The identification of individuals by observational gait analysis using closed circuit television footage: comparing the ability and confidence of experienced and non-experienced analysts

Ivan Birch, Maria Birch, Nadia Asgeirsdottir

Research output: Contribution to journalArticle

Abstract

Gait is known to have been used as evidence since 1839, initially based on the apocryphal belief that a person can be identified by their gait. The potential uniqueness of gait has yet to be proven, and therefore gait is currently considered to be a contributor to identification rather than a method of identification. In 2013 Birch et al. [1] published the findings of an investigation into the ability of individuals with experience in gait analysis to identify people by observing features of gait recorded by closed circuit television cameras. The study showed that the participants made correct decisions in 71% of cases, significantly better than would have been expected to have occurred by chance. However, the presentation of gait evidence is not limited to witnesses with experience in gait analysis. This study compared the abilities and confidence of participants with experience in gait analysis with those of participants with no experience of gait analysis using the methodology of Birch et al. 2013 [1]. The results showed no statistically significant difference in the number of correct identification decisions made by the two groups of participants, although the participants with experience of gait analysis made slightly more false negative than false positive decisions, whereas the participants with no experience made more false positive than false negative decisions. The participants with no experience in gait analysis reported significantly more confidence in their decisions than did the participants with experience (p < 0.05). The results suggest that lay people giving gait based evidence are likely to be more confident in their assertions as to identity based on that evidence, than would a witness with experience of gait analysis. Careful consideration therefore needs to be given to the submission of gait based evidence by lay witnesses.
Original languageEnglish
Pages (from-to)79-85
Number of pages6
JournalScience and Justice
Volume60
Issue number1
DOIs
Publication statusPublished - 22 Oct 2019

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