everything you said, everything you did,

available in a perfect memory store at your fingertips,

so you could go back

and find memorable moments and relive them,

or sift through traces of time

and discover patterns in your own life

that previously had gone undiscovered.

Well that's exactly the journey

that my family began

five and a half years ago.

This is my wife and collaborator, Rupal.

And on this day, at this moment,

we walked into the house with our first child,

our beautiful baby boy.

And we walked into a house

with a very special home video recording system.

(Video) Man: Okay.

Deb Roy: This moment

and thousands of other moments special for us

were captured in our home

because in every room in the house,

if you looked up, you'd see a camera and a microphone,

and if you looked down,

you'd get this bird's-eye view of the room.

Here's our living room,

the baby bedroom,

kitchen, dining room

and the rest of the house.

And all of these fed into a disc array

that was designed for a continuous capture.

So here we are flying through a day in our home

as we move from sunlit morning

through incandescent evening

and, finally, lights out for the day.

Over the course of three years,

we recorded eight to 10 hours a day,

amassing roughly a quarter-million hours

of multi-track audio and video.

So you're looking at a piece of what is by far

the largest home video collection ever made.

(Laughter)

And what this data represents

for our family at a personal level,

the impact has already been immense,

and we're still learning its value.

Countless moments

of unsolicited natural moments, not posed moments,

are captured there,

and we're starting to learn how to discover them and find them.

But there's also a scientific reason that drove this project,

which was to use this natural longitudinal data

to understand the process

of how a child learns language --

that child being my son.

And so with many privacy provisions put in place

to protect everyone who was recorded in the data,

we made elements of the data available

to my trusted research team at MIT

so we could start teasing apart patterns

in this massive data set,

trying to understand the influence of social environments

on language acquisition.

So we're looking here

at one of the first things we started to do.

This is my wife and I cooking breakfast in the kitchen,

and as we move through space and through time,

a very everyday pattern of life in the kitchen.

In order to convert

this opaque, 90,000 hours of video

into something that we could start to see,

we use motion analysis to pull out,

as we move through space and through time,

what we call space-time worms.

And this has become part of our toolkit

for being able to look and see

where the activities are in the data,

and with it, trace the pattern of, in particular,

where my son moved throughout the home,

so that we could focus our transcription efforts,

all of the speech environment around my son --

all of the words that he heard from myself, my wife, our nanny,

and over time, the words he began to produce.

So with that technology and that data

and the ability to, with machine assistance,

transcribe speech,

we've now transcribed

well over seven million words of our home transcripts.

And with that, let me take you now

for a first tour into the data.

So you've all, I'm sure,

seen time-lapse videos

where a flower will blossom as you accelerate time.

I'd like you to now experience

the blossoming of a speech form.

My son, soon after his first birthday,

would say "gaga" to mean water.

And over the course of the next half-year,

he slowly learned to approximate

the proper adult form, "water."

So we're going to cruise through half a year

in about 40 seconds.

No video here,

so you can focus on the sound, the acoustics,

of a new kind of trajectory:

gaga to water.

(Audio) Baby: Gagagagagaga

Gaga gaga gaga

guga guga guga

wada gaga gaga guga gaga

wader guga guga

water water water

water water water

water water

water.

DR: He sure nailed it, didn't he.

(Applause)

So he didn't just learn water.

Over the course of the 24 months,

the first two years that we really focused on,

this is a map of every word he learned in chronological order.

And because we have full transcripts,

we've identified each of the 503 words

that he learned to produce by his second birthday.

He was an early talker.

And so we started to analyze why.

Why were certain words born before others?

This is one of the first results

that came out of our study a little over a year ago

that really surprised us.

The way to interpret this apparently simple graph

is, on the vertical is an indication

of how complex caregiver utterances are

based on the length of utterances.

And the [horizontal] axis is time.

And all of the data,

we aligned based on the following idea:

Every time my son would learn a word,

we would trace back and look at all of the language he heard

that contained that word.

And we would plot the relative length of the utterances.

And what we found was this curious phenomena,

that caregiver speech would systematically dip to a minimum,

making language as simple as possible,

and then slowly ascend back up in complexity.

And the amazing thing was

that bounce, that dip,

lined up almost precisely

with when each word was born --

word after word, systematically.

So it appears that all three primary caregivers --

myself, my wife and our nanny --

were systematically and, I would think, subconsciously

restructuring our language

to meet him at the birth of a word

and bring him gently into more complex language.

And the implications of this -- there are many,

but one I just want to point out,

is that there must be amazing feedback loops.

Of course, my son is learning

from his linguistic environment,

but the environment is learning from him.

That environment, people, are in these tight feedback loops

and creating a kind of scaffolding

that has not been noticed until now.

But that's looking at the speech context.

What about the visual context?

We're not looking at --

think of this as a dollhouse cutaway of our house.

We've taken those circular fish-eye lens cameras,

and we've done some optical correction,

and then we can bring it into three-dimensional life.

So welcome to my home.

This is a moment,

one moment captured across multiple cameras.

The reason we did this is to create the ultimate memory machine,

where you can go back and interactively fly around

and then breathe video-life into this system.