From: Ben Houston (ben@exocortex.org)
Date: Wed Apr 10 2002 - 20:25:30 MDT
Eliezer S. Yudkowsky wrote:
> Ben Houston wrote:
> > I enjoyed Deacon's stuff as well. :-) I choose to review Deacon's
book,
> > M Donald's "Origins of the Modern Mind" and W Calvin's "How the
Brain
> > Things" for one of my core cognitive sciences courses back in early
> > 2000. Although, I found Deacon's work was worthwhile and
interesting I
> > found I preferred Donald's work.
>
> What'd you think of my alternate formulation for Deacon's "awkward
step"
> using DGI's levels of organization and functional decomposition
instead of
> the iconic-indexical-symbolic model Deacon was stuck with?
You'll have to give me some time for a reply to that one. :-) I looks
like I might have to read something to answer that well.
> > Interesting. :-) I've never had many problems with understanding
the
> > neural substrates of the phenomena of "internal narrative." I
guess I
> > has just assumed that it was realized by the same systems that were
> > responsible for the phonological loop and normal linguistic output
with
> > the exception of the [phonological-code to motor-plan] and
[motor-plan
> > to movement] "modules". (I am just regurgitating the seminal Levelt
> > framework.)
>
> I'm not just talking about hearing the words "I want ice cream" in
your
> head; when I talk about the internal narrative I mean the internal
> narrative
> as one manifestation of the deliberation process - I'm talking about
> actually wanting ice cream and how that gives rise to the concept
> structure
> "I want ice cream" and what the concept structure does internally
aside
> from
> echoing linguistically in the auditory cortex. That's what I mean
when I
> say that auditory working memory may observe the internal narrative
but
> does
> not implement it.
I think that it is a mistake to believe that you can actually "want ice
cream" at lower levels of cognition.
The wanting of "ice cream" can just be a conceptual interpretation of a
specific lower-level biological desire. All the evidence suggests that
most nutritional desires are realized in the thalamus very precisely in
term of sugar/sweets, fat, liquid, etc.... As has been shown the
thalamus can influence the brain reward system of the NAc/VTA. This
modulation can make concepts that are associated with fulfillment of
specific needs more desirable. Soon as the motivational system starts
to bias towards specific thoughts it doesn't take too long for us to get
on to thinking in that area. These thoughts can also be triggered by
"not feeling well" which in turn results in a conscious "search" for
plausible causes. Such a conscious search of plausible causes usually
results in our realization that we want a specific thing because
thinking about it seems "right" as a result of the motivation/reward
bias. As we know the NAc/VTA system can play a role in modulating
attention in regards to predicted rewards (via NAc->VTA->PFC
projections) and thus this may explain why such desires seem to
monopolize our attention sometimes.
VTA: ventral tegmental system
NAc: nucleus accumbens
PFC: prefrontal cortex
DA: dopamine
Also, I must add that sometimes the desire for ice cream can arise
without any underlying biological need. Such a desire could be
triggered by an activation of the brain reward system directly by the
concept (if thought or seen, etc...) if it has been previously resulted
in "pleasure" (actual or vicarious) (realized as DA release in the NAc).
In that case we can view the desire as resulting from basically
reinforcement learning or in some cases conditioning.
But looking at how concepts are triggered by internal vocalizations: I
believe that the internal vocalizations are interpreted by the standard
linguistic interpretation "modules" in and around Wernicke's area.
(Again I am just repeating from Levelt's work.) Like speech from
external sources, this internally generated speech triggers, as a
product of its interpretation, various "concepts". Most importantly,
these concepts triggered during the interpretation do not have to
correspond to the concepts that were responsible for the construction of
the speech -- this is the neat "feature" that makes this mechanism to
useful in thought.
Does this concept of "internal narrative" resemble Daniel Dennett's
concept of "Cartesian Theater"?
I don't think I answered that question well. I guess I still do not
totally understand what you are getting at.
-ben houston
http://www.exocortex.org/dsp
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