This study examined investigators' perceptions of the reliability of incriminating and exonerating evidence of different types. Police trainees in the role of investigators read the background of a homicide case and then received a piece of evidence that either confirmed or disconfirmed their prior suspicion against the suspect. Despite identical objective characteristics of the evidence, participants rated the disconfirming (vs. confirming) evidence as less reliable and generated more arguments to question its reliability. This asymmetrical scepticism was stronger for participants judging witness evidence, compared to DNA and photo evidence, supporting the hypothesis that different types of evidence vary in 'elasticity'-the extent to which subjective interpretations can be justified. Interestingly, the observed effects were not limited to the specific evidence in the case, but also affected the ratings of the type of evidence in general, suggesting that reliability criteria for witness information are highly malleable and sensitive to contextual influences.

Previous research has shown that exposure to social information can influence behaviour through the automatic activation of goals. In the first study to examine such influences in a legal setting, an experiment with 104 experienced criminal investigators tested the idea that exposure to occupational norms can activate distinct information-processing goals. As predicted, exposure to norms associated with efficiency (vs. thoroughness) sped up and reduced the depth of investigators' processing of criminal evidence, thus reducing their openness to sequentially late witness evidence. In addition, the goal activation operated outside investigators' awareness, illustrating the insidious cognitive influence of occupational norms. The results are discussed in terms of practical significance and contributions to the goal activation literature and the applied study of criminal investigations.

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