Perceptual , Cognitive and Motor task theories

In my last blog, I described the Model Human Processor and made reference to the GOMS model.
Here I will explain the GOMS model.
I will discuss the various perceptual, Cognitive and motor task theories related to HCI.

There are different perceptual, cognitive ad motor task theories applied to HCI

Perceptual Theories

Perceptual theories deals with how we perceive the world around us. The sensory system, for example, the eye in the case of visual perception, incorporate information about the natural world into their design and "relate" incoming stimuli to this information, rather than analyzing sensory stimulation into its components.

Perceptual theories are used for -

- predicting reading times for free text, lists and formatted displays

Cognitive Theories


Cognitive theories are based on the assumption that human beings are logical beings and it analyzes the thought processes of human beings.

Motor-task performance times theories


After thinking, the next step is action or motor tasks. Motor-task performance theories can be used for:-

- Predicting key-stroking or pointing times

Models


There are various models in cognitive science that pertains to human-computer interaction.For example:

1. Stages of Action Model
2. Goals, Operators, Methods, and Selection rules(GOMS) Model
3. Widget-level theory
4. Object-Action Interface Model

Stages of Action Model


Norman's seven stages of action :


1. Forming the goal
2. Forming the intention
3. Specifying the action
4. Executing the action
5. Perceiving the system state
6. Interpreting the system state
7. Evaluating the outcome

Norman seven stages of actions can be broken into two loops:


1. Execution Loop
2. Evaluation Loop

Execution Loop


Execution loop means when the execution begins.

Evaluation Loop


Evaluation loop involves evaluation and perception.

The following stages of the seven stages are a part of Execution Loop :

2. Forming the intention
3. Specifying the action
4. Executing the action

The following stages of the seven stages are a part of Evaluation Loop :

5. Perceiving the system state

6. Interpreting the system state

7. Evaluating the outcome

Image from http://www.cc.gatech.edu/classes/cs6751_97_fall/projects/spin/mayc/action.gif

Let's Understand this by an example:

Let's say you are working on your laptop computer and your  battery is getting lower and lower. So, you need to charge your battery using an AC adapter.

Execution phase example:

So, the GOAL is to charge the battery of the adapter.

To accomplish this goal, you need to stretch your hands in a certain way and plug in the adapter.  So, the GOAL has translated into an INTENTION which has translated into an ACTION SEQUENCE.

So, first the goal is formed. Then, there is an intention. Then, the intention is translated into an action sequence. 

Nothing happens until EXECUTION, which means that the action is executed in the real world

Evaluation Loop Example:

After we have turned on the charger, we Evaluate how it is affecting the system and make an evaluation.

GOMS Model

Goals : what the user has to accomplish

Operator: An action performed in the service of the goal

Methods: Sequences of Operators and sub-goal invocations that accomplish a goal.

Selection rules: If there is more than one method applicable to  the goal, selecting rules are necessary to represent the knowledge of which method is to be applied.

Using these elementary actions as a framework an interface can be studies. There are several different GOMS variations which allow for different aspects of an interface to be accurately studied and predicted.

Widget-Level Theory

WLT deals with higher level components that are self-contained and reuseable

Widgets are interface components, such as buttons, selection lists, radio buttons, sliders.

Object/Action Interface Model

"Direct Manipulation" is an important concept in interface design.

The principle of direct manipulation contends that having real-world metaphors for objects and actions can make it easier for a user to learn and use an interface.

There are many applications of direct manipulation in interface design. For example, computer graphics, 3D animations are based on the principle of direct manipulation.

The Object/Action interface model is based on the principle of direct manipulation.

Object-action design:

1. Understand the task

           - real-world objects

           - action applied to those objects

2. Create metaphoric representations of interface objects and actions

3. designer makes interface actions visible to the users

In an object-action model, the user first selects an object and then performs an action.

Example of object-action model: If you have to copy a file from one folder to another in a Windows-based system. You first select the object(a file in this case) and then perform the action(i.e. copy)

I will conclude this page here. The models discussed here are very important to the interface design. The applications of these models will be shown in my upcoming posts.


References:


http://www.cs.umd.edu/class/fall2002/cmsc838s/tichi/oai.html

http://en.wikipedia.org/wiki/GOMS

http://en.wikipedia.org/wiki/Seven_stages_of_action

http://www.d.umn.edu/~ddunham/cs5551f08/shneidppt/DTUI_chap02p.ppt.