Wednesday, October 03, 2007



To Mr. Ahmet ARZIK,

Brain is one of our organs which does not have the ability to move. Think of the brain’s functional development during the process in which a new born grows up to become an adult. Our brains develop from the cognitive level of a little ‘snail’ which moves with its nutrition instinct, to a chess master who challenges a supercomputer…

What surprises us is not solely the impressive amount of change that our cognitive abilities undergo in our personal development process… This organ of ours which can not even move by itself, can deviate itself in a matter of a season, a couple of days or a few seconds because of the changing environment or its own inner conditions. According to our mood may this organ remember what it likes or forget what it does not, namely it deviates our remembering ability depending on the subject, it certainly does not work very well in hot summer days, on the other hand ina state of emergency, your brain orders your body to make the correct move in a much shorter time than you can consciously decide...

If we look in our cognitive activities closely, we can notice a complexity rising from variety and adjustability. This complexity increases because of the variety and uniqueness of each adult person’s individual solution in comparison to many others… ‘No two fingers of a single hand are the same’. On the other hand, ‘Every person is different but not different from all’…

The fact that our brains have many different abilities, gives us the possibility of creating our cognitive functions one by one through different combinations of these abilities. For example, a not very well educated person can still make quick and correct decisions with his/her feelings and instinct. University language preperatory school English teachers can at least handle ‘sharp’ students who have got much higher grades in the university entrance exam than them, with their teaching experience and knowledge. Our cognitive abilities can not only change depending on the mental, social and physical conditions but they also vary from person to person. The effect of his/her family’s child upbringing, the individual’s knowledge and experience reservoir, the point he/she stands in life, creates variety between individuals and how they survive in the competition to be successful.

Society and individuals reduce the difficulty of problems they meet by converting them to easily percievable models. Even to a single symbol or figure... In this process our brain is sometimes reduced to a small black box by the model makers. Society has the tendency to group everything related to cognitive ability under the title of ‘intellect’… Also, if a person is ‘sharp’ he/she is frequently considered to be so always and under all conditions whatsoever…

Everyone of us takes an important exam at one stage of his or her life. We all remember the level of ‘intellectual sharpness’ or acuteness we have reached during our preparations. On the other hand, there may be moments you may have difficulty to utter even a single word after you wake up in a hot summer morning. Then, which of these two people is you, yourself? The ‘sharp’ or the ‘moron’? The answer is ‘None of them solely’. Then what is wrong about the question? The mistake is in the way we look at the cognitive abilities of human-beings… We should never forget that, even though our brain can not move an inch by itself our mind does not have a static and frozen architecture or capacity. Our brain manages to cope with changing situations not by changing its location but by deviating its own self.

A person’s mental abilities change according to its age, the situation he is in, the current subjects he deals with and many similar factors. If an experiment were made, even the sharpest person on earth might not be able to make the right decision if he were being interrogated as a prisoner of war or if his airplane lose one of its motors at 10000m’s altitude, given that he does not have the necessary training and experience… Moreover, even if he had the knowledge and experience to do so, he might still not be able to make the right decision in some cases, because the professional human brain can not stay as constant as it were when it took the qualification exam…

When the architecture of the human mind is inspected, an anatomical and biological wealth can be observed underneath its functional variety. It is not a wonder such a complex living architecture can create personalities with extraordinary abilities… The most wonderful is the fact that brain is able to provide the human-being everything needed to cope for its complex social and individual challenges.

The complexity of our brains is reflected in the way we percieve and interact with things and other people. Designing tools and systems to be used by humans requires to handle this complexity in a simplified way. Faced with any complexity, we tend to make abstractions. Abstractions not only reduce the number of the things we are concerned but also limits the domains of their items. This also applies to our approaches to the complexity of our brains.

Wickens Information Model is developed to calculate how long it will take for the user to respond to an input. The below given depiction has got so much popular that it has gained a function similar to the model that describes to primary school kids the creation of seasons based on the so called ellipse shaped path of earth around the sun.

