Stickiness, Part 3

We encounter sticky surfaces and sticky substances everyday, but what exactly IS “stickiness?” In this episode of Stuff to Blow Your Mind, Robert and Joe discuss the physical properties of stickiness and look at some very sticky examples from the natural world. 

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Episode Transcript

Speaker 1 (00:03):
Welcome to Stuff to Blow Your Mind, a production of iHeartRadio.

Speaker 2 (00:12):
Hey, welcome to Stuff to Blow Your Mind. My name
is Robert.

Speaker 3 (00:15):
Lamb and I'm Joe McCormick, and we're back with Part
three of our series on the physical property of stickiness.
Maybe you didn't know we were going to do a
part three, Maybe we didn't know we were going to
do a part three, but here we are back to
finish it out today.

Speaker 2 (00:30):
Now.

Speaker 3 (00:30):
In Part one of this series, we talked about starches
and sticky foods, most notably sticky rice aka sweet rice
aka glutinous rice, a wonderful food stuff that has a
lot of interesting chemical properties. And this sort of came
up in the context of my inspiration for this series,
which was, you know, my young child is eating fruits

(00:55):
and fruit based foods and those tend to like leave
mysterious sticky patches all over the house. Now, but so
we did that in part one. In Part two, we
talked about the unbelievably sticky feet of geckos, and we
also talked about a chapter in a book I've been
reading called Sticky, The Secret Science of Surfaces by Lori Winkless,
which is out just this year. And this chapter talked

(01:18):
about different ways that adhesive materials actually stick to one another.
Seems like it is much more complicated and less well
understood than you might guess.

Speaker 2 (01:27):
That's right. The one of the realities we keep coming
up against in this series is that, yeah, the word
sticky covers a lot of ground, and so you know,
if you can't just narrow it down and say, oh, look,
this is sticky and this is something else, like what
kind of sticky? What flavor of sticky are you talking about?
It's a very general turn.

Speaker 3 (01:48):
And as we come back to explore the topic for
one more episode, I'm going to take us in a
much less physical and more metaphorical direction because I got
very interested in the idea of sticky mental content. What
makes a memory or an idea stick in the mind.
And of course this is a question that could be

(02:09):
looked at a ton of different ways. I just isolated
one facet of this issue because it was so interesting
to me. What I want to talk about is something
known as flash bulb memories. Rob, I wonder if you
have similar experiences to this. I remember, when I was
young hearing my parents and friends of theirs. People in

(02:30):
my parents' age. You know, they'd be talking at a
party or get together or something, and I remember them
saying almost this exact sentence. I remember exactly where I
was when I heard about the Kennedy assassination.

Speaker 2 (02:44):
Yeah, absolutely, I remember hearing the sort of thing growing up,
and then of course post nine to eleven there were
all new versions of this. Everyone not everyone, but a
lot of people had a similar take. I remember exactly
where I was, what I was wearing, what breakfast cereal,
the ceial I was eating when this occurred.

Speaker 3 (03:04):
Right, exactly right. So in these types of memories, you
find out about some public event that has happened, and
you seem to have a memory of that moment of
finding out that is just rich with incredible, vivid detail,
and you have extreme confidence about the accuracy of those details.
I remember my parents saying this about the Kennedy assassination,

(03:25):
or people my parents were talking to. People our age,
like you say, might have similar memories about the nine
to eleven attacks. And if you're one of these people
and you have a memory of this kind, you can
almost like go back to that moment bodily right now.
You remember exactly where you were, who you were with,
how you heard about it and so forth. I actually

(03:46):
do have a very clear and strong memory of finding
out about the nine to eleven attacks in high school.
I remember we were gathering for some kind of morning
school assembly and I saw a friend of mine and
I sat down next to him, and he mentioned that
he had heard something. I think he think he said
on the radio or something, but he said mentioned he

(04:08):
had heard something about a plane hitting the World Trade Center.
And I have no way of knowing now if this
memory is actually accurate, but it feels extremely accurate. It
has stuck in my mind like glue.

Speaker 2 (04:21):
Yeah, I mean, I have similar memories. But I also
feel like we've covered the we've covered false memories enough
on the show before, and we've discussed this exact scenario
regarding these these memories that we think we can trust,
but ultimately, upon close scrutiny, you know, the details fall apart.

(04:42):
Like that's enough to where I really I probably distrust
these memories more compared to other memories, just because I
know the sort of thing that goes on with them, right,
So I'm yeah, so I'm hesitant to really even state
that I was wearing this or I was with so
and so, and I even even even more recent examples
of this sort of thing, like I remember where I

(05:04):
was when I heard about the last presidential election results,
that sort of thing. But when I pause to think
about it for more than a moment and ask myself, well,
do you really can you really name all the people
that were there? Do you remember exactly where you were
when you were finishing up this kayak excursion and then
you somebody checked their phone and found the news. No,

(05:26):
I'm not that confident in the memory.

Speaker 3 (05:28):
Well, yeah, I guess the irony is that, given how
much we read about memory research and how much we've
been primed by all of these studies finding you know,
the illusory confidence people have in things. Yeah, maybe maybe
the fact that it feels so so sticky in my
brain makes me actually more suspicious of it. But people
in general, I think, are mostly not suspicious of memories

(05:51):
like this. People in general think, well, yeah, maybe memory
is inaccurate sometimes. But one I'm absolutely certain about is
I remember hearing about the Kennedy assassination, or you know,
decades and decades later, or I remember where I was
when I heard about nine to eleven. That is like
the highest quality memory in my brain. And yet, given
neither of these historical examples, you know, nine to eleven

(06:13):
or the Kennedy assassination, do we usually have vivid, elaborate
memories about other events the same week? You know, if
you ask somebody who strongly remembers exactly how they heard
about the Kennedy assassination, they don't have detailed memories of
what they had for lunch the day before or what
they did after school the day after. So what causes

(06:33):
the details of a specific memory to become sticky in
this way where it stays in your mind for, you know,
sixty years later and still feels like it's in such
incredibly vivid detail, like you know that you're remembering it
exactly right. And why do these memories seem so accurate
compared to our forgetfulness of other memories from around the

(06:53):
same time in our lives. And why do these kinds
of intense, detailed snapshot memories tend to be associated. Of course,
we have similarly intense memories about other types of things,
But why is a category for these intense vivid memories
learning about a big, momentous public event, often a public tragedy.

