Eye-typing forces users to think in terms of individual letters. This has a cognitive cost and is not a fluid means of communication.

To use such a switch for typing, the SGD interface must be designed with this in mind from the beginning. The most common solution is a scanning keyboard.

TTF refers to the ability of technology to support a task [197]. 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.

A system may be usable for some tasks and less usable for others; it may be usable for some users but not for others.

Usability concerns how easily computer-based tools may be operated by users trying to accomplish a task. Usability differs from utility. Usability concerns whether users can use the product in a way that makes it possible to realize its utility; utility is about whether the goal is important to the user.

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.

Users actively repurpose tools to make them more personally usable and relevant. Design should support such repurposing. For example, Renom et al. [696] conducted a study on text editing using a novel user interface. They found that exploration and technical reasoning facilitate creative tool use. Users who explore available commands in a tool are better at repurposing its functionality. More surprisingly, engaging in technical reasoning (reasoning about functionality and objects) supports repurposing more than procedural knowledge inherited from other software.

Tversky and Jamalian [833] proposed that embodied action is at the core of this. We move our bodies and toss, push, and pull objects. These movements can be thought about, imagined, and referred to in language. This, in turn, can change the substrate of thinking.

Davis [180] proposed that whether an individual ends up using a system, that is, their usage behavior, depends on their intention to use the system.

The theory of task–technology fit (TTF) can illuminate what users consider useful and how this affects their decision to adopt a particular technology. TTF refers to the ability of technology to support a task [197]. 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. TTF theory posits that a rational user will choose the tool with the highest fit due to its efficacy and efficiency. Conversely, a system that does not offer a good fit will not be used.

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 [180]. Furthermore, the perceived ease of use affects the perceived usefulness: If technology is hard to use, it is less useful.

While a tool can enhance performance in cognitively challenging tasks, its extended use may erode the cognitive capability of the user.

The tool itself may become 'transparent' and we start perceiving 'through it.'

Using a tool for extended periods can fundamentally change the way a user thinks and perceives both the tool and the world.

accessibility concerns the match between a user's abilities and the system's required abilities.

TTF theory posits that a rational user will choose the tool with the highest fit due to its efficacy and efficiency. Conversely, a system that does not offer a good fit will not be used.

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. Furthermore, the perceived ease of use affects the perceived usefulness: If technology is hard to use, it is less useful.

usability is multidimensional. This means that in most settings, a valid characterization of usability will need to employ several dimensions and measures.

usability is measurable, that is, it is possible to quantify usability based on users' behaviors or opinions.

usability is relational; it arises as an interplay between people, tasks (problems), and interactive systems (tools)

Usability concerns how easily computer-based tools may be operated by users trying to accomplish a task. Usability differs from utility. Usability concerns whether users can use the product in a way that makes it possible to realize its utility; utility is about whether the goal is important to the user.

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.

Users actively repurpose tools to make them more personally usable and relevant.

Utility centers what users want from technology.

Usability is one of the best predictors of users' willingness to adopt software.

Cognitive integration means that we internalize the operation of the tool. We not only act but also start thinking as defined by the unique constraints and mechanisms of the tool.

accessibility concerns the match between a user's abilities and the system's required abilities. As such, it differs from usability (which is about the relationship between users, tools, and tasks) and utility (which is about whether a tool may be used to complete a task).

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.

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. Furthermore, the perceived ease of use affects the perceived usefulness: If technology is hard to use, it is less useful.

The second dimension, social acceptability, concerns whether interactions map well to the social norms and roles in the settings where they occur.

Acceptability has two main dimensions. The first dimension, practical acceptability, includes costs, the reliability of the interactive system, and its compatibility with other systems. The perceptions of utility and usability may also influence the judgment of practical acceptability.

usability is multidimensional. This means that in most settings, a valid characterization of usability will need to employ several dimensions and measures.

usability is measurable, that is, it is possible to quantify usability based on users' behaviors or opinions.

usability is relational; it arises as an interplay between people, tasks (problems), and interactive systems (tools)

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.

Usability concerns how easily computer-based tools may be operated by users trying to accomplish a task. Usability differs from utility. Usability concerns whether users can use the product in a way that makes it possible to realize its utility; utility is about whether the goal is important to the user.

a scrollbar is an interaction instrument, or tool, that operates on documents

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.

For example, the abacus is a wooden device used for teaching basic calculations. It consists of a frame with rows of wires along which beads can slide. 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.

TTF has been used to assess users' willingness to use various technologies such as email or spreadsheets.

For example, social acceptability was an important consideration for early smart glasses, that is, eyewear with computational capabilities, particularly models fitted with cameras [426].

For instance, Nielsen and Levy [592] compared users' performance and their preferences across 57 studies and found what they called a strong positive correlation. Nevertheless, they concluded that "there are still many cases in which users prefer systems that are measurably worse for them, so one should exercise caution" [p. 75].

For instance, Whiteside et al. [886] showed how to make explicit quantitative goals for usability. They provided an example of the usability of software installation. This was quantified through the time it takes to install software. This could take one hour or, in the best case, just 10 minutes.

For example, Renom et al. [696] conducted a study on text editing using a novel user interface. They found that exploration and technical reasoning facilitate creative tool use. Users who explore available commands in a tool are better at repurposing its functionality.

For example, Koelle et al. [426] studied the adoption of data glasses (e.g., Google Glass, Meta Pro) over multiple years. They asked experts familiar with data glasses what would need to be improved to make data glasses more acceptable. Usefulness, functionality, and usability were the most important factors—more important than security, privacy, pricing, experience, and compatibility.

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.

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

TTF refers to the ability of technology to support a task [197]. 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.

One prominent definition of accessibility is given by ISO 9241-171, which defines it as "the usability of a product, service, environment or facility by people with the widest range of capabilities."

The second dimension, social acceptability, concerns whether interactions map well to the social norms and roles in the settings where they occur.

The first dimension, practical acceptability, includes costs, the reliability of the interactive system, and its compatibility with other systems.

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

usability is relational; it arises as an interplay between people, tasks (problems), and interactive systems (tools)

the "extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use."

Usability concerns how easily computer-based tools may be operated by users trying to accomplish a task. Usability differs from utility. Usability concerns whether users can use the product in a way that makes it possible to realize its utility; utility is about whether the goal is important to the user.

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.

What makes these objects tools is that they are not attached to the body but can be held to bring about changes in the condition of other objects [772]. By extension, the idea of tool use in human–computer interaction (HCI) is that a computer system is a tool for controlling something else.

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

accessibility is given by ISO 9241-171, which defines it as 'the usability of a product, service, environment or facility by people with the widest range of capabilities.'

TTF refers to the ability of technology to support a task

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

social acceptability, concerns whether interactions map well to the social norms and roles in the settings where they occur

practical acceptability, includes costs, the reliability of the interactive system, and its compatibility with other systems

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

usability is multidimensional

usability is measurable, that is, it is possible to quantify usability based on users' behaviors or opinions

usability is relational; it arises as an interplay between people, tasks (problems), and interactive systems (tools)

the ISO 9241-11 definition, based on work by Bevan and many others, which defines usability as the 'extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.'

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

utility is 'whether the functionality of a system in principle can do what is needed'

The utility of an interactive system concerns its match with the tasks of users.

tools may be more or less easy to manipulate when used. This is called usability

understanding computers as tools emphasizes the utility of a tool, by which we mean how well it supports what people want to do