<s>
The	O
P300	B-Algorithm
(	O
P3	O
)	O
wave	O
is	O
an	O
event-related	B-Algorithm
potential	I-Algorithm
(	O
ERP	O
)	O
component	O
elicited	O
in	O
the	O
process	O
of	O
decision	O
making	O
.	O
</s>
<s>
More	O
specifically	O
,	O
the	O
P300	B-Algorithm
is	O
thought	O
to	O
reflect	O
processes	O
involved	O
in	O
stimulus	O
evaluation	O
or	O
categorization	O
.	O
</s>
<s>
It	O
is	O
usually	O
elicited	O
using	O
the	O
oddball	B-Algorithm
paradigm	I-Algorithm
,	O
in	O
which	O
low-probability	O
target	O
items	O
are	O
mixed	O
with	O
high-probability	O
non-target	O
(	O
or	O
"	O
standard	O
"	O
)	O
items	O
.	O
</s>
<s>
When	O
recorded	O
by	O
electroencephalography	B-Application
(	O
EEG	B-Application
)	O
,	O
it	O
surfaces	O
as	O
a	O
positive	O
deflection	O
in	O
voltage	O
with	O
a	O
latency	O
(	O
delay	O
between	O
stimulus	O
and	O
response	O
)	O
of	O
roughly	O
250	O
to	O
500ms	O
.	O
</s>
<s>
Early	O
observations	O
of	O
the	O
P300	B-Algorithm
(	O
more	O
specifically	O
,	O
the	O
component	O
that	O
would	O
later	O
be	O
named	O
the	O
P3b	B-Algorithm
)	O
were	O
reported	O
in	O
the	O
mid-1960s	O
.	O
</s>
<s>
When	O
examining	O
evoked	O
potentials	O
to	O
these	O
stimuli	O
(	O
i.e.	O
,	O
ERPs	O
)	O
,	O
Chapman	O
and	O
Bragdon	O
found	O
that	O
both	O
the	O
numbers	O
and	O
the	O
flashes	O
elicited	O
the	O
expected	O
sensory	O
responses	O
(	O
e.g.	O
,	O
visual	B-Algorithm
N1	I-Algorithm
components	O
)	O
,	O
and	O
that	O
the	O
amplitude	O
of	O
these	O
responses	O
varied	O
in	O
an	O
expected	O
fashion	O
with	O
the	O
intensity	O
of	O
the	O
stimuli	O
.	O
</s>
<s>
Chapman	O
and	O
Bragdon	O
speculated	O
that	O
this	O
differential	O
response	O
to	O
the	O
numbers	O
,	O
which	O
came	O
to	O
be	O
known	O
as	O
the	O
P300	B-Algorithm
response	O
,	O
resulted	O
from	O
the	O
fact	O
that	O
the	O
numbers	O
were	O
meaningful	O
to	O
the	O
participants	O
,	O
based	O
on	O
the	O
task	O
that	O
they	O
were	O
asked	O
to	O
perform	O
.	O
</s>
<s>
These	O
early	O
studies	O
encouraged	O
the	O
use	O
of	O
ERP	O
methods	O
to	O
study	O
cognition	O
and	O
provided	O
a	O
foundation	O
for	O
the	O
extensive	O
work	O
on	O
the	O
P300	B-Algorithm
in	O
the	O
decades	O
that	O
followed	O
.	O
</s>
<s>
The	O
P3a	B-Algorithm
,	O
or	O
novelty	O
P3	O
,	O
has	O
a	O
positive-going	O
amplitude	O
that	O
displays	O
maximum	O
amplitude	O
over	O
frontal/central	O
electrode	O
sites	O
and	O
has	O
a	O
peak	O
latency	O
in	O
the	O
range	O
of	O
250	O
–	O
280ms	O
.	O
</s>
<s>
The	O
P3a	B-Algorithm
has	O
been	O
associated	O
with	O
brain	B-Application
activity	I-Application
related	O
to	O
the	O
engagement	O
