Odours can stimulate memories enabling people to recall details about an event, research has revealed.
Psychologists at the University of Liverpool have found that smell is much more powerful than images or words in evoking memories. They discovered that people had vivid and detailed memories when given olfactory cues.
It is a common belief that odours are powerful reminders of autobiographical experience but the study is believed to be the first which directly compares memory recall using smell and words or pictures.
The findings could have important implications for police obtaining witness statements and students sitting exams. In both cases smells associated with the crime or revision sessions could be used when people are trying to recall detailed memories, the researchers said. Alzheimer's patients could also benefit from using smells to aid their memory.
"People do not think odours are important in life and they tend to rely on verbal and visual cues," said Dr Simon Chu, a psychology lecturer at the University of Liverpool.
The theory that smells could conjure memories dates from ancient Chinese oral tradition. After an important event the family would sit and go through the day's details with a pot of smouldering herbs. As they retold the story to the next generation they would get out the particular herb mix to aid recall.
The researchers tested the recall of more than 100 people using 27 smells, including oranges, boot polish, vinegar, menthol and ink. Subjects were given a word, such as oranges, and asked if it conjured a particular memory. They were then given a picture of an orange and asked if they could remember any more details of the event. Finally they were exposed to the smell of oranges.
"When we gave the smells to people the memories they retrieved were more vivid than any others. The amount of detail was greater in response to odour than to a word a picture," he said.