People most sensitive to acute stressors are those who regularly have higher stress levels. But this increased sensitivity to new stressful events also perpetuates the high chronic stress state

While it has been known for some time that environmental stressors, such as noise and increased light levels, have a greater psychological impact on certain groups than others, less is known about the impact of odour in provoking emotional responses. Could it affect some people more than others or is there a consistent response across the board?

A study carried out by the School of Psychology at Cardiff University and Balance Activ aimed to discover more. It found that odour appears to provoke similar responses in those same groups that are affected by the other environmental factors, contributing towards a broader picture of the way humans react to external stimuli. 

The study researched 2,000 UK men and women to determine their reactions to, and perceptions of, both pleasant and unpleasant odours.  Results show that women, young people and those who experience stress, anxiety or depression are most likely to be impacted negatively by unpleasant odours.

Results showed that those who regularly experience negative psychological states, including stress, anxiety or depression, are highly adversely affected by negative odours and highly positively responsive to pleasant odours. These results support previous findings which show that the people most sensitive to acute stressors are those who regularly have higher stress levels.  This increased sensitivity to new stressful events also perpetuates the high chronic stress state.

Within the negative psychological group, 41 per cent reported reduced wellbeing when exposed to unpleasant odours compared to only 31 per cent of the positive group, while almost half said they always find others attractive if they have a pleasant odour, compared to just 39 per cent of the second group.

Over two fifths of women said their confidence was hit by having an unpleasant odour, compared to just a third of men, while almost two thirds of women said they would stop interacting with someone who smelled, compared to half of men. Interestingly, despite this apparent increased sensitivity, women are less likely to complain about another person’s unpleasant odour than men. The majority of women, 73 per cent, had declined to make a complaint about someone else’s odour, compared to 63 per cent of men. 

There are good evolutionary reasons why we avoid unpleasant smells, such as repelling us from sources of disease or infection, but there are large individual differences in sensitivity and response to them, which are largely dictated by social pressures including the need to fit in with certain groups.

Complaining behaviour often reflects the extent to which people internalise issues or express them to others. Unpleasant odours are rarely discussed and this stigma may be important in both sensitivity and internalisation.

The study is important because it helps psychologists to gain a fuller understanding of how and why humans are affected by the world around them. It examined a type of unpleasant stimulus - bad odour - that has rarely been investigated before. Not only do the results provide novel insights into this topic but they show strong similarities to the effects seen with well-studied stressors such as noise.

By Professor Andrew Smith, Cardiff University School of Psychology