to process it in the short-term memory. When we process that data, we essentially create a long-term memory folder in our brain. Visual data brings together all aspects of memory. There are three types of memory that process information in our brain: sensory memory, which takes about a second where pre-attentive processing happens; short-term memory, which is also called working memory, takes about a minute to hold and process five to nine chunks of information; long-term memory is where the information is stored. Let's look at long-term memory first. The long-term memory is where things we memorize and remember are stored. The storage of information is based on meaning and association. There are two types of long-term memory: explicit memory and implicit memory. When we are trying to intentionally remember something, like a formula from your statistics class or a list of dates from your history class, this information is stored in your explicit memory. We use these memories every day, from remembering information for a test to recording the date and time of a doctor's appointment. Implicit memory is kind of the memory that is both unconscious and unintentional. Things that we don't purposely try to remember are stored in our implicit memory. Riding a bicycle is a great example. Even after many years without riding one, most people are able to hop on a bike and ride it effortlessly. When trying to leverage a person's long-term memory, you can utilize an emotion or make it relevant to your audience. However, when designing visualizations, we should focus more on the sensory memory and short-term memory as they are the ones that interact with the visualizations. So, let's look at them in depth. When we see an image, the information remains in the sensory memory for a tiny period of time, less than a second. Sensory visual memories are the raw information that the brain receives from the eyes. We store and process sensory memories automatically-- that is without any conscious effort to do so-- and it happens prior to our paying attention to the information. The processing of this information is called pre-attentive processing. It is a limited form of processing which does not attempt to make sense of the whole image received, but rather a small set of features of the image, such as color, shapes, or constrast. Short-term memory is the memory we use when we are actually working with a visual. New data is passed in from the world through the senses, and old data is swapped in from long-term memory. This process works much faster than the conscious speed of thought to help us make sense of the world. Information stays here for a minute, and short-term memory has a limited capacity. According to Miller's law, it's "the magical number 7 plus or minus 2," suggesting the number of objects an average person can hold in short-term memory is between 5 and 9 similar items. Later studies found out that the formulation given here is generalized as the real flow depends on many factors, including the nature of the information. On average, individuals can remember 7 for digits, 6 for letters, and about 5 for words. In design perspective, this information plays a vital role in building up a usable and clean layout. Design that demands users to remember too many options at once can create tensions and get users irritated even if they aren't able to describe the reason of the unpleasant emotions. Chunking is a process in brains' short-term memory. Individual pieces of information are organized into meaningful wholes, so they can be recorded easily. If items can be grouped into chunks in our memory, the capacity can be greatly increased. Take a quick glance at the list of ten concurrent numbers. Difficult to remember? Now look at the same numbers broken into the three-part configuration that is familiar to US citizens. Easier to recall? That's because that information has been re-chunked into three sets. Data visualization takes advantage of chunking. When information is displayed in the form of visuals that show meaningful patterns, more information can be chunked together. Therefore, when we look at a visual, we can process a great deal more information than what we can when we are looking at the information in the form of a table. Cognitive tunneling is a mental state in which our brain hangs on to the things that are closer to us and does not see the rest of the relevant data. When this happens, as the old saying goes, "you can't see the forest for the trees." In other words, you become obsessed in some sense that you lose perspective of the whole graphic. When cognitive tunneling occurs, the individual may become lost in internal thought and lose focus on the present action and environment. Data visualization with animation looks pretty cool as the Wind Map example shows. But it's also hard to direct and guide readers to the most salient content. Readers may only focus on the fancy animation itself without trying to understand the whole content. The cognitive tunneling effect can easily happen with interactive data visualizations. Humans are strange. We like to say we want as many options as possible, but when we get them, we get confused and can't make a decision. Designers can improve the efficiency of a design by understanding the implications of Hick's law. The law describes the time it takes for a person to make a decision as a result of the possible choices he or she has. Increasing the number of choices will increase the decision time. Having too many options with equally perceived hierarchy can cause cognitive overload. Yeah, that leads to feeling frustration and is not the best user experience. TV remote controls often provide a great example of a complicated interface. Some remote controls have more than 50 buttons all together. One reason the remote control has so many buttons is that it can help to make the device look impressive in the shop, but once you get home, many of the buttons become redundant or confusing. The remote control shown here has several buttons that could potentially do the same things. Some buttons are named Guide, Function Menu, and Option, but it's very hard to predict which is which. Complicated TV remotes will increase the time it takes to complete an operation. In contrast, the Apple remote has very few buttons, keeping the options for a user minimal. There's only one menu to choose, So it's fairly obvious what to do to select the controls needed. Data visualization, especially those that are interactive, can contain many features, and if they are visible at the same time-- for example, menus, toolbars, buttons, palettes, or tabs-- this could be very overwhelming, especially for a new user. Highlighting is another way to speed up the decision process. Make a few important options stand out among the cluttered user interface to speed up the response times. We don't see images with our eyes; we see them with our brains. The real power of visualization is the ability to get across a lot more complex information than what our visual and verbal memory can generally hold. So, in summary, visual design for retention makes communication decisions that target every stage of the memory process. Use contrast and color to attract immediate notice. Create associations with familiar subjects to help the user store the information. And provide parsed, accessible chunks of content for easy retrieval. To resist cognitive tunneling, we should adopt interactivity and animation, within reason. Finally, we should minimize resource consumption. Having more choice can give more distractions. This leads to slower response times. Later in the course, we will through specific design principles to limit cognitive load in data visualizations.
