Before The Question Ends: Provisional Answer Formation In Language Models

A language model may form an answer preference before a question is complete. Whether this early preference causally influences its final decision after question completion remains unclear. In binary Yes/No question answering, we introduce the preference score (PS) as a behavioral measure of provisional answer preference. Across four models, final-answer accuracy is lower when the correct answer conflicts with the early preference than when it aligns with that preference. To examine the causal role of provisional answer preference, we intervene on question-prefix representations and find that they carry this preference and influence final-answer computation. At the circuit level, question-prefix circuits selected solely for their contribution to final-answer computation also carry provisional preference. Steering against the early preference and suppressing these circuits both make final decisions less likely to follow the initially favored answer. Our findings provide causal evidence that preferences formed before question completion bias final decisions even after the complete question is available.