When emotions get the better of us: the effect of contextual top-down processing on matching fingerprints

Abstract

Twenty-seven participants made a total of 2,484 judgments whether a pair of fingerprints matched or not. A quarter of the trials acted as a control condition. The rest of the trials included top-down influences aimed at biasing the participants to find a match. These manipulations included emotional background stories of crimes and explicitly disturbing photographs from crime scenes, as well as subliminal messages. The data revealed that participants were affected by the top-down manipulations and as a result were more likely to make match judgments. However, the increased likelihood of making match judgments was limited to ambiguous fingerprints. The top-down manipulations were not able to contradict clear non-matching fingerprints. Hence, such contextual information actively biases the ways gaps are filled, but was not sufficient to override clear bottom-up information.The need to identify people accurately is widespread and is on a sharp rise. With advances in science and technology a variety of tools are now available for identifying people. Nevertheless, fingerprints continue to be the major method used for identification in forensic and other domains (Alam, Akhteruzzaman, & Cherri, 2004). Fingerprints are quite easy to find, collect, and process; and they are also relatively non-intrusive and cost effective. With the development and increased use of computer technology in searching very large amounts of fingerprints held in databases, fingerprints are likely to continue to be the major method for biometric identification, and we can perhaps even expect its use to increase further.The strength of fingerprint identification also derives from perceived reliability. The use of fingerprints has evolved over a long period of time and for over 100 years fingerprints have been used quite successfully as a means of identification. The reliability of fingerprint evidence stems from applied scientific knowledge of the uniqueness of friction ridge skin within the fields of biology, embryology, and genetics. During all this time there has not been a single reported case of two people having identical fingerprints (even identical twins have differentiated fingerprints). Fingerprint identification seems to have withstood the test of time and proven itself as a sound and authoritative tool. Consistent with the above,

Cognitive bias in line-up identifications: The impact of administrator knowledge

“…The mounting body of evidence that cognitive and subjective biases are likely to resonate throughout the forensic and investigative sciences [2,3,4,5] means that practitioners cannot stay 'blind' to the value of blind testing for much longer. For, as Krane et al [3] observe; the full potential and value of forensic testing will only be realised if cognitive bias and related expectancy and subjectivity effects are minimised throughout the process.…”

“…Whilst the potential for biases and subjectivity effects in forensic science disciplines has been discussed for a number of years [1,2,3] only recently has the question of the true objectivity of forensic practices come to the fore [4], largely as a result of the National Academy of Science (NAS) report on Strengthening Forensic Science in the United States [4]. A number of empirical studies have begun to emerge which, between them, demonstrate the range of impacts that practitioners can have on the reliability and consequent validity of evidential evaluations [4,6].…”

The vision in "blind" justice: Expert perception, judgment, and visual cognition in forensic pattern recognition

“…A recent study utilizing signal detection theory (SDT) reported three experiments whose aim was to examine the extent to which people can correctly by a human expert. But since the AFIS examines millions of prints, it is not a surprise that similar look-alike prints are found by the mere scope of the search (Cole, 2005;Dror & Mnookin, 2010;Dror et al, 2005). The similarity makes it easier for cognitive biases to take over and affect the identification decisions.…”

“…Furthermore, for the ambiguous prints, in the control group that did not include any background information, 47% of the prints were judged to be from the same source. When the same prints were presented in the lowemotional context, 49% were judged to be from the same source, whereas in the high-emotional context, 58% were judged to be from the same source (for details, see Dror et al, 2005).…”

“…To study whether emotional context can affect judgment on fingerprints, Dror et al (2005) presented pairs of prints to psychology student participants, who were required to decide whether or not the two prints originated from the same source. The participants (N 27) received 96 pairs of prints (48 of them were clearly from the same source or clearly not from the same source, and 48 were ambiguous).…”