If you want to design user-friendly interfaces, you need to understand how users perform tasks on your system. One way to do that is to use the GOMS model, a method that breaks down tasks into four components: goals, operators, methods, and selection rules. In this article, you will learn how to apply the GOMS model to analyze user task complexity and estimate task completion time.
The GOMS model is a cognitive framework that describes how users interact with a system to achieve their goals. It assumes that users have a set of goals, such as sending an email or booking a flight, that they can accomplish by applying operators, such as clicking a button or typing a text, using methods, such as following a sequence of steps or choosing an option, and following selection rules, such as deciding which method to use based on the context or the feedback. The GOMS model can help you identify the cognitive and physical demands of a task, as well as the possible errors and difficulties that users may encounter.
To apply the GOMS model, you need to start by defining the task and user profile. Then, list the operators, methods, and selection rules for the task, estimating the time for each one. Finally, sum up the time for the whole task to evaluate the efficiency and usability of your design. This includes considering how many steps are involved and in what order, as well as using existing data or making reasonable assumptions based on your knowledge of the system and users.
Applying the GOMS model effectively involves careful task analysis and thoughtful consideration of the cognitive and motor processes involved. Here are some tips to help you apply the GOMS model: 1.Clearly Define the Task 2.Thoroughly Decompose the Task 3.Use Action Verbs 4.Consider User Expertise 5.Use Existing GOMS Models as Reference 6.Include Error Considerations 7.Account for Learning Effects 8.Be Realistic with Time Estimates 9.Consider Parallelism 10.Validate with User Testing
The GOMS model can be a valuable tool when designing user interfaces. It can help you gain insights into user mental models, expectations, and strategies, as well as evaluate and compare design alternatives. Additionally, it can be used to identify and eliminate usability problems, such as sources of confusion or frustration, and suggest improvements to simplify or optimize the user experience.
The GOMS model has some limitations that need to be taken into account. It does not consider individual differences or preferences, and it is not capable of capturing emotional or aesthetic aspects of the user experience. Additionally, the model does not reflect the dynamic and unpredictable nature of the real world, as it relies on predefined scenarios and assumptions that do not take into account variability and uncertainty.
The GOMS model is a useful tool for usability testing, but it should not be used in isolation or as a substitute for user research. To maximize its effectiveness, you should combine it with other methods and metrics, such as user interviews, surveys, or observations, and other usability metrics. Additionally, you should validate and update the model regularly by testing predictions and hypotheses with real users and data. Moreover, use the GOMS model as a communication and collaboration tool to share findings and recommendations with other stakeholders, such as developers or clients, and involve them in the design process.
Use standardized estimates for the time required for each type of operation, both physical and cognitive. This helps ensure fairness when comparing GOMS analysis of different designs. Note that legibility of typeface, color contrast and styling of visual components, the choice of terms in a label or prompt can all affect the real world efficiency of a sequence of steps, but can be difficult to notice those differences in a GOMS analysis. For example, the researcher can calculate a standard time necessary to move a mouse pointer from an input field to a button a certain distance away on a screen, but may need to separately validate button labels with the target user group to predict cognitive delay due to unfamiliar or ambiguous terminology.