<s>
The	O
contingent	B-Algorithm
negative	I-Algorithm
variation	I-Algorithm
(	O
CNV	O
)	O
is	O
a	O
negative	O
slow	O
surface	O
potential	O
,	O
as	O
measured	O
by	O
electroencephalography	B-Application
(	O
EEG	B-Application
)	O
,	O
that	O
occurs	O
during	O
the	O
period	O
between	O
a	O
warning	O
stimulus	O
or	O
signal	O
and	O
an	O
imperative	O
(	O
"	O
go	O
"	O
)	O
stimulus	O
.	O
</s>
<s>
The	O
CNV	O
was	O
one	O
of	O
the	O
first	O
event-related	B-Algorithm
potential	I-Algorithm
(	O
ERP	O
)	O
components	O
to	O
be	O
described	O
.	O
</s>
<s>
The	O
importance	O
of	O
this	O
finding	O
was	O
that	O
it	O
was	O
one	O
of	O
the	O
first	O
studies	O
which	O
showed	O
that	O
consistent	O
patterns	O
of	O
the	O
amplitude	O
of	O
electric	O
responses	O
could	O
be	O
obtained	O
from	O
the	O
large	O
background	O
noise	O
which	O
occurs	O
in	O
EEG	B-Application
recordings	O
and	O
that	O
this	O
activity	O
could	O
be	O
related	O
to	O
a	O
cognitive	O
process	O
such	O
as	O
expectancy	O
.	O
</s>
<s>
The	O
experimenters	O
found	O
that	O
EEG	B-Application
responses	O
to	O
the	O
warning	O
stimulus	O
seemed	O
to	O
have	O
three	O
phases	O
:	O
a	O
brief	O
positive	O
component	O
,	O
a	O
brief	O
negative	O
component	O
,	O
and	O
a	O
sustained	O
negative	O
component	O
.	O
</s>
<s>
Walter	O
et	O
al	O
labeled	O
the	O
sustained	O
component	O
the	O
"	O
contingent	B-Algorithm
negative	I-Algorithm
variation	I-Algorithm
"	O
because	O
the	O
variation	O
of	O
the	O
negative	O
wave	O
was	O
contingent	O
on	O
the	O
statistical	O
relationship	O
between	O
the	O
warning	O
and	O
imperative	O
stimuli	O
.	O
</s>
<s>
the	O
amplitude	O
of	O
the	O
EEG	B-Application
response	O
became	O
attenuated	O
,	O
or	O
habituated	O
when	O
the	O
warning	O
stimulus	O
was	O
repeated	O
without	O
a	O
subsequent	O
imperative	O
stimulus	O
;	O
</s>
<s>
In	O
1990	O
Bozinovska	O
et	O
al	O
devised	O
a	O
CNV-based	O
brain-computer	B-Application
interface	I-Application
to	O
control	O
a	O
computer	O
buzzer	O
.	O
</s>
<s>
In	O
2009	O
,	O
Bozinovski	O
and	O
Bozinovska	O
designed	O
a	O
CNV-based	O
brain-computer	B-Application
interface	I-Application
experiment	O
,	O
where	O
the	O
CNV	O
controlled	O
a	O
physical	O
object	O
,	O
a	O
robot	O
.	O
</s>
<s>
This	O
is	O
the	O
contingent	B-Algorithm
negative	I-Algorithm
variation	I-Algorithm
.	O
</s>
<s>
A	O
related	O
,	O
important	O
issue	O
has	O
been	O
the	O
question	O
of	O
whether	O
all	O
or	O
part	O
of	O
the	O
CNV	O
corresponds	O
to	O
the	O
readiness	B-Algorithm
potential	I-Algorithm
.	O
</s>
<s>
The	O
readiness	B-Algorithm
potential	I-Algorithm
is	O
the	O
neural	O
preparation	O
for	O
motoric	O
responses	O
.	O
</s>
<s>
In	O
fact	O
,	O
many	O
researchers	O
claimed	O
that	O
the	O
terminal	O
CNV	O
,	O
or	O
E	O
wave	O
,	O
was	O
in	O
fact	O
the	O
readiness	B-Algorithm
potential	I-Algorithm
,	O
or	O
Bereitschaftspotential	B-Algorithm
.	O
</s>
<s>
For	O
example	O
,	O
Hultin	O
,	O
Rossini	O
,	O
Romani	O
,	O
Högstedt	O
,	O
Tecchio	O
,	O
and	O
Pizzella	O
(	O
1996	O
)	O
used	O
magnetoencephalography	B-Algorithm
(	O
MEG	O
)	O
to	O
determine	O
the	O
location	O
of	O
the	O
electromagnetic	O
source	O
of	O
the	O
CNV	O
wave	O
.	O
</s>
