- Welcome everyone to
Wednesday Nite @ the Lab.
I'm Tom Zinnen.
I work here at the UW-Madison
Biotechnology Center.
I also work for the Division
of Extension Wisconsin 4-H.
And on behalf of those folks
and our other co-organizers,
PBS Wisconsin, the Wisconsin
Alumni Association,
and the UW-Madison
Science Alliance,
thanks again for coming to
Wednesday Nite @ the Lab.
We do this every Wednesday
night, 50 times a year.
Tonight, it's my pleasure to
introduce to you Haley Vlach.
She's a professor here
in the Department of
Educational Psychology
and our School of Education.
She was born in
Portland, Oregon,
and went to high school at
Mountain View High School
in Bend, Oregon.
And then she went to
Carnegie Mellon University
in Pittsburgh and studied
business administration
and psychology.
Then she moved back west
to go to the University of
California at Los Angeles
for her master's degree and PhD,
both of which in psychology.
Tonight, she's going
to be talking with us
about forgetting, what it is,
and how it helps us remember.
Pretty fascinating topic,
a paradox.
Please join me in
welcoming Haley Vlach
to Wednesday Nite @ the Lab.
- Thanks for that introduction.
I'm very excited to be here
and to speak with you all
about some of the work
that we've been doing in my lab.
I'm Director of the Learning
Cognition and Development Lab.
And in my lab,
we're really interested in how
people think and learn.
We spend a lot of time
thinking and learning
about thinking and learning.
And in particular,
we're interested in
cognitive development.
That is, how does thinking
change across the lifespan?
We're particularly interested
in thinking and learning
during childhood, but we
also study adults as well.
And we spend a lot of our time
thinking about memory
and memory changes and how
those changes in memory
might contribute to our
thinking and learning.
And we're really
interested in memory
for a number of reasons.
So the first reason
is that it's theoretically
very interesting.
Like how does memory work?
We take in a seemingly
infinite amount of information
from the world
and somehow manage
to decode that
information, store it,
and then retrieve it
later when we need it.
And so that process
is still a mystery
and is very motivating to study,
just coming up with a
theory of how memory works.
Memory is also practically very
important for many reasons.
So first, it's important to
our day-to-day functioning.
So for instance, when we're
going to the grocery store,
we need to remember the things
on our shopping list.
And we often think in our mind,
"Hmm, do I need more milk?"
And you have to remember
whether or not
you have milk in the
fridge currently.
There's also many ways
in which memory
can be implied into training,
educational and
health interventions.
Memory is at the core of
allowing us to think and learn,
as we will discuss more today.
And so there are
numerous applications.
But on a more sort of
spiritual or emotional level,
memory is fascinating
because it's what defines us.
In other words,
we are our memories.
When we create
our sense of self,
we think back to all
of our experiences,
and what those experiences are,
are the memories that
we've stored in our brain.
So memory truly serves
at the foundation of the self.
So there are many, many
reasons to study memory.
One thing that is
very interesting
to most people who are learning
about memory for the first time
is that remembering is not the
most common part of memory,
but instead the most
ubiquitous process in memory
is the fact that we forget.
Today, what I'm going
to do is I'm gonna first
provide an overview
on forgetting.
What is it and what do
we know about forgetting?
After that brief introduction,
we're gonna dive into
talking about forgetting
helping us to learn.
And this is counterintuitive
as we will discuss,
because normally we
characterize forgetting
as a process that deters memory.
And then finally, I'll end
with some concluding thoughts
about where we can go and how
we can think about forgetting
in our day-to-day lives.
So first let's dive in,
let's talk about
what forgetting is
and how scientists
think about forgetting
when we study it from a
scientific perspective.
Forgetting is operationally
defined as the declining ability
to retrieve information
across time.
And what you can see
here in this image
is on the X-axis is time.
So number of days or a month,
and then on the Y-axis,
you see this equation,
and this equation is
called a saving score.
And you can think about
this as the percent
that is recalled across time.
And what you can see is that
the nature of forgetting
is such that soon
after learning something,
we have pretty
good memory for it.
But over time, that ability to
retrieve the memory declines,
and it declines according to
what we call a forgetting curve.
Okay, so the curve is
fast-changing at first,
but then over time slows down
and gives sort of a
U-shape to the curve.
And we've been
studying this process
for a considerable
amount of time,
dating back to the late 1800s
at the birth of
psychological science.
So because forgetting has been
such a well-studied process,
we know some things about it.
And I'm gonna give you a brief
overview of what we know.
So first, we know that we
forget across the lifespan.
So forgetting happens
in young infants,
in adulthood, and
in older adulthood.
In other words, every stage of
life, we observe forgetting.
The next thing that we
know about forgetting
is that forgetting happens
across tasks and timescales.
And it's a very
predictable pattern.
And in fact, that pattern is
what I just showed you earlier,
the forgetting curve.