(07:14):
Another often cited example is the Challenger explosion, and it
turns out psychologists have actually studied this phenomenon and have
looked into these questions. They have firmer answers to some
of these questions than other ones. These types of memories
have a special name. They're called flash bulb memories. So
I think the idea behind the name is it's kind
of like there is a flash photograph taken in a

(07:37):
darkened room, so everything around it is dark and obscure,
but the flash goes off and a picture of a
particular moment is captured and then frozen in memory, perhaps
for the rest of your life.

Speaker 2 (07:48):
In fact, I think if we could ask JJ to
do this, JJ, can you hit us with just the
sound effect of a flash bulb, because many of you
haven't heard it in real life life at this point
or happened in a long time, but you've probably heard
it in movies, often with kind of a freeze framed
black and white effect, which does kind of get to

(08:09):
the heart of it, like the idea that here is
something has occurred and it is just you know, flash
bulb sound effect. It is it is set in your
mind and it will never change. This is a pristine
memory of what is occurring.

Speaker 3 (08:22):
Okay, so time to mention a source. I've been reading
a paper collecting and summarizing the research on flashbulb memories.
This paper is called flashbulb Memories, published in Current Directions
in Psychological Science in the year twenty sixteen, and this
is by William Hurst and Elizabeth A. Phelps. So this
is trying to look at all of the research that
had been done up till that point and see what

(08:44):
conclusions could be drawn. So the term flashbulb memories traces
back to a pair of researchers named Roger Brown and
James Koolick who studied the phenomenon and published important research
on it in the year nineteen seventy seven. So to
briefly separate out, just so there's no confusion what flash

(09:05):
bold memories are and what they are not. Flash bold
memories are memories of the circumstances in which one learned
about a public event. So it's when you found out
about a public event, and this differentiates it from first
hand memories, like the kind of memory where you remember
an event that happened to you personally, something you were

(09:26):
there for, rather than something that you heard about or
read about. So flash bold memories are kind of interesting
that they straddle two different kinds of memory at the
same time. In one sense, they are autobiographical because they're
directly asking you to remember things about where you were
and who you were with and what happened to you

(09:46):
and what you felt. But they concern that that situation
that you're remembering in your own life is elicited by
a public event. It's not something that happened directly to you,
but a moment of gaining in information, of learning about
something that happened to other people. Another distinction is because
their autobiographical flashbuld memories are different from what are called

(10:10):
event memories in the literature. That name can be a
little confusing because it's like, if you have a memory
of an event in your life that sounds like that
would be an event memory, but what this refers to
is information about the public event itself. So you might
have your flashbuld memory of finding out about the Kennedy assassination.
That's where you were, how you heard about it, all
that stuff. But then also there would be public event memories,

(10:34):
which would be things like the date that had happened,
what time of day, the city it took place in,
what type of car Kennedy was riding, in the name
of the alleged assassin, and so forth. This is like
information about the eliciting event. That's also a different kind
of memory. So the flash bold memory is an autobiographical
memory about yourself in the circumstance of learning about this

(10:55):
important public event. And examples of events that have been
studied for creating slash bold memories include assassinations and other
politically charged public events. Also things with a more positive connotation.
The paper cited, like relevant World Cup victories like if
your country wins the World Cup, also events like the

(11:15):
fall of the Berlin Wall, and also natural disasters like
major earthquakes.

Speaker 2 (11:21):
Okay, but at least some positive things thrun in the mix.

Speaker 3 (11:24):
A lot more negative things than positive things have been studied,
and I want to talk about that later because that
may be interesting. I wonder if there are differences in
how those things are recorded. I guess the news that's
worth reporting is more often bad than good, right right.
So Brown and Kolick, the two researchers who did this
important early work on flash bold memories, argued that even

(11:45):
though these public events don't happen to us personally. They
involve so much emotion that the brain records them kind
of as if they did happen to us personally in
the moment that we find out about them. So we
have these unusual levels of accurate and exquisite detail. So
ultimately they sort of said, these memories seem to be

(12:06):
reliable and unchanging, like a photograph. In fact, the words
they use, which are quoted in this review paper, they
say these memories were quote unchanging as the slumbering rhine gold.

Speaker 2 (12:19):
Oh oh, that's nice. You know, it is interesting the
idea that even though it doesn't happen to you directly,
like through our media absorption, we do a lot of
living vicariously through people in the media, celebrities and the
public eye and so forth. And then I also wonder
too you think about how we've evolved as a species

(12:42):
and the sort of groups we are supposed to occupy,
and the sort of information about said groups who would
have like we didn't we didn't evolve to live in
a continental or global society in which you could have
something catastrophic occur that did not directly or potentially directly affect.

Speaker 3 (13:01):
You, right, I mean yeah, So I almost think there
is maybe a mental switch that has to be flipped
where we can like ignore most of the news we
encounter as being like, well, that doesn't directly affect me.
But for some reason, there's an emotional switch that you
can flip where even if it doesn't directly affect your life,

(13:21):
it's hit that emotion and now it feels like it
does It feels like it happened. You know, something that
happened to the president of the United States feels like
it happened to the leader of your ten person band.

Speaker 2 (13:32):
Yeah, yeah, I guess there are a lot of moving
parts here because you can also you know, draw in
things like social norms and our you know, intense need
to fit in socially with our given survival group and
so forth.

Speaker 3 (13:44):
Right, maybe we can come back and speculate more on
this when we finish with what the research has found.
So what we have brown and cool, Like they say,
these memories, they are as unchanging as the slumbering rine goal.
Do you just remember what happened in that moment and
it never changes the rest of your life. It is
like the treasure the under the river, is that under
the water being guarded by the Rhyine Maidens.

Speaker 2 (14:06):
Yes, yes, the three Rhine Maidens.

