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Knowledge in the head and knowledge in the world are concepts introduced by Don Norman in his classic book, “The Design of Everyday Things”. knowledge in the head or internal knowledge. If we examine how people use their memories and how the retrieve information. Another is is Knowledge in the world acts as its own reminder.It can help us recover structures that we otherwise would forget. Knowledge in the head is efficient no search of the environment in required. Well I will share you a simple example to create it. I think this is a very important concept to keep in mind when doing software design. who is your user? What job are they doing? Often will they be doing that job? Will the same people always do it over and over again? The answers to these questions will help you decide if you should emphasize knowledge in the world or knowledge in the head.

If you are building a public facing website that many people will visit, you want to emphasize knowledge in the world.If you are building an application for something like data entry you may want to emphasize knowledge in the head.



                      Fig: 1

Human knowledge and memory has faulty nature.United States demonstrates that, students cannot recall the pairing of letters and numbers on telephones in a common classroom exercise.Why the apparent discrepancy between the precision of behavior and the imprecision of knowledge?Because not all of the knowledge required for precise behavior has to be in the head. Human knowledge is partly distributed in the head and in the world or in constrains of the world.Precise behavior can emerge from imprecise knowledge for four reasons. Four reasons are,


1.      Information is in the world.

2.      Great precision is not required.

3.      Natural constraints are present.

4.      Cultural constraints are present.


Because of these natural and artificial constraints, the number of alternatives for any particular situation is reduced, as are the amount and specificity of knowledge required within human memory.


                                Fig: 2



Information’s are available in this world. The information is available in the environment; the information you internally code in memory need be precise enough only to sustain the quality of behavior you desire. This is one reason people can function well in their environment and still be unable to describe what they do. For example, a person can travel accurately through a city without being able to describe the route precisely.Procedural knowledge is difficult or impossible to write down and difficult to teach.

Knowledge from the world is usually easy to come by. Designers provide a large number of memory aids. The letters on the typewriter keyboard are one example. Social networks, Family and teachers, TV and radio, Websites, Books,Newspaper and magazines all from this we collect information or knowledge. We make extensive use of written notes. We place items in specific locations as reminders. In general, people structure the environment to provide a considerable amount of the information required for something to be remembered.


                     Fig: 3




Precision refers to how well experimental knowledge and values agree with each other in multiple tests. It is not necessary to precise memory information. People can remember enough to distinguish one familiar coin from another although they may be unable to remember the faces, pictures, and words on the coins. But make more precise memory necessary and you get havoc.

Suppose I keep all my notes in a small red notebook. If this is my only notebook, I can describe it simply as my notebook. If I buy several more notebooks, the earlier description will no longer work. Now I must call the first one small or red, or maybe both small and red, whichever allows me to distinguish it from the others. But what if I acquire several small, red notebooks? Now I must find some other means of describing the first book, adding to the richness of the description and thereby to its ability to discriminate among the several similar items. Descriptions need discriminate only among the choices in front of me, but what works for one purpose may not for another.




Embrace limitations and boundaries as a source of inspiration. Appreciating the obstacles helps you see more fully how to overcome or adapt to them. Accepting constraints, they can morph into useful forms that open up new possibilities, spurring creativity.

Back in the good old days of oral tradition-performers traveled around reciting epic poems thousands of lines long.It turns out that external constraints exert powerful control over the permissible choice of words, thus dramatically reducing the memory load.

Rather than accepting with enthusiasm the constraint of, for instance, a poorly ventilated meeting room, perhaps the greater wisdom is to ask why we are meeting here.


I was working with a network of native youth at the Snug about five years ago, and they had a strategy they had adopted that they were getting all the native organizations across the province to adopt a youth seat in their Executive boards. They were meeting as they were completely frustrated and were angry that they weren’t being taken seriously. I said, “What do you expect, you are young, native people, mostly women…who’s going to give you the time of day?” They looked grim. So you know what this means, is that you are free. They have no expectations of you… so …what can we do?” And that changed the agenda… they became more politically influential as a result. There was a limitation, a constraint, which young people are not given political power, and they had to “make friends’ with this idea.




We will not get our heads cut off if we fail to remember a secret code although it is very hard to do. It is possible to memorize one or two secrets: a combination, or a password, or the secret to opening the door. But memory fails when the number of secret codes gets too large. There seems to be a conspiracy, one calculated to destroy our sanity by overloading our memory. Consider what we are asked to remember in our “convenient” world. A simple search through my own wallet and papers reveals the following things.

1.      Postal codes

2.      Telephone number.

3.      Access numbers for telephone credit cards.

4.      Passwords or numbers for ATM booth.

5.      Driver’s license number.

6.      Social security numbers for my wife, my children, and me. Nine digits each.

7.      Passport numbers, again for my whole family.

8.      My employee number.

9.       License plate numbers for our cars.

10.    Birthdays.

11.    Ages.

12.   Clothing sizes.

13.   Addresses.

14.   Credit card numbers.

15.   Bah and humbug.

So many of these numbers and codes must be kept secret.





