Expectations or Perceptual Sets

Our expectations about what we are likely to perceive in a given situation also shape our actual perception. This tendency -- sometimes called perceptual familiarisation or perceptual generalisation -- reflects a strong pull toward seeing what we already expect to see, even in cases where the results do not accurately reflect what is really there. A simple, everyday example makes this vivid: if a milkman regularly delivers milk to a household at about 5.30 a.m. every day, then any knocking sound heard around that same time is likely to be immediately interpreted as "the milkman", even on an occasion when it is actually someone else entirely. …