Surprise effect
The surprise effect is the disproportionate weight the mind gives to what it did not predict, which is why an unexpected small detail is remembered when hours of competent work are not.
How it works
Attention is spent on error, not on quality. The brain runs a prediction of what should be happening and pays only for the parts that came back wrong, so the expected is compressed to nothing and the unexpected carries the freight. A warm cookie at check-in survives fourteen years in a memory that has lost everything else about the stay, and it works precisely because no reasonable process would have approved it. One of the talks puts the multiplier on emotion at several times, attributed to survey analysis and stated without its bounds.
What it changes for a personal brand
Find the single moment where someone deals with you and expects nothing, such as the reply to a first message or the thing they get after they subscribe, and put something there that nobody would put in a plan. It does not have to be big. It has to be unpredicted, and it has to stay slightly unscalable.