HCI: Lesson 1

In this collection of articles, I will resume all the courses that we had to follow in the Human Computer Interactions field. Here is the first one, dealing with human perception and different affordances that can be useful to think while creating softwares for example.

To introduct the subject, HCI is a subject where we think about the design, the evaluation and the implementation of interactive environments. In fact, we passed through different eras, from a one where we first had one electonic device for many people to a one where each person can have mutliple devices. Optimizing the functionnalities without helping the user will become an important stake. However, to do that, we must take into considerationthe cognitive basics of human in order to understand what to compute.

Cognition

The Model Human Processor

First, what is cognition ? This is a set of mental processes like perception, attention or memory, that our mind does. Indeed, our model human processor is a model composed of three main blocks, that is quite similar to what a computer can do: an input (sensory), a central information system and an output (actions).

For the memory part, we can distinguish three categories:

- Sensory memory: this is what we can feel or see (haptic, iconic), this can be transferred to the short-term memory by attention

- Short-Term Memory: informations that we remember for a short amount of time, capacity around 7/12 chunks (elements like words, phrases,...)

- Long-Term Memory: huge capacity of what we "know", forgetting occurs more slowly

This is the model of a human like processor, however it has some limitations. In fact, it is too simple if we want to describe everything. Also, this diagram comes froma laboratory study, it is a scientific and isolated view: a person has interactions with others, and isn't alone. And finally, emotions are not reprensented. So we need to integrate the context into the model.

Situated Action/Context-Aware Computing

While creating some models, we must remember that people use their emotions, and it is hard to modelize this parameter. In order to resolve that, we must consider the context.

In class, we saw an example of research at Xerox PARC by Lucy Suchman. In this study, we put a copier in a room and see how people react. In fact, two researchers that worked on difficult informatics project were here not able to use a simple copier. It rises a problem: the most important for HCI is to create simple interfaces that are easily usable not only in a laboratory, but also in a normal context.

Distributed Cognition/Extended Mind Theory

Another nothion that we can consider while creating applications linked with cognition is the fact that the human spread his knowledges to multiple places thanks to various tools. Ed Hutchins distinguished between internal and external representation, and David Chalmers talked about a theory of extended mind (we put parts of our memory inside different devices like our own smartphone where we write everything we don't want to forget).

Embodied

Last think to think about is that the mind is influenced by the body. Affection and love is directly linked to the warm sensation for example. This idea leads to a notion that is primordial: affordance.

Affordance are properties or features of an artifact which indicate a certain type of usage, often grounded in our body. In fact, perceived affordances tell the users how to use them. If we take doors, we know easily depending on the shape of the handle how to use it. If we have a chair, we instincly know what to do with it, even if we have a lot of designs.

Here is another example: a Playstation controller has a really good affordance, because the joysticks are placed naturally where the thumbs are, the triggers are place where the index are,... The design is made for the hand to know what to do. However, the tactile lamps have a pretty poor affordance. If we don't know the rule, we can't predict what to do. If we want to move the lamp, we can light it by error. If we want to turn off the light, sometimes we must tap many times according to the different intensities.

A pretty good affordance Why does it exist ?

This concept is really important because we must use it while implementing some softwares. If we put a button that seems like one, the user will automatically know how to use it. Same for a slide button. We must take that into consideration.

Perception

Perception are experiences resulting from the stimulation of the senses such as seeing, hearing, tasting, smelling and touching. How can it affect the human computer interaction ?

Visual Perception

The visual perception is one of the most important, and dominates the other ones. The fucntionning is not too difficult: the light bounces on the retina, and sensors (cones and rods) transfer the informations to the brain by the optic nerve. Inside the eye, we have the fovea (precise point) where the color is fully detected.

Other informations are important to include, like the retinal blur, occlusions, shadow distribution or relative size. All these parameters are really crucial while creating a design. We must combinate the the cognition part with this perception. This is the functionning of our brain, but sometimes some bias cause some troubles. Indeed, the image received by the retina is ambiguous, and our conscience does a pre-processing that can sometimes be problematic.

Gestalt Laws of Perception

Gestalt principles are laws that describe how human recognize patterns and simplify complex images when perceiving objects. We have:

- Law of Proximity: things that are close together are more related to each other. This law is used almost everywhere in UX design (we place similar thinks next to each other, in a form for example)

- Law of Similarity: things that are grouped together and that seems similar have the same function. This law is used in websites with text, forms, buttons that don't have the same colors and shapes because they don't have the same utility.

- Law of Common Region: things that are located in the same region are perceived as grouped. This law is used when we do some blocks in blogs, with specific subjects.

- Law of Continuity: things that are aligned must be related. This law is used in navigation bars with scrolling menu.

- Law of Closing: things with complex arrangements can have some hidden patterns. This law is used in many logo design.

Here is a great example of logos that use the law of closing.

- Law of Figure Ground: we can recognize some depth using different shapes and colors. It is always used to create layers on websites.

Dark Design Patterns

Dark desing patterns are tricks used by websites to make us do things we don't want to do. It is really useful for marketing and commercial purposes. Here are the main ones:

- Nagging: when we do actions many times for the user to finally agree (for example, asking to put 5 stars on an app)

- Obstruction: when some actions are really hard for the user not to use it (the deleting account function for example)

- Sneaking: when we hide some informations that is relevant for the user (add sign in some posts)

- Interface Interference: when the app manipulates the user to privilege some options (objectives of money on Uber,...)

- Forced Action

Auditory Perception

The human can percept sound by the vibrations of the bones in the ear. The ear has also another functionnality: to balance the body thanks to the fluids inside it. Simulator sickness is due to a difference between what we can see and what we feel. We must think about this while creating some applications in VR for example.

Haptic Perception

The human can also feel with the touch. It is called the haptic perception. We can distinguish two kinds of perception: the kinaesthetic one (perception of weight by the muscles and tendons) and the cutaneous one (perception of temperature or pain through the skin). This perception can be use to improve the sensations of immersion (sensation of weight used by gyroscopic effect, sensation with haptic captors,...).