Speaker 3 (14:08):
But the authors of this review paper point out that
Brown and Kulick didn't actually have information that would justify
the claim that flash bold memories were unchanging as the
Rhine gold because they had nothing to compare their subject's
accounts too. Essentially, people would be prompted to recall a
flash bold memory like do you have a memory of this,

(14:30):
and then people would say, just like we've heard before, yes,
I remember exactly where I was. This is how I
found out, Here's what happened. Here are all the details. Now,
in light of other findings in psychology that people can
have the strong genuine impression of remembering things in ways
that you can prove objectively are inaccurate, some researchers started

(14:52):
to doubt whether these flash bold memories were actually as
accurate as Brown and Kulick suggested and as act as
people generally feel that they are in their own lives.
But this would be a difficult thing to test, right, Like,
what can you do? You can't follow people around twenty
four to seven with a video camera and just wait
for them to hear about a major public event and

(15:14):
then test them on it later and compare it to
the videotape that's obviously not feasible. So while testing the
true accuracy of flash Bold memories to the direct events themselves,
the moment people find out about these things, that would
be extremely difficult. But researchers did come up with what
I think is a very clever proxy, and it's very simple.

(15:36):
Instead of testing accuracy, they would test consistency, and so
this would work on the test retest method. So it
works like this, as soon as possible after a major
public event, the same day, if possible, or the very
next day, you give people a questionnaire asking them to
narrate how they found out and answer a whole bunch

(15:57):
of autobiographical questions about that moment. You know, where were you,
how did you hear about it, who was with you,
and so forth, And then you just hold on to
their answers to that questionnaire, and then after a delay,
you give subsets of that initial sample group at different
periods exactly the same questionnaire. So maybe a few days

(16:18):
later some people will get it, maybe a few weeks later,
a few months, even years down the road, and you
simply compare their answers to the later questionnaire to what
they said immediately after the event. So what do studies
of this sort reveal. Well, the results are a little
bit mixed. There were a few reports supporting some broad

(16:39):
levels of consistency after delays, but the majority of these
studies have found substantial changes to flash Bold memories over time,
and for the most part, we have no idea that
these changes are happening In our own brains. We remember
the flash Bold moment one way a year later, and
it feels intensely vivid, inaccurate, and we are sure this

(17:02):
is exactly how it happened. We could not be wrong,
but it's not what we said happened the same day
or the day after. Now, I guess you could say
it's possible that the first questionnaire is wrong, that the
initial reports from right around the time of the event
are not accurate. But if there are differences between what
you remember the same day or the day after and

(17:23):
what you remember a year later, is it likely that
the memory from a year later is the more accurate one.
I would tend to think no. And so while consistency
is different from accuracy, I think it's a decent proxy
for it.

Speaker 2 (17:37):
Yeah, absolutely, of course, This also brings me back to
other memory of related topics we've discussed in terms of
retrieval errors and the idea that every time you retrieve
a memory, it is susceptible to change. So frequently retrieved memories,
or the memories we retrieve the most, are also the
ones that have been augmented the most. And I can

(17:58):
imagine you have a synay, it's like, what is causing
you to retrieve said memory, and the necessity of the
retrieval then alters the surface of the memory retrieved.

Speaker 3 (18:10):
You know, yeah, yeah, I think that may well play
a role in what's going on here, because there are
patterns of how we treat different types of autobiographical memories,
and these flashbulb moments are things that may well be
sort of unusually rehearsed compared to other day to day memories.

Speaker 2 (18:30):
Yeah, yeah, And then think, for instance, they can be
potentially altered by someone else retrieving said memory, someone else
telling you where they were when such and such happen,
And then you retrieve your story. But maybe it's a
little bit different this time. Maybe it's a little more
like the one you just heard, or it's sort of
almost intentionally different in some regards compared to the one

(18:51):
you just heard. There's so many ways you could slice it.

Speaker 3 (18:54):
Despite the fact that I think Brown and Kolick we're
wrong about these memories being accurate and unchanging, or at
least being wrong about them being unchanging, they did discover
something important, which was that these memories are sticky in
one sense. The research reveals the memories are sticky, but
they're not sticky in the way that we think they are.

(19:14):
They're sticky in the sense that they do stick in
the memory, and we recall them later with great ease
of retrieval and confidence in their details, and great depth
of feeling about our ability to relive the moment. But
they're not actually sticky in the sense of preserving the
details of what happened on that day unchanged, at least

(19:34):
not as well as it feels like they do. In
the words of the authors of this review paper, Hurston
Phelps quote Brown and Kulick, and researchers employing the test
retest method are discussing two different claims about forgetting. Brown
and Kulick treated forgetting as a failure to have a memory.
You know, somebody's saying I can't remember anything whereas those

(19:57):
employing a test retest methodology treat forgetting as a failure
to remember the past consistently. When Brown and Kolik stated
that there is no forgetting, they are right in the
sense that most members of the public report having a
memory even after ten years. That's not true about a
whole lot that goes on in our lives. But then

(20:19):
the authors go on as the test retest work indicates
the memory may not be consistent, but it is long lasting.
I think that's a really interesting distinction they're making.

Speaker 2 (20:30):
Yeah, yeah, there is something about the memory that is lasting,
which raises the question why does it last? Why does
it remain stuck to the fridge of memory even if
the details of the node or the drawing or whatever
have changed even substantially.

Speaker 3 (20:48):
I think that's a great question. So one thing I
was fascinated by was details about how the memories change,
like what actually changes about them. A few interesting observations
they mentioned. One is that there is a type of
consistency that emerges in how we remember these memories, but
it's not consistency to the day to like the original event.

