Unattended streams

[Al Bregman <BREGMAN@xxxxxxxxxxxxxxx>]

Dear Michael,

I believe you are right to argue that the background streams are
at least partially organized, but it's a hard question to attack
experimentally.  You may have given a hint as to how to go about
it when you wrote: "you can switch attention from a foreground
stream A to one of a pair of background streams B and C in less
time than it takes for two streams to form from B and C without A
(though I haven't found a published ref for this)."  In other
words, we know that it takes time (T) for a stream to form.  If
switching attention allows the system to skip the T interval, it
suggests that the switched-to stream was already formed.  So far
as I know, the only person to attack this problem by getting
subjects to switch streams is Bob Carlyon.  His results seem to
imply that there is no (background) stream until the switch
occurs.  [Bob, is there an online version of your article that
interested persons could read?]  His results seem to be at odds
with Elyse Sussman's
findings with evoked potentials (method of mismatch negativity)
that show that an unattended stream still evinces "surprise" when
the order (but not the identities) of tones in the stream
changes.  It is hard to reconcile these two findings as well as
the everyday experience recounted by you.  Clearly more thinking
and research are in order.


Al

----------------------------------------------------------------
Albert S. Bregman, Emeritus Professor
Psychology Dept., McGill University
1205 Docteur Penfield Avenue
Montreal, QC, CANADA  H3A 1B1

Office:
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  Fax:+1 (514) 398-4986

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Michael Norris wrote:

> Has anyone looked into what qualities of the organization of
unattended
> streams differ from the attended stream? I believe that the
background
> streams are organized to some extent because (from my own
informal
> experiments) you can switch attention from a foreground stream
A to one
> of a pair of background streams B and C in less time than it
takes for
> two streams to form from B and C without A (though I haven't
found a
> published ref for this). The question then is in what ways are
the
> background streams less organized than the foreground?
>
> -m.




-------------------------------------------------
Albert S. Bregman, Emeritus Professor
Dept of Psychology, McGill University
1205 Docteur Penfield Avenue
Montreal, QC, Canada H3A 1B1

Office:
     Phone:  +1 (514) 398-6103
     Fax: +1 (514) 398-4896
Home:
     Phone & Fax: +1 (514) 484-2592
Email:
     bregman@psych.mcgill.ca
-------------------------------------------------