According to the dual-process theory, moral decisions result from either one of two distinct mental processes.
The automatic-emotional process is fast and unconscious, giving way to intuitive behaviours and judgments. Deontological decisions are of this type - it feels wrong to lie, so we believe it is.
The conscious-controlled process involves slow and deliberative reasoning. In ignoring the immediate emotional features of decision-making, instead one draws from general knowledge and abstract moral conceptions. Combined with a more controlled analysis of situational features, it is often considered a utilitarian approach.