The Fundamental Principles of HCI

One of the fundamental principles of HCI is perception. Perception is the process and end product of your brain putting together the objects that you see to make a full, clear picture. Perception is a very unique thing; everyone sees things differently, and this is because people’s minds have been formed and have grown in different ways. Though a property most people have in common is the ability to fill in missing parts of perception with their minds, such as with negative space images. When working in Human Computer Interaction, perception is a very important part of the design process, and there are several things that have to be addressed when designing. Colour is a very important aspect of design work, because everyone sees colours differently. There is a theory which is that every single person in the world sees colours slightly differently, be it different shades or different levels of light affecting the overall colour, but because of this a colour that I can see very well when placed on the background of a different colour, other people may find harder to read, or maybe easier. There are some people who have visual disabilities, such as dyslexia or colour blindness, and these people have trouble reading due to colour co-ordination as well, though these disabilities influence the way the affected people see things differently. Colour is one of the ways that the brain differentiates objects within perspective, though colours are subjective to your surroundings and you personally. Colour is affected by surrounding or overlapping colours, as well as light exposure, but it can also be affected by your state of mind. If you are incredibly tired then that can have an effect on what colour you see, as well as any disabilities including colour blindness. Choosing the colour the background should be is a big part of presentation, especially in HCI. For example, a good example of use of colour is yellow writing on a black background, while a poor choice of colour would be yellow writing on a white background. This is due to the contrast of colour allowing the yellow to appear sharper while on the white background it appears as though the yellow bleeds into the background, making the letters and detail harder to see. As you can see in the chart below, background colours can make a lot of difference to how easy the font is to read. Trichromacy, or trichromaticism, is the condition of having three separate channels independent of each other for conveying colour information. In HCI there is a practice which attempts to combat trichromats, which is using luminance contrasts. The hierarchy of luminance is red and green first; these are the colours which will be seen most prominently over the top of all the others. On the second layer there are blue and yellow, which will sit over the third layer but are covered by the first layer. On the third and last layer are the colours black and white. These are called opponent colour channels because they transmit information about opposite colours. There are ways of making objects and text stand out and therefore easier to read, which is called pre-attentive processing theory. This could be from using different shapes to wrap around it, or using different colours so you are able to see it more clearly, though it is important to understand that the overuse of colour will make the interface look unprofessional. If your page has a lot of different uses of colour then you have to make sure that they are colour coded efficiently, which will help the user navigate the interface. Warnings and important information should be highlighted or made to stand out with a bright colour so that they are easily distinguishable as important parts of text. Common colour codes depict green as a calm colour, while orange is a warning and red is a danger colour, though in reality there is no universal colour code, because in some situations red can mean things such as hot. For example, black can mean mourning in Western cultures, while in the East white is the official mourning colour. When displaying text on an interface it is important to pay attention to how it is being displayed. When using colour codes you must make sure that the audience will be able to understand the code, or it will be lost on them. Using a colour code which is known by the audience can be beneficial as it can allow the audience to perform selective reading, which is where they understand the colour code and can hone in on the important parts and what they want to read. In HCI when something is being designed it is created along a template called a design pattern. This ensures that everything is kept appropriate and consistent, allowing the user to relax and feel more comfortable with the product. Design patterns log a lot of the detail of the interface, such as colours, grouping manners, format and layout. The Gestalt laws determine a lot of the rules of HCI design patterns. Gestalt means ‘form’ or ‘shape.’ It is the rule that mentally, we tend to group things that are similar sizes, shapes or colours. This principle can be used to group things even if they are apart, such as; • Proximity – If things are close together we tend to view these as a group. • Continuity – Smooth, continuous lines are more easily interpreted than rapidly changing lines. • Symmetry – We see symmetrical shapes more easily than unsymmetrical shapes. • Similarity – Similar objects tend to be viewed as a group, while dissimilar objects are viewed as individual items. These all relate to common groupings; • Fate – We see objects which stay together as a group. • Region – We see objects that are enclosed together in some manner as a group. • Connected – We see objects linked via continuous lines as related to each other.