Perception

What is perception in HCI?

Perception is what allows the user to see and feel when using a human computer interface. In order to understand and allow the users to see and feel, designers use colours, patterns and objects.

Colour

When building a human computer interface it is important that the designer takes note and thinks whether the user of the interface will be able to navigate around it and use it with ease. In order to resolve such issue and ensure that the user will be able to use the interface, the designer should draw up colour charts with a mixture of backgrounds and text colours which can be seen by the user or any user that uses the interface.

It is always a good idea to make sure the colours chosen for the HCI are suitable for all types of users and offers a way to change the colour if required. For example some users do find and will find that yellow is easy to see and read on a white background though for others it would appear fuzzy and difficult to see and read. Some users that are hoping to use the HCI may be found with dyslexia that would require them and the designer to offer different colour overlays and also people with colour diffusion often confuse red and green or blue and yellow, while others see only in monochrome; this means that there is quite a lot that the designer has to take into consideration when building a HCI.

Luminance is when you are able to see a colour above another layer / colour. It's known that people tend to have troubles seeing text above another layer as designers do not take in to consideration that users and screen brightness of peoples computer monitors. Also as above, some people find it hard to read yellow text on a blue background, so what the designer needs to do is make sure that the colour of the text is easy for every reader to read.

The pop-out effect is when you are able to make one image stand out more than the other images around it by using a different shape, colour or size. It gives the illusion that something is popping out of the screen and the images around it are further away or hidden. 

Pattern

Pattern is made up of 6 sections which consist of Proximity, Continuity, Symmetry, Similarity, Common groupings and Connectedness. However, what are these sections and what do they means? 

• Proximity - This is a way of saying that we view things which are close together as a group or look closer than they actually are. An example of this would be to look in a wing-mirror on a car and notice how cars seem closer than they actually are when you look back at the car behind. Warning signs are placed on such mirrors notifying them that objects would appear closer than they actually are to the humans eye.
• Continuity -  This means that we take more of an interest in straight smooth lines rather than lines that are rigid and constantly change shape / size. 
• Symmetry - This is when a shape or object is repeated on both sides to make it an mirror image / copy. It's proven that us humans are capable of seeing patterns better when they are symmetrical.
• Similarity - This is when a group of objects and shapes are placed together because they look similar to one another, whereas dissimilar objects tend to be seen as individuals.
• Common groupings - This is when us humans notice and see a set of images and group them together if they are related or closely related to one another.
• Connectedness - This is when we see objects that are related to one another joined together by a continuous straight line.

Objects

When we look at an interface the designer needs to think about and take note of the size and shape of a particular object so when a user goes to see this object and interact with it, it doesn't take long for the user to click on it. Objects in a GUI (Graphical User Interface) would include Geons and Gross 3D. 

• Geons - These are 2D shapes which can be easily viewed and given a perspective of 3D. They are quickly recognizable and are also cheap to produce and doesn't take as much time to produce. The shapes are broken up and arranged to give the illusion of being a 3D object. 

• Gross 3D- These are 2D shapes that also give the illusion of being 3D, however it can be difficult for some users to interact with and look at, in order to make the illusion of it being 3D the shape is copied and placed slighter higher or lower on the page. 

Bibliography
http://www.colourtherapyhealing.com/colour/colour_perception.php
http://www.skidmore.edu/~hfoley/Perc5.htm

Information Processing

There are three functional principles of Information Processing to remember these include 

• Human as a component
• Human Information Processing (HIP)
• GOMS

Human as a component

The main principle is where people believe and understand that part of the computer / HCI is human. Without humans, HCI would not be possible. In HCI the user is the main component, the user will want the system to be able to calculate and preform complex tasks which would take the human brain a lot longer to process. The company / person who builds the HCI needs to take into consideration how long it takes for a human brain to calculate data because that way, they can create a HCI which is a lot faster and can process thousands of data every second. In order to create a HCI, they need to know what the user wants to be able to accomplish with it, how it is going to be used and how long it will take to process information. Once they know what the user wants, they will then have to preform research to see if it has already been made and if so, how to improve on the HCI. In order to make sure the HCI is appropriate and usable, I will have a group of users test the interface before it is released to the public.

