0:01

It's one of memory's strangest tricks.

0:03

You're visiting a new city, one you've never been

0:06

to before, when you turn a corner,

0:08

and suddenly, you get the overwhelming sense you've

0:11

been there before. You can't

0:13

shake the feeling even though your rational mind

0:15

knows that it can't be true. That

0:18

fleeting, eerie sensation, déjà vu,

0:21

has puzzled psychologists for more than

0:23

a century. Now, researchers are

0:25

learning more about the causes of déjà vu,

0:28

as well as its lesser-known opposite, jà mé

0:30

vu, when a previously

0:32

known thing seems suddenly strange and

0:34

unfamiliar. So why did

0:36

déjà vu and jà mé vu happen? Why

0:39

does our brain play these tricks on us? Are

0:42

some people more prone to déjà vu and jà

0:44

mé vu than others? How

0:46

do you study these sensations in the lab? And

0:49

what can studying them teach us about memory

0:52

more broadly? Welcome

0:54

to Speaking of Psychology, the flagship

0:56

podcast of the American Psychological Association

0:59

that examines the links between psychological

1:01

science and everyday life. I'm

1:03

Kim Mills. My

1:08

guest today is Dr. Chris Mullen, a

1:10

professor in the Laboratory of Psychology

1:12

and Neurocognition at Grenoble Alpes University

1:14

in France. He is a cognitive

1:17

neuropsychologist known for his work on memory,

1:19

especially déjà vu and jà mé vu. He

1:22

is the author of hundreds of scientific studies,

1:25

as well as the book The Cognitive

1:27

Neuropsychology of déjà vu. And

1:29

finally, his work on jà mé vu

1:31

won a 2023 Ig Nobel Prize, an

1:34

annual award given for scientific research that

1:36

makes people laugh and then makes them

1:38

think. Dr. Mullen, thank you for

1:40

joining me today. Thank you very much for having

1:43

me. We're going to talk about both

1:45

déjà vu and jà mé vu and some

1:47

related phenomena, but let's start with déjà vu,

1:49

which I would imagine most of us have

1:51

heard of. I mentioned a

1:53

classic example of déjà vu in the introduction,

1:56

when a place you've never been before seems

1:58

familiar and you have the sense that

2:00

you've been there? Are there other types of

2:02

deja vu or other examples of when this

2:05

happens? So that is the

2:07

classic example to find

2:10

yourself in a place where you've never been

2:12

before and feel like you've been there before.

2:14

So we know that there's a kind of

2:17

sense of place involved in deja vu, but

2:19

it's not the only kind. The

2:22

people who fill in my questionnaires tell me

2:24

that it often arrives in conversations. Conversations

2:27

you might be having at a party or

2:29

something like that, and you'll have the sensation

2:31

that you've had the same conversation before.

2:35

So we think it happens for

2:37

pretty much most of the things that

2:40

you can be conscious of and you can

2:43

think about, but certainly right up

2:45

there is places. We seem to

2:47

have it more for places than

2:49

for other things. Interestingly,

2:53

one of the strange data

2:55

sets that we have to explain

2:57

is the reason why people

3:00

in our questionnaires also seem to have more

3:03

deja vu the more they travel, which

3:05

is a very interesting idea, especially if you

3:07

think it's to do with the places you

3:10

visit. It seems the more likely you are

3:12

to go to novel places, the more likely

3:14

you are to experience deja vu, which is

3:16

a very interesting idea. It

3:20

sounds like that's one of the triggers, travel.

3:22

Are there other things that may trigger deja

3:24

vu? For deja

3:27

vu, one of the things we have to

3:29

think about is who's having the deja vu.

3:31

Let's just talk now about healthy deja vu.

3:35

We do know that there are some triggers

3:37

for healthy deja vu. That's for people like

3:40

you and I who may have

3:42

this rarely and there's no kind

3:44

of neurological reason why we're

3:46

having deja vu. We

3:48

might have it more when we're tired. It

3:51

seems that we might have it

3:53

more when we're stressed. Travel

3:56

is a big idea. You have it

3:58

more when you're young. than

4:00

when you're older. And

4:03

there's some research, but I think we need to

4:05

do some more work on those kinds of things,

4:07

which suggests that you have deja

4:09

vu, not necessarily whilst

4:12

you're intoxicated, but having been intoxicated

4:14

with drink and drugs, for instance.

4:18

So there's some interesting data

4:21

about those kinds of things. But

4:23

essentially, I'm telling you about general patterns

4:25

from questionnaire research. I think it's best

4:27

to characterize deja vu as being unpredictable.

4:30

So we know you get it more in places

4:32

than for other things, but you can get it

4:35

in conversations. And I think the main thing about

4:37

deja vu is that it's unpredictable and you don't

4:39

know when it's going to strike. Does

4:42

there any reason, is there any research behind

4:44

why younger people may have it more often

4:47

than older folks? So

4:50

the first reason that could explain

4:53

this pattern of data would be

4:55

that older people have deja

4:57

vu the same amount, but they just forget

4:59

that they've had it, because it's pretty infrequent

5:02

and pretty rare. So maybe they do have

5:04

it as much, but they've forgotten about it.

5:06

We've tried to control that by asking people

5:08

about the last time they had it and

5:10

asking people to remember a specific

5:12

instance of it. So we think it's not

5:14

that. What we think

5:16

is, is this is the first piece of

5:19

evidence in our idea that deja vu is

5:21

a healthy thing and a good thing. So

5:23

we like to describe it as a fact-checking

5:26

mechanism. As you get

5:28

older, there's very subtle but real changes

5:30

in your memory, which mean you're not

5:32

quite so able to verify

5:35

the certainty that something has

5:38

not yet happened to you.

5:41

So in my daily life, as

5:43

I get older, I have far

5:45

fewer experiences of deja vu. But

5:48

what I have instead is a bit more

5:50

of that horrible hesitation. Have I already made

5:52

this joke? I

5:54

feel like I'm repeating myself. I

5:57

feel like I Probably am

5:59

repeating myself. Do I think

6:01

as you get older that that

6:03

relationship with your memory changes and we

6:05

call that messy cognition so that

6:07

you're you're less aware of what's going

6:10

on in your memory system. and

6:12

and as you get older you to

6:14

like that hundred certainty. That.

6:17

It's impossible the you've already had this

6:19

conversation or it's impossible that seen you've

6:21

already been hit. more like to get

6:23

else you might say. Well, I probably

6:25

read about his face in a book

6:27

or it's very similar to some other

6:29

place I've been. So your interpretation of

6:31

the same feeling possibly changes. As

6:34

he gets older man, that's

6:36

that's probably a best case

6:38

explanation for that, but but already

6:40

against a very interesting. Peter

6:43

Baker for us because. If

6:45

you think that memory gets worse as you

6:48

get older, you'd expect to have more Deja

6:50

Vu. If you're saying of memory is a.

6:53

Is behind Deja Vu is like this of

6:55

who the memory era but in fact you

6:58

get the opposite said us. That's really why

7:00

we we come to this idea of it's

7:02

not quite about memories about your relationship with

7:05

human. You. Forthwith pieces with

7:07

epilepsy and dimension who have cry to

7:09

several that as they have a cast

7:11

and sense that everything is happening to

7:14

them as familiar still talk about that.

7:16

why does that happen and what's life

7:18

like for those patients. Yeah,

7:20

so I'm my whole entry point

7:23

into researching Deja Vu was and.

7:25

Was. Through and looking at

7:27

somebody working closely with somebