Interactive Systems

A system is a group of entities that operate together in order to achieve a goal. IEEE: Electronic Terms defines a system as "a combination of components that act together to perform a function not possible with any of the individual parts".

A system can be interactive or non-interactive. An interactive system is one that interacts with other objects in the environment. These objects can be humans or mechanical- machinery. Although in the context of computers when we talk about interactive systems we usually mean a system that humans have to interact with in order to operate or control it.

Lets illustrate the above definition by giving some examples:

A chair is a system. It's made of components (legs, the seat, hand rests, back rest, screws, etc) that are combined together.

A normal chair is a non-interactive system. But an office chair is an interactive one. There are handles and other controls to interact with and control the state of the chair. Using the controls one can adjust the height, the titl, etc. This was a very basic example of an interactive system just to give you an idea of what an interactive system is.

Here's a more complex example:

A computer system. Again it's made of components that are combined together to achieve a goal.

A computer system that does the operation by itself without any inputs from other objects and without any sort of out put to the environment is a non-interactive computer (which I'm not aware of any!)

However, a normal desktop computer is an interactive one. The user uses the keyboard, mouse, etc to give inputs to the system. Monitor, printer, etc are used to see the outputs. Simply put, the user interacts with the computer.

The list of interactive systems go to more than thousands of goodies we all use in everyday life (microwaves, mobile phones, radios, to name a few). The aim of user experience designers is to make these devices more usable by having them designed in a more intuitive manner. I'm sure you all have had experiences of frustration and/or anger when you were not able to use a gadget. As the number of these devices are growing the main focus should be on making them more intuitive so the users can work with them more easily.

References:

[1] Wikipedia, Jan 08, http://en.wikipedia.org/wiki/System

Usability Defined

The term usability is used to indicate the ease of use of an object. A more formal definition of usability is: "a term used to denote the ease with which people can employ a particular tool or other human-made object in order to achieve a particular goal."[1] The object can be a simple object such as a scissor or it can be a complex one such an aircraft's cockpit.

There are a number of different factors that affect the usability of a system. The so called components of usability are: Effectiveness, Efficiency, Learnability, Guessability, Satisfaction, Memorability etc. [1][2][3][4][5]

Below is a brief explanation of each term to provide a better understanding of them, hence a better understanding of the term usability.

Effectiveness: Producing a desired result successfully. In other words doing the right thing in the right manner.

Efficiency: Producing the results utilizing the minimum number of recourses.

Learnability: The quality of being easy to learn.

Guessability: The quality of being easy to guess the function. Being easy to guess how to deal with the object.

Satisfaction: Fulfillment of the user's expectations and wishes.

Memorability: The quality of being easy to remember the working/operating of the object after being away from it for a while.

A good combination of the above factors results in a system which - no matter how complex - is easy to use.

Reviewing the literature suggests there are more factors that affect a system's usability. However I believe the above definition is pretty much comprehensive for the purpose of this article.

References:

[1] Wikipedia, Jan 08, http://en.wikipedia.org/wiki/Usability

[2] Wickens, Christopher D. et al. 1998. An Intoruction to Human Factors Engineering. United States: Addison Wesley Educational Publishers Inc.

[3] The TNL.net weblog, Jan 08, http://www.tnl.net/blog/2003/06/18/usability-101-efficiency/

[4] The TNL.net weblog, Jan 08, http://www.tnl.net/blog/2003/06/17/usability-101-learnability/

[5] The TNL.net weblog, Jan 08, http://www.tnl.net/blog/2003/06/19/usability-101-memorability/