Loss aversion isn't just a behavioral pattern observed from the outside — it has a measurable neural signature. When people make choices framed either as "keeping" part of an initial amount or "losing" part of it, even though the underlying mathematical options are completely identical, brain-imaging shows different regions activating depending on the frame, with loss-framed choices driving stronger activity in the amygdala, a region closely tied to emotional and threat processing.
This matters because it rules out a tempting alternative explanation for framing effects — that they're merely a quirk of how survey questions get answered, with no deeper psychological reality behind them. The neural evidence shows the loss frame isn't just changing what people say; it's changing what's actually happening in the brain in response to a mathematically identical choice.