TiChi Introduction

Fitt's Law
Object-Action Interface
Prescriptive Theories
Fisheye strategy
Conceptual, semantic,
    syntactic, & lexical

Direct Manipulation

Information Processing
Hacker's Action Theory
Attention & Memory
Andersen's ACT-R
Knowledge & Mental
Social & Cultural

Theories in Computer human interaction
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Information Processing  
Umut Akdemir 
October 2002


Information processing is one of the main approaches in psychology that points out how the information is stored in our memories. Atkinson and Shriffin's "stage theory" (1968) forms a good basis for research in this area[7]. With three other well known theories we can categorize main theories in this approach as:

1. Stage theory model: This theory divides information processing of our brain into stages. In this model there are 3 stages to record information into our memory.
   1.1.Sensory Memory       
   1.2.Short term memory
   1.3.Long term memory
2. Level of processing theory
3. Parallel Distributed
4. Connectionist

After explaining these theories, we will have a glance at their application areas, and we will finish our discussion by looking into its applicability to HCI.


Scope, Application

Educational Software
An important application area is educational software. If educational software application designers know how the students will gather the given information, they can organize the information to let the students grasp the concept faster. It is similar for the educational software also. After giving tutorials, the software can intentionally give summaries+ADs- encourage the users to repeat the material by themselves. Also usage of audiovisuals to stimulate their spatiovisual sketchpad, interesting bindings, which will both take users+IBk- attention and let them form easier relationships with their previous data will be helpful.

Organization of Help structures:  
Information processing can also be useful in providing help for the users of the software. The aid provided by the software should be given at appropriate time (it should be leading the user when he is stuck, not distracting his attention). Help should be both specific (pinpointing the exact situation), and procedural (giving complete directions to user in an atomic fashion to encourage the user link the steps of his solution). And of course the user should not need any other help to understand the help system! It should be instructive having as few menus, icons and windows as possible. Chapter 7 of [1] provides further insight to the design of aiding systems.   
Organization of Interface for users:
User computer interaction is the way users map their tasks from their own minds to available software. Hence knowledge in human information processing can be extremely helpful in designing the interface, which will help the user map his mind to upcoming tasks. See examples.


Stage Theory Model:

This model divides recording process into three stages. In order to record the information for later use, our brain needs to pass the information through all of the stages. Information stored in long-term memory is permanent. However if we do not pass information to this final stage, we will not be able to remember it after a small period. (figure 1)

Sensory Memory:
This is the initial stage in the process. To process an information, we should first obtain it. If we make an analogy with computers we can think of this as the initial input stage to the computer. In order to write it to the hard disk, first the information should be entered by means of an input device. Our input devices are 5 senses of our nervous system. This memory is very short and temporary. We tend to forget everything we get from these senses, unless we change our focus and attention immediately to inputs coming from our sensors. For instance our eye takes around 12 frames/sec. meaning that we have on the average 12*60*60*16(hours we are not sleeping) = 691.200 frames/day. However we remember much less. When we pay our attention, information is passed onto our short-term memory.     
An interesting feature or a known pattern in the environment may increase frequency of attention.(figure 1)

Short term memory:

Next stage is short-term memory, also known as working memory. This is a concentrated stream of incoming knowledge, which is available until we pay our attention to another subject.  


For instance if you suddenly try to answer the question, unless you already passed the information to your long-term memory you will forget where you were in the text at that moment. If brain does not pass to the final stage of recording from short-term memory (STM), the information is lost when the attention is distracted. Think of it as a computer RAM with a small capacity. If we suddenly quit a program we are working on without saving, the information will be gone. 

Alan Baddeley, extracted three different subsystems of STM in his book Working Memory[6].

1. Speech system : We sometimes whisper to ourselves to remember a given set of numbers.

2. Spatiovisual sketchpad: We sometimes try to remember scene or a schematic we have seen as a whole (nonverbal).

3. Central executive: The main unexplored part of short-term memory that contains short-term controls and cognitive processing.

