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In-Depth Information
valuable information that re
ects the user mental states (Cutrell and Tan
2007
;
Girouard
2009
; Zander et al.
2009
).
In passive BCI, the user does not try to control his/her brain activity, and he/she
can remain mainly concerned by his/her primary task. The brain activity is analyzed
to read out the user mental state which is used to adapt the interaction rules or the
content of the application.
In this chapter, we present an overview of the use of passive BCI in different
contexts: adaptive automation, multimedia content tagging, video game adaptation,
error correction, etc. We describe how implicit BCI are used and the commonly
employed signal processing schemes.
13.2
Passive BCI Definition
Cutrell and Tan were the
first to introduce the expression
“
passive BCI.
”
In Cutrell
“
and Tan (
2007
), they wrote
We think there is a potential to use brain sensing in a
more passive context, looking beyond direct system control to make BCI useful to
the general population in a wide range of scenarios.
”
Girouard (
2009
) referred to the
work of Cutrell and Tan and de
Passive BCI are
interfaces that use brain measurements as an additional input, in addition to stan-
dard devices such as keyboards and mice.
ned the term
“
passive BCI
”
as
“
By developing passive BCI, her aim was
to use the brain activity information to create
”
“
applications that pay attention to the
user
”
by adapting them to user
'
is mental state. Another point of view is presented by
Zander et al. (
2009
) who de
BCI based not on intended
actions of the user, but instead on reactive states of the user
ned passive BCI as
“
'
s cognition automat-
ically induced while interacting in the surrounding system.
”
Recently, Makeig et al.
(
2012
) described passive BCI as
“
BCI that produce passive readout of cognitive
state variables for use in human
computer applications without requiring the user to
perform voluntary control that may restrict performance of and attention to con-
current tasks.
-
”
To summarize brain
computer interface (or interaction) could be
-
categorized as:
active BCI
computer interaction): The user deliberately tries to
control his/her brain activity;
passive BCI
(explicit brain
-
computer interaction): The user does not try to
control his/her brain activity, he/she is mainly concerned by his/her primary task.
(implicit brain
-
It should be noted that there is no consensus about the integration of passive BCI
in the BCI de
ni-
tion of BCI. For example, Pfurtscheller and Scherer defined a BCI as a commu-
nication system where a
nition. Indeed, some researchers use a somewhat restrictive de
“
brain signal that the user can intentionally modulate
”
is
used for sending control commands (Pfurtscheller and Scherer
2010
). This de
ni-
tion does not include passive BCI. However, the BCI community seems to accept
passive BCI more and more as a new extension of BCI (Makeig et al.
2012
).