Now in this figure,
what I have here
are two different graphs.
On the left side of the screen,
you'll see that the
X-axis indicates time
as a matter of seconds.
However, on the right side,
there's a different
dimension of time,
which is years, like 0 to
50 years in particular.
And then on the
Y-axis for both graphs
is the percent correct.
That's the percentage
remembered.
And what we can see
is regardless of whether
or not the timescale
is a matter of seconds as
such in the left graph,
or a matter of years,
such as what we see
on the right graph,
we see the exact same pattern,
that forgetting curve.
Now, for those of you that
are mathematical buffs,
what you can see is that
what is charted here
is a power function.
That's that equation at
the top of the graphs.
And indeed, forgetting
follows a power function
with a high degree of fit.
So those are squared values,
or what you're seeing
is like the percentage
at which the power function
can account
for the data that we
observed via forgetting.
And one thing that's
fascinating about forgetting
is that one of the things
that we can mathematically
model the best
of human cognition.
Indeed, capturing about 88% or
90-some percent of the variance
is very high.
And so forgetting is very
predictable across timescales,
but also across tasks.
We see the similar forgetting
curves across tasks.
The next thing we know
about forgetting
is that we can
observe forgetting
on multiple levels of analysis.
In other words,
we see forgetting
on the level of an individual
neuron in our brain,
but we can also
observe forgetting
in complex human behaviors,
such as those day-to-day
functions that we engage in,
especially more complex things
like learning new concepts
in the classroom.
So we're seeing forgetting
at multiple levels
of our being as humans.
We also know that
we're not alone.
Humans are not the
only ones that forget.
We can observe forgetting
in other species,
even organisms that don't
have our nervous system.
So for example,
in very simple organisms
that only have a
matter of cells,
we observe that those
cells will forget.
So forgetting is not something
that's specific to
the human experience
or our nervous systems;
it's much more widespread
across organisms.
Okay, so at this point,
what you were probably
thinking is that,
"Wow, so what you're telling me
is that we're forgetting
everything all the time."
And that's right.
We are forgetting
everything all the time.
It is predictable
and it's inevitable.
So why does this happen?
Why is this happening
to us all the time
in a predictable manner?
Well, the truth is,
is that we don't know.
It's a scientific mystery.
We don't know what
causes forgetting,
but currently, there
are two primary theories
about why it is that we forget.
The first collection of
theories focus on interference.
In other words,
these theories posit
that because we're
continually acquiring
more and more information,
that that new information
blocks us from retrieving
the old information
in our mind and brain.
So if we weren't to
learn anything new,
we wouldn't forget,
is essentially what
they're arguing.
However, there's a different
collection of theories
that center on time and the
properties of the universe
with regards to energy.
So according to these theories,
the reason that we forget
is that energy passes
across biological membranes
according to this power function
that you've seen earlier,
in other words,
the forgetting curve.
And because of that,
we observe forgetting at
different units of analysis,
like a single cell, but also,
that scales up to complex
human behavior as well.
Now, one issue is that we can't
control for time and energy.
In other words, we can't
put people in a vacuum
where they're not
experiencing time
in order to understand whether
it's truly interference or time.
Moreover, we can't control time
when we're doing
interference studies.
So with additional learning
comes additional time.
And so the reason
that it's a mystery,
is it interference
or is it something
about the properties
of the universe?
We just may never know
because we can't put
ourselves in a vacuum
in order to control
these two variables.
So the debate rages on,
but we're pretty sure that
it's either interference,
time, or some
combination of the two.
Okay, so that was the
overview of forgetting,
what it is and what
we know about it.
Now I'd like to move on and
I'd like to tell you more
about why forgetting is
actually a good thing,
because at this point
you might be wondering,
"Well, if it's
inevitable, predictable,
"and gonna prevent us
from remembering things,
it must be bad."
Well, it turns out that
that's not the case.
Forgetting can be used
to help us remember.
So if forgetting is inevitable,
how do we remember?
This has been a central research
question for many years.
And what researchers
have discovered
are that certain
learning environments
or conditions of the environment
can actually improve our memory.
They can help us to
retrieve information.
One of the most
well-studied conditions
of the learning environment
is called spaced learning.
And what scientists
have observed
is that when we distribute
learning events across time,
people have better memory
for that information
compared to it being massed
in immediate succession.
So here's a real life example
of that.
Imagine that you are
studying for a test.
You have one or two options:
you could cram the night before
and just cram, cram, cram
right up until the test.
Well, that behavior would be
studying in immediate
succession.
We would call that
massed learning.
The other option is to
distribute your learning
during the week and study
a little bit every day.
So you might study a
little bit on Monday,
a little bit on Tuesday,
a little bit on Wednesday
and so on and so forth,
building up to the test.
And what you may
experience if you cram
is that you do okay on the test,
you do well enough,
but a few days later
you might say,
"Wow, I don't remember anything
from the test that I took
earlier in the week."