Human Information Processing (HIP)

What exactly is human information processing? Information Processing is the change in a state of information. It allows us to split information down into steps which can be easily read and understood by the human brain. It allows people to store, retrieve and use information with ease. 

There are four steps to how information is collected and used:

• Absorb the information
• Analyse the information
• Use the information
• Do something with the information

HIP works like a computer in which includes hardware and software. At first, the brain will first input the data as hardware, which will then be processed using software and then stores the information in either the STM (Short Term Memory) or LTM (Long Term Memory). It then acknowledges the information and makes a decision on the output.

Computers however, can preform at a faster and more efficient rate. Computers can process and produce information 24/7 and not require sleep. Computers can process hundreds of thousands of requests every second, whereas humans can only preform calculations one at a time. However, computers can not hear and understand what people are saying; it requires a person to type the information in to the system for it to be processed.

GOMS (Goals, Operators, Methods, Selection Rules)

What is GOMS? GOMS stands for Goals, Operators, Methods and Selection Rules. It is a model that can be used to allow users and developers to understand, see and perform tasks that are undertaken in a Human Computer Interface.

Goals is what the user wants to accomplish from the system, what task they want to complete. In order to complete a goal, the HCI must be used. An example of a goal would be finding a e-mail address from a contact list on Microsoft Outlook.

Operators are the actions that are physically taken and performed in order to complete a given goal. Again, this must be used under a HCI model. An example of a operation that is needed to take place in order to complete the goal would be to click on a menu and then pressing the contacts button under Microsoft Outlook.

The Methods are a set of tasks that are needed to be put in sequence in order to complete the goal. There are always more than one method that can be taken in order to find the information and complete the goal, for example using a menu or a search bar which includes the 'select name from contact list' or 'enter contact name' for a quicker and more efficient search.

Selection Rules is the rules that people take in order to choose between the different methods of completing the goal given. This is a human choice which we chose which interface we prefer and how it is beneficial to the user. An example of a selection rule is the number of ways to find the address.

Bibliographyhttp://www.brianmac.co.uk/infomodel.htm

Behavior Models

There are 6 types of behavior models which are split up into Predictive and Discriptive. Behavior Models help HCI developers and designers understand and work out how the interface will preform tasks and how efficient it is, is it worthy of computer use or device, or is it to slow?

The Predictive models are as of follows:-

• Keystroke-level-model (KLM)
• Throughput (TP)
• Fitt's Law

 The Discriptive models are as of follows:-

• Key-action-model (KAM)
• Buxton's three state model
• Guiard's model of bimanual skill

As there are many predictive and discriptive models I am only going to look at one of each.
 

Predictive

The keystroke-level-model was built and proposed by Card, Moran and Newell in the 1980s. They proposed that it would improve the efficiency of the HCI for an expert user. The keystroke model was made to predict and estimate how long it takes for a user to input letters on the keyboard. The model is made up of 11 steps which is used by both users and organisations however, some organisations who can't afford specialist software usually use this method instead.

The keystroke-level-model measures how long it takes to complete the 5 components that make up the model. The first one is how long it takes to press and release a button on the keyboard, measured in seconds. The second is to point the mouse on the screen and then to see how long it takes to switch hardware devices for example the home button on the keyboard. Fourthly how long it takes for the human brain to prepare to perform an action and Fifthly how long it takes to enter a string of characters and finally how long it takes for the system to preform the action. 

Key-action-model

Computer keyboards to date contain a lot of buttons and functions, the buttons can be categorized into 3 sections: Symbol keys, Executive keys, Modifier keys.

The Symbol keys can deliver graphic symbols such as letters (eofeof), numbers (1234567890) or symbols (!"£$%^&*@) which can then be inputted into a text editor such as word or notepad.

Executive keys are actions that are used and placed at the application or system-level. The keys that are used in executive situation would be the ENTER, F1 or ESC keys.

Modifier keys don't generate the symbols or invoke actions but instead set up a condition that is necessary to modify the effect of a key that was pressed subsequently and provide new options . For example without using SHIFT+1 it would show (1) however if i press SHIFT+1 it will show (!). The key action model basically looks at how users will interact with the HCI using the keyboard and using specific functions.