What will happen next? Sonja Belle/EyeEm/Getty

We used to think that planning for the future was a skill most children have by the age of four, but now it seems that we don’t develop the kind of memory needed to do this until we’re older.

Episodic memory lets us reflect on our past, and imagine ourselves in the future. To find out when children develop this, Amanda Seed at the University of St Andrews in the UK and her colleagues devised a test for 212 children between the ages of three and seven.

Each child was taught how to use a box that released a desirable sticker when the correct token was placed in it. An examiner showed them two boxes of different colours and told them that one would remain on a table while they left the room, and the other would be put away.


The children were later offered three tokens to choose from, in a different room. Two matched the colours of the boxes they had previously seen, but the third was a new colour to distract them. Unknown to the children, only matching tokens would work – but thinking about the boxes they had used, and their colours, should enable them to predict that it might be best to pick a token that is the same colour as one of the boxes.

Try to remember

The 3- and 4-year-old children didn’t choose the right token more often than they would by chance, suggesting they weren’t able to make this inference, but children aged 5 and older did.

“Typically both episodic memory and the ability to plan have been thought to come online at 4, but our 4-year-olds find this task challenging,” says Seed.

After the children chose tokens, they were asked whether they could remember the colour of the box on the table. Again, children under 5 named the right colour at the same rate as they would by chance, but the older kids were nearly perfect at remembering, suggesting they were able to use episodic memory to make a good choice for the future.

Theory of mind

“This study shows the fragility of episodic memory in 4-year-olds, and the fact that planning and implementing a complex goal-direction action depend on a combination of cognitive abilities,” says Iroise Dumontheil at Birkbeck, University of London.

Dumontheil likens this to the use of theory of mind – the ability to imagine someone else’s perspective. This skill also seems to emerge at around five-years-old, and similarly relies on memory and understanding another person’s intentions in a situation like this.

Seed says episodic memory may play into theory of mind because both require disconnecting from your current reality and simulating another – either seeing your own perspective from another time frame, or seeing someone else’s point of view.

It’s possible that five-years-old may be the time when these cognitive skills emerge because beginning to attend school sharpens memory use. “Would they be able to do the same task if they didn’t happen to be going to school at age five? It would be interesting to look at it cross-culturally and see if it’s different,” Seed says.

Journal reference: Current Biology, DOI: 10.1016/j.cub.2018.05.052

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