Attenuating information in spoken communication: For the speaker, or for the addressee?

Speakers tend to attenuate information that is predictable or repeated. To what extent is
this done automatically and egocentrically, because it is easiest for speakers themselves,
and to what extent is it driven by the informational needs of addressees? In 20 triads of
naive subjects, speakers told the same Road Runner cartoon story twice to one addressee
and once to another addressee, counterbalanced for order (Addressee1/Addressee1/
Addressee2 or Addressee1/Addressee2/Addressee1). Stories retold to the same (old)
addressees were attenuated compared to those retold to new addressees; this was true
for events mentioned, number of words, and amount of detail. Moreover, lexically identical
expressions by the same speaker were more intelligible to another group of listeners when
the expressions had been addressed to new addressees than when they had been
addressed to old addressees. We conclude that speakers’ attenuating of information in
spontaneous discourse is driven at least in part by addressees. Such audience design is computationally
feasible when it can be guided by a ‘‘one-bit” model (my audience has heard
this before, or not).