Gretchen brought Peggy in this morning to say hello. I was taking a
bath. Her attention was distracted by a moth fluttering across the
bathroom. Peggy pointed excitedly [fly…fly]. I thought she referred to
the moth as a fly. Peggy pointed to the moth again: [ant fly].

Relevance: This incident shows, however “standard” some part of
Peggy’s speech production is, just how much interpretation is required
to understand her sense of what she says.

As another example of sequential speech, it goes against a topic and
comment expressive structure. The comment “fly” about the “ant”
manifestly preceded the latter as a focus of attention. Unless some
topic and comment structure can propose a model of flux of form from
one topic to the next, how can it be understood ?