<s>
Pandemonium	B-Algorithm
architecture	I-Algorithm
is	O
a	O
theory	O
in	O
cognitive	O
science	O
that	O
describes	O
how	O
visual	O
images	O
are	O
processed	O
by	O
the	O
brain	O
.	O
</s>
<s>
It	O
has	O
applications	O
in	O
artificial	B-Application
intelligence	I-Application
and	O
pattern	O
recognition	O
.	O
</s>
<s>
The	O
theory	O
was	O
developed	O
by	O
the	B-Application
artificial	I-Application
intelligence	I-Application
pioneer	O
Oliver	O
Selfridge	O
in	O
1959	O
.	O
</s>
<s>
Pandemonium	B-Algorithm
architecture	I-Algorithm
arose	O
in	O
response	O
to	O
the	O
inability	O
of	O
template	B-Algorithm
matching	I-Algorithm
theories	I-Algorithm
to	O
offer	O
a	O
biologically	O
plausible	O
explanation	O
of	O
the	O
image	O
constancy	O
phenomenon	O
.	O
</s>
<s>
The	O
basic	O
idea	O
of	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
is	O
that	O
a	O
pattern	O
is	O
first	O
perceived	O
in	O
its	O
parts	O
before	O
the	O
"	O
whole	O
"	O
.	O
</s>
<s>
Pandemonium	B-Algorithm
architecture	I-Algorithm
was	O
one	O
of	O
the	O
first	O
computational	B-Application
models	I-Application
in	O
pattern	O
recognition	O
.	O
</s>
<s>
Although	O
not	O
perfect	O
,	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
influenced	O
the	O
development	O
of	O
modern	O
connectionist	O
,	O
artificial	B-Application
intelligence	I-Application
,	O
and	O
word	O
recognition	O
models	O
.	O
</s>
<s>
The	O
earliest	O
theory	O
that	O
attempted	O
to	O
explain	O
how	O
we	O
recognize	O
patterns	O
is	O
the	O
template	B-Algorithm
matching	I-Algorithm
model	O
.	O
</s>
<s>
Although	O
some	O
machines	O
follow	O
a	O
template	B-Algorithm
matching	I-Algorithm
model	O
(	O
e.g.	O
,	O
bank	O
machines	O
verifying	O
signatures	O
and	O
accounting	O
numbers	O
)	O
,	O
the	O
theory	O
is	O
critically	O
flawed	O
in	O
explaining	O
the	O
phenomena	O
of	O
image	O
constancy	O
:	O
we	O
can	O
easily	O
recognize	O
a	O
stimulus	O
regardless	O
of	O
the	O
changes	O
in	O
its	O
form	O
of	O
presentation	O
(	O
e.g.	O
,	O
T	O
and	O
T	O
are	O
both	O
easily	O
recognized	O
as	O
the	O
letter	O
T	O
)	O
.	O
</s>
<s>
As	O
a	O
result	O
of	O
the	O
biological	O
plausibility	O
criticism	O
of	O
the	O
template	B-Algorithm
matching	I-Algorithm
model	O
,	O
feature	O
detection	O
models	O
began	O
to	O
rise	O
.	O
</s>
<s>
The	O
best	O
known	O
feature	O
detection	O
model	O
is	O
called	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
.	O
</s>
<s>
The	O
pandemonium	B-Algorithm
architecture	I-Algorithm
was	O
originally	O
developed	O
by	O
Oliver	O
Selfridge	O
in	O
the	O
late	O
1950s	O
.	O
</s>
<s>
+	O
The	O
four	O
major	O
processing	O
stages	O
of	O
pandemonium	B-Algorithm
architecture	I-Algorithm
Stage	O
Demon	O
nameFunction	O
1	O
Image	O
demon	O
Records	O
the	O
image	O
that	O
is	O
received	O
in	O
the	O
retina	O
.	O
</s>
<s>
Similar	O
findings	O
were	O
discovered	O
in	O
frogs	B-Algorithm
,	O
octopuses	O
and	O
a	O
variety	O
of	O
other	O
animals	O
.	O
</s>
<s>
Octopuses	O
were	O
discovered	O
to	O
be	O
only	O
sensitive	O
to	O
verticality	O
of	O
lines	O
,	O
whereas	O
frogs	B-Algorithm
demonstrated	O
a	O
wider	O
range	O
of	O
sensitivity	O
.	O
</s>
<s>
Moreover	O
,	O
this	O
architecture	O
is	O
capable	O
of	O
learning	O
,	O
similar	O
to	O
a	O
back-propagation	O
styled	O
neural	B-Architecture
network	I-Architecture
.	O
</s>
<s>
In	O
principle	O
,	O
a	O
pandemonium	B-Algorithm
architecture	I-Algorithm
can	O
recognize	O
any	O
pattern	O
.	O
</s>
<s>
Generally	O
,	O
the	O
results	O
from	O
these	O
experiments	O
matched	O
the	O
error	O
predictions	O
from	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
.	O
</s>
<s>
A	O
major	O
criticism	O
of	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
is	O
that	O
it	O
adopts	O
a	O
completely	O
bottom-up	O
processing	O
:	O
recognition	O
is	O
entirely	O
driven	O
by	O
the	O
physical	O
characteristics	O
of	O
the	O
targeted	O
stimulus	O
.	O
</s>
<s>
Although	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
is	O
built	O
on	O
the	O
fact	O
that	O
it	O
can	O
account	O
for	O
the	O
image	O
constancy	O
phenomena	O
,	O
some	O