The Wickens Information Processing Model was created to provide a convenient method to calculate the response time of the user to a signal from a system.

………………….Attention Resources

(transfer to ……………............….(math,decide,……….…Response
working memory)…................memory transfer)

Short term sensory store…..…Long term memory

Visual Image Store………….....Dltm=infinity

Auditory Image Store……... Working Memory
Daud=200[70-1000]msec….Dwm=3[2.5-4.1] chunks
……………………………............…Kwm=Acoustic or visual

Transfer durations:

- Attention resources are used in all three stages..
- D = decay, M= residing duration in memory, K= representation format of the information
(EBERTS, Prentice Hall, User Interface Design, sayfa 166).

An other name of this model is Discrete Stages Model. The contributions of the Wickens Model may be outlined as:

1. Perception does not happen in a single moment. On the contrary, human processes the inputs and a functional transformation (for ex. from visual to semantical) happens.

2. Processing information requires time. The time that passes between the moment input comes and human responses is called the reaction time.

3. The mental timing of events that happen in a single response process. The nomenclature of the stages, durations and the definition of operations or transformations done in each stage.

4. Transformations related to the presentation of information.

5. Limits that do exist in the time and quantity domains.

6. The unit of information. Miller’s seven plus/minus two rule is alluded above in the working memory. This also points at the effect of the gained experience on the size of chunks and thus determines the perception speed.

Today, all sorts of references to this model, are not limited to engineering books as it should. Many other psychology related books refer to this model or at least have similar approaches although this model is created primarily for guessing the response time of the human to certain systems.

In this model, there are visual and auditory image stores in the short term perception memory. When we think of memory we tend to imagine a single area or even a single organ. In fact, our brain is composed of many sub-structures and sub-functions, or sub-processors as in the computer nomenclature. The visual store should be located somewhere related to the visual part of the brain and auditory memory likewise…

Wickens model states that any information written into the longterm memory is never erased.
This does not mean that, that information is accessible. Commonly established belief is ‘our memory works linearly’. On the contrary, experiments have shown that we can remember some parts of the past better than others. For example, we may remember 30-40 year old events better than closer events in the past. Our memories do not work linearly on the time basis.

Our memories have an addressing mechanism which is triggered by content. Human memory is a marvel on one hand and an enigma on the other because of its non-linearity… The complexity of social events may be explained by the complexity of the minds of people who create them and the way their minds work… Writing to the memory and access to it is determined not only by content but also the environment, the mood, etc. Our memories’ refreshing mechanism is also not linear… It is a scientificly proven fact that a person who remembers a bad event in the past tends to remember bad things after this… An other example for the content triggered addressing mechanism is the fact that we can remember things related to ourselves better than other things…

The basic speciality of the Wickens model is the transformation of the information’s presentation format. For example, a figure percieved by the eye is stored in the visual image store in the physical format but transformed to the visual format when passed to the working memory…
It is the most reasonable approach to assume that these physically percieved information are accessed in the working memory through some buffer zones. This also implies that the working memory does not have a homogenous function as commonly assumed. The saying that people working under heavy mental load ‘can not see or think anything else than their work’ has a piece of truth in it. The increased mental load causes temporary changes in the memory usage. These people become forgetful or get easily distracted when doing even simple daily things. The reduction of perception abilities of people working under heavy mental load can be attributed to the reduction of input buffer space by the working memory to increase space for logical etc. cognitive tasks.

A common misunderstanding in the society that is fostered by the Wickens model is that human memory is a uniform single structure. For example the episodic bellek which is located in the frontal part of our brain is a special memory that helps to form the sense of time and reality. Episodic memory keeps track of events and provides information about sequence, duration, reality to the general use of our brain. People who work under heavy mental load frequently forget what they have done. They first take a book from the table and put it on the bookshelf, then a few moments later they forget what they have done and try to put the book on the shelf again, thus they can not find it on the table. While working at EUROCONTROL Software Team Karlsruhe, Chritian PETIT who was working on a difficult task in a terrible political climate had told me ‘This is a natural situation, I can not remember the color of the traffic light after I pass them while driving’ as an answer to my similar complaints.

