What are you going to eat for lunch tomorrow?
What are your plans for this weekend?
Where do you see yourself in five years?
Answering these questions requires looking into the future.
But when you make these predictions,
what you're actually doing is accessing your memories.
Being able to accurately predict the future
gives humans an evolutionary advantage.
I'm not talking about a fortune cookie or a horoscope
that says your true love will find you next Tuesday.
I'm talking about the practical ability to anticipate
when crops will be ready to harvest
or to prepare for a meeting with your boss.
Planning beyond the present moment and even years into the future
is indispensable to human life in society.
But how do we do it?
Researchers believe that we rearrange
our memories of the past
to put together a vision of what the future might look like.
They've discovered that memories and predictions
take place in the same regions of the brain and appear
to use the same underlying processes.
Scientists first learned about this connection
by observing amnesia patients.
Not only were these patients unable to access their memories,
but they also didn't have any idea of what they might do in the future.
More, recently fMRI studies have allowed researchers
to see into the brains of healthy people
while they remembered the past
and predicted the future.
The psychologist Carl Spooner observed that the activity
in the brain during both tasks was almost completely overlapping.
Researchers have also found that as people age
and start to develop memory loss,
their ability to imagine the future declines as well.
This ability to envision moments in both the past and the future
is known as mental time travel.
Mental time travel is different from just remembering facts.
It's about reliving scenes in your mind.
If you think about the last time you went to the beach
your brain reconstructs the setting.
You feel the sunshine on your skin and the sand
between your toes and you can smell the salt on the breeze.
In a similar way, when you imagine an event in your future,
you're essentially pre-living it.
You construct a similar scene using details from your memory.
So the next time you plan a beach trip, you can imagine the feel
of the sun in the sand before you've even packed your sunscreen.
Likewise if you're imagining your future wedding,
you'll probably cherry-pick elements from weddings you've been to
as well as weddings you've seen on TV and movies or in magazines.
But the ability to predict the future using your memories
does have one big disadvantage:
People often expect the future to be too much like the present.
Studies back up the conventional wisdom
that if you go to the grocery store when you're hungry,
You'll buy too much food,
not realizing you won't always be this hungry.
Similarly if you try to predict how you'll feel in the future
about something, you're likely to be blinded by your current emotions.
For a vivid example of how future predictions are affected by the present,
just watch an old sci-fi movie.
Take Back to the Future 2, which was made in 1989
and set in 2015.
It successfully predicted things like videoconferencing,
drones, and facial recognition, but it assumed people
would be still be using fax machines
and pay phones.
Two technologies integral to life in the '80s
which the filmmakers seemingly couldn't imagine a future without.
The future is always going to be full of surprises we can't predict.
But one thing's for sure:
without our memories, we'd be totally in the dark.
This is You Are Here, a series about the science behind everyday life.
Tell us what topics you'd like us to discuss in the comments.
I'm Julie Beck. Thanks for watching.