INTRODUCTION:

The concepts discussed here are derived from the book "The Design Of Everyday Things" by Don Norman. Any quoted text comes directly from the book.

“Good design is actually a lot harder to notice than poor design, in part because good designs fit our needs so well that the design is invisible, serving us without drawing attention to itself. Bad design, on the other hand, screams out its inadequacies, making itself very noticeable.”
— Don Norman

The fundamental principals of interaction are the basis of human centered design, a design framework that revolves around the human perspective. It is my aim to present the knowledge I learned in this book in an easy-to-understand format, and to inform not only those interested in design, but anyone who may happen upon this site.

AFFORDANCES:

"The design aspect of an object which suggest how the object should be used; a visual clue to its function and use."

In order to be effective, afrordances must be percieveable. Take a door for example. When you look at a door, you should be able to determine how the door is to be used. Whether to push or pull, and on which side. Affordances help people figure out what actions are possible without instruction. Also, an affordance is a relatioship and depends on both the object and it's user. If an affordance cannot be percieved by the user, a signifiers may be required.

By looking at this door a user should be able to tell that it needs to be pushed, and that it needs to be done from the center.
This door affords pulling because of the presence of the handles. A user should be able to walk up to the door and understand that it is to be pulled without much thought.
Here we can see examples of how three different designs afford different actions. A user will use their knowledge of the world, the knowledge they have built by using doors in the past, to determine how each door is to be used.

SIGNIFIERS:

"Affordances determine what actions are possible. Signifiers communicate where the action should take place. We need both."

A signifier is any mark or sound that communicates how an object should be interacted with. Signifiers are signals that drive a user's perception. Signifiers must be percieveable or else they do not work.

The designer of this door did not think the design afforded pushing and therefore added a label indicating the door should be pushed. Sometimes, signifiers indicate bad design, as a user should be able to understand how to use an object with as little instruction as possible.
Since the hardware on these two doors is identical, a signifier had to be used. A user would most likely think that these doors could be used in the same way, but the signifiers indicate otherwise.
Sometimes signifiers can be added to a design by accident. The hinges on these doors signify that it must be pulled, and the door stops on the ground also signify pulling. These example were not intended to be used as signifiers, but act as such. These types of signifiers do not indicate bad design.

MAPPING:

"The relationship between the elements of two sets of things."

Mapping deals with the layout of controls and displays. "Well designed mapping uses spatial correspondence between the layout of the controls and the devices being controlled." Controlls should be close to the object being controlled. The best mapping comes when the controls are mouted directly to the item being controlled if possiible. Otherwise, it is best to arange controls in the same spatial configuration as the item or items that are being controlled.

Click the buttons in order to turn on the stove burners.

This is an example of bad mapping. The buttons are not arranged in the appropriate spatial configuraion and it is difficult to turn on the correct burner without memorizing the controls.
This is an example of good mapping. The buttons are arranged in the same spatial configuration as the burners. Someone who has never used this stove should be able to use it without reading instructions or memorizing the controls.

FEEDBACK:

"Feedback — communicating the results of an action — is a well-known concept from the science of control and information theory."

Feedback is used to inform the user on whether or not they have succesfully completed an action or interacted correctly with an object. Feedback serves to tell users when they can move on from a certiain task, or to signify when a task has been completed. Poor frrdback can be worse than no feedback at all, and excessive feedback can be distracting or annoying.

In our stove example from the mapping section, feedback is given in the form of the circles changing colors. The user knows they performed the action correctly because of the feedback they are given. Click button 4. Notice that nothing changed. How would you know that you did the right thing? Without feedback, you might walk away leaving a stove burner on thinking you never turned it on in the first place.
Have you ever pressed a button on an elevator multiple times because the bulb that lights it up is burned out or malfunctioning? Without feedback, it is hard to know whether or not the elevator is working.
Ever seen someone press the crosswalk button repeatedly until the signal changes? If there is no feedback, rushed users get frustrated, which is a sign of failed design.

CONCEPTUAL MODELS:

"A conceptual model is an explanation, usually highly simplified, of how something works."

"Conceptual models are valuable in providing understanding, in predicting how things will behave, and in figuring out what to do when things do not go as planned. A good conceptual model allows us to predict the effects of our actions." Conceptual models are representations of how humans use and understand systems. Conseptual models exist to enhance understanding of systems, and to document the system for future reference. Mental models are the coneptual models that humans hold that represent the way their understanding of how things work. These models are sometimes passed down by teachers or parents, or they are learned through experience or reading a manual. These models help us interact with the world more efficiently by allowing us the ability to predict behaviors and the effects of our actions.

We build conceptual or mental models of things we use, and use those models in the future to interact with the object in a more predictable way. We can also use these models to help us interact with unfamiliar objects. If we have a conceptual model of how a pair of siccors work, we may also be able to figure out how to use a pair of pliars. Websites and applications tend to use similar means of interaction, giving us the ability to interact with multiple websites, even those we have never visited, with confidence.