The human action cycle is a psychological model which describes the steps humans take when they interact with

computer system A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These progr ...

s. The model was proposed by

Donald A. Norman Donald Arthur Norman (born December 25, 1935) is an American researcher, professor, and author. Norman is the director of The Design Lab at University of California, San Diego. He is best known for his books on design, especially ''The Design ...

, a scholar in the discipline of

human–computer interaction Human–computer interaction (HCI) is research in the design and the use of computer technology, which focuses on the interfaces between people (users) and computers. HCI researchers observe the ways humans interact with computers and design tec ...

. The model can be used to help evaluate the efficiency of a

user interface In the industrial design field of human–computer interaction, a user interface (UI) is the space where interactions between humans and machines occur. The goal of this interaction is to allow effective operation and control of the machine f ...

(UI). Understanding the cycle requires an understanding of the user interface design principles of

affordance Affordance is what the environment offers the individual. American psychologist James J. Gibson coined the term in his 1966 book, ''The Senses Considered as Perceptual Systems'', and it occurs in many of his earlier essays. However, his best-know ...

feedback Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handled ...

visibility The visibility is the measure of the distance at which an object or light can be clearly discerned. In meteorology it depends on the transparency of the surrounding air and as such, it is unchanging no matter the ambient light level or time of ...

and tolerance. The human action cycle describes how humans may form goals and then develop a series of steps required to achieve that goal, using the computer system. The user then executes the steps, thus the model includes both cognitive activities and physical activities.

The three stages of the human action cycle

The model is divided into three stages of seven steps in total, and is (approximately) as follows:

Goal formation stage

* 1. Goal formation.

Execution stage

* 2. Translation of goals into a set of unordered tasks required to achieve goals. * 3. Sequencing the tasks to create the action sequence. * 4. Executing the action sequence.

Evaluation stage

* 5. Perceiving the results after having executed the action sequence. * 6. Interpreting the actual outcomes based on the expected outcomes. * 7. Comparing what happened with what the user wished to happen.

Use in evaluation of user interfaces

Typically, an evaluator of the user interface will pose a series of questions for each of the cycle's steps, an evaluation of the answer provides useful information about where the user interface may be inadequate or unsuitable. These questions might be: * Step 1, Forming a goal: ** Do the users have sufficient domain and task knowledge and sufficient understanding of their work to form goals? ** Does the UI help the users form these goals? * Step 2, Translating the goal into a task or a set of tasks: ** Do the users have sufficient domain and task knowledge and sufficient understanding of their work to formulate the tasks? ** Does the UI help the users formulate these tasks? * Step 3, Planning an action sequence: ** Do the users have sufficient domain and task knowledge and sufficient understanding of their work to formulate the action sequence? ** Does the UI help the users formulate the action sequence? * Step 4, Executing the action sequence: ** Can typical users easily learn and use the UI? ** Do the actions provided by the system match those required by the users? ** Are the affordance and visibility of the actions good? ** Do the users have an accurate mental model of the system? ** Does the system support the development of an accurate

mental model A mental model is an explanation of someone's thought process about how something works in the real world. It is a representation of the surrounding world, the relationships between its various parts and a person's intuitive perception about thei ...

? * Step 5, Perceiving what happened: ** Can the users perceive the system’s state? ** Does the UI provide the users with sufficient feedback about the effects of their actions? * Step 6, Interpreting the outcome according to the users’ expectations: ** Are the users able to make sense of the feedback? ** Does the UI provide enough feedback for this interpretation? * Step 7, Evaluating what happened against what was intended: ** Can the users compare what happened with what they were hoping to achieve?

Related terms

Gulf of evaluation In computer science, the gulf of evaluation is the degree to which the system or artifact provides representations that can be directly perceived and interpreted in terms of the expectations and intentions of the user. Or put differently, the gul ...

exists when the user has trouble performing the evaluation stage of the human action cycle (steps 5 to 7). *

Gulf of execution In human computer interaction, the gulf of execution is the gap between a user's goal for action and the means to execute that goal. Usability has as one of its primary goals to reduce this gap by removing roadblocks and steps that cause extra thi ...

exists when the user has trouble performing the execution stage of the human action cycle (steps 2 to 4). *

OODA Loop The OODA loop is the cycle ''observe–orient–decide–act'', developed by military strategist and United States Air Force Colonel John Boyd. Boyd applied the concept to the combat operations process, often at the operational level during mi ...