Human-computer interaction (HCI)

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Last Update

  • Updated.jpg 1 December 2015


See also Affordance definition | Human information interaction (HII) | Information architecture (IA) | Metadata | 3D printing | Typography

"...Human-computer interaction is defined as the study, planning and design of the interaction between people (users) and computers...and referred to as the intersection of computer science, behavioral sciences, design and several other fields of study. Interaction between users and computers takes place at the user interface which includes both software and hardware..."

Human-computer interaction (HCI) is an area of information practice and theory that looks at the design, implementation and evaluation of user interfaces. Its aim is to improve our interactions with computers by ensuring that they are receptive to our "human" requirements. As a field at the intersection of computer science, engineering and cognitive psychology, it draws generously from information disciplines including library and information science. As a metafield dealing with design, evaluation and implementation of interactive systems (i.e., graphical and web-user interfaces), HCI is chiefly concerned with how computers can be developed for optimal usability by people. Usability is one of its central concepts.

In user-interface design, the concept of affordance is an aid to exploring the notion of perceptions of design from the perspective of users. Norman's ideas on the affordances of everyday things is an important text in the field of interface design (2002). Ideally, HCI design should take into account all functions required of an interface based on a clear sense of users' needs. Many of his ideas supply the intellectual elements of HCI theory and research.

HCI has come a long way as a discipline in a short period of time. It's felt that the graphical user-interfaces (GUI) of the 1990s triggered the need to engage web users and HCI designers in dialogue. By simplifying user-interfaces and emphasizing "point and click" functionality, GUIs have made it easier for users to use the web in a more direct way. Admittedly, the need for directness came about because of user frustrations with the web, and the need to make it more functional for users. Symbols, icons and metaphors have been used in HCI to convey function, and are still important to the field - as are aesthetics, design and end-user perception.

Fitts' Law as HCI principle

One of the more salient principles underlying user interface design is Fitts' law. In the 1960s, Ohio State University psychologist, Paul Fitts, created a mathematical model of fine motor control to predict how long it would take to move from one position to another as a function of the distance to and size of the target. He published two papers in 1954 and 1964 that outline the concepts of the law that carries his name.

Fitts was an expert in aviation psychology, and developed ergonomic layouts for cockpit instrumentation. His model was soon seen to be relevant in the area of computer input devices. Although Fitts originally formulated his ideas to predict how quickly someone would point at a physical button, his law can be applied to how quickly computer users target spots on a screen with a mouse. Put simply, Fitts' law is expressed within these two statements:

  1. The farther away a target is, the longer it will take for the user to find it
  2. The smaller a target is, the longer it will take for the user to find it

The key takeaway for HCI designers is that the farther away a button is from the current mouse position, the larger it needs to be to have the same acquisition speed. Put similarly, there are two main ways to improve mouse efficiency. Put the controls closer to the user, or make them larger on the screen (i.e., easier to see)

Norman's design guidelines

In the first chapter of The design of everyday things (2002), Donald Norman pokes fun at bad designs. He mocks smooth, beautiful doors that give no indication to the user about how to open them and complex office phones with more functions than buttons. According to Norman, design is " act of communication between designers and users". In his view "all communication takes place through the system image". Further, a device should clearly communicate its available actions, and the consequences of invoking them. The user should be able to work directly on a problem without having to be aware of the device itself (or its affordances).

The four main design guidelines proposed by Norman (2002) are:

  1. visibility ~ indicates the correlation between intended actions and actual operations
  2. affordances ~ like natural mappings, affordances are clues (often visual) that suggest how a control can be used; door handles afford grasping and buttons afford pushing; an affordance helps users to discover how to invoke actions the device makes visible.
  3. natural mapping ~ controls should bear a metaphorical relationship to the real world, a “natural mapping”. (Norman uses examples from the layouts of light switches and compares them to positions of lamps); any design that requires labels, diagrams or instructions, he says, is probably faulty: unnaturally mapped
  4. feedback ~ the two aspects of action are execution and evaluation; after executing an action, watch for effects, and determine whether what was accomplished was what was expected; feedback about actions gives users confidence about a device and emboldens them to use it

Shneiderman's Eight (8) Rules of Interface Design

  • 1) Strive for consistency
  • consistent sequences of actions should be required in similar situations
  • identical terminology should be used in prompts, menus and help screens
  • consistent colour, layout, capitalization, font should be used throughout
  • 2) Enable frequent users to use shortcuts
  • increase pace of interaction use abbreviations, special keys, hidden commands and macros
  • 3) Offer informative feedback
  • for every user action, the system should respond in some way
  • button will make a clicking sound or change colour when clicked to show user something has happened
  • 4) Design dialogs to yield closure
  • sequences of actions should be organized into groups with a beginning, middle, and end
  • informative feedback at the completion of a group of actions shows the user their activity has completed successfully
  • 5) Offer error prevention and simple error handling
  • design form so that users cannot make a serious error
  • do not allow alphabetic characters in numeric entry fields
  • if users make errors, instructions should be written to detect error and offer simple, constructive, specific instructions for recovery
  • segment long pages and send sections so users are not penalized by having to fill in forms - make sure you inform users that multiple sections are coming
  • 6) Permit easy reversal of actions
  • 7) Support internal locus of control
  • experienced users want to be in charge; tedious sequences of data entries, inability or difficulty to get necessary information, inability to produce action all build anxiety and dissatisfaction
  • 8 ) Reduce short-term memory load
  • one study showed humans can store only 7 (plus or minus 2) pieces of information in their short term memory; you can reduce short term memory load by designing screens where options are clearly visible, or using pull-down menus and icons

Iterative design methods

One of the more commonly-used approaches to HCI design is to engage users in the design process. By including real users early, the end product is more apt to address the actual needs of users. Getting their input early is a critical step whether it's about determining the key tasks of a website or the required search functionalities. Any eventual interface should be put through a rigorous evaluation which can make the difference between a successful project and one beset by problems. Academic librarians should take steps to determine how many users they will involve in performing task(s) and who are their most appropriate users. Anyone who is not apt to use the interface in the future is probably not the best to engage in the process. Designers will need to define task(s) users will perform and how often they will be performed.

During testing, it may be important to demonstrate the interface and establish usability specifics for users ~ such as the number of tasks to be performed, in what time and any errors made. Once users, tasks and empirical measurements are made, analyze the results and proceed to refinements. The design process is iterative and will cycle until the interface created is favoured by the majority. Once an interface has been developed, an inspection can be carried out by interface professionals. Several experts can evaluate the interface against a set of guiding principles, and they can analyze it by considering what users would need to do to perform tasks.


See also HCI Bibliography : Human-Computer Interaction Resources

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