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dynamic increase of the interaction's customization
and therefore an improvement of the user's
engagement, focusing on how self-induced emotions
could be utilized in a BCI paradigm (real-time data
processing).
In this view, the real-time acquisition of
information about the emotional state of the user
provided by the system should be used to adapt the
characteristics of the interaction: That should give
the chance of better reaching the intended emotional
effects on each individual user. In this paper we
conduct a BCI-based pilot study for determining if
the contents of a given AVE (see section 4 for more
details) could result in high subject agreement in
terms of elicited emotion.
2 MEASURING EMOTIONS BY
BCI
Emotions are a really complex phenomenon, so
there is no universal method to measure them.
Methods may be categorized into subjective and
objective ones. Questionnaires or picture tools (Self-
Assessment Mainkin (SAM) (Bradley and Lang,
1994) or the Affect grid (Russell et al., 1989)) could
be used as self-report instruments. Objective
methods use physiological cues derived from the
theories of emotions which define universal pattern
of autonomic and central nervous system responses
related to the experience of emotions. Other
modalities used for measuring emotions include
blood pressure, heart rate, respiration. This paper
exploits emotion assessment via EEG.
A BCI records human activity in form of
electrical potentials (EPs), through multiple
electrodes that are placed on the scalp. Depending
on the brain activity, distinctive known patterns in
the EEG appear. To account for user emotional state
during BCI operation, most of the literature suggests
an exhaustive training of the BCI classification
algorithm under various emotional states: In the
general approach the user is exposed to an opportune
affective stimulation. The type of mental activity
elicited is then processed to obtain features that
could be grouped into features vectors. Such features
vectors are then used to train the BCI classification
algorithm, which can then recognize the relevant
brain activity.
If a passive BCI is employed, as in our case,
active user involvement is not required. The
interpretation of his/her mental state could be a
source of control to the automatic system adaptation
(from the application interface to the virtual
environment), for example in order to motivate and
involve him/her by the application feedback.
3 EMOTIONAL RECOGNITION
BY Emotiv
tm
EPOC
Emotiv
TM
Epoc (http://www.emotiv.com), is a high-
resolution, low-cost, easy to use neuroheadset
developed for games. Based on the International 10-
20 locations, it captures neural activity using 14 dry
electrodes (AF3, F7, F3, FC5, T7, P7, O1, O2, P8,
T8, FC6, F4, F8, AF4) plus CMS/DRL references,
P3/P4 locations). The headset samples all channels
at 128Hz, each sample being a 14 bit value
corresponding to the voltage of a single electrode.
Directly based on the user's brain activity,
Emotiv
TM
Epoc reads different emotion-related
measures. Among the other, the Instantaneous
Excitement (IE) and the Long term Excitement
(LTE). The first is experienced as an awareness or
feeling of physiological arousal with a positive
value. It is tuned to provide output scores that more
accurately reflect short-term changes in excitement
over time periods as short as several seconds; LTE is
experienced and defined in the same way as IE, but
the detection is designed and tuned to be more
accurate when measuring changes in excitement
over longer time periods, typically measured in
minutes. Both these measures are time-independent:
At each arousal variation the IE and LTE are
detected.
4 THE ADAPTABLE VIRTUAL
ENVIRONMENT
Some application require detection of and
management of user's emotions to provide an
appropriate user experience or even to avoid
psychological harm. As main example of this kind of
application, we consider a Nazi extermination camp.
Moreover, sooner the only way to preserve the
remembrance of that terrible historical period will
entrusted on indirect documentation in the form of
videos, images and texts reporting interviews to last
witnesses. A way to maintaining alive the dramatic
meaning of that experience could be to reconstruct a
3D virtual environment of one of those camps, such
as Auschwitz.
In our VE a digital character representing a
prisoner guides users through different parts of the
camp. During the navigation, the VE activates links
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