However, if you had
distributed your learning
or spaced it out across time,
you would probably
experience more memory
for what you studied for.
In other words, you'd
actually remember
what you were studying.
And that's a real life example
of how spaced learning
promotes memory to a greater
degree than massed learning.
In the lab, scientists
do this kind of work
using word lists.
What they do is they present
words to participants
one at a time.
So what you're seeing
here on this list
is a series of words,
and what you'll notice
is some of the words
like the word cat
are presented in
immediate succession,
one right after the other.
Whereas other words on the list,
such as the word dog,
is distributed across time.
You'll see the word dog,
and then you'll see
some other words
and then the word dog
will come back.
The consistent finding
across these studies
that use word lists
is that participants
have stronger memory for the
words distributed across time,
like dog, relative to the
words that are massed in time,
like the word cat.
We know from over a
thousand published studies
that spaced learning
promotes memory.
It's a highly
replicable phenomenon
that's been studied
across many timescales
and many contexts.
One of the primary reasons
that spaced learning
supports memory
is actually that
we're forgetting
during the learning events.
So let me briefly
describe why this happens.
So in between each
spaced learning event,
you'll forget information.
And what that forgetting does
is it makes it harder to
retrieve what you've learned.
But at subsequent
learning events,
what you'll do is
you'll retrieve
your prior information
from memory
and the cognitive effort
that you engage in
in remembering that information
will then be translated
into a slower forgetting
for that information.
In other words,
by trying to remember
and practicing that retrieval,
you'll then have a slower
forgetting rate in the future.
And so by engaging in that
retrieval practice
across distributed
learning events,
you're actually
slowing forgetting
and promoting your memory.
Now, researchers have
for a long time now
known that spaced learning
promotes memory
and that forgetting can be
manipulated to promote memory,
but this isn't true
for all forms of memory.
For example, researchers
have questioned
whether or not this
process of forgetting
is good for everything.
And in particular,
researchers have asked,
can forgetting promote
categorization
and concept learning?
And the categorization
and concept learning
is learning that things
share similarities
and differences in the world.
So for example, a golden
retriever is called a dog
and a wiener dog is
also called a dog.
Even though they
look very different,
they share similarities
and thus belong
to the category of dog.
And general intuition would say,
"Hmm, I don't know if
forgetting is good,"
because in general,
intuition tells us
that forgetting is not good,
that it's a bad thing.
However, even researchers
who are experts in this field
really argued that yes,
forgetting should
deter categorization
in concept learning.
It's really fun to go back
through the previous literature
and read old studies
because there's some
fighting words out there.
People really had strong beliefs
that forgetting would deter
conceptual development.
My favorite quote is
from Ernie Rothkopf,
where he argued that
things like forgetting
and spaced learning would
be the "friend of recall,"
so help us to remember,
"but the enemy of induction."
So in other words, it would
deter our ability
to learn categories
or learn concepts
where we have to abstract out
across our experiences.
Let me walk you
through this argument.
So imagine that
you're a young child
and you're learning
about the category
of bunny for the first time.
You'll see one bunny
in one context,
and then you'll see another
bunny in another context.
Then you might see a third bunny
in a different context,
and what you need to do
in order to learn
the category of bunny
is to abstract out the
similarities and differences
across these experiences.
So you might see that,
well, the bunnies
share the same shape.
And so maybe that's
a relevant feature
of the category of bunny.
However, there are other
features that vary.
So for instance,
the color of the hair is
different across these bunnies.
And a child might think,
"Hmm, I guess the hair color
is not a relevant category.
It's irrelevant to the
category of bunny."
And the reason that
children need to abstract
across these experiences
is they have to know
what to generalize
based on when they
see new bunnies
that they've never seen before.
They should generalize
based on body shape
rather than on something
like the color of the hair.
Now, Ernie and others
thought that the forgetting
would deter this process
because how are you
supposed to abstract
across all of your experiences
if you can't remember
your experiences?
So for instance, if you can
only remember the body shape
of one bunny you've seen before,
how are you supposed
to know that body shape
is a relevant feature
to the category of bunny?
You can't remember
that all the bunnies
shared the same body shape.
Same thing goes
for irrelevant features.
If you only see
one color of hair
and you don't see that it varies
across all the
different bunnies,
you might think that hair
is a relevant feature.
You know, the
first bunny you see
might be a certain color
and you would think
that that color
defines the category of
bunny when it does not.
So in other words, forgetting
should be bad for abstraction.
Now what's interesting is that
despite these fighting words
being out there and strong-held
belief by researchers,
no one had really tested it.
So what we decided to do
was to test this hypothesis,
and one of the most common
methodologies that we've used
to test this hypothesis
is called the novel
category induction task.
And this task is designed
for young children
who are learning words and
categories for the first time.
