An Introduction To Human Computer Interaction

Introduction

This report will provide a background of the fundamentals of Human Computer Interaction (HCI). What considerations need to be taken when designing an interface and why the user is the most important element during the design process.

What is Human Computer Interaction

HCI is a relatively young discipline, which describes ways users interact with computers and its importance is continuing to rise within computer sciences. Montuschi, et al. , (2014) explains that designers did not produce products to be user friendly, however when the amount of users started to grow so did the requests for more user friendly devices. Researchers started to focus on usability which is defined by Technical Committee ISO/TC, (2018) as "The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use". Since then more products are being made with the user-experience in mind. Today we have many products which connect us with technology and all of these have interfaces which have the user’s needs central to their design. Saffer, (2010) suggests there are designs that work well, such as using a cash machine and making online purchases which enable the user to complete their goals with only a few steps. The reverse is also true, not knowing what the fault is with a car or a self-service till error would require the user to find additional assistance and could lead to frustration. To assist designers in making interfaces user friendly and which enhance the user-experience there are models and guidelines that can be followed.

Theories of Human Computer Interaction

Saffer (2010) explains there are four approaches to design which are User-centered, Activity centered, System and Genius. Interactive products designed with the user-experience and usability in mind will be broken down into six goals which areis the product effective to use; the efficiency of carrying out the required task;is the user safe from dangerous or undesireable situations;utility, refering to the fuctions of the product;how easy the system is to learn to use; and once learned can the uere remember how to use the product.

Starting a design by first thinking of the user means we can use Norman’s Model of Interaction. This model is used to identify a user’s goal, what steps are required to achieve the goal and being able to evaluate the outcome of the steps. -

Behaviour modelling is used as a basis for designing interfaces, without undertaking time-consuming and resource intensive experimentation, allowing hypothetical designs and gathering the same observations without involving real users. There are two main types of modelling predictive and descriptive and both are as important as each other when designing an interface.

Predictive modelling

Fitts’ law (1954) provides a way to predict the time it would take for a user to move a curser from one target to another. Measuring the distance from a target then dividing by the size of the target, shows the further the distance and smaller the target, the longer it will take to reach. Karafillis (2012), states that using Fitts’ law seems to indicate that a designer should make clickable items large, simple to use and as close together as possible. However, doing so could cause problems, for example, having very large buttons to click could take up all available interface space. Further to this, placing everything that a user is likely to click on as close as possible could mean having an interface that is cluttered and where mistakes like clicking incorrect buttons, more likely to occur. Ideally designers should make interfaces as easy to use as possible with simple one touch or click options. In an iPhone screen, the buttons on the screen are separated by a gap, meaning selection of the required slider is easily possible. The use of sliders will decrease the chance of accidental shut down whilst it is inside a pocket due to the increase of precision required to activate.

The Keystroke-Level Model

The Keystroke-Level Model (KLM) is defined as, “the time it takes an expert user to perform a given task on a given computer system”. The KLM uses standardised timings which can be applied to any operation such as, editing a word on a document, and will provide the time for completion. The term ‘expert user’ refers to a user that is already able to use the interface and can complete the task without errors. This model enables designers to compare various versions of the same interface and select the most efficient setup. Furthermore, as the model can be used before there is a prototype and uses standardised timings the user is not required to test the interface, saving time and money.

Descriptive Models

Saffer (2010) explains, Hick’s Law finds that the time it takes a user to make a decision is determind by the amount of possible choices. Further, a user offered choices in more then one list will take longer to make a decision then if all the choices were in one list. Keeping things as simple as possible is an aim to not confuse users. Therefore, breaking down choices into submenus or categories, which expand when selected, is an effective way of giving users access to all the choices they will need.

Hick’s Law also sates that familiarity of the process of making a choice and the format the choices are presented in will affect time it takes to make a choice. Key-Action Model Keeping familiarity within interfaces extend to the way users input commands therefore, designers make use of the Key-Action Model (KAM).

Where KAM is concerned with the keyboard, Buxton’s 3-state model CITATION Bux90 l 2057 (Buxton, 1990) focuses on pointing devices.

Who is a user?

Users in simple terms are the people who are going to be using the interfaces that the designers create. They are the most important consideration when designing a product because they are the people that are going to be using it. Interfaces need to be designed, prototyped, and created with regular testing and feedback from users. Users generally know what they want, but not what they need or what is needed to accomplish their task.

Cognition

Cognition is a mental process that revolves around the abilities to think, learn and aids with decision making. Cognition is split into fast and slow thinking. Fast thinking is vital when driving and talking whereas new ideas, mental effort and attention are attributed to slow thinking. The human brain has limited time (15-30 seconds) and space (5-9 items) in short term memory. Shneiderman, (2013) states that “the limitation of human information processing in short-term memory requires that displays be kept simple”. This can be achieved by having less clutter present on the screen and highlighting important information.

Perception

As important as cognition is to interaction, perception is just as vital because users receive information from interfaces using vision, sound and touch. Galitz (1997) states, experience partly influences people’s awareness and understanding of their environment through physical sensations. This places more emphasis on designing interfaces to be a familiar to users as possible. A good example would be the ribbons and toolbars within the Microsoft Office suite, all of which look and feel the same easing the ability to transfer learned functions from program to program.