Sensory Marketing – the Power of Smell to Affect Behaviour


Research into sensory processing has predominantly centred on the visual sense.  In the last decade however, there has been a surge of interest in olfaction, the sense of smell. Although the sense of smell in humans is considered weak and feeble in comparison to other mammals it is still remarkably sophisticated and impacts mostly at an unconscious level on emotion, cognition and action1. Much of this work has focused on findings related to the ability of smell to change behaviour. Marketing people have known this for many years, piping the smell of freshly baked bread around the supermarket in order to increase the purchasing of products by consumers.2   A study run by Nike showed that adding scents to their stores increased intent to purchase by 80 per cent.  Estate agents have long been aware that pleasant smells such as bread baking or freshly ground coffee help with house sales.  In these cases of “sensory marketing”, smells have a direct effect on behaviour and action.

The Scent of Success

The billion dollar perfume industry attests to the power of smells in relation to sexual attraction and the most important aspect of human survival (in the genetic sense) – mate selection. However, we also know that pheromones (odourless chemicals released from one person and detected by another) provide us with information about the immune system status of the other individual – and mate selection is based on whether or not our noses detect that the other has a different but complementary immune system to our own.3


Scents to change emotion and cognition


Fearful smells can also have an impact on how we behave whereby performance is enhanced. One study showed improvements in cognitive performance across a range of tasks when participants were exposed to the smell of “fear sweat”4 When we smell “fear sweat”, the sweat produced by another human in an emotionally stressful situation, this activates the “fight or flight” region of the brain, the amygdala, in a way that does not occur when we smell the sweat of someone who has just been doing physical exercise5.  These studies show that humans are extremely sensitive to olfactory cues and that smells have a direct effect on the brain.  This in turn leads to changes in cognition and behaviour.

Malodorants – Really Bad Smells

Disgusting smells activate a specific region of the brain called the anterior insula (in fact specifically the anterior insula on the right side of the brain).6  This region of brain is implicated in gustation (eating), as well as the detection of the emotional expression of disgust on faces.  It also co-ordinates signals from emotional and movement centres of the brain – controlling whether or not the animal approaches or avoids the object. The sight or smell of disgust is a cue for the animal to avoid or move away from a substance that may be harmful or toxic if ingested. Thus the human brain learns very quickly that disgusting smells mean stop or move away.


This property of the olfactory system and how it is represented in the brain has been exploited  to change behaviour on a larger scale, in the case of malodorants used to control crowds or as a military application (malodourous munitions to either calm or distress).7


  1. Fox, Kate The Smell Report. Director, Social Issues Research Centre see : The Smell Report – An overview of facts and findings
  2. Chen, D, et al (2006) Chemosignals of fear enhance cognitive performance in humans. Chem Senses., 31(5):415-23.
  3. Mujica-Parodi LR, et al (2009) Chemosensory cues to conspecific emotional stress activate amygdala in humans. PLoS One. 29;4(7):e6415.
  4. Heining et al (2003) Disgusting Smells Activate Human Anterior Insula and Ventral Striatum Ann. N.Y. Acad. Sci. 1000: 380–384.