Nosewitness identification: effects of negative emotion.

Laura Alho,Mats J Olsson,Marta Rocha,Sandra C Soares,Carlos F Silva,Jacqueline Ferreira,Veronika Schöpf

doi:10.1371/journal.pone.0116706

Abstract

Every individual has a unique body odor (BO), similar to a fingerprint. In forensic research, identification of culprit BOs has been performed by trained dogs, but not by humans. We introduce the concept of nosewitness identification and present the first experimental results on BO memory in witness situations involving violent crimes. Two experiments indicated that BO associated with male characters in authentic videos could later be identified in BO lineup tests well above chance. Moreover, culprit BO in emotional crime videos could be identified considerably better than the BO of a male person in neutral videos. This indicates that nosewitness identification benefits from emotional encoding. Altogether, the study testifies to the virtue of body odor as a cue to identify individuals observed under negative emotion.

Highlights

Trained dogs can distinguish between any two individuals and have been used in forensic settings to match a scent left at the crime scene by a possible suspect [9,10,11]
We explored nosewitness identification following violent and emotional videos of crimes
Olfactory lineup identification performance was significantly better following emotional videos compared to neutral ones

Summary

Introduction

Determinants of body odor are diet [1], age [2], hormonal status [3], parasite load [4], and foremost and pertinent to this study, genetic factors. The major histocompatibility complex (MHC) is a gene cluster that constitutes the main factor in determining immunological individuality. Humans have the ability to match body odors of monozygotic twins, even when they are living apart (i.e., exposed to different environments), which reinforces the role of odors in communicating individuality and genetic information [7]. Trained dogs can distinguish between any two individuals (possibly including monozygotic twins [8]) and have been used in forensic settings to match a scent left at the crime scene by a possible suspect [9,10,11]

Methods

Results

Conclusion