learnability matters

Let us first understand what a mental model is. It is an explanation of a person’s thought process of how something works in the real world. In other words, it represents human emotions, feelings, perceptions and other psychological processes that surface externally. Let us explain this with the help of an example. We know exactly how a telephone looks and functions. It would typically have buttons to punch in a phone number and a receiver to communicate. Have a look at the figure below. We know how exactly this telephone would function. Right? You pick up the receiver, wait for a dial tone, punch in the number, wait for a ring tone, and you’re connected.

What if the buttons or the receiver doesn’t function as it is supposed to? What if the there is no dial tone? This is when our mental model is disrupted, which would leave us confused and frustrated. Look at the figure below. Would you know how to operate this phone? Wouldn’t the design and functions go against your mental model?

How have these models evolved?
The concept was first introduced by Kenneth Craik in his book The Nature of Explanation (1943). It was then used by cognitive scientists to understand how people think, behave, and act in an environment. These scientists have also studied how children develop such models and how the knowledge in one domain is used as an analogy in another domain. Today, Human-Computer Interaction (HCI) has adopted this concept of mental models in its main area of concern, usability. For HCI practitioners, a mental model is a set of beliefs about how a system works. That is, they discuss human interaction with systems based on thorough processes and beliefs. Usability ensures that the user’s mental model matches and aims to predict the action of a system.

As users gain experience of a particular system, they acquire knowledge about the system’s behavior, and on this basis they are able to develop theories about its inner workings (Olson, 1992). This is known as conceptual design. The concept examines and helps people accumulate knowledge about the system they use. Users gradually form a working ‘model’ of the system around which they organize their knowledge and theories. For example, people have mental models of how an ATM machine works, how a computer boots, and so on.

Let’s consider the three aspects of mental models, which is important in Usability.
System Model. A systems model is a designer’s perception and relationship with the system. These are the two interactive components of a design process. Let us consider the example of the telephone. The way in which the designer engineers the telephone is the system model. He/she designs the phone according to his/her knowledge and experience in the domain. Therefore, the product is designed in relation to the designer’s experience.

System Image. In order to understand the relationship between a designer and a system, we have to understand the system. A system image reflects on the system and how it works and does not consider the designer. Taking the previous example, the telephone by itself is the system. The system image indicates how the telephone functions, its features and how the user interacts with the system. It is the image that the user sees, i.e., the interface, behavior and documentation. It is important to remember that the user acquires all knowledge of the system through the system image.

User’s Model: A user model on the other hand, deals with the user’s perception and relationship with the system. Using the example of the telephone, a user model is the relationship between the user and the telephone. The user has certain theories about how the telephone ought to function. The way in which the user makes use of the telephone and how effectively it can be used determines the user’s mental model. If the user is able to efficiently use the telephone, it indicates that the system model matches with the user’s mental model.

The figure below explains the interaction between the three aspects. The best way for an interface designer to guide a user from novice to expert status is to conceal the system model and indulge the user’s mental models (Donald Norman). The user does not have to understand how a telephone is engineered to learn to effectively use it in their day to day lives. That is, the system model should be able to match the user’s metal model of a telephone.

Applying mental models while designing software applications and websites.
Let us understand the principles that will help us use mental models effectively while designing software applications and websites.

1. Simplicity. It is important to keep the design simple to engage and encourage the user to perform a task. For example, according to the system model (designer), an error message would appear as ‘Error: C5’. Will the user understand this? No, he/she certainly won’t. This message can be written as: ‘The printer is not available at this moment. Please try again.’ This message is simpler and ensures that the user understands. .

2. Familiarity. The user must be able to relate the task being performed to a real world scenario. The use of mental models that the user already associates from his real world experience allows him/her to get started quickly and make progress immediately. Labels should not be confusing. We often use the term ‘Folder’. Where do you think that came from? That’s right! It’s from our day to day usage of the term. The users are familiar with this metaphor, resulting in easier and effective interaction with the system.

3. Availability. Just like in the real world, it is important for an interface to provide visual cues either automatically or on request. Users are good with recognition than recall. For instance, the user must not be given the chance to search for files or folders. It should be available at every step of the task being performed.

4. Safety. The interface should allow a user to easily recover from errors. It is important for him/her to feel confident while performing a task. For example, a user who pays his bills online is extremely cautious. During payment, if the page that verifies his/her payment amount is missing, he/she is going to be confused. This confusion happens because in reality people can verify the amount being paid just by cross checking.

5. Flexibility. An interface should support alternative actions that the user can perform during a task. That is, the user should be able to perform the same task in any sequence. It is important to allow him/her to recognize that there are alternative methods. For example, if the user wants to contact a company online, the system image should allow him to perform this task either by contacting the company from a toll free number or through messages from a secure messaging centre available on the website. This is an important as the user will feel safe while performing a task, just as he/she will in reality.

6. Feedback. A positive feedback at every step is important to strengthen a user’s mental model. This should also be a continuous process. We use checklists while we shop for groceries, while we do assignments or even while we track our expenditures. Along the same lines, providing a checklist while navigating, not only allows the user to go ahead, but it also matches the mental model of the real world.

7. Affordances. An affordance is a certain property of an object that allows it to perform an action. A door affords pushing or pulling, a chair affords sitting, a handle affords holding. It is dependent on how a person perceives an object. An interface can have cues to afford how a task can be performed. This can be done by replicating real world experiences into the interface design. Taking an example from our day to day lives, we have a certain image of a traffic light signal. Just as the ‘Go’ signal affords moving forward, the ‘Go’ button affords proceeding further during navigation. Consider a ‘submit’ button or even a ‘search’ button. They are all terms derived from our usage of the terms in reality, that is, our mental model.

By reading this article we have come to see that users form mental models that they apply across applications and websites. Knowledge of the real world can help users focus on their goals and not worry about operating the interface. Keep in mind that you cannot cause friction during a user’s online experience. If you do, all this can come to an end as the users’ preconceived mental models are broken.

So let’s bring out good design solutions that would reflect your interface.

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