Definitions of common HCI terms

… it seems more productive to construct an integrated portrait of direct manipulation:

  • Continuous representation of the object of interest.
  • Physical actions (movement and selection by mouse, joystick, touch screen, etc.) or labeled button presses instead of complex syntax.
  • Rapid, incremental, reversible operations whose impact on the object of interest is immediately visible.
  • Layered or spiral approach to learning that permits usage with minimal knowledge. Novices can learn a modest and useful set of commands, which they can exercise till they become an “expert” at level I of the system. After obtaining reinforcing feedback from successful operation, users can gracefully expand their knowledge of features and gain fluency.

Ben Shneiderman (1983) Direct Manipulation: A Step Beyond Programming Languages

Human–computer interaction (HCI) researches the design and use of computer technology, focused on the interfaces between people (users) and computers. Researchers in the field of HCI both observe the ways in which humans interact with computers and design technologies that let humans interact with computers in novel ways. As a field of research, human–computer interaction is situated at the intersection of computer science, behavioral sciences, design, media studies, and several other fields of study. Wikipedia contributors. (2018) Human–computer interaction

Human-computer interaction is a discipline concerned with the design, evaluation and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them. Hewett; Baecker; Card; Carey; Gasen; Mantei; Perlman; Strong; Verplank (1992) ACM SIGCHI Curricula for Human–Computer Interaction

Implicit human computer interaction is an action, performed by the user that is not primarily aimed to interact with a computerized system but which such a system understands as input. Albrecht Schmidt (2000) Implicit Human Computer Interaction Through Context

A substrate is a digital computational medium that holds digital information, possibly created by another substrate, applies constraints and transformations to it, reacts to changes in both the information and the substrate, and generates information consumable by other substrates. Substrates are extensible, composable with other substrates, and they can be shared. They provide the fabric of the digital world. Michel Beaudouin-Lafon (2017) Towards Unified Principles of Interaction

an interaction instrument is a mediator between the user and objects of interest: the user acts on the instrument, which in turn acts on the objects. Michel Beaudouin-Lafon (2000) [Instrumental Interaction: An Interaction Model for Designing Post-WlMP User Interfaces] (

An interaction model is a set of principles, rules and properties that guide the design of an interface. It describes how to combine interaction techniques in a meaningful and consistent way and defines the “look and feel” of the interaction from the user's perspective. Properties of the interaction model can be used to evaluate specific interaction designs. Michel Beaudouin-Lafon (2000) [Instrumental Interaction: An Interaction Model for Designing Post-WlMP User Interfaces] (

In human-computer interaction (HCI), interaction paradigms (also called interaction styles) describe general philosophies about how humans can interact with computers. Traditional interaction paradigms include command line interfaces (CLIs) where the user issues commands to the computer, or direct manipulation where the user can directly modify visual representations of digital objects, e.g., changing the size of a rectangle by dragging its corners with the mouse pointer. Interaction paradigms typically encompass a custom vocabulary, a consistent model of concepts and their properties, and a set of interaction techniques that allow users to interact with said concepts. preliminary own definition by Raphael Wimmer, as the literature is missing a common definition

The concept of Interaction Styles refers to all the ways the user can communicate or otherwise interact with the computer system. […] In HCI textbooks, such as Shneiderman (1997) and Preece et al. (1994), the types of interaction styles mentioned are usually command language, form fillin, menu selection, and direct manipulation. Mads Soegaard (n.d.) The Glossary of Human Computer Interaction, 26. Interaction Styles

Interaction tasks are low-level primitive inputs required from the user, such as entering a text string or choosing a command. Robert J.K. Jacob (1996) Human-computer Interaction: Input Devices

An interaction technique is a way of using a physical device to perform an interaction task. Robert J.K. Jacob (1996) Human-computer Interaction: Input Devices

the fusion of input and output, consisting of all software and hardware elements, that provides a way for the user to accomplish a task. K. Hinckley, R. Jacob, and C. Ware. Chapter “Input/Output Devices and Interaction Techniques” in: A.B. Tucker (2004), Computer Science Handbook, Second Edition. Chapman & Hall/CRC. pp 20–2.

a way of using a physical input/output device to perform a generic task in a human-computer dialogue. J.D. Foley, A. van Dam, S.K. Feiner and J.F. Hughes (1990), Computer Graphics: Principles and Practice, Addison–Wesley.

Polymorphism is the property that enables a single command to be applicable to objects of different types. Polymorphism allows us to maintain a small number of commands, even as reification increases the number of object types. Michel Beaudouin-Lafon, Wendy Mackay (2000) Reification, polymorphism and reuse: three principles for designing visual interfaces

Reification is the process by which concepts are turned into objects. For example, in a graphical editing tool, the concept of a circle is represented as an image of a circle in a tool palette. Reification creates new objects that can be manipulated by the user, thus increasing the set of objects of interest. Michel Beaudouin-Lafon, Wendy Mackay (2000) Reification, polymorphism and reuse: three principles for designing visual interfaces

Reuse can involve previous input, previous output or both. Input reuse makes previously-provided user input available for reuse in the current context. For example, the redo command lets users repeat complex input strings without having to retype them. Output reuse makes the results of previous user commands available for reuse. For example, duplicate and copy- paste let users avoid re-creating complex objects they have just created. Michel Beaudouin-Lafon, Wendy Mackay (2000) Reification, polymorphism and reuse: three principles for designing visual interfaces

User interfaces are a mapping from the sensory, cognitive, and social human world to […] collections of functions exposed by a computer program. Andy J. Ko (n.d.) User Interface Software and Technology, Chapter 2: A Theory of User Interfaces