(21:10):
The way they put it is, once a consistency emerges
in our memory of a flash bulb event, it tends
to stick. So I'm just making up this example. But
for illustration, let's say you answer a questionnaire on the
day of the event saying that you heard about the
event because you were up in the morning by yourself

(21:31):
making coffee and you heard about it on the radio
in the kitchen, and you can give all these details
about that. And then you do the same questionnaire a
couple of months later, or even a few weeks later,
and you say, you heard about it when you were
stuck in traffic with your carpool group on the freeway
on the way to work, and you heard about it
on the radio. What the research tends to find is

(21:52):
people will tend to pretty consistently reproduce the second story.
So you ask them again years on and they will
tell the same story they told in the later questionnaire,
So that one tends to stick as if it were
the original one, and people think it's the original one.
But for some reason, there's this change that occurs early on,

(22:14):
within the first year after the event. So it's kind
of like there is a stickiness quality and a consistency equality.
But what sticks is not the memory of the event itself,
but the way it emerges as a narrative in your
brain typically it's sort of fine. They say that it
finds this form within the first year after the event,

(22:34):
and once it finds that changed form in the brain.
Of course, to be fair, I want to make sure
I'm saying it doesn't always change. It just does in
a whole lot of cases. Once it finds that changed form,
it tends to change a lot less after that. So
it's the inaccurate or inconsistent story that we start telling

(22:55):
about how we remember the about how we remember the event,
that we keep remembering for years on after that fascinating.
Another interesting thing the author has mentioned here is that
the inconsistent details that emerge in later questionnaires about these
flashbulb events are not always like just you know, fabricated

(23:16):
details from out of nowhere. One common thing that happens
is what they call time slice confusions, and this is
essentially the tendency to remember a second or third time
you found out about an event as the original time.
So maybe you hear about the event on the radio,
and then you say in this original questionnaire that later

(23:39):
the same day you had a conversation with a friend
about the event a few weeks down the road, you
might remember the conversation with the friend as how you
found out about the event.

Speaker 2 (23:50):
That's interesting, again, a lot of moving parts there, right,
because the first version in theory here is just like
a solo discovery of the event of the same second
one is like a social interaction and you know, conceivably
a discussion about the event with social ramifications. And then
you're coming back and remembering that. You know, what does

(24:11):
that mean? Is it? How much of it is like
the power of narrative, like we were talking about, You've
given it narrative form, You've given it more life and stickiness.
Or is social interaction is that something that gives it
more stickiness, et cetera.

Speaker 3 (24:23):
Yeah, it also strikes me as though that was just
a possible example I brought up. I mean, it strikes
me that generally combining multiple finding out about something events
into a single event is the same kind of It's
the same kind of work like you might do when
you're revising a story you've written to like condense things
and to like make it punchier.

Speaker 2 (24:44):
You know. Yeah, Like, I mean, it even applies I
think to really unimportant things. I mean, you know subjectively,
you know things about like where did you discover a
particular artist? You know, where did you first hear a
particular song? Like, you know, the less interesting version is like,
oh I heard it a few times and I didn't
like it or didn't notice it, and then finally one

(25:05):
day I just suddenly it sounded good. No, No, you
want like a more pure discovery story if you want
to impress people, It's like, well, I was driving along
this deserted stretch of road and this song started playing
and it was like unlike, it was unlike anything I'd
ever heard before.

Speaker 3 (25:21):
I bet this happens a lot, and this wouldn't be
a flashbold memory, but I bet this same kind of
streamlining of memories happens a lot in how people remember
meeting like their partner significant other, because I think a
lot of times people might be kind of in the
social orbit of somebody and like meet them a few
times and it just doesn't really make any impression, and

(25:43):
then they have a moment where they're like, oh, here's
the first time we really like talked and got to
know each other, and they remember that as their first
meeting when it was not. Actually it was just that
these other earlier meetings are just not very interesting and
nothing happened, so you don't actually remember you met them.

Speaker 2 (25:58):
Then, yeah, because sometimes it happens like that in the movies,
but more often than not it doesn't. More often than not,
you have that big dramatic moment, you know, that that
sappy moment of eyes meeting across the room and the
music kicks in, and on some level, yeah, you want
to retell your story in a way that fits the myth,
that fits the you know, the ideal version that has

(26:21):
presented you to you in popular narratives.

Speaker 3 (26:33):
So, coming back to this paper, studies have tried to
figure out what are the necessary and sufficient conditions for
the formation of flash bulb memories, when and under what
conditions are they formed, But the goal of finding these
conditions has been it's proven elusive, like it's hard to
identify features common to all flash bulb type memories. So

(26:54):
the researchers have asked questions like, is the event being
consequential to a person's life necessary or sufficient to call
us a flash bold memory? The answer seems to be no.
We create flash bold memories for things that don't personally
affect us. Of course, we do also for things that
do but they don't have to affect us personally. Sometimes

(27:15):
things that really have no tangible impact on our lives
will make one of these type memories. Also, there are
lots of things that have major direct impacts on our
lives and they don't elicit flash bold memories when we
find out about them, so it seems to be neither
necessary nor sufficient for it to have impact on us personally.

Speaker 2 (27:34):
Plus, the impact is subjective, right, because I can think
of plenty of examples where a celebrity has passed and
you'll see or know people, or perhaps you are the
person who has like a real significant reaction to it,
And sometimes it's because it lines up with something else
in your personal life, or it's just you know, you're
a huge fan and all that's fair, but you know,

(27:56):
it's a different animal than perhaps hearing about this other
celebrity that the same week that you don't have the
connection with, or they don't remind you of your dad
or your mom or your grandfather or something.

Speaker 3 (28:08):
Right, And unsurprisingly, there's at least some research finding that
people are more likely to report high confidence in the
accuracy of their flash bold memories if the central figure
in the public event is someone they feel a social
bond with. And that comes around to another factor influencing
the formation of these memories that the researchers bring up,

(28:30):
and that's the concept of social identity. It seems like
flash bold memories, even though they relate to finding out
about public rather than personal events, are more likely to
be things that somehow kind of form the story of yourself.
So to read a passage from Hurst and Phelps here
quote they play this role in part because they mark

(28:52):
those instances during which people feel that they are part
of the history of their social group. In nineteen eighty two,
wrote and here they're quoting this other researcher. One quote
recalls an occasion where two narratives that we ordinarily keep separate,
the course of history and the course of our lives,

(29:13):
were momentarily put into alignment. Details are linked between our
own history and history capital h flashball memories are the
places we line up our lives with the source of
history itself, and say, I was there, I thought that
was really interesting. Yeah, yeah, about the intersection of the

(29:35):
two lines. So, yeah, we tell the story of ourselves.
But sometimes there's just like the moment that connects with
the event that everybody else remembers, with something that was
known and experienced by everyone, almost kind of like the
forest gump syndrome, you know it just keep you're intersecting
with known public events in history, and for some reason

(29:57):
we form these feelings were remembering these events very strongly,
and they stick with us throughout our lives.

Speaker 2 (30:04):
Hmm.

