Halloween is our chance to role play, misbehave and scare each other silly. We swap our regular clothes for colourful spandex, capes, wigs and elaborate makeup, exposing ourselves to disgust, horror and fantasy. Of course the costumes and props of Halloween are symbolic and don’t pose any real threat; they provide safe thrills. But what is it about this custom of candies and costumes that makes it so exciting? Psychologist Dr Chua Sook Ning explores the psychology of Halloween.