If we study this example closely, with the assumption that the episodic memory has a buffer;
the events that have happened should have been written to the buffer in their happening sequence… If the working memory is overloaded during the events, the memory allocated to the episodic memory buffer is deallocated and put in the service of general purpose or other working memory. As a result of this the working memory allocated to the episodic memory buffers is cancelled or dramatically reduced. In this case, the mentally overloaded person can not remember an event which has happened a few moments ago, because the episodic memory input buffer related to that event has been erased and used for some other purpose.

An other example to the case of mental overload reducing the perception is: a person driving an automobile, airplane or any system loses control of command due to the increase in his reaction time caused by mental overload(mostly talking). A special case related to this situation is air traffic controllers making mistakes while working with divided attention (Investigating Controller Blindspots, Dr. Barry Kirwan, HINDSIGHT 5 – July 2007 ). When dealing with a difficult situation with a relatively calm background , the controllers have to focus on the high priority troublesome situation but after fixing this problem they should remember the cases in the background. Unfortunately in some cases it has been observed that after the primary problem is solved, some of the secondary problems related to the general situation have been completely forgotten and thus they have caused other important problems. The problem is the same as in the example of Ray EBERTS’s, User Interface Design book of a driver not hearing the radio when the traffic gets dense… I believe, the problem is not inability to percieve but the insufficiency of working memory resources(input buffers) which enables the resolution of the perception process in the consciousness.

Let’s study the hypothesis of mentally loaded person’s perception deficiency reversely. A person whose perception is heavily loaded should have reduced or weakened cognitive(logical, decision making etc) functions… Let’s imagine a commando soldier in a commando exercise as a person whose perception is heavily loaded. Fast moving targets appear suddenly or move in front of him during the exercise. The soldier is expected to fire and hit the targets with his reflexes rather than think and make decisions cognitively. Balthazar GRACIAN alludes to an old addage in his ‘The Art of Worldly Wisdom’… ‘It is difficult to make decisions when driving a horse’. The more the percieved things, the more buffers for different inputs… If you continue to increase the inputs even more, wrong actions produced by making decisions based only on reflexes rather than judgement appear. We end up with incidents such as the 1992 incident when an American pilot fired at an helicopter which carried American and Turkish officers.

An other aspect of this subject is how much should the system user be loaded when designing complex screens such as radar displays. Displaying every information spatially makes the access to them easy but the designers’ general tendency is to abuse this principle. The requirements creep also fosters this tendency… The output of these wrong tendencies is visually overloaded screens. The overloaded screens is developing at the expense of losing and leaving the judgement ability of the large systems or air traffic controller out of function… The large system controller is turning out to be a simple sensor that reacts rather than judges and decides…

Contrary to this phenomenon, Situation Awareness should depend on human mind’s variable thinking depth, variable thinking speed and ability to think with things it does not know or remember, its multi-processor pseudo-god control ability which directs its conscious-subconscious balance.

I tried to drive your attention to the common misbeliefs about the human mind. Besides this, I outlined the popular Wickens Model and noted some misunderstandings about it which reduces the system user to a simple sensor. I hope to be pondering on thinking speed vs thinking depth, the balance between conscious and subconscious and mental control vs automatic processes in my future articles.

An antique Hellenic philosopher has said ‘Know yourself’. A weak point of this adage is that the person or anonym persons who used this adage have at least a single self. The Anatolian-Eastern tolerance of Mevlana, although not that old, reflected in the adage ‘There is a self in myself’ would perhaps say ‘My son, be aware of yourself from time to time without any intention to do so and do not forget to feel your poor body once in a while’.

‘May your mind be fresh and be all the rest nice’.


Note: Besides serving the benefit of the general public, has this article been written to be used in the education of air traffic controllers, large system operators and the engineers.