'Assisting' listeners to hear words that aren't there: dangers in using police transcripts of indistinct covert recordings

Results are reported of a new experiment using an indistinct covert recording from a real murder trial, along with the police transcript admitted to ‘assist’ the court to hear its contents. Previous research using the same material has shown that the police transcript is inaccurate, yet nevertheless highly influential on the perception of listeners ‘primed’ by seeing words it suggests. The current experiment examines the effects of priming participants with a made-up phrase that vaguely fits the acoustics of one section of the recording. Results indicate that a very high proportion of listeners are easily ‘assisted’ to ‘hear’ the made-up phrase. Discussion argues that audio of this quality should only be used as evidence if accompanied by a reliable independent transcript.