Speaker 3 (30:05):
Fascinating, And the authors point out interesting findings that the
common feelings of a social group about a historical event
may affect and alter how members of that group remember
the autobiographical details of learning of that event themselves. For example,
the authors cite one study that this is the kind

(30:26):
of finding that it's like almost too perfect, So I
wouldn't want to hang too much on this study. In
less similar findings were replicated all over the place, but
in isolation. It is interesting. So the researchers were Berntson
and Thompson in two thousand and five, and they studied
elderly Danes who had something like flash bolt memories of

(30:48):
when they learned about the German invasion of Denmark, the
Nazi invasion of their country in World War Two, and
when they learned about the German withdrawal from their country.
In these autobiographical memories related to these public events, the
Danes were more likely to remember the weather as being
worse than it was on the day they found out

(31:08):
about the invasion, and to remember the weather as being
better than it actually was on the day of the withdrawal.
So like these autobiographical memories are being influenced by like
you know, sort of like feelings as part of a
social group about the moral valence or the positive or
negative valance of what's happening in the news. Finally, another

(31:32):
feature of these these sticky memories can be illustrated in
the title of a paper from two thousand and three
by Jennifer M. Talerico and David C. Rubin, and that
title is confidence, not consistency, characterizes flash bold memories. This
was in psychological science again this the year two thousand
and three. Hurston Phelps write, quote One agreed upon difference

(31:55):
between flash bold memories and everyday autobiographical memories, even those
that are raed as important, is that confidence in flash
bold memories remains high even when consistency declines, whereas confidence
in every day autobiographical memories declines along with consistency, So
does that make sense? Like the memories for regular events,

(32:18):
they decline in consistency, you know, trying to remember what
you had for lunch or what you talked about at
work or whatever, that declines in consistency of recall. Over time,
we remember them differently. But also for those regular events,
we lose confidence in how accurate those memories are. So ironically,
for normal memories, we're sort of accurately assessing that our

(32:39):
fading memories might be wrong. Whereas with these incredibly sticky,
flash bold memories, we lose consistency of recall. Over time.
They do degrade in quality, and you can show that
it changes how we remember them, but we're much more
likely to say in these cases with very high confidence, no, no, no,
it's not changing. I remember exactly how it happened.

Speaker 2 (33:01):
Well, yeah, the way that I recall it being discussed
before in the past, when I read about it was that, yeah,
these these additional details, things like what what was I
eating for breakfast? Or what did I wear that day,
or even you know, some of the other things surrounding
the discovery or the you know, the or the hearing
of the word you. The brain kind of fills in

(33:23):
the blanks on that. Uh, it's like that there's something
more important that has to be solidified in your memory,
and therefore it kind of like the memory. The rest
of the memory is rushed. They're like, well, it's like
there's an assembly crew in there, and it's like, well,
what should we put down for breakfast on this memory?
It doesn't matter, just put down anything. We can change
it later. We will change it later. The important thing

(33:44):
is that this terrible thing happened or this great thing happened,
and they heard about it and and yeah, yeah, and
that you were that they were there, and that they
they are part of it. I like this idea that
it's like, yeah, it's like the capital h h history
and lowercase age history converging. Like in a way, it's

(34:04):
you know, it's it's it's defining self in comparison to
the larger group. You know, perhaps you can also throw
in the you know, vital survival information as well. Something
terrible happened and it has to be remembered because I
want slash need to avoid terrible things. But yeah, the
details are not as important. It's that it's that central

(34:27):
detail that has to be recorded, right.

Speaker 3 (34:29):
That moment of finding out feels entirely like you can
recreate it in your mind right now. But there's a
good chance that if you had written down what happened
to that day and you compared it to what you
remember now, it would be different. And so a question
would be, why are we so confident about the accuracy
of our flash bold memories when research shows that, you know,

(34:50):
you can show that they're not as accurate as we
think they are, And this is hard to say, The
authors point out, you know, there's a general finding about
memory that quote, vivid elaborateness and ease of retrieval are
thought to influence the judgment that an event occurred. So
if you can make the details of a memory really vivid,

(35:11):
you know, you can just see them in your mind,
And if you can add lots of details, and if
you can make the memory come to mind without much effort,
people have more confidence that the memory is accurate, even
if it's not. And this would apply to other memory,
other types of memories too, And they're just maybe features
of flashbold memories that incubate these qualities of vividness, elaborateness,

(35:35):
and an ease of retrieval. Maybe because they come up
often in conversation or maybe because of this, maybe it
has something to do about this, Yeah, this intersection or
connection point with history more broadly, that that causes us
to almost kind of like write them out as a
detailed story in the mind in a way that you
don't do for most other events, even important events.

Speaker 2 (35:57):
Yeah, and then you end up having high confidence in
this narrative that is ultimately you know, it can be,
you know, defining of yourself. And so of course you
can have confidence in it, because what happens when you
don't have confidence in the in the autobiographical stories that
define who you are, I mean, you end up like
I guess, you know, at least like me, because I
feel like every time we cover these these memory topics

(36:20):
that kind of if it forces a lot of self
reflection on the memories that do define me, you know,
and I think back on them as like, well, you know,
to what extent is that what happened? And then to
what extent doesn't matter if it's not like you have
to sort of face the fact that you know, all
memories are potentially incorrect to some degree.

Speaker 3 (36:42):
Right, And you know, I want to come back on
the other hand, and say that all these studies about
the faultiness of memory, they don't mean that, like, none
of your memories are accurate. You know, probably a lot
of your memories are basically accurate. The point is that
they're not as reliable as they feel.

Speaker 2 (37:00):
There's a lot of truth in your memories.

Speaker 3 (37:02):
Yes, yeah, there's just like there's a decent chance that
you remember a lot of things with high confidence and
in fact it didn't happen that way. Yeah, but plenty
of things did happen more or less the way you
remember them.

Speaker 2 (37:13):
Yeah, I mean, and it cuts both ways, right, I mean,
it can You can certainly have a memory that is
more traumatic because it has been made more traumatic through
recall and through you know, the way that it is
ultimately embellished through memory. But other times, like you remember
something with kind of rose tinted glasses, you know, you
remember the fun part of a particular vacation as opposed

(37:34):
to the you know, the minor squabbles that may have
accompanied the endeavor. Right.

