Remembering to turn the gas off, or water the plants before a weekend away, can prove an impossible feat when the mind is churning with other tasks.

But Harvard University has uncovered a simple ‘brain hack’ to bring back those forgotten to-do lists – the mental equivalent of tying a piece of string around the finger.

The trick is to associate the task with an object near to where it has to be carried out, which when spotted later on can trigger the missing memory.

For example, thinking of calendar hanging near to the washing machine at the same time as remembering to unload the washed clothes will help in recollecting the chore when walking past the calendar later on.

“Our results suggest that people are more likely to follow through on their good intentions if they are reminded to follow through by noticeable cues that appear at the exact place and time in which follow-through can occur,” said study author and psychological scientist Dr Todd Rogers of Harvard Kennedy School.

The researchers had theorised that visual clues could help people remember and devised an experiment to see if it was true.

87 participants were asked to complete an hour-long computer task, for which they would be given compensation for their time. They were also told that an extra donation to charity would be made if they remembered to pick up a paper clip when collecting their cash.

Half the students were told that an elephant statue would be sitting on the counter as a reminder to pick up the paper clip, while the other half were simply thanked for their participation.

The results showed that 74 per cent of people who had been given the elephant cue remembered to pick up the paper clip compared with just 42 per cent of those that were given no help, a 43 per cent increase.

Co-author associated professor Katherine Milkman, of the University of Pennsylvania, said: “People often fail to follow through on good intentions. While limited self-control is frequently the culprit, another cause is simply forgetting to enact intentions when opportunities arise.

“This approach involves associating intentions, e.g. to mail a letter on your desk tomorrow with distinctive cues that will capture attention when you have opportunities to act on those intentions.

“They can be more effective than written or electronic reminder messages, and they are undervalued and underused.

“The reminders-through-association approach, developed by integrating and expanding on past research on self-control, reminders, and prospective memory, can be a powerful tool for policymakers and individuals.”

Researchers say that the cues could be useful for businesses.

A separate experiment followed 500 coffee shop customers who were given a money-off voucher to be used at the shop two days later. Some customers were told that a stuffed alien would be sitting near the cash register to remind them to use the coupon.

Around 24 per cent of those who received the alien cue claimed the money off, compared to 17 per cent who did not know about the stuffed toy, a 40 per cent increase.

The researchers say the findings suggest that ‘reminders through association’ offer a no-cost, low-effort strategy for remembering to complete the tasks that tend to fall through the cracks in daily life.

The team is now planning further research to see if the cues can help people stick to medical and health-related regimes, such as fitness programmes or taking medication.

The research was published in the journal Psychological Science.