Models and Theories in Human-Computer Interaction/Affordances and Conceptual Models

Affordances and Conceptual Models (Briana Bettin)

In Don Norman's wonderful book "The Psychology of Everyday Things", one of his key coined terms is the concept of affordances. Not only can his notion of affordance help us understand how ourselves and other users interpret and navigate the world, but it also can provide us with a better way of understanding how creators can ensure their products and digital artefacts are easy to leverage in a world filled with tasks, ideas, and things.

What Is an Affordance?

Norman's concept of affordances is the idea of our intuitive notions about an object based on its design. It is the "thing's" properties - those which we can actually see, feel, and otherwise sense, and also those which we perceive it to have. This is a very critical addition to Norman's definition. What an object physically is formulates the affordance, but the affordance itself is determined by our perception. A door is perceived as a door based on its physical manifestation - it likely has hinges on which to swing, we may have seen people walking in and out of it, and it likely has some sort of indication of where and how to leverage weight in order to swing those hinges. The intuition of affordances comes to light in how the method of opening the door is applied and perceived. A door that needs to be pushed but has a handle that gives us the notion to pull is not designed well with affordances in mind. The design of the door is perceived to be pulled, thus this is what the user is likely to do even though the actual function is reliant on pushing. This dissonant information results in a less than ideal experience for the user and can be considered poorly designed. Design in objects with uses should be created in a way that perception matches use.

Conceptual Models at Work

Affordances as a concept are well and good, but how can we presume to know what others will know when they encounter our design? The short answer is we can't - however, we can take every measure possible to afford enough in our design that something the user knows meshes with our use case. The idea of conceptual models is very prevalent here. A conceptual model is a user's knowledge or understanding of how one thing works, and utilizing this knowledge to simulate an outcome and likely complete an action based on the result their conceptual model seems to portray.

Routine actions are great examples of conceptual models at work. When we wake up we likely turn off our alarms, get dressed, make breakfast, brush our teeth, and start our cars. We visualize the next step in our process as we go through each item to get our morning routine done - and we especially visualize these operations if we need to speed up or change our routine so that we can imagine where we can save time or divert to another task. This concept of "how our morning should work" is an everyday equivalent to the idea of conceptual models. We visualize the operations and all steps needed in the operation, and we can imagine the outcome. If we need to take a trip somewhere we've been before, we can visualize mentally the path our car would take, where we might need to stop along the way, where our turns are, and where to park. This works with our understanding of objects and our encounters with them as well. Imagine you see a car with square, cement wheels. Automatically, you're likely to say "it won't work" - because your conceptual model of a car has run through how a car functions, and realized the wheels cannot turn. Almost any time we blurt out "that won't work" before we've had time to articulate why, we're caught up in a conceptual model - our brain has processed our concept of the operation and deduced success or failure, which results in our perception of the situation.

Conceptual Models and Affordances: Hand in Hand

The idea of conceptual models and affordances must be linked, and in that linking we can find areas of exploration for human and object interaction. If conceptual models are our knowledge of how the world works and how it relates to current situations and operations, than affordances are built upon our conceptual models: based on what we've seen or learned of the world, we have an idea of how it should work. When we see an object, our conceptual model kicks in based on what we are seeing - this means the affordances guide how our conceptual models consider the operation, and how the user is led to their idea of what actions to attempt.

This means it is imperative when creating designs to draw as much as possible from parallels a user is likely to have experienced and to ensure those actions maintain similar operation. For instance, if a new model of toaster has for whatever reason a button dashboard that looks similar to a touchpad phone, and users who may use the toaster are likely to be familiar with touchpad phone functionality, why divert from their conceptual model? The user is likely to attempt to apply conceptual models from other related objects (toasters) they've experienced, and if those fail, they are likely to try conceptual models of other objects they are reminded of - in this case, a touchpad phone.

By drawing upon existing conceptual models in design, we reduce the amount a user has to learn and increase the amount of the design that is intuitive - in the above example, it's unlikely a touchpad phone design is intuitive to a toaster's interface, but in the assumption that for the given functionality it is (perhaps it has many presets or timer options and this was the best display design), maintaining as many parallels to user's existing models as possible can ensure a stronger design as the object's affordances appear to incline it to function similarly to something users have seen before. In the phone/toaster example, a button that seems familiar to "end call" should not be the button that starts the toaster - the "on" button should, while this "end call" seeming button would likely be to turn off the toaster.

Even in this rather odd example, our conceptual model of the affordance the look of the buttons gives us leads us to an intuition of their functionality and what should and should not happen when we use them based on our conceptual models.

Works Cited

Norman, D. (1988). The psychology of everyday things. New York: Basic Books.