Scents and emotions

Symbolic picture for the article. The link opens the image in a large view.
Ob angenehm duftend oder übel riechend - der Wirkung von Gerüchen kann sich der Mensch nicht entziehen. (Bild: FAU/David Hartfiel)

Summer smells like sun cream and the sea; Christmas smells like cinnamon and cloves. Scents can bring back memories of happy times. Medical researchers can use this to their advantage.

By Ilona Hörath

‘Odours have a power of persuasion stronger than that of words, appearances, emotions, or will. The persuasive power of an odour cannot be fended off, it enters into us like breath into our lungs, it fills us up, imbues us totally. There is no remedy for it.’ These words are from Perfume by Patrick Süskind, and if you think back to the last time you experienced a scent that means something to you, you will understand what he is talking about. More than any of the other senses, the sense of smell is known as being subjective and being connected to our feelings. A given scent represents something different for everyone. A smell that one person finds pleasant and fascinating can be repellent to someone else. Just a few scent molecules floating in the air are enough to change our mood completely.

Smell is the sense of memory and desire

Jacques Rousseau once wrote that ‘smell is the sense of memory and desire’ – a fact that industry knows how to use to its advantage. Products with enticing scents are a lucrative billion-euro industry and do not just include perfumes – supermarkets use the smell of freshly baked goods to boost their sales. Scents can control our behaviour and influence our emotions.

We can’t get away from the effect of scents

‘We can’t get away from the effect of scents,’ says Prof. Dr. Norbert Thürauf from the psychiatry department at Universitätsklinikum Erlangen. In contrast to industry, as a doctor he uses scents in a targeted way in the treatment of psychiatric patients with the symptom of anhedonia, an inability to feel pleasure. ‘Joylessness and limited emotions are symptoms of depression but also occur in anxiety disorders, schizophrenia and dementia,’ Prof. Thürauf explains. ‘Or in people who have previously suffered from long-term drug addiction and are so numb that they are unable to feel happy or to cry.’

What does the inside of an old leather bag smell like?

Prof. Thürauf is also head of the sensory laboratory. ‘We study objectifiable sensory disorders in the field of psychiatry,’ the sensory researcher explains, ‘Our research focuses on measurable declines in the emotional experience of olfactory cues in various psychological disorders.’ Olfactory disorders can also be sign of dementia or Parkinson’s disease. They can also provide an indication of how advanced a psychosis is.

Scents can bring back memories of happy times. Medical researchers can use this to their advantage. (Image: FAU/David Hartfiel)
Scents can bring back memories. Medical researchers can use this to their advantage. (Image: FAU/David Hartfiel)

One of the tools that Prof. Thürauf uses both in his research and in his work as a therapist is a small box with 16 scent sticks, each labelled with a number. The Sniffin’ Sticks, as they are called, look like marker pens but the difference is obvious from their smell, as each of the sticks contains a different natural or artificial aroma. Norbert Thürauf pulls out a stick, takes the lid off and lets the visitor smell the tip. It smells almost like Christmas; like fir trees, mulled wine and biscuits.

The list of guesses could be extended, but it is difficult to pinpoint what the smell is. Prof. Thürauf is able to help. ‘People know the smell but find it much more difficult to say what it is,’ he says. ‘It’s cloves.’ He has pulled out another stick already and explains, ‘The smell is not a primary emotion, but it triggers emotions.’

Prof. Thürauf already knows of course that the next, unpleasant smelling stick will trigger unpleasant feelings and lead to a wrinkling of the nose. He is now presenting a very unique smell: the inside of a leather bag after many years of use.

The key to positive feelings

‘We use this test in psychiatry to measure intensity and the positive reaction; how pleasant or unpleasant a smell is perceived to be,’ Prof. Thürauf explains. The method also tests the threshold at which a patient begins to perceive a scent and how the scents differ from one another. ‘The emotional olfactory memory is activated during therapy,’ explains the trained psychiatrist and psychotherapist.

Image: FAU/David Hartfiel
Image: FAU/David Hartfiel

The smells trigger images and memories. ‘Scents can be used to bring back positive childhood memories, for example.’ In therapy, smelling and the Sniffin’ Sticks are ‘a good starting point for guiding patients’ emotions in a pleasant direction.’

‘We want to trigger positive emotions and sensitise patients to them.’ This is especially important for patients who are distressed, who see their surroundings in a mostly negative way, or who are experiencing a severe depressive phase and no longer able to feel pleasure. ‘The less scents a patient experiences as pleasant, the more severe the anhedonia.’

Rediscovering scents

Prof. Thürauf and his team have observed in therapy sessions that the facial expression of patients changes when they smell certain scent sticks and talk about them. ‘Some suddenly start to display positive emotion.’ And others bring something that they have come across to the next session, such as sun cream or an elder branch, pleased that they have rediscovered the scent.

It is important that it is explained to patients that it is possible to feel happiness by consciously smelling a scent, such by smelling coffee in the morning rather than seeing it simply as a liquid to be drunk. ‘Patients become more balanced emotionally,’ Norbert Thürauf explains. ‘Our therapy is received positively by patients as there are not many therapies that focus on positive experience.’

Would you like to learn more?

This article was originally published in our research magazine friedrich in an issue which is all about the senses. Find out in why it might be better not to rely on our senses in certain situations and how machines are learning to hear in issue 115 of friedrich (German).