And what we do is we present
them with novel objects
and novel words to ensure
that they're learning
these objects and words
for the first time.
So just as an example,
an experimenter
might show children
a series of novel objects like
this and label them and say,
"This is a wug, this is a wug,
and this is a wug."
And then at a post-test,
present children
with a series of objects.
Some they've never seen
before, some they have.
So for example, they'd
seen a cat before.
And then it's the child's job
to generalize the category
that they just learned to a
new instance of the category.
So what the experimenter
would say is,
"Can you hand me the wug?"
And it would be the child's job
to pick up that novel wug
they haven't seen before that
shares a similar feature,
in this case shape, to the
objects that they saw
during learning.
So this is referred to as the
novel category induction task.
And today I'm gonna show
you two experiments,
Experiments 1 and 2.
And the participants in these
experiments were typically
developing two to two and a half
year-old children.
And again, we were
really interested
in how this process unfolds
when it's organically unfolding
a lot during development,
which is the toddler period.
They're learning lots of
words and new categories
during the toddler period.
We made very simple manipulation
on the classic paradigm.
And what we did in Experiment 1
is we presented children
with novel words and objects
on one of three schedules:
simultaneous, massed, or spaced.
I'm gonna walk you through
each of these presentation
schedules now.
In the simultaneous condition,
children were presented with
four objects at the same time.
They were all put on the
table simultaneously.
What the experimenter would do,
would label each of the objects.
So the experimenter would say,
"Look, this is a wug," and
point to the first object.
They would wait 10 seconds
and then point to the
second object and say,
"Look, this is a wug,"
wait 10 seconds and
so on and so forth
for all four objects.
Now in this condition,
forgetting is minimized
because all of the objects
are present to the child
at the same time.
And they keep hearing the
word wug over and over again.
So children don't have
to rely on their memory
to abstract out what are the
similarities and differences
among the objects.
They're all on the table
at the same time.
The second condition was
the massed condition.
And in this condition,
we presented children
with objects one at a time.
So the experimenter would
put an object on the table
and say, "Look, this is a wug,"
wait 10 seconds, take
the object off the table,
and then put it
back on the table
or put another object
on the table and say,
"Look, this is a wug,"
wait 10 seconds for the child
to play with the toy,
take it off, and then
put a third object on,
and so on and so forth.
So in other words, the objects
were presented one at a time.
Now in this case,
children need to rely on
their memory a little bit
to remember what
they've seen earlier.
Because they only
see one at a time,
they have to think back,
"Hmm, what were the colors
and shapes of the objects
that I saw earlier?"
The final condition was
the spaced condition.
In this condition,
what children did
is they also saw one object
at a time,
but instead of seeing them
in immediate succession,
like in the massed condition,
there were 30-second delays
between each presentation
of the object.
So what children would do
is they'd see an object,
the experimenter would put
one on the table and say,
"Look, this is a wug."
And then the experimenter
would take it away.
And there'd be 30 seconds
of irrelevant activities
like playing with Play-Doh,
putting stickers on paper,
anything to keep the kids
at the table and entertained.
After that 30-second
play period,
children would then be
presented with another object
and the experimenter would say,
"Look, this is a wug."
And that would happen
so on and so forth
for four objects in total.
Now what you can see
across these conditions
is that the only thing
that's being manipulated here
is the timing.
Either children see all objects
simultaneously,
preventing forgetting, or
they see them one at a time.
And what the spaced
condition does
is it introduces the most
forgetting during learning
because there are those
30-second intervals
between each presentation
that gives children the
opportunity to forget
in between each object.
And so they have to
think harder and harder
about what they saw earlier
in order to abstract
the relevant and irrelevant
features of the category wug.
Children were also presented
with a distractor item
during learning, and the
experimenter did not label this.
They would say,
"Look at this toy."
And it was presented for the
same amount of time
as the objects, 40 seconds.
And then there was
either a immediate test
or a test after a delay,
a 15-minute delay.
And the reason for this
difference across conditions
is that we were interested
in not only forgetting
during learning,
that's those three conditions
I showed you earlier,
but we were also
interested in forgetting
between learning and test.
And so immediate condition
prevents forgetting
from happening
between learning and test,
and a 15-minute delay introduces
the opportunity of forgetting
between the immediate
and delayed test.
So we're introducing forgetting
at different levels of
the learning process.
And then the test item
was very similar
to what I showed you earlier.
Children would be presented
with four objects,
and then it was the
child's job to pick out
a novel instance of the category
that they learned about.
So the experimenter would say,
"Can you hand me the wug?"
And it's the child's job
to pick up the wug
and place it into the
experimenter's hand.
Okay, what I'm going to do
is show you some results.
This is the results
of Experiment 1.
And what you're seeing on the
X-axis is the testing delay.
So either children being
tested immediately,
or a 15-minute delay,
and then on the Y-axis is the
number of correct responses.
