Most perception and judgment happens before conscious awareness kicks in

Mlodinow argues that the brain processes vastly more sensory and social information unconsciously than it ever brings into conscious awareness, meaning that by the time a person consciously notices a feeling or forms a judgment, extensive unconscious processing has often already determined much of its content and direction. He cites research showing the brain makes rapid, automatic assessments of things like a stranger's trustworthiness or competence within a fraction of a second of seeing their face, well before any conscious deliberation begins.

This isn't framed as a flaw or malfunction; Mlodinow presents unconscious processing as generally efficient and adaptive, evolved to handle the overwhelming volume of information the brain receives at every moment, since conscious deliberation over every detail would be far too slow for functioning in real time.

The unsettling implication is that conscious reasoning, which people experience as the source of their judgments, often actually arrives after the unconscious has already done most of the real work, leaving consciousness to interpret or justify a conclusion already substantially formed.

Takeaway: by the time you consciously form an opinion, your unconscious mind has usually already done most of the deciding.