Conversational norms
Also known as: Gricean maxims, Conversational maxims, Logic of conversation
Listeners assume everything mentioned is relevant, so asking changes what an answer means.
What it means
Conversational norms are the tacit rules of cooperative communication that lead listeners to assume a speaker is being informative, truthful, relevant, and clear, and so to infer far more than the literal words say. Grice framed them as maxims: say enough but not too much, say what you believe true, stay relevant, be orderly. The mechanism carries over from talk to questionnaires, instructions, and interfaces, because people presume that whatever has been put in front of them was put there for a reason. This generates effects that look like irrationality but are sound inference from a bad cue: irrelevant details get used because their mention implies relevance, earlier questions set the topic for later ones, and response scales are read as the researcher's picture of normal behavior. Many classic 'biases' shrink once the conversational cue is stripped out. It matters because no question is ever neutral—asking is itself a message.
Examples
Asked how much television they watch, people report more hours when the scale tops out at 'over four hours' than when it tops out at 'over two and a half.'
An interviewer asks a candidate, 'any concerns about the commute?' She infers the commute must be a known problem and begins weighing an obstacle she had not considered at all.
A doctor asks during a routine check, 'have you been sleeping badly?' The patient infers sleep must bear on his symptoms and recalls worse nights than he would have volunteered.
First described in Grice (1975); Schwarz (1994) applied to judgment.