Knowledge in the Head and In the World

• Neither knowledge in the head nor knowledge about the world are sufficient for understanding devices.
• Knowledge for precise behavior need not be present in the head because:
  • Knowledge can be both in the head and in the world. Much of what is needed can be derived from the world.
  • Great Precision is not Required. Only a sufficient amount of knowledge is required.
  • Natural Constraints Exist in the World. This simplifies the possibilities of things by eliminating the impossible from the search space.
  • Knowledge of cultural constraints and conventions exist in the head. These constraints also apply to various circumstances.
• What appears good in principle can sometimes fail when introduced in the world.

Environment §

• We can arrange things so that we do not need to have complete knowledge or we rely upon the knowledge of the people around us. Design should exploit this.
• We only need to remember sufficient knowledge to let us get our tasks done. People can function well in their environment and still be unable to describe what they do.
  • One reason is through declarative knowledge - the knowledge of things. It is taught through instruction. declarative memory is recollected as bits of information.
  • Another is through procedural knowledge - the knowledge of how to do things. It is learnt through demonstration. procedural memory is recollected through recreating it in one’s head.
• Knowledge in the world can be accessed via signifiers, physical constraints, and natural mappings.
• Everything works fine unless the environment changes so that the combined knowledge is no longer sufficient.
  • Descriptions need discriminate only among the choices in front of me, but what works for one purpose may not for another.
• There is a tradeoff between keeping knowledge in the head and knowledge in the world

Memory §

Memory Mechanisms §

• See more in Thinking Fast And Slow
• Short Term Memory retains the most recent experiences or material that is currently being thought about. It is the memory of the immediate present.
  • It has fast retrieval but only a small amount of information can be retained.
  • It is prone to being lost when one is distracted. Thus Don’t count on much being retained in STM.
  • How much is retained depends upon the familiarity of the material. It is affected by both time and the number of items.
  • The limitations of STM can be mitigated By presenting different information over different modalities such as sight and sound.
• Long Term Memory is memory for the past.
  • It has slow retrieval and information is transferred slowly to LTM, but it can hold more information (theorized to be limitless).
  • We do not remember our experiences as an exact encoding, rather as bits and pieces that are reconstructed and interpreted each time.
    • We may reconstruct events the way we would prefer to remember them, rather than the way we experienced them
  • Knowledge in memory is meaningful, and at the time of retrieval, a person might subject it to a different meaningful interpretation than is wholly accurate
• Prospective Memory is memory for the future. That is, remembering a planned action to be carried out in the future.
  • While memory can be used, it is often unreliable.
  • If the event is far into the future, it is wise to transfer some of the burden to the world via reminders.
  • There are two different aspects to a reminder
    • The signal is knowing that something is to be remembered. A meaningful signal is given at the correct time and location.
    • The message is the information itself
  • The sheer number of different reminder methods also indicates that there is indeed a great need for assistance in remembering, but that none of the many schemes and devices is completely satisfactory
• Transactive memory involves the memory of the collective. That is, allocating the cognitive load of remembering to many people or devices.
  • Keep in mind that external knowledge is often erroneous.
  • The partnership of technology and people makes us smarter, stronger, and better able to live in the modern world

Knowledge §

• Arbitrary Knowledge is the simple remembering of things that have no underlying structure.
  • It is usually learnt via rote learning which is problematic because:
    • The learning is inherently difficult because what is being learnt is arbitrary.
    • When a problem arises, the memorized sequences of actions gives no hint of what has gone wrong.
  • We learn arbitrary associations by artificially providing structure. Artificial structure simplifies the memory task.
    • Part of this is the use of conceptual models.
    • Thus, It is easier to remember things when there is a meaningful relationship between them.
• Approximations are good enough for practical use.
• Models need not be accurate as long as they lead to he correct behavior in the desired situation.

Design Implications §

• Provide meaningful structures. Make memory unnecessary by putting the required information in the world. The most effective way of helping people remember is to make it unnecessary
• The easier it is to enter the information into the relevant equipment as it is heard, the less chance of memory error.
• Constraints remove the burden of remembering things about the world by reducing the amount needed to be learned to a reasonable quantity.
• Technology also removes the burden of remembering.
• The burden or remembering is that the more complex the thing, the more we need simplifications which, themselves, can add another layer of vulnerability. Complexity, in this case, does not imply security as people tend towards remembering simplified things. Make something too secure, and it becomes less secure.

Natural Mappings §

• In order of goodness, we have the following:
  • Controls are mounted directly on the item to be controlled.
  • Controls are close as possible to the object to be controlled.
  • Controls are arranged in the same spatial configuration as the objects to be controlled. Beware, this mapping might be ambiguous.
• Proper natural mappings require no diagrams, labels or instructions.
  • We underestimate our ability to understand the devices we purchase. Thus, test products before they are bought.
• Natural mappings can be influenced by cultural conceptions.
  • For example, different cultures have different views of time and this translates to different mappings for time-based controls (such as for slide decks)
  • The choice of metaphor dictates the proper design for interaction. Design difficulties occur when there is a switch in metaphors
  • It is possible to break convention and switch metaphors, but expect a period of confusion until people adapt to the new system.

Links §

• Design of Everyday Things