load and children's language processing

[Brian MacWhinney]

Dear Info-CHILDES,
     Julie Lewis from UBC asked me whether I could point her to some
studies of the effects of processing load on language processing in
children and I was surprised to admit to myself that I could not think
of a consistent attempt to examine this issue.  Specifically, in the
framework of the theory of automaticity espoused by Schneider and
Shiffrin (1977) increases in processing load created by the imposition
of a dual task (saying "kestral-kestral",  tapping your foot, counting
back from 100 by threes, etc.) are supposed to have various interesting
interactions with non-automatic tasks, but little impact on automated
tasks.  There is, of course, the Gathercole and Baddeley work on
phonological interference in list memory, but this hardly gets to the
level of sentence memory or processing.  Moreover, only a small
fraction of that work is with children.  Gupta. MacWhinney, and Feldman
did some work with children with focal lesions, and Evans did parallel
work with SLI, but never really focusing on dual tasks. Instead, most
of this work uses work memory capacity as an individual differences
measure.  Liz Bates and Arturo Hernandez did a nice study with load and
adult bilinguals, but that is back into the adult literature.  Maybe
people have just found that kids cannot handle dual tasks.
    It would seem that processing load studies would be an excellent way
of tapping into issues in the study of SLI and perhaps Dorothy Bishop
did some of this, but I can't think of the study.
   So, can any of you out there help us out with references or ideas.
If these studies have not been done, either with normals or SLI, maybe
it is time to do them.

--Brian MacWhinney