So this is the mean number
of times
that children correctly handed
the wug to the experimenter.
So here's what we found
at the immediate test.
Children in the
simultaneous condition
significantly
outperformed children
in the massed and the
spaced conditions.
So if Ernie Rothkopf
were here, he would say,
"Look, I'm right.
"The condition that had the
least amount of forgetting
led to the most learning."
'Cause the simultaneous
condition at the immediate test
introduced no learning or no
forgetting during learning,
but also no forgetting
between learning and test.
So this would sort of prove
Ernie and others right
that forgetting does deter
conceptual development.
However, let's look at the data
from the 15-minute delay.
What we observed at the
15-minute delay
is that children in the
spaced condition
significantly
outperformed children
in the simultaneous
and massed conditions.
And you might wonder here,
"Well, wow, this
is an interaction,
"a completely different
pattern of results
of the delayed test."
And indeed, what we see here
is children that had the most
opportunities of forgetting
perform the highest, because
indeed the 15-minute delay
was the most amount
of forgetting
between learning and test,
and then the spaced condition
introduced forgetting
during the learning process.
So this is the exact opposite
of what Ernie would predict.
Here what we see is
that forgetting might be
facilitating abstraction
and generalization.
I'm going to jump to
Experiment 2 quickly
and just explain why
we did Experiment 2.
So in Experiment 2,
what we were interested
in is we said,
"Well, we think that
forgetting is happening
between learning events."
In other words, we think
that these 30-second gaps
introduced opportunities
for children to forget.
But what we wanted to know
is we wanted to have data
to actually show that the
forgetting is happening.
So what we decided
to do in Experiment 2
is ask children to retrieve
their learning during learning.
And here's how we did this.
So imagine children are in the
simultaneous condition,
they have four objects put on
the table at the same time.
And the experimenter would
label the first object and say,
"Look, this is a wug."
Wait 10 seconds and then point
to the second object and say,
"What is this called?"
They would wait five seconds,
and then regardless of
what the children said,
the experimenter would say,
"This is a wug."
And then they'd move
on to the third object,
and they point to it and they'd
say, "What is this called?"
They'd wait five seconds,
and then regardless of
what the child said,
they'd say, "This is a wug."
And they did that
for all four objects.
The same thing
happened in the massed
and the spaced condition.
Children would hear,
"This is a wug,"
on the first presentation.
And then on the
subsequent presentations,
the experimenter would
first prompt the children
to report the word by saying,
"What is this called?"
Wait five seconds and
then say, "This is a wug."
And what these retrievals did
is it gives us a sense
of how readily children
are retrieving information
during learning.
And what we predicted
is that children in the
spaced learning condition
would demonstrate
the most forgetting
because of those
30-second intervals.
Okay, here's some data
comparing the final test
from Experiment 1
and Experiment 2.
And what you can see is
we observe the same pattern
of results across experiments.
The bars are a little bit
higher in Experiment 2.
This is to be expected.
It's because children are
getting more retrieval practice
by us asking them,
"What is this called?"
And so they overall did better,
basically a retrieval
practice effect here,
but we see the same pattern,
that at the immediate test,
children do better in the
simultaneous condition,
but at the delayed test,
they do better in the
spaced condition.
Here, what you're going
to see are three bars
representing the overall
retrieval successes
in the simultaneous, massed,
and spaced conditions.
So that's what will be
on the X-axis.
And then on the Y-axis,
what you'll see is the mean
number of retrieval successes
out of 24.
So there were eight trials
with three retrieval attempts
on each, so that adds up to 24.
Here's what we found.
We found that children in
the simultaneous condition
had significantly
higher performance
than children in the
massed condition.
And we found that children
in the massed condition
had significantly
higher performance
than children in the
spaced condition.
And this is exactly
what we predicted.
Children in the
simultaneous condition
are having a lot easier time
retrieving the label
for the category
because they're not experiencing
the same degree of forgetting
as children in the massed
or spaced conditions.
And indeed, children
in the spaced condition
are struggling the most.
We took this same data
and we plotted it by time.
And just as a reminder,
what we did is we
had Retrieval 1
be at the second learning event,
Retrieval 2 was at the
third learning event,
and Retrieval 3 was at the
fourth learning event,
'cause on that first
learning event,
we labeled the object.
We said, "This is a wug."
And then asked them
what it was called
on subsequent learning event.
So on the X-axis, what
you're seeing here
is retrieval attempt 1, 2, 3,
which corresponds to
learning 2, 3, and 4.
And we wanted to know if
the nature of retrieval
changed across the
learning phase.
So what you're seeing here first
is performance for the
simultaneous condition.
And what you see as a
relatively flat line
across the three
retrieval tasks.
And what this suggests
is that children
in the simultaneous condition
are observing overall
high performance
that doesn't change much
across the learning phase.
The next line that you're seeing
is performance in the
massed condition.
