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Hacker's Action Theory
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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. With three other well known theories we can categorize main theories in this approach as:
theory model: This theory divides information processing of our brain
into stages. In this model there are 3 stages to record information into our
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.
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)
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.
WHAT IS YOUR TELEPHONE NUMBER?
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.
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
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.
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.
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:
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.
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 .
Design of Visual Programming Languages:
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 .
Applicability to HCI
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.
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".
 Mark Antonius
Neerincx, Harmonizing tasks
to human knowledge and capacities- (dissertation), Groningen , 1995
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.
power point presentation on information processing model by
Lawrence R. Rogien
A site for gaining insight about short-term memory by Kumar Narayanan