researchers	O
have	O
argued	O
otherwise	O
;	O
and	O
pointed	O
out	O
that	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
might	O
share	O
the	O
same	O
flaws	O
from	O
the	O
template	B-Algorithm
matching	I-Algorithm
models	O
.	O
</s>
<s>
Thus	O
we	O
might	O
end	O
up	O
with	O
a	O
system	O
that	O
requires	O
a	O
large	O
number	O
of	O
cognitive	O
demons	O
in	O
order	O
to	O
produce	O
accurate	O
recognition	O
,	O
which	O
would	O
lead	O
to	O
the	O
same	O
biological	O
plausibility	O
criticism	O
of	O
the	O
template	B-Algorithm
matching	I-Algorithm
models	O
.	O
</s>
<s>
However	O
,	O
it	O
is	O
rather	O
difficult	O
to	O
judge	O
the	O
validity	O
of	O
this	O
criticism	O
because	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
does	O
not	O
specify	O
how	O
and	O
what	O
features	O
are	O
extracted	O
from	O
incoming	O
sensory	O
information	O
,	O
it	O
simply	O
outlines	O
the	O
possible	O
stages	O
of	O
pattern	O
recognition	O
.	O
</s>
<s>
Some	O
researchers	O
have	O
also	O
pointed	O
out	O
that	O
the	O
evidence	O
supporting	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
has	O
been	O
very	O
narrow	O
in	O
its	O
methodology	O
.	O
</s>
<s>
Additionally	O
,	O
some	O
researchers	O
have	O
pointed	O
out	O
that	O
feature	O
accumulation	O
theories	O
like	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
have	O
the	O
processing	O
stages	O
of	O
pattern	O
recognition	O
almost	O
backwards	O
.	O
</s>
<s>
The	O
pandemonium	B-Algorithm
architecture	I-Algorithm
has	O
been	O
applied	O
to	O
solve	O
several	O
real-world	O
problems	O
,	O
such	O
as	O
translating	O
hand-sent	O
Morse	O
codes	O
and	O
identifying	O
hand-printed	O
letters	O
.	O
</s>
<s>
Based	O
on	O
the	O
original	O
pandemonium	B-Algorithm
architecture	I-Algorithm
,	O
John	O
Jackson	O
has	O
extended	O
the	O
theory	O
to	O
explain	O
phenomena	O
beyond	O
perception	O
.	O
</s>
<s>
This	O
multiple	O
agent	O
approach	O
to	O
human	O
information	O
processing	O
became	O
the	O
assumption	O
for	O
many	O
modern	O
artificial	B-Application
intelligence	I-Application
systems	O
.	O
</s>
<s>
Although	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
arose	O
as	O
a	O
response	O
to	O
address	O
a	O
major	O
criticism	O
of	O
the	O
template	B-Algorithm
matching	I-Algorithm
theories	I-Algorithm
,	O
the	O
two	O
are	O
actually	O
rather	O
similar	O
in	O
some	O
sense	O
:	O
there	O
is	O
a	O
process	O
where	O
a	O
specific	O
set	O
of	O
features	O
for	O
items	O
is	O
matched	O
against	O
some	O
sort	O
of	O
mental	O
representation	O
.	O
</s>
<s>
The	O
critical	O
difference	O
between	O
the	O
two	O
is	O
that	O
the	O
image	O
is	O
directly	O
compared	O
against	O
an	O
internal	O
representation	O
in	O
the	O
template	B-Algorithm
matching	I-Algorithm
theories	I-Algorithm
,	O
whereas	O
with	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
,	O
the	O
image	O
is	O
first	O
diffused	O
and	O
processed	O
at	O
the	O
featural	O
level	O
.	O
</s>
<s>
This	O
granted	O
pandemonium	B-Algorithm
architectures	I-Algorithm
tremendous	O
power	O
because	O
it	O
is	O
capable	O
of	O
recognizing	O
a	O
stimulus	O
despite	O
its	O
changes	O
in	O
size	O
,	O
style	O
and	O
other	O
transformations	O
;	O
without	O
the	O
presumption	O
of	O
an	O
unlimited	O
pattern	O
memory	O
.	O
</s>
<s>
It	O
is	O
also	O
unlikely	O
that	O
the	O
template	B-Algorithm
matching	I-Algorithm
theories	I-Algorithm
will	O
function	O
properly	O
when	O
faced	O
with	O
realistic	O
visual	O
inputs	O
,	O
where	O
objects	O
are	O
presented	O
in	O
three	O
dimensions	O
and	O
often	O
occluded	O
by	O
other	O
objects	O
(	O
e.g.	O
,	O
half	O
of	O
a	O
book	O
is	O
covered	O
by	O
a	O
piece	O
of	O
paper	O
,	O
but	O
we	O
can	O
still	O
recognize	O
it	O
as	O
a	O
book	O
with	O
relative	O
ease	O
)	O
.	O
</s>
<s>
Not	O
surprisingly	O
,	O
the	O
results	O
often	O
favored	O
a	O
hierarchal	O
feature	O
building	O
model	O
like	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
.	O
</s>
<s>
The	O
Hebbian	O
model	O
resembles	O
feature-oriented	O
theories	O
like	O
the	O
pandemonium	B-Algorithm
architecture	I-Algorithm
in	O
many	O
aspects	O
.	O
</s>
