By Victoria Allen

The next time it's raining outside and you need to remember your umbrella, imagine the tip being stuck in the lock of the front door, preventing you from opening it.

It may seem an unnecessarily complicated way to keep dry in bad weather, but this technique has been shown to work dramatically for people who are forgetful.

The strategy means if you often lose your keys, it might be helpful to imagine them badly scratching the kitchen table you have left them on.

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The key, scientists have found, is to imagine an action between two objects, such as the umbrella lodged in the door lock, and a potential consequence, such as being unable to unlock the door.

They tested the tactic in 80 people aged 61 to 88, who boosted their performance significantly in memory tests.

This is because getting older, people can remember individual things like the table and keys, or umbrella and rain, as well as when they were younger, but are worse at recalling the relationship between them.

It makes remembering and future planning tricky, because they are less able to remember, for example, that the keys are on the table.

HOW DOES THE TECHNIQUE WORK?

Imagining an action and a consequence together, such as the keys scratching the table, gets round the problem by fooling the brain into grouping the two separate items together as one.

The study on the "unitisation" memory strategy is published in the journal Memory & Cognition.

Co-author Professor Jennifer Ryan, from the University of Toronto, said: "Previous research has shown that imagining two objects fusing into one will help people work around these memory deficits, but our work demonstrated that understanding the relationship between the two items is also important.

"We know that cognitive function is impaired during ageing and this strategy could be one workaround for minor memory problems, depending on what you need to achieve."

SIMILAR TO ROCK, PAPER, SCISSORS

The memory trick is similar to the playground game of rock, paper, scissors.

It is easy to remember which wins when making hand signals to represent each, as rock blunts scissors, scissors cut paper and paper covers rock.

In their experiment, the researchers used a similar game but with abstract objects on a computer screen.

The older study participants were asked to use one of four memory techniques to figure out the winner in each pair.

THE FOUR MEMORY TECHNIQUES

The first was unitisation, where they understood that one object would because of an action and consequence - one object would squash, cover or stab another in an animation which ends with both fused together.

The second was an "action and consequence" strategy, with participants also told it would help to imagine the objects interacting, but the pair never touching on screen.

A third strategy involved one object moving towards another, which people are sometimes told to imagine to remember items in real life.

The fourth animation, using a "fusion" strategy, linked the two items, but without any action pulling them together.

WHAT DID THEY FIND?

The results reveal that an action and consequence between two objects makes it far easier to keep them in mind.

The threshold in a memory test is 67 per cent to show that a particular mental strategy has worked better than simply trying to remember.

But people using the action and consequence technique, or unitisation, achieved 78 per cent after being trained in the memory game and playing it following an hour's break.

The motion and fusion strategies fell below the threshold, suggesting they were little or no help.

NO SINGLE STRATEGY WILL DEFINITELY WORK

Professor Ryan, who carried out the research with colleagues from Baycrest Centre for
Geriatric Care in Canada, where she is senior scientist, said: "We are trying to understand what's important to unitisation and what people need to learn in order to benefit.

"There is no single strategy that will fix your memory, but one method may be more suitable than another."

The use of action and consequence to remember objects is only found to work in older people who are not suffering from cognitive decline, as it requires the brain to carry out more than one function at once, but it is described as a "critical cognitive component" of memory in the study.

Previous studies have suggested a mental "mind map" can help in remembering separate items or episodes.