Speaker 3 (37:39):
Oh, And because so one thing that springs up is
that with flashbul memories, because they often involve these these
public events that are negative in quality that could lead
people to the to the erroneous assumption that flashbul memories
work the same way like traumatic memories of first hand
events work, and that's not necessarily true. We don't know

(38:02):
the extent to which there are similarities and differences there fully,
first hand traumatic memories I think are going to be
governed by possibly some different thing this than these flash
bold memories are. But that also brings us to this
question that you brought up earlier, that I think is
a good one. A few studies have looked at flash
bold memories elicited by positive public events. You know, follow

(38:25):
the Berlin Wall, a lot of people who remember that
see that is a positive thing, or you know, maybe
World Cup victories for your home country or something. But
most of these studies look at negative events, and that
probably just has a lot to do with like the
nature of big public events in the news. You know,
there's more often a big negative event than a big
positive event, at least in how it's covered in the media.

(38:47):
So if we had more investigations of big public positive events,
do you think there would be any major differences in
memory responses or would it be pretty much the same thing?

Speaker 2 (38:58):
Yeah, I guess one of the I mean one of
the problems is just like the the negative the catastrophic
headlines are the ones that like instantly come to mind,
Like when when you try to, I have trouble just
thinking of of significant good news events that would have
that kind of magnitude. They would have to be you know,

(39:19):
you know, things like the you know, the end of
major wars, the you know, just overwhelmingly good news. And
it seems like the moon landing maybe moonlanding, moon landing,
moon landing is a good one.

Speaker 3 (39:33):
Yeah, this might just be a fact of reality that
good news is stuff that tends to develop gradually over time,
and then you can sort of discover it retrospectively. You
can be like, oh, something very good happened over the
last twenty five years gradually, whereas bad news often tends
to happen all at once.

Speaker 2 (39:53):
Yeah, I think, I think. I think you're right. Though.
It's like the way we retrospectively evaluate the importance of
them moment is key, and you know it's and is
there like this one moment that really like rings out
as opposed to like a gradual swelling.

Speaker 3 (40:09):
Right, Like if you're trying to remember a public person,
if it's a person you have positive feelings about the
good things they did are probably like a whole career
of good things that developed gradually and you could develop
an appreciation for it. It didn't happen one day, but they
might they die on one day.

Speaker 2 (40:28):
Right. It punctuates this lifetime of achievements or contributions, et cetera.
You know, forces you to reflect on those and value
those often, you know, value those even more while also
feeling you know this at very least intense bitter sweetness
regarding the whole situation where you realize, oh, I loved
all these albums that say David Bowie put out, I

(40:49):
liked the last album, but I didn't know it was
going to be the last album, and now I do. So,
you know, a lot of emotions to feel about those moments.

Speaker 3 (40:57):
So there we go. Flash bold memories actually very stick
but not in the way people think they are. Yeah,
illusory stickiness maybe so. So I thought that was very interesting,
and maybe we can come back to other types of
sticky memories and sticky memory research in the future.

Speaker 2 (41:16):
Absolutely, I think we will. You know, we'll always come
back to memory based topics. All right. For the last
little bit here, I want to bring it back to
physical stickiness, I thought it might be interesting to think

(41:36):
about sticky substances, specifically glues and adhesives in history. The
most crucial sticky substance to consider in all of this
is plant resin. Plant resin is exuded by some trees
and other plants, such as fir and pine trees in particular,
and most resin trickles out in response to injury of
some sort to the tree or plant in question. These

(42:00):
resins are not soluble in water, and they typically lose
volatile compounds via evaporation, leaven behind a soft residue that
is initially soluble but becomes insoluble as it ages. Okay, initially, however,
it's viscous, it's sticky. And if you don't already have
like the smell memory in your nostrils, well, then if

(42:21):
you're of a certain age, then perhaps you remember a
key scene in nineteen eighty nine's Christmas Vacation starring Chevy Chase.
There's a scene where he has just cut down a
Christmas tree, and now it's the evening. He's laying in
bed next to his wife played by Beverly D'Angelo, and
Chevy Chase is like messing around with them with a

(42:42):
magazine he's trying and then he's trying to turn off
the light and his fingers are sticking to everything because
it's they're covered with tree resin.

Speaker 3 (42:50):
This is a great scene because it's not the point
of the scene. He's just happening in the background that
every time he touches a magazine page it tears off
on his fingers.

Speaker 2 (42:58):
Yeah.

Speaker 3 (42:59):
I'm myself have vivid memories which may or may not
be accurate to reality, of being a kid and climbing
on pine trees in uh, I guess on around the
playground at my school and getting sap or resin whatever
it is from the tree stuck to my hands, into
my arms. Actually, I remember it going up my wrists

(43:20):
and stuff, and again may or may not be accurate,
but what I remember is that it was really really
difficult to wash off, Like you'd rub it with water
and soap and it would just stay on there.

Speaker 2 (43:32):
Yeah. Yeah, it's just very sticky stuff where, Yeah, if
you're horsing around in the woods at all, you're going
to encounter it at some point and you may wonder
like if will this ever come off? And you know,
eventually it does anyway. Yeah, then, as far as Christmas
Vacation goes a lot of broad comedy in that movie.
But that's kind of like one of the nice scenes
of more subtle comedy that I always liked, though I
guess it gets a little broad towards the end of that.

(43:53):
That's the sequence swimming, knocking over the lamp and so forth,
and his hand gets stuck to her hair.

Speaker 3 (43:59):
Oh yeah, I forgot about that. I just remember them,
Am I remembering this right? Like he touches the magazine
pages and they just tear off on his fingers.

Speaker 2 (44:06):
Yeah.

Speaker 3 (44:06):
Okay.

Speaker 2 (44:08):
Now, speaking of movies from the eighties and nineties, if
you've ever seen a little film titleed Jurassic Park from
nineteen ninety three, then you know the basics of what
I'm going to talk about next. Insects and other organic
bits winding up stuck in the tree resin and eventually
becoming amber. A whole host of insects were trapped in

(44:30):
this way and later discovered by humans, includes flies, lice, beetles, ants, butterflies,
and moths. Amber has also been found to contain spiders, webbing, frogs, crustaceans, hair, feathers,
all sorts of stuff.