Say aloud the numbers 1, 7, 4, 2, 8. Next, without looking back, repeat them. Try again if you must, perhaps close your eyes, the better to ‘hear’ the sound still echoing in mental activity. Have some- one read a random sentence to you. What were the words? The memory of the just present is available immediately, clear and complete, without mental effort. “What did you eat for dinner three days ago? Now the feeling is different. It takes time to recover the answer, which is neither as clear nor as complete a remembrance as that of the just present, and the recovery is likely to require considerable mental effort. Retrieval of the past differs from retrieval of the just present. More effort is required, less clarity results. Indeed, the ‘past’ need not be so long ago. Without looking back, what were those digits? For some people, this retrieval now takes time and effort.

In psychology, memory is an organism’s mental ability to store, retain and recall information. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing the memory. The late nineteenth and early twentieth century put memory within the paradigms of cognitive psychology. In recent decades, it has become one of the principal pillars of a branch of science called cognitive neuroscience, an interdisciplinary link between cognitive psychology and neuroscience.

Human memory is essentially knowledge in the head, or internal knowledge. If we examine how people use their memories and how they retrieve information, we discover a number of categories. Three are important for us now:

1. Memory for arbitrary things. The items to be retained seem arbitrary, with no meaning and no particular relationship to one other or to things already known.

2. Memory for meaningful relationships. The items to be retained form meaningful relationships with themselves or with other things al- ready known.

3. Memory through explanation. The material does not have to be remembered, but rather can be derived from some explanatory mechanism.




Most things in the world have a sensible structure, which tremendously simplifies the memory task. When things make sense, they correspond to knowledge that we already have, so the new material can be understood, interpreted, and integrated with previously acquired material. Now we can use rules and constraints to help understand what things go together. Meaningful structure can organize apparent chaos and arbitrariness.

Without the proper interpretation, it was difficult to remember the switch directions. With it, both the remembering and the performance of the task became trivial. Note that Tatiana’s interpretation of the switch movement did not explain anything. It simply let him relate the proper direction to move the switch with the direction in which he was turning the motorcycle. The interpretation is essential, but it should not be confused with understanding.








The arrangement of burners and controls on the kitchen stove provides a good example of the power of natural mappings to reduce the need for information in memory. Without a good mapping, the user cannot readily determine which burner goes with which control. Consider the standard stove with four burners, arranged in the traditional rectangle. If the four controls were truly arbitrary, as in figure 3.3, the user would have to learn each control separately: twenty-four possible arrangements. Why twenty-four? Start with the leftmost control: it could work any of the four burners. That leaves three possibilities for the next leftmost. So there are 12 (4 X 3) possible arrangements of the first two controls: four for the first, three for the second. The third control could work either of the two remaining burners, and then there is only one burner left for the last control. This makes twenty-four possible mappings between the controls and burners: 4X3X2X1 = 24. With the completely arbitrary arrangement, the stove is unworkable unless each control is fully labeled to indicate which burner it controls.




Knowledge or information in the world and in the head are both essential in our daily functioning. But to some extent we can choose to lean more heavily on one or the other. That choice requires a trade- off—gaining the advantages of knowledge in the world means losing the advantages of knowledge in the head


User-Centered Design


User-centered design (UCD) is a type of user interface design and a process that contain the needs, wants, and limitations of end users of a product are given extensive attention in the each stage of the design process. It is characterized as a mulch-stage problem solving process that not only requires designers to analyze and foresee how users are likely to use a product, but also to test the validity of their assumptions with regard to user behavior in real world tests with actual users. Such testing is necessary as it is often very difficult for the designers of a product to understand intuitively what a first-time user of their design experiences, and what each user’s learning curve may look like.



For this picture we can see that how User Centered design evaluate or works. Analysis that’s mean is process of users understanding of it. That’s the main point of need of user. Or another is Design many things need to be designed for a certain lack of understand. To design first of all we have to sure, difficult designs shouldn’t be entirely difficult. And another is Evaluation and Implementation.

For example: we can see that the user-centered design process can help software designers to fulfill the goal of a product engineered for their users. It is all about user friendly. Well, to create a user- centered website, you must think about the needs of your users through each step of the process, including planning collecting user data.


The ISO standard describes 6 key principles that will ensure a design is user centered:


1.     The design is based upon an explicit understanding of users, tasks and environments.

2.      Users are involved throughout design and development.

3.      The design is driven and refined by user-centered evaluation.

4.      The process is iterative.

5.      The design addresses the whole user experience.

6.      The design team includes multidisciplinary skills and perspectives.




Importance of User-Centered Design

Users visit your website to find information or accomplish tasks. If they don’t find your website helpful, you risk them leaving. By focusing on the end user you:

  • Satisfy the user user-friendly experience
  • Establish a more relevant and valuable website
  • Create websites that supports rather than frustrates the user.

 User-centered design can be characterized as a mulch-stage problem solving process that not only requires designers to analyses  and foresee how users are likely to use a product.





May be all you are thinking why I have included this picture? (UCD) just does what you want and doesn’t make you waste time doing what it wants? This picture contains the opposite things of (UCD). It’s clear that if a interface don’t become user friendly then that will be a great problem. It is necessary to think carefully about who is a user and how to involve users in the design process. The people who manage the users have needs and expectations too.


Everything is designed. Not everything is designed effectively. The target of any design is meeting needs when specific situations, for users (human, animal and vegetable) and products (component, contents…. Design does not exist if there is no beauty. Good design begins with the needs of the user.  There is no design, no matter how beautiful and different, is any good if it doesn’t fulfill a user need.




3 notes

  1. atiburrahman said: nice work…..interesting…..
  2. sabihanoorcse posted this
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