It's a similar pattern
to children in the
simultaneous condition,
it's just lower.
So it's a little bit harder,
but there's no change
during learning
for children in the
massed condition.
However, we see something
fundamentally different
in the spaced condition.
What we observe is that the
first retrieval attempt,
children really struggle
to retrieve information.
In fact, it's not significantly
different than zero.
So essentially, when children
get to that second
retrieval attempt,
they kind of stare
at the experimenter
and they don't know what to say.
They're unable to
produce the word wug.
However, across the learning
phase, we observed performance.
So they get better and better
at retrieving the word wug
during learning.
So what this data does is
it confirms our hypothesis
that this paradigm
does introduce
different levels of
forgetting during learning,
but what this data also does
is it provides evidence
for a theoretical count
that explains
why forgetting is
promoting learning.
And what we have argued
is that forgetting
is a form of abstraction,
forgetting acts as abstraction
in order to promote
conceptual development.
So I wanna walk you
through now how this works.
So imagine that you're a child
and you're seeing a wug or a
new toy for the first time.
Well, you're gonna see that wug
and you're immediately
gonna forget
everything about that wug
according to the
curvilinear pattern
that I showed you earlier.
And here, what we see is
that forgetting curve.
So you'll see a wug,
and a certain amount
of time will go on,
and you will then
experience another wug
or another new toy that
shares the category label.
And what will happen
is that that new wug
will prompt you to recollect
information that is similar
to the information
that you saw earlier.
So in this case,
what is similar across these
two items is their shape.
And so what you'll do is
you'll retrieve the shape
that you saw earlier
and you'll engage
in cognitive effort doing so
because you've
forgotten about it.
And so you have to
dig through your mind
to find that information,
that past memory.
And what that
cognitive effort does
is it slows the
memory for shape,
which in this category
is the relevant feature.
Now that second object
won't cue you to recall
other types of information,
like the color or the
texture of the object
that you saw earlier,
because there isn't a
match across the items.
And so what that means
is that you'll continue
to forget that
irrelevant information,
the texture and the color
at the same rate as earlier,
when you first saw
the original wug.
And what you can see from
looking at this image is now
there's different
forgetting rates
for information that's relevant
and information
that's irrelevant.
Let's do another
demonstration of this.
So let's just say
that more time goes on
and a child then
sees yet another wug.
And what that third wug
is gonna do
is prompt children
to recall information
from the first and second wug
that's similar to that item.
And again, that similar
feature is shape.
And so what children will do
is they'll engage
in cognitive effort,
searching for that
shape information.
And what that cognitive effort
will translate into
is a slowed forgetting
for that feature shape.
So it's again, slowing
the forgetting.
However, features
like color and texture
are continuing to be forgot,
according to that
original forgetting curve.
So they're being forgotten
at a much different rate
than the relevant information.
And what we hypothesize happens
across early development
or learning about something
new for the first time
is this process of
where we continually
re-retrieve relevant
information in the world
and then we don't re-retrieve
irrelevant information
in the world.
And as this process happens
over and over and over again,
we end up with different
forgetting curves
for information that's relevant
and information
that's irrelevant.
And so by the time
children or adults
need to generalize to
something new in that category,
they will more readily
retrieve relevant information
like shape, compared to
irrelevant information
like color and texture.
And this will support
generalization
and conceptual development
because they're re-retrieving
what's important
and then applying it
to that new category.
So in other words, it's
helping children, adults,
everyone to abstract what's
relevant in the world,
and therefore helping us to
learn categories and concepts.
Just as a quick summary.
For a long time, going
back to the 1800s,
researchers and general
intuition told us
that forgetting should deter
conceptual development.
It should prevent us from
abstracting what's relevant
and irrelevant in the world.
However, my lab's work
has shown the opposite:
that forgetting can actually
act as a form of abstraction,
speed up abstraction,
and help us to learn
new categories and concepts.
And so while we've always agreed
that forgetting can help
learning and memory,
we now know that it can
help us think and develop
our most higher order
forms of learning,
like learning a new language
or learning complex concepts.
So that's the silver lining,
is that even though forgetting
is inevitable and predictable
and will prevent us from
remembering information,
it's also gonna help us.
It's gonna help us
remember what's important
so that we can generalize
across our experiences
based on the
important information.
So I have a number of
concluding thoughts
that I'd like to share
with you all.
The first concluding thought
is to share some of the
exciting work that we're doing,
trying to build off this
basic research
to design interventions
for children.
One of the things that
we've done is we've thought,
"Well, why don't we integrate
forgetting into curriculum?"
In other words, we should
work with teachers and parents
in order to get
them to encourage
their children to forget.
Now, I know this sounds
very counterintuitive
because wow, teachers are
trying to help kids remember,
parents are trying to
help kids remember.
But remember, forgetting
can help us to remember.