of	O
attention	O
(	O
especially	O
the	O
orienting	O
,	O
involuntary	O
shifts	O
to	O
changes	O
in	O
the	O
environment	O
)	O
,	O
and	O
the	O
processing	O
of	O
novelty	O
.	O
</s>
<s>
The	O
P3b	B-Algorithm
has	O
a	O
positive-going	O
amplitude	O
(	O
usually	O
relative	O
to	O
a	O
reference	O
behind	O
the	O
ear	O
or	O
the	O
average	O
of	O
two	O
such	O
references	O
)	O
that	O
peaks	O
at	O
around	O
300ms	O
,	O
and	O
the	O
peak	O
will	O
vary	O
in	O
latency	O
from	O
250	O
to	O
500ms	O
or	O
more	O
,	O
depending	O
upon	O
the	O
task	O
and	O
the	O
individual	O
subject	O
response	O
.	O
</s>
<s>
The	O
P3b	B-Algorithm
has	O
been	O
a	O
prominent	O
tool	O
used	O
to	O
study	O
cognitive	O
processes	O
,	O
especially	O
psychology	O
research	O
on	O
information	O
processing	O
.	O
</s>
<s>
Generally	O
speaking	O
,	O
improbable	O
events	O
will	O
elicit	O
a	O
P3b	B-Algorithm
,	O
and	O
the	O
less	O
probable	O
the	O
event	O
,	O
the	O
larger	O
the	O
P3b	B-Algorithm
amplitude	O
.	O
</s>
<s>
However	O
,	O
in	O
order	O
to	O
elicit	O
a	O
P3b	B-Algorithm
,	O
the	O
improbable	O
event	O
must	O
be	O
related	O
to	O
the	O
task	O
at	O
hand	O
in	O
some	O
way	O
(	O
for	O
example	O
,	O
the	O
improbable	O
event	O
could	O
be	O
an	O
infrequent	O
target	O
letter	O
in	O
a	O
stream	O
of	O
letters	O
,	O
to	O
which	O
a	O
subject	O
might	O
respond	O
with	O
a	O
button	O
press	O
)	O
.	O
</s>
<s>
The	O
P3b	B-Algorithm
can	O
also	O
be	O
used	O
to	O
measure	O
how	O
demanding	O
a	O
task	O
is	O
on	O
cognitive	O
workload	O
.	O
</s>
<s>
Since	O
the	O
initial	O
discovery	O
of	O
the	O
P300	B-Algorithm
,	O
research	O
has	O
shown	O
that	O
the	O
P300	B-Algorithm
has	O
two	O
subcomponents	O
.	O
</s>
<s>
The	O
subcomponents	O
are	O
the	O
novelty	O
P3	O
,	O
or	O
P3a	B-Algorithm
,	O
and	O
the	O
classic	O
P300	B-Algorithm
,	O
which	O
has	O
since	O
been	O
renamed	O
P3b	B-Algorithm
.	O
</s>
<s>
Since	O
the	O
mid-1980s	O
,	O
one	O
of	O
the	O
most	O
discussed	O
uses	O
of	O
ERPs	O
such	O
as	O
the	O
P300	B-Algorithm
is	O
related	O
to	O
lie	O
detection	O
.	O
</s>
<s>
In	O
a	O
proposed	O
"	O
guilty	O
knowledge	O
test	O
"	O
a	O
subject	O
is	O
interrogated	O
via	O
the	O
oddball	B-Algorithm
paradigm	I-Algorithm
much	O
as	O
they	O
would	O
be	O
in	O
a	O
typical	O
lie-detector	O
situation	O
.	O
</s>
<s>
This	O
practice	O
has	O
recently	O
enjoyed	O
increased	O
legal	O
permissibility	O
while	O
conventional	O
polygraphy	O
has	O
seen	O
its	O
use	O
diminish	O
,	O
in	O
part	O
owing	O
to	O
the	O
unconscious	O
and	O
uncontrollable	O
aspects	O
of	O
the	O
P300	B-Algorithm
.	O
</s>
<s>
The	O
technique	O
relies	O