Speaker 3 (44:44):
It's nature's museum display case.

Speaker 2 (44:47):
Yeah, it's just I mean, come and get back to
what happens. Imagine a scenario where a tree is injured
one way or another by another organism, by something falling
into it, et cetera. And things on the trees, things
come into contact with the trees, and then they get
caught in it. They may overflow them and then ultimately

(45:07):
preserve them. Now, it is of note on the whole
Jurassic Park idea. The idea of DNA extraction from a
mosquito in amber has seen in Jurassic Park. This seems
to remain unrealized, despite some starts and stops and actual
scientific attempts to do just this. Contamination by modern DNA
seems to have played a role in some of the

(45:29):
false positives that have popped up. Examples, you know, where
scientists have come forward with the study and said, we've
done it. We've been able to successfully retrieve DNA in
one form or another from the contents of this amber.
And I believe in those cases it tends to be
a situation where you actually have modern DNA that has
contaminated the results.

Speaker 3 (45:50):
I sort of hesitate to say this because I didn't
double check before we recorded. But I think there would
be a real problem trying to extract DNA from like
dyne era insects and amber like they do in Jurassic Park,
just because the DNA molecule degrades too much over time
for it to last that long. But maybe you could
feasibly get DNA from an insect in amber from more

(46:12):
recent times.

Speaker 2 (46:14):
Yeah, apparently there's still scientific debate about how long DNA
can survive in different settings, but you know, I guess
it's a never say never situation. Some scientists continue to
pursue this angle for potential ancient DNA retrieval, and of
course ancient covers a lot of ground. In twenty twenty,
scientists actually succeeded in pulling insect DNA from amber, though

(46:35):
the amber in question was from twenty fourteen common era
twenty fourteen to be clear. So it's you know, it's
not not a not a not a home run, not
a not a touchdown, or what have you, but you
know it's something to go on now. As a as
a tangent, I was looking around about ancient DNA retrieval
and I got kind of interested in a few different

(46:56):
a different different angles on this and a twenty twenty
two paper that the title caught my attention. It was
from the journal Molecular Biology and Evolution titled Ancient Human
Genomes and Environmental DNA and the sement attaching two thousand
year old headlice knits. And this paper indeed explored to

(47:17):
what extent quote host DNA is protected by the cement
that glues headlice knits to the hair of ancient Argentinian
mummies fifteen hundred to two thousand years old.

Speaker 3 (47:29):
Wow, this is my kind of study. What do they find?

Speaker 2 (47:33):
Well, the findings suggest that ectoparasitic lyce sheaths may prove
to be a reasonable tool in ancient DNA retrieval. So
stickiness strikes again here, Like there's this idea that you know,
as we're trying to again, you know, ongoing debate about
to what extent DNA survives and where it can survive

(47:53):
and what conditions, this study indicates that, yeah, the place
to look might be these knits, these little places where
lice have used their glue to, you know, to hold
eggs in place. Beautiful though, of course, one can't help
but go in a sci fi direction. With all of this,
and imagine half lice, half human mummy hybrids shambling out

(48:15):
of the cloning tanks. You know where it's like, we
did it, we clone the mummies. Oh, we've forgot about
all that lice DNA.

Speaker 3 (48:21):
I am brundle lice.

Speaker 2 (48:22):
Yeah. At any rate, Amber has managed to preserve insect activity.
You know, we have examples of mating, examples of egg laying, parasitism,
swarming behavior, just a few examples of the things where
we can look and say, Okay, not only do we
see a particular species, not only do we see this
snapshot in time of what the organism look like. Sometimes

(48:45):
we can make out behavior. You know, we can also
sometimes make out key details about individual structures. I believe
some of this has come up on the show before.
You know, what did this particular type of insects head
look like? What did its particular you know, feeding apparatus
look like? Millions of years ago? Structural colors another thing

(49:06):
that is sometimes preserved and can be analyzed. And you know,
we're talking about specimens from as long ago as like
two hundred and thirty million years.

Speaker 3 (49:15):
Okay, So whether or not Amber can successfully preserve the
DNA molecule intact enough over time, it can certainly preserve
macroscopic objects, structures, and almost like scenes or dioramas in
some case.

Speaker 2 (49:31):
Yeah, so something that is physically sticky ends up preserving
creating a kind of like sticky physical memory for humans
to contemplate in the far future.

Speaker 3 (49:42):
Interesting.

Speaker 2 (49:43):
Now, speaking of prehistoric stickiness, speaking of the ancients and sap,
I thought we might turn to the oldest manufactured glue
that we know of in human history, and that's birch
bark tar. This is created by heating birch bark via.
I think there are four different methods that are that
are generally recognized. I was reading about this in a

(50:03):
twenty nineteen paper by Nikas at All published in the
journal Anthropology. According to these authors, there's condensation method, there's
ash mound method, there's pit and vessel method, and there's
raised structure method, which involves earth and mound containing a
vessel and screen. Those are in order of complexity as well,

(50:24):
and the more complex the greater the yield. So my
understanding based on this is like, yeah, if using the
condensation method, you would have to do so much more
of it to get the same amount of birch bark
tar that you would get using the raised structure method.
So birch bark tar use dates back to the Paleolithic period.
Our ancestors used it to have to tools to decorate objects.

(50:49):
But this wasn't only a technology of Homo sapiens. This
really I found this really fascinating. Archaeological evidence shows that Neanderthals,
are extinct evolutionary cousins also used it and seem to
have produced it, using it on at least some of
their tools. I don't think all of them, but we
have found Neanderthal artifacts where they used this tar to

(51:12):
construct their tools, and they use some of the more
complex methods of driving the birch bark.

Speaker 3 (51:20):
Tar ah so like higher up the list of four.

Speaker 2 (51:23):
Yeah, yeah, so they weren't just using the most primitive
version of it, which which I think is also pretty
you know, potentially insightful about who the Neanderthals were and
what they were up to. And I think in general,
whether you're talking about prehistoric humans or or Neanderthals, it's
it's easy for a lot of us, you know, certainly

(51:43):
without deeper knowledge of actual tool construction, you know, and
methods of tool construction specifically in prehistoric times. To assume
that you know, everything was lashed together, right, everything kind
of looked like there's kind of an image of a
stone age tool that may enter your mind and it
involves like a you know, something wedged in wood, maybe
strapped with some hide in wood, and you don't think

(52:04):
about how important adhesive technology was and has never stopped being.

