HCI Lecture 9 - Stages and Steps in a Theory of Action

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HCI Lecture 9
Stages and Steps in a Theory of Action.

Date page last modified : 10 Feb 1998
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The questions

What is the Theory of Action?
What are the Stages involved?
What are the different Steps in each stage?

A theory of action basically describes the creating of an action through a series of mental steps. These gradually transform one mental representation (or stage) into another and arrive at an external action.
A complete theory is not only about making these movements but also about perception.

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What are the Stages involved?

There are 2 stages in the Theory of Action.
One deals with the generation of action, i.e. doing of a task.
The other is the perception stage, i.e. finding out and interpreting the visible signs after the task has been carried out.

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What are the different Steps in each Stage involved?

We will use an example to illustrate the varies steps in each stage.
Example Eric is preparing a document. He has the following goals :

Spell Check
Grammar Check
Swap order of the word "Failure" and "the"

The Doing side
Decision - Select one of the many goals which the person has and make it his/her current intention.
e.g. Eric decided to swap the order of the word "Failure" and "the".

Planning - Breaking down the intention of the current goal into simplier steps. If necessary, put the steps into sequence of tasks.
e.g. Eric tries to find the word "Failure" and move to buffer. Then place the insert point after the word "the" and retrieve the word from buffer.

Translation - This involves finding out how to carry out each step in plan (translating each step into executable actions).
e.g. Eric highlights the word "Failure", do a cut and then click at the point of insertion and do a paste.

Execution - Actual physical movement to achieve the selected goal.
The Perception side
Segmentation - The gathering of basic sensory information like pixels or lines into basic computer units such as icons or letters.

Recognition - This stage does a translation from visual items to computer items : from surface appearance to meaning.
e.g. Eric recognises the words on the screen

Interpretation - When the user combines items into conclusions about their relationship, realising how something works with regards to it's contents or surroundings.
e.g. Eric saw the changes in the order of the 2 words.

Evaluation - The evaluation process is based on the user's own private mental idea of what's happened during the whole process, a comparison between the current computer state to what the user intended it to be (this process can create other goals and the process would start again).
e.g. Eric would check that he has correctly changed the order of the words "Failure" and "the". He then decides if the current goal has been achieved.

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