the lamp reads the lie
which is a brass-faced falsehood and dismissed as such by R. Tine Jr., and so the light stays right on Molly Notkin’s glabrous unhappy face
Context
The lamp is not just atmosphere but instrument. When Notkin claims she could help more if they'd only kill the light, Tine Jr. reads the request as "a brass-faced falsehood" — a bid to escape scrutiny — and answers by leaving the light exactly where it is, later escalating to "a much higher wattage" as the interviewers' patience thins. The engagement is a reading contest: the source manages what her face shows, the officer manages how much light is on it, and every attempt to dim the exposure is itself taken as data.