To retain information in STM and also to pass it to long-term memory we can use repetition (immediate repetition does not help, we should make regular and conscious repetitions) and organization (categorization and linkage of new information with the previous knowledge). (figure 1)
1.3 Long-term memory:

Long-term memory (LTM) is the permanent memory and available to us for a quite large period of time. Sigmund Freud separates LTM to 2 parts:

1. Preconscious: Knowledge in our permanent memory. In order to reach there the information needs to be recalled, however the knowledge is reachable using normal recalls (although this recall may last 2 seconds or 2 years!!).

2. Unconscious: This is the knowledge we obtained, however we do not know that we know it!!! In order to obtain it, we need to have specific methods like hypnosis. We are unable to reach this knowledge with our own methods. (figure 1)  

We can categorize LTM knowledge as (Look in figure 2):

1. Declarative: This is used to identify and categorize everyday objects we meet and events we live.

1.A) Episodic: It is the personal life experience which turns out to be "good old day memories". Important both consciously and subconsciously in our future actions.

1.B) Semantic: It is the general concept of objects around us, each object has certain specifications in its class. Semantic knowledge helps us to identify that object and distinguish it from other objects. For instance we can distinguish whether the object is a 5 year old child or a 60 year old adult.

2. Procedural: This is a step-by-step knowledge on how to realize a certain accomplishment.

3. Imagery: This is pictorial view of the things we have seen, for instance a beautiful painting of Salvadore Dali can just flash to your mind.


                                    -figure 1- Representation of human information processing in Stage Theory Model.
                                     taken from: http://chiron.valdosta.edu/whuitt/col/cogsys/infoproc.html 

                                    -figure 2-Different types of knowledge representations in our LTM.
                                     taken from: Dr. El-Hindi's course slides.

Level of processing theory:    This theory tells that the endurance of the information is also dependent on the depth of learning process. There are different levels of information processing, the deeper we examine a subject the more we learn about it.

Parallel Distributed theory:  This theory asserts that information processing is done through multiple parallel paths in our mind rather than being a single process. Knowledge is represented in a distributed fashion rather than a single location. When we obtain information about a subject we are gathering information about the subject we focus onto and information about the sub-branches at the same time while strengthening the main subject with these branches.

Connectionist Approach: This approach also defines knowledge representation as a distributed group of units in the mind. However in this approach, these units are individually meaningless. A unit is activated by stimulations coming from other units and sends a transfer function to the neighbor units. From the union of these activations knowledge may be recalled or formed.

So what: Lesson Of the day:   

The frequency of processing the information we obtained depends on us. Increasing the frequency of stages means processing information faster and better self-improvement. Hence it is important for us to understand our system of learning in order to improve ourselves. To pass important data in our daily lives to our versatile memory we can practice and repeat it in a distributed fashion in time, and we can find interesting creative relationships to bind the knowledge onto previously recorded data.   


Creativity Software:

As information processing gives a deeper insight to the structure of human mind, it can be helpful in designing creativity software. For instance brainstorming itself is a fast implementation of working memory; it is like using the ram of your computer without storing on the hard disk. You just use your fast processing short-term memory without making any transition to long-term memory. "So long as ideas, plans, and drafts are locked inside a writer s head, then modifying and developing them will overload the writer's short-term memory. By putting them down on paper (or some other suitable medium) the writer is able to explore different ways of structuring the content and to apply systematic transformations..." [2, p. 135]. These strategies are also seen on the creativity support software. For instance "Comedy writer", a creativity software for writers, has a utility of scratch sheet to which you can add your ideas and unload your short term memory at any time during the program flow. 

Usage of Multiple Windows:

In software, limitations in short-term memory of a user are mostly a serious problem. While the user traces through a program he needs to buffer some of the knowledge for future recall. However, frequently his short-term memory is not enough. In this case the usage of multiple windows acts as a local cache for the user improving his capacity to wander around the main topics and then to recall back on the local windows he needs to concentrate. These types of layouts are known as cognitive layouts, as they support cognitive processing capacity of the user. An excellent article about application of cognitive psychology to software user interaction can be found in [3].

