A new study has found that our sense of smell may be just as reliable as sight when it comes to identifying a criminal. For example, if you got a whiff of a man’s body odor right as he ran up and snatched your purse, you may be able to pick him out of a line-up based on his smell.
The reasoning behind this is that our sense of smell is directly linked to the areas of the brain associated with emotion and memory: the hippocampus and the amygdala. Furthermore, research has shown that humans have the ability to distinguish individuals by their unique body odor.
“Police often use human eye-witnesses, and even ear-witnesses, in lineups but, to date, there have not been any human nose-witnesses,” said Professor Mats Olsson, experimental psychologist at the Karolinska Institutet in Sweden. “We wanted to see if humans can identify criminals by their body odor.”
To gain a better understanding of human odor memory associated with stressful events, the researchers investigated how well we identify body odor in a forensic setup. In their first study, participants watched video clips of people committing violent crimes, accompanied by a body odor that they were told belonged to the criminal.
The participants were also shown neutral videos, with a similar setup. Then they identified the criminal’s body odor from a lineup of five different men’s odors with 70 percent accuracy.
“It worked beyond my expectation,” explained Olsson. “Most interestingly — participants were far better at remembering and identifying the body odor involved in the emotional setting.”
Next the researchers conducted the same experiment but varied the lineup size (three, five, and eight body odors), and the time between observing the videos and looking at the lineup (from just 15 minutes up to one week). In lineups of up to eight body odors, participants were still able to identify the perpetrator.
The accuracy of their identification did reduce with the larger lineup size, which is similar to results using eye and ear-witnesses. The findings also show that the ability to distinguish the criminal’s body odor is significantly impaired if the lineup is conducted after one week of having smelled the offender’s body odor.
While there is quite a bit of research into how emotion can affect one’s memory of a crime scene, it is largely focused on sight memory as visual lineups are the common method of criminal identification.
“Our work shows that we can distinguish a culprit’s body odor with some certainty,” said Olsson. “This could be useful in criminal cases where the victim was in close contact with the assailant but did not see them and so cannot visually identify them.”
The new findings are published in the journal Frontiers in Psychology.