Speaker 3 (52:10):
We talked about this in our Invention episode on chewing Gum.
I believe, but the Iceman Oatzy, the fourth millennium BCE
Stone Age mummy who was preserved in a glacier in
the Italian Alps, was discovered in the early nineteen nineties.
Oatzy so many fascinating things about Otzy, but one of

(52:31):
which was he carried with him this copper axe. And
the copper axe, the blade of the axe was secured
to the handle with multiple means. It did have some
wrapping of leather straps like you were talking about, but
it also was glued in place using birch bark tar

(52:51):
adhesives made from the birch tree. Also in that episode,
we talked about a paper called chewing Tar in the
Early Holocene that was about indications that lumps of birch
bark tar had been chewed, and the idea is like, okay,
was this being used as like chewing gum in the

(53:13):
ancient world, or maybe maybe was chewing on it a
way of treating it so that it could be used
in the creation of tools.

Speaker 2 (53:21):
Yeah, I remember this discussion now, Yeah, it's it's fascinating again.
It's so easy to dismiss the importance of adhesives, the
importance of glues and sticky things, you know, but I
mean it makes sense too, because again, humans would have
gone out into the world, they got sticky, they got
sticky things on them, and everything that they encountered, they

(53:43):
you know, inevitably asked the question can I use this?
Is this of use to me? How can I combine
this with other things to create useful things? And of
course sticky is going to play an important role there,
and you know, factors into construction. Obviously we already talked
a bit of We talked about mud bricks in previous episodes.
We talked about sticky rice mortar earlier in this series.
But there are also plenty of other methods of construction

(54:06):
out there, Like one that I was reading about is
wattle and daub which you know, sounds like an interesting
law firm or something. But now this is where you
have woven flexible branches called wattle, and they're essentially daubed
up with a sticky combination of such materials as mud
and clay and possibly dun you know, not all that different,

(54:26):
I guess in some respects than you know, compared to
mud bricks. But but again another construction method, another recipe
for building something that involves using something that is sticky.
And of course, if you get back into the problem
of the word sticky and just how vague it is,
I mean basically that can bring in any kind of

(54:47):
like plaster scenario, mortar scenario, brick making scenario, and more.
Now I have to say I really wanted to end
it on a monster here. I was like, there's got
to be a nice sticky monster out there, and perhaps
there is, and I just didn't have time to find it.
I got really excited when I discovered a Japanese yokai
known as Beto Beto Son, which is sometimes translated as

(55:11):
mister Sticky, though this ultimately doesn't really hold up because
apparently the more accurate translation is mister footsteps. This is
the connection I think only makes sense within the Japanese language.
But basically, this is a yokai that follows people around
at night on dark streets and you hear his footfall,
so it's like they you know. The whole idea is

(55:32):
just the sound of being followed in the dark, or
the potential of being followed in the dark. It doesn't
actually have anything to do with like a super sticky
ghost creature, much to my dismay.

Speaker 3 (55:43):
Bummer, I wish it was a monster with like sticky hands,
like the sticky hand toy.

Speaker 2 (55:47):
Yeah. Yeah, so I don't know if anyone out there
can think of any sticky monsters, especially as we get
into our Halloween festivities here. Let us know, I guess
you could. You could have talked about the z morph
to some extent. It didn't like sticking people to walls
and in walls.

Speaker 3 (56:04):
Uh yeah, it's secreted a stick. You never really see
it secreting that stuff, do you You see the you
see the caustic blood. I wonder do you think it's
only the queen that secretes all of that that sticky
material that cocoons the people.

Speaker 2 (56:21):
I don't know if it has So I know this varies.
There's no like hard cannon on this, but I guess
you have like the warrior xenomorphs, you have the queen zenomrph.
Do you have like some sort of like construction drone
type xenomorphor would that be done by the warriors? Like
who's building that elaborate nest? Like she's busy creating eggs?

(56:41):
Right that if we're going to compare it to you know,
like say ant and termite models, you know, her role
is very specific within the hive, and you must have
some other classification of the species that's busy building these
things and secreting stuff and sticking people in walls after
you know they've after an egg has been positioned in

(57:03):
the proximity.

Speaker 3 (57:05):
That's right. Ripley famously asks an alien, so who's laying
the eggs? But I have a secondary question, so who's
secreting the gunk?

Speaker 2 (57:13):
Yeah, there we go. We knowed that's what we need
for the next alien film. Let's really dive down into
who's secreting here.

Speaker 3 (57:21):
It must be something we haven't seen yet.

Speaker 2 (57:25):
A whole movie about the most boring member of the
but scientifically interesting member of the xenomorp five I'm in
all right, we're gonna go ahead and close it up there,
but hey, we'd love to hear from everyone out there.
What are your thoughts on stickiness? Can you think of
the sticky monster in general? Oh, and sticky memories? You know,

(57:45):
this is something we can all relate to, So I'm
hoping we'll hear from a lot of folks on that. Also,
Like I just said, we're getting into the Halloween season here,
and we're gonna quickly be you know, putting together a
loose outline of what we're going to be covering. But
now's a great time if you have something particular in mind,
or if you want to remind us of something we
said we'd cover in the past but didn't, then yeah,

(58:07):
write in. We'd love to hear from you. A reminder
that Stuff to Blow Your Mind is a science podcast
with core episodes on Tuesdays and Thursdays, listener mail on Monday,
short form artifact or monster Fact on Wednesday, and on Friday,
we set aside most serious concerns to just talk about
a weird movie on Weird House Cinema.

Speaker 3 (58:24):
Huge thanks to our excellent audio producer JJ Posway. If
you would like to get in touch with us with
feedback on this episode or any other, to suggest a
topic for the future, or just to say hi. You
can email us at contact stuff to Blow your Mind
dot com.

Speaker 1 (58:46):
Stuff to Blow Your Mind is production of iHeartRadio. For
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