A notion is a lightweight mental sensation. Instinct pulses from our lower brain. We may have these notions and instincts UNTIL we “consider… florists and bakers,” but “consider” implies some serious contemplation, and Greenhouse’s use of “until” suggests that she thinks that the instant we see the names of those lowly occupations — florists and bakers — we will shake off the notions and instincts and know that the “expression” template is wrong. But she hasn’t considered it, and she doesn’t expect her readers to consider it. She is whipping up snobbery for people who are engaged in expressive work.