Eye-typing is an effective means of communication; however, it is not efficient. Three fundamental problems prevent high entry rates. First, the eyes are sensory organs and not control organs. It is difficult for users to artificially maintain fixation on specific keys. Second, the dwell timeout provides a low ceiling on performance. Third, people think in terms of words, phrases, and sentences when they communicate. Eye-typing forces users to think in terms of individual letters.

Supple++ [266] is a computational method developed in HCI that can improve graphical user interfaces to better fit a user's unique motor and vision abilities. In Supple++, the user is first asked to perform a series of motor tasks. This information is used to calibrate an internal computational model of the user's motor ability. Once the calibration is complete, Supple++ optimizes the user interface automatically by changing the size and location of user interface elements and the organization of the user interface, subject to constraints specified by the designer.

Galletta et al. [267] warned against the effect of spell checkers on verbal ability. Having a spell checker in a word processing program may make users overly rely on the tool even if it makes several mistakes, both false positives and false negatives. The authors showed experimentally that university students who had a spell checker on during a document editing task had more errors left in the document than those who did not.

Blind cane users are a good example [756]. When blind users learn to sense the environment with a cane, their perception of tactile and auditory stimuli slowly changes. Instead of sensing stimuli close to their hand, when they hold the cane, they can integrate tactile (vibration) and auditory stimuli close to the tip of the cane. They develop multimodal, integrated percepts that correspond to the tip of the cane.

Students who learned to do calculations with an abacus solve mathematical problems differently from others [796]. They rely more on mental imagery of the movement of beads on the abacus, which makes their mental calculations highly efficient for certain types of calculations.

Beaudouin-Lafon [53] departed from the idea that the manipulation of physical objects with our hands can be used as the basis for designing new user interfaces. He separated domain objects that are manipulated from interaction instruments, which are computer artifacts that manipulate domain objects. For example, a scrollbar is an interaction instrument, or tool, that operates on documents. Further analysis reveals it has low integration because a 1D action is controlled by a 2D mouse, and it has low compatibility in some designs because the content moves in a different direction from the movement of the scrollbar.

TAM posits that the intention to adopt a particular technology is driven by two kinds of perceptions: (1) how easy it is to use a system and (2) how useful it will be to use it.

Cognitive integration means that we internalize the operation of the tool.

TTF refers to the ability of technology to support a task. The capabilities of the technology should match the demands of the task and the skills of the individual; in this case, the fit is perfect.

acceptability of the tool, that is, whether users choose to use the tool when given that option.

One prominent definition of accessibility is given by ISO 9241-171, which defines it as

Usability concerns how easily computer-based tools may be operated by users trying to accomplish a task.

The utility of an interactive system concerns its match with the tasks of users. If the match is good, the tool has high utility; if the tasks that users want to do are not supported by the tool, the tool has low utility.

the idea of tool use in human–computer interaction (HCI) is that a computer system is a tool for controlling something else.

Newman and Taylor presented a concrete approach to selecting usability measures, which they called selecting critical parameters, that is,

Research has shown that SUS can discriminate between systems with poor and good usability, can be used with a range of technologies, correlates modestly with task performance, correlates well with other questionnaires, and has good reliability.

The UMUX-Lite consists of just two items,

The answers to these questions are summed to calculate the overall SUS score. For odd-numbered items, subtract 1 from each score (1–5); for even-numbered items, subtract each score from 5. Then, sum these values to obtain the total SUS score.

The SUS consists of 10 questions answered on a Likert scale (from

The User Burden Scale is a questionnaire for measuring the felt burden in software use. It consists of six subscales: difficulty of use, physical burden, time and social burden, mental and emotional burden, privacy burden, and financial burden.