So what we've been doing
is we've been working
with classrooms and teachers
and helping teachers to
integrate spaced learning
into their curriculum.
Here's a quick example.
In a lot of early
childhood curriculum,
teachers use units.
So they might have a lion month
or a flower month,
where they talk
about the same thing
in extensive conversation
for a month and then move on.
So in other words, it's
an immediate succession.
It's kind of like cramming.
So instead, what we've done
is we've encouraged teachers
to distribute lessons
out across time.
We've done a series
of experiments
to provide empirical evidence
for teachers
that this is a good thing to do.
So for example, in some
of our studies,
we come up with different
learning schedules
for science curriculum.
And the example that
I'm gonna show here
is the context of children's
science curriculum
about food chains.
And food chains
are a perfect context
because what teachers do is
they introduce food chains
across different biomes.
So they'll introduce the
food chain in the grasslands
and then the desert.
And then what they
expect children to do
is to abstract out across all
these different biomes
in order to generalize
to a new biome,
like the Arctic or the swamp.
And so what we do is we work
with classrooms and teachers
and develop a schedule such
as the schedule you see here,
where there's one of three
presentations options.
There's a massed schedule,
a clumped schedule,
and a spaced schedule.
What you'll see in the
massed schedule
is that lessons
about food chains
are presented
in immediate succession,
just like we do in the
lab with the word lists.
The spaced condition
distributes all the lessons
out across days of the week
so there's time in
between each lesson,
which maps onto the
spaced schedules
that we use in the lab as well.
In these studies, we use
an intermediate condition
called the clump condition,
which introduces a combination
of massing and spacing.
So some of the
lessons are presented
in immediate succession,
whereas other lessons are
distributed across time.
And we have each lesson be
about the same amount of time,
so that we control for time
across these experiments.
And we have a test for
children that happens one week
after their last lesson
to understand what they remember
from the varied conditions.
And I'm gonnashow
you some data here,
where we had two
different types of tests,
a simple generalization
or simple concepts.
This is things like learning
that bigger creatures
typically eat smaller creatures.
And then we also had
some complex concepts.
And the idea that we tested here
was the idea of interdependence.
So in other words,
if something happens to a
particular creature in a biome,
it affects all the
other creatures.
So for example, if there are no
more fish in the ocean to eat,
that affects all the
other creatures
that live in the ocean.
They will have less to eat
because there are no more fish,
especially creatures higher up
on the food chain.
So that's what you're
gonna see on the X-axis.
On the Y-axis,
what you're gonna see
is the difference between the
pre-test and the post-test.
So we gave the tests before
learning and after learning.
And what you'll see is for the
simple generalization
or the simple concept,
we found that children
in the spaced conditions
significantly outperformed
children in the massed
and the clumped conditions.
And this is what we expected
from prior research.
We expected to see
this based off of
the relatively
simple categories,
like the wugs that
you saw earlier.
In this work, it was actually
our first time testing
whether or not we would
find this phenomenon
in a more complex task, like
learning about interdependence,
but let me show you the results.
Here they are.
We found the same pattern.
We found that children
in the spaced condition
significantly outperformed
children in the clumped
and massed conditions.
So what these
classroom-based studies do
is they help teachers
to understand
how they can
manipulate forgetting
by using spaced learning
in their curriculum
and in their teaching practices.
And indeed, it's been a real joy
for us to work one-on-one
with teachers in classrooms
to help improve STEM learning
by just making these
simple changes.
It's amazing how
just small changes
in the timing of the lessons
can create more learning
in the classroom.
And indeed, this is a
free, innovative way
to improve education.
And we're actively
studying how to develop
these types of interventions
so that we can encourage
forgetting in the classroom
and encourage teachers
to think about
how they can encourage
forgetting in their students.
So this is just an
active area of research
and is, you know,
to be determined
how much more
we can do with this.
You know, in another
year or two,
please contact me and
we'll have more information
about how the curriculum
interventions are going.
Another concluding thought
that I really wanted
to share with you today
is how researchers
are actively studying
forgetting in the current times,
namely during the
COVID-19 pandemic.
And if you're like me,
you may have noticed,
particularly during
the lockdown period,
that your thinking
and learning have changed
during the pandemic
and in particular,
that you've forgotten
faster than you normally do.
So you might lose your keys.
You might not know
what you had for lunch.
You're forgetting things that
you normally wouldn't forget.
And there's a number
of reasons of why
you were experiencing
that faster forgetting.
Here's a quick summary of what
research has found.
So first, we know that
there are routine changes.
You're not going
into the office,
you're not going to the gym.
And the reason that
that affects our memory
is that our routines
serve as memory cues.
We learn where we
always put our keys
when we go to the office,
where we put our lunch,
who we talk to and have
chit-chat with in the hallway.
And when we lose that routine,
we lose the cues.
And so what that's doing is
it's speeding up forgetting.
