Information Technology Reference
bandwidth and the graphic devices (touch screens, virtual or augmented
reality and so on).
Nowadays, the research in the field of HCI is oriented towards the use
of computers inside a workgroup, the so-called Computer Supported Co-
operative Work (CSCW), media integration and 'multimodal interfaces', and
the effects of new technologies in working and domestic environments.
Implicit and explicit HCI
2.1 Implicit and explicit HCI: a comparison
When considering current computer technology, interaction is explicit:
commands are issued to the computer using a particular abstraction level
(command prompt, GUI, gestures, and written or spoken natural
language). In implicit interaction, the user performs an action that is not
intended to be a computer command, but it is 'interpreted' by the machine
as an input.
Implicit interaction relies on the computer's ability to understand human
behaviour in a specified context. Let us consider as an example a computer-
ized trash can that is able to read bar codes of the items the user throws away
and suggest the shopping list accordingly.
The user performs a simple action that would be the same regardless of
the garbage can. Moreover, the user does not interact with computer that is
embedded in a particular can, so the whole process describes an implicit
interaction. The example points out that implicit interaction is based on two
In general, implicit interaction is used in addition to the explicit one.
Three main concepts can be devised that facilitate implicit interaction:
the user's ability to perceive the usage, the environment and the circum-
some mechanisms to understand sensors percepts and
some applications that are able to use such information .
2.2 Implicit HCI
In human communication, most of the information is exchanged implicitly.
Often, implicit contextual information like posture, gestures and voice intona-
tion ensure the robustness in man-to-man communication. Moreover, body and