Design of Visual Programming Languages:

An other important example on organization of interface for users is the design of visual programming language interfaces. In these languages design is done in order to optimize the brain usage. Most writers defend that human mind is optimized for vision. "Computer scientists are familiar with the fact that simultaneously processing two-dimensional images usually employs advanced parallel computers, and conclude that vision makes the fullest use of the human brain. It is hardly necessary to point out that brain always works in a highly parallel way, not just when processing when processing visual data...". Hence in order to optimize the usage of brain during programming, visual languages are used. An explanatory paper on metacognitive theories of visual programming can be found in [4].

Applicability to HCI

Theory classification:    

Information processing can be thought as explanatory and generative. It is explanatory because it explains our behaviors and the way we obtain new information. It is generative, because it gives a good model of users in terms of obtaining the knowledge, and it is a good model for design of the applications that are listed in the scope/application. However we may not be able to count this theory as predictive, because it does not show us how different designs can improve the performance directly. It just gives designers important tips about what the consider about the user during the design phase. In fact we may count this theory predictive for the formation of help systems, and educational software, however this is not the case for software many people use in their daily life for improving their work performance.

Limitations and impact on other people:

Although it is a perfect theory in terms of human cognition, on the side of HCI it is not that applicable when compared to other theories and approaches that take their source directly from HCI (GOMS, 8 golden rules...). Still, it represents the human side of human-computer interaction, and success in this interaction depends upon correct modeling of both analogous sides. It has beautiful organization in terms of modeling a very abstract subject, the human mind. Yet it still is unable to explore the fine details of the system. For instance Allen Baddeley's book "Working Memory" (also referenced early in the site) counts Central executive as the main unexplored part of short-term memory that contains short-term controls and cognitive processing. For the researchers cognitive processing in short-term controls is still a mystery. Also the variations of stage theory are not successfully integrated onto HCI. Only connectionist approach has strong connections with neural networks, yet still remaining ones seem to be standing alone as powerful theories in psychology. 

Especially the usage of short term memory models had important impacts in the past. It gave designers the opportunity to use extra features (like multiple windows) in user interfaces that will store extra cognitive load for the user.However after the development of more application specific theories that give better predictive results about software systems, it seems like it is a dying theory at least in terms of HCI. P.J Barnard states this as: "The real question is whether or not we can develop our theoretical approaches in such a way that their substance appropriately informs, supports, and triggers relevant argumentation and insight in design"[5].



[1] Mark Antonius Neerincx,  Harmonizing tasks to human knowledge and capacities- (dissertation), Groningen , 1995

[2]24. M. Sharples. Writing as creative design. In C. M. Levy and S. Ransdell, editors, The Science of Writing: Theories, Methods, Individual Differences, and Applications, Lawrence    Erlbaum Associates, 1996.

[3]Ehrhart, L.S. , New approaches to human-computer interaction-research and design for decision aiding systems,5th IEEE International Symposium on Intelligent Control, Proceedings, 1990

[4] Blackwell, A.F. ,Metacognitive theories of visual programming: what do we think we are doing? ,IEEE Symposium on Visual Languages, 1996. Proceedings.,

[5]Barnard, P.J. , Connecting psychological theory to HCl: science, craft or just plain craftiness? IEE Colloquium on Theory in Human-Computer Interaction (HCI),1991

[6]Baddeley A., Recent developments in working memory., Curr Opin Neurobiol. 1998 Apr;8(2):234-8. Review.

[7]Atkinson, R., & Shiffrin, R. (1968). Human memory: A proposed system and its control processes.


An explanatory website on stage theory

A power point presentation on information processing model   by Lawrence R. Rogien

A site for gaining insight about short-term memory by Kumar Narayanan



An introductory site about connectionist approach