If we don't have the cues,
we're not gonna remember,
and we're gonna
continue to forget
according to that faster rate.
The second reason
that we observe
faster forgetting
during the pandemic
has to do with a lack
of social interaction.
Social interaction is
important for so many reasons.
And I want to highlight two now.
So during the pandemic,
you haven't spent as
much time with people
and people also
serve as memory cues.
They prompt you to
talk about your past.
So just imagine that you're
chatting with a friend
or a family member,
they might say,
"So what'd you do last week?"
And you responded with,
"Well, I got to talk
to some friends.
I spent some time,
it was so much fun."
And what you're doing
by having that conversation
is you're recollecting
your past experiences
and sharing them with that
other person.
And so when people aren't
around to prompt you,
you're not engaging as much
practice in retrieving the past.
And again, that contributes
to how fast you forget.
The other reason that social
partners are so important
for our memory is
that they contribute
to our emotional well-being.
And we know from a long history
of research
on emotions and memory
is that when we're
experiencing more volatile,
emotional experiences,
and when we're sort
of experiencing
more negative life events,
that we actually forget faster
during those times.
And so for those of you
who are really missing
being with other people,
and, you know,
are just sort of having
a case of the blues,
you're forgetting faster may be
because of your
current emotional state
or the emotional state
that you experienced,
particularly during the lockdown
when you had little to no
social interaction with people.
So there are many reasons
that our social partners
are particularly important
for our memory.
The third reason that we think
people are forgetting faster
during the pandemic is that
we're engaging in more behaviors
that speed up forgetting.
And one of those behaviors
is alcohol consumption.
So there's a lot
of research showing
that during the last 18 months,
people have been
drinking more alcohol
and engaging in more drug use
than they did prior
to the pandemic.
And we know from research
on alcohol and drugs
that they act as a
memory destabilizer
and therefore cause
faster forgetting.
So if you're engaging
in an over-consumption
of these substances, that can
lead to complete memory loss.
Not only are you
forgetting faster,
but you might not have
any access to memories
from those states
of over consumption.
So certainly we think that
a lot of the forgetting
that's happening
because of the pandemic
is because people are choosing
to engage in behaviors
that are negative, that they
for memory at least,
that they didn't before.
The last reason is that many
of us during the pandemic
had lifestyle changes.
And one of the
big lifestyle changes
is that many of us
exercised less.
And this is even despite the
public service announcements
in the news encouraging people
to get out there
and go on a walk,
be outside, exercise.
And one of the reasons for that
public service announcement
or why it was in the news
all the time
is that we know that
exercise is so valuable
for so many things,
our physical health,
our mental health,
and the rate at which
we forget information.
We have a long sort of
big body of work showing
that for those of us who engage
in more cardiovascular exercise,
but exercise more generally too,
that we are more,
we're more readily able
to retrieve important
information when we need to.
So in other words,
exercise is good
and supports our ability
to retrieve information.
And so, because of that, we,
you know, are forgetting faster
if we're exercising less.
So in brief, there's a lot
of lifestyle changes
that we made that aren't for the
benefit of our memories.
And that's yet another reason
why we might be
forgetting faster.
And researchers are
actively studying,
now that we're coming
out of the pandemic,
how our forgetting is changing.
We expect that once we establish
those new routines,
live a healthier lifestyle,
that our forgetting
will slow and go back
to be what it was pre-pandemic.
But we're also concerned that
a small group of individuals
might not make those changes,
might continue to experience
negative effects of the pandemic
and thus have faster forgetting.
So researchers are actively
trying to figure out
how we can identify
those individuals
so that we can help them.
My final concluding thought
is just to say
that we don't know
why we forget,
and we are actively
studying it now,
but we do know that forgetting
is essential for our lives.
Forgetting can help us
to remember.
It can help us
to learn new things,
like new words and concepts.
But most importantly,
it can define who we are.
If we think back
to the pandemic,
there's a lot of things
that we probably want
to forget, right?
We had a lot of
negative experiences,
particularly during
the lockdown period,
and that forgetting is good.
So even though you may
have forgotten faster
during the pandemic and
forgotten a lot of the things
that happened to you,
I would argue that
that's a good thing.
What your mind and
brain are doing
is they're abstracting out
what's important to remember,
hopefully the good things
and the parts of yourself
that were able to endure
during the pandemic.
And I'm hoping for all of you,
that you have a
stronger sense of self
and know more about how you
can endure in tough situations.
And forgetting is
gonna help you do that.
It's gonna help you to
remember when you were strong.
So on that note, I just
want to say forgetting,
although intuitively may
seem like a bad thing,
is a great thing,
and it's helping you with all
facets of your life.
Thank you so much for listening.
Please feel free to reach out
if you have questions
about forgetting.
As I mentioned at the
beginning of the talk,
I spend lots of time
thinking and learning
about thinking and learning,
and I would love to do that
with you as well.
Good evening.