The Design of Everyday Things by Don Norman: chapters 3–4 summary
In the third chapter, Knowledge in the Head and in the World, Don Norman describes how we attain and use knowledge. He asserts that we must combine knowledge in the world and the head to accomplish goals since neither is sufficient on its own (Norman, 2013, p. 74).
At the start of the chapter, he states that we can have precise behavior without having precise knowledge because as mentioned above we use both knowledge in the head and the world. He adds that knowledge does not have to be precise to be applied, that natural constraints in the world help us find knowledge and reduces memory load, and that cultural norms and constraints exist as knowledge in the head (Norman, 2013, pp. 75–76).
Norman describes that design needs to give enough clues so people can use their knowledge in the world to make interpretations and be able to accomplish the desired task and combining knowledge in the head can increase adoption. The more knowledge is derived from the world to do a task the less we need to learn anything to accomplish it (Norman, 2013, p. 77).
There are two kinds of knowledge that people use to function. One is declarative knowledge which is based on facts and rules, and it is easy to teach. The other is procedural knowledge of how to do something and it is learned through demonstration and practice (Norman, 2013, pp. 78–79).
In addition, Norman also describes short-term memory (or working memory) and long-term memory as the actual knowledge in the head and both have implications for design. The information in short-term memory can be easily retrieved but not as easily kept. We can keep about more or less seven items at a time. This is why we must put the memory in the world by writing things down (Norman, 2013, pp. 86–92). For instance, it is hard to remember all of the grocery items at the store, therefore we use tools like a list on our mobile phone to aid our memory. To maximize working memory, designers should use a variety of sensory modes (sounds, sight, touch, hearing, gestures, and spatial location) to convey information (Norman, 2013, p. 95). Long-term memory on the other hand takes effort to store and retrieve information and our long-term memory fails us constantly since when recalling a memory, we must reconstruct it and reinterpret it causing distortions. Moreover, false memories can easily be implanted into people’s minds making it hard to distinguish fact from fiction (Norman, 2013, pp. 95–97). This could explain why witness accounts of events that happened many years in the past can be so faulty.
The retrieval of knowledge is discussed in this chapter as the memory of arbitrary things and meaningful things. Arbitrary knowledge consists of remembering things with no meaning or relationship to one another such as recalling the letters of the alphabet. Meaningful things are remembered through established relationships to other things already known (Norman, 2013, pp. 75–76). For instance, when attending a networking event making an association with an accessory with the name of the person you are meeting.
Thought processes can be simplified, according to Norman (2013) by applying approximate models. For instance, the formula for temperature can be simplified to create a close estimate by simply subtracting 30 from the Fahrenheit temperature and dividing the results by two to derive an approximate temperature in Celsius (pp. 100–105).
Norman (2013) also describes prospective memory as remembering a task that is set in the future and the ability to plan for it and to visualize the future. People rely on reminders and use knowledge in the world to compensate for faulty memory (pp 107–108). For instance, relying on digital calendar reminders to remember notable events. Designers need to recognize that there are two aspects for meaningful reminders: the signal to communicate what is the task to be remembered and the message to communicate information on how to do it (Norman, 2013, pp. 108–109).
Later in the chapter, Norman (2013) emphasizes, the need for natural mapping or mapping that makes the relationship between what is controlling and being controlled obviously. This is necessary to bridge the knowledge between the head and the world, otherwise, it can lead to error or fatalities since a higher burden is placed on memory. Further, natural mapping can be influenced by culture. He cites various examples such as the difficulty with the design of stove burner controls and having to remember which control ignites which burner every time one uses the stove. (pp. 113–122).
In chapter four, Norman (2013) focuses on how Design can provide the right information so that people can accomplish tasks without any experienced and applying knowledge from the world (p. 123).
He describes the four kinds of constraints. Physical where no special training is needed since it relies on properties of the physical word to show meaning. It is effectively used when the constraint is easily understood to prevent an erroneous action from taking place. A culture that can change over time is expressed as a model of general rules of acceptable behavior and how to interpret situations. Semantic, relies on the situation and knowledge of the world to interpret the meaning of a situation to control the set of outcomes. Logical is the relationship of the functional components and how they affect other things (Norman, 2013, pp. 125–131).
In this chapter, Norman (2013) highlights how a long string of switches can be difficult to use mainly because it lacks good natural mapping. However, design can mitigate such issues by performing a task analysis. That is, observing how the task is performed, and solving for the actual ways the task needs to be done. Switches potentially could be mapped by the activities they control. For instance, having a switch specifically for the projector in a classroom. However, designers need to be mindful that activity-centered controls are only effective when they match real-world scenarios since there can always be edge cases (pp. 135–141).
Norman also addresses how certain types of constraints can induce behavior. One he names is forcing functions. It is a type of physical constraint that prevents advancing to a later stage if an error was committed earlier. Another is “interlocks” which forces operation in a particular sequence and safety-related-interlocks are used to prevent a series of events if the user cannot continue to perform the task. The other is lock-ins keeping the operation going even if the user tries to stop it too early. Lastly, lockouts prevent an event from happening or blocks passage into a space (Norman, 2013, pp. 141–145).
He also discusses how we perceive affordances through conventions that are decided by culture. They provide understanding in new situations but can also make people averse to change. This is the case he presents with destination control elevators. It was hard for many to be comfortable with not pressing a button and be taken to by a pre-selected floor, however, the benefits of this new technology outweigh the difficulty of the change since it saves time especially in very tall and high trafficked buildings (Norman, 2013, pp. 145–150).
He also mentions standards in design, but according to him it is a “principle of desperation (Norman, 2013, p. 155).” Nonetheless practical when no other solution is clear so that people can learn only once. Furthermore, these standards should reflect psychological conceptual models (Norman, 2013, pp. 155).
He ends the chapter by describing how sound can be an effective signifier as it tells us about things that cannot be seen or when our sight is focused on a different task. However, if used improperly or excessively noise can be disturbing or ignored. Norman also examines how electric and hybrid cars pose a design challenge since they have no sounds and the visually impaired have difficulty knowing when a car is approaching. The convention of sound can be a helpful signifier to alert those that cannot see an oncoming car (Norman, 2013, pp. 155–161).