The D'oh! effect

We have all done it. You go upstairs but can't remember why. Or you pull on an item of your partner's clothing. Or you squeeze moisturiser onto your toothbrush. These are life's 'd'oh moments', and last week psychologists revealed they are much more common than many people realise. Indeed, we can experience as many as 30 a week.

'What we call "action slips", or mental lapses, usually happen in the context of well-rehearsed or routine action sequences that we usually can perform pretty successfully without paying attention,' said Maria Jonsdottir, who led the team of investigating Finnish neuropsychologists.

'They probably reflect some temporary fault in this otherwise very efficient system, much like when we mispronounce words or use the incorrect word in our native tongue. Somehow the brain has to be at fault, though an action slip doesn't mean that something is wrong per se with that person's brain.'

Jonsdottir and her team surveyed 189 people to produce their report, 'A Diary Study of Action Slips in Healthy Individuals'. They found the weekly average for such slips is 6.4, although numbers varied greatly. One professor admitted to committing 30. However, age, gender and intelligence had little influence on 'd'oh moments' - named by Dr Christian Jarrett, editor of the British Psychological Society's research bulletin, after Homer Simpson's famous exclamation. Most happen on weekdays between noon and 8pm, it was found.

Busy lifestyles, the popularity of email and mobile phones, and high levels of stress are also factors, said Jonsdottir, who believes such moments of absent-mindedness are probably becoming more common because people have more demands on their time than before. Her team's findings will appear in the Clinical Neuropsychologist later this year.

The authors divided action slips into five categories. The most common were 'storage failures' in which people forgot or misrecalled an action plan, for example remembering they had to call someone but forgetting who it was, so that they had to ring home to check if it was someone there. Others involved 'test failures' - for example, trying to turn on a light that was already on and which was then switched off.

One male participant in the study admitted having put on his female partner's jacket instead of his own, a 'discrimination failure', while another threw their child's toy in the rubbish but placed its nappy on the shelf, a 'programme-assembly failure'. Other mix-ups involved, for instance, going out to buy coffee but coming back with groceries, a 'sub-routine failure'.

Jonsdottir also noted that confusion often arose in the kitchen, especially at breakfast time, with people putting the coffee in the fridge and the milk in the cupboard, probably because they were in a rush.