on	O
reproducible	O
elicitation	O
of	O
the	O
P300	B-Algorithm
wave	O
,	O
central	O
to	O
the	O
idea	O
of	O
a	O
Memory	O
and	O
Encoding	O
Related	O
Multifaceted	O
Electroencephalographic	B-Application
Response	O
(	O
MERMER	O
)	O
developed	O
by	O
Dr.	O
Lawrence	O
Farwell	O
.	O
</s>
<s>
Applications	O
in	O
brain-computer	B-Application
interfacing	I-Application
(	O
BCI	O
)	O
have	O
also	O
been	O
proposed	O
.	O
</s>
<s>
The	O
P300	B-Algorithm
has	O
a	O
number	O
of	O
desirable	O
qualities	O
that	O
aid	O
in	O
implementation	O
of	O
such	O
systems	O
.	O
</s>
<s>
The	O
P300	B-Algorithm
waveform	O
can	O
also	O
be	O
evoked	O
in	O
nearly	O
all	O
subjects	O
with	O
little	O
variation	O
in	O
measurement	O
techniques	O
,	O
which	O
may	O
help	O
simplify	O
interface	O
designs	O
and	O
permit	O
greater	O
usability	O
.	O
</s>
<s>
One	O
negative	O
characteristic	O
of	O
the	O
P300	B-Algorithm
is	O
that	O
the	O
amplitude	O
of	O
the	O
waveform	O
requires	O
averaging	O
of	O
multiple	O
recordings	O
to	O
isolate	O
the	O
signal	O
.	O
</s>
<s>
The	O
algorithm	O
proposed	O
by	O
Farwell	O
and	O
Donchin	O
provides	O
an	O
example	O
of	O
a	O
simple	O
BCI	O
that	O
relies	O
on	O
the	O
unconscious	O
decision	O
making	O
processes	O
of	O
the	O
P300	B-Algorithm
to	O
drive	O
a	O
computer	O
.	O
</s>
<s>
When	O
a	O
column	O
or	O
row	O
contains	O
the	O
character	O
a	O
subject	O
desires	O
to	O
communicate	O
,	O
the	O
P300	B-Algorithm
response	O
is	O
elicited	O
(	O
since	O
this	O
character	O
is	O
"	O
special	O
"	O
it	O
is	O
the	O
target	O
stimulus	O
described	O
in	O
the	O
typical	O
oddball	B-Algorithm
paradigm	I-Algorithm
)	O
.	O
</s>
<s>
A	O
number	O
of	O
such	O
trials	O
must	O
be	O
averaged	O
to	O
clear	O
noise	O
from	O
the	O
EEG	B-Application
.	O
</s>
<s>
Scientific	O
research	O
often	O
relies	O
on	O
measurement	O
of	O
the	O
P300	B-Algorithm
to	O
examine	O
event	B-Algorithm
related	I-Algorithm
potentials	I-Algorithm
,	O
especially	O
with	O
regard	O
to	O
decision	O
making	O
.	O
</s>
<s>
Because	O
cognitive	O
impairment	O
is	O
often	O
correlated	O
with	O
modifications	O
in	O
the	O
P300	B-Algorithm
,	O
the	O
waveform	O
can	O
be	O
used	O
as	O
a	O
measure	O
for	O
the	O
efficacy	O
of	O
various	O
treatments	O
on	O
cognitive	O
function	O
.	O
</s>
<s>
There	O
is	O
a	O
broad	O
range	O
of	O
uses	O
for	O
the	O
P300	B-Algorithm
in	O
clinical	O
research	O
.	O
</s>
<s>
Some	O
research	O
groups	O
have	O
performed	O
fMRI	O
combined	O
to	O
EEG	B-Application
in	O
order	O
to	O
achieve	O
inner-speech	O
dictation	O
and	O
the	O
approach	O
of	O
inner-speech	O
recognition	O
.	O
</s>
