abc123Priming is a fascinating phenomenon well known to all branches of cognitive psychology, and becoming more familiar to the general public, under headings such as ‘cognitive bias’ and ‘suggestibility’.

The effect of context

We say priming has occurred when expectations created by the context in which a person sees or hears something cause them to perceive it in a particular way, different from the way they would perceive it in another context.

Priming in speech perception

The tendency for the perception of speech to be primed by contextual expectations is less well known by the community at large. Indeed speech priming operates in somewhat different ways from general psychological priming, sometimes not well understood even by scientists from other disciplines.

Though many have experienced deliberate priming of a humorous kind, there is little recognition of the implications for the legal system.

However, the effect of priming – especially, but not only, on poor quality recordings – is very well established within phonetic science. Here’s a brief account of one famous study from the 1950s that helps explain the concept and demonstrate its power.

More recently, the effect of priming has been demonstrated specifically to convince a (rightly) sceptical legal system, using  disputed utterances from real cases, in the crisis call experiment and the PACT experiments.

These have confirmed, among other interesting results:

  1. how easy it is for listeners’ perception to be unknowingly influenced by a transcript, especially when it is given in the context of a story about a crime – even if the transcript is clearly inaccurate;
  2. how hard it is for this effect to be reversed, even when listeners are provided with an alternative transcript that is objectively more plausible;
  3. how much the effect flows on to influence opinions about guilt and innocence.

These findings emphasise the danger of allowing evaluation of poor quality covert recordings to be ‘a matter for the jury’. Our case study on this site shows a dramatic real-life example of a judge allowing himself to be primed by a police transcript.

Evaluation of covert recordings is not a matter for personal opinion, any more than evaluation of DNA or fingerprint evidence is a matter for personal opinion. There is a fact of the matter regarding what was said and what it means, which can potentially be determined through scientific analysis by an expert in phonetics and linguistics. If it can’t be determined, the evidence should be deemed inconclusive, like a smudged fingerprint, or inconclusive DNA evidence – not left for the jury to evaluate for themselves.

Putting the responsibility to evaluate a transcript on the jury is not fair to the jury, let alone to the defendant. The only way to be sure that inaccurate or otherwise unreliable transcripts do not influence a jury is to design the system so that juries are never exposed to them.

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