KLM (human computer interaction)

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KLM stands for Keystroke-Level Model, a hard science approach to human computer interaction, based on GOMS, developed by Card, Moran & Newell, and spelled out in their book The Psychology of Human Computer Interaction, 1983.

It is designed to be easier to use than other GOMS methods, such that companies who cannot afford HCI specialists can use it.

The CogTool project has developed an open-source tool to support KLM-GOMS analysis.

[edit] How does it work

The KLM-GOMS model is designed to be as straightforward as possible. The user is supposed to be the most experienced in order to see the minimal time required for a specific task.

The sequence of operations is minimized to a default set with a specific (medium) time associated to each one.

Kieras (1993) defines the following operations:

K, key press and release (keyboard) - 0.28 sec
P, point the mouse to something - 1.1 sec
B, button press or release (mouse) - 0.1 sec
H, hands movement from mouse to keyboard or reverse - 0.4 sec
M, mental thinking - 1.2 sec
W(t), wait time (system) - t msec

Note that a mouse click is BB while a sequence of keys is KKK... or T(n) (T stands for 'type').

For example a common operation that involves pointing and clicking something on the screen is expressed as: MPBB (think, point, press, release).

This test can't be taken obviously as the only one to do to evaluate an interface, but it's useful as a complement and to compare two different interfaces designed to perform the same task.