Biomedical Engineering Reference
In-Depth Information
Physical:
It constitutes all interactions involving direct use of senses and muscle
actions [
57
].
Cognitive
: It includes all mental capabilities of the user connected with under-
standing, learning and reasoning [
59
]. The cognitive aspect is also emphasized in
a more direct manner in Brain Computer Interfaces (BCIs) where the interface
senses the user's cognitive state of the brain (via EEG) [
60
].
Affective
: The second class of mental capabilities focuses on the emotional state,
e.g. if the user is tired or angry. Sensing this allows the system to react on emotions
and to create emotional feedback [
61
].
Cognitive and affective activity approaches are still relatively new fields in HCI.
This overview focuses more on the physical interaction, which can be divided in
three subcategories, related to human senses [
62
]:
Vision:
Many input devices rely on human vision, as for example, pointing devices:
mice, trackballs, graphic tablets and touch screens. Also commonly used visual
output devices are screens and printers.
Audition:
This category includes all means that involve hearing, human speech
and audio signalization.
Touch:
Although keyboards and buttons could be classified here, this category
focuses more on all force passing interfaces. This includes sending sensations to
human skin and muscles and receiving force feedback from the user.
It is important to note that even for the simplest interfaces, this categorization can
be vague. Since humans process information from the environment using different
senses in parallel, it is difficult to distinguish between meaningful and meaningless
stimuli. For example, keyboard keys have glyphs, which allowselecting keys visually,
but they have also a force threshold that permits to sense the state by touching.
Recent Trends in HCI
Although HCI and MMI have a long research tradition, only recent technological
advancements allowed the implementation of techniques that were already proposed
in the 1960s, like Augmented Reality (AR) [
63
]. This advancement enabled testing
of new ideas in practical trials, giving rise to further investigation. New research
trends that have become prominent in the past years are: Intelligent HCI, Adaptive
HCI, Ubiquitous Computing and Ambient Intelligence [
64
,
65
].
Intelligent HCI
refers to all techniques that are intelligent in the sense of pre-
processing data received from the user. Hence, simple interfaces become complex
systems, enhancing the received data into a complete stream of information.
Adaptive HCI
refers to the adaptiveness of interfaces to become better suited to a
certain user. An example of this is the T9 system [
66
] used in cell phones, allowing
input of alphanumeric text with just a single press of the digit keys for each alphanu-
merical sign. It uses a formof intelligence, i.e. algorithms that process key sequences,
comparing themwith statistical models of languages and providing missing informa-
tion. The T9 example is also useful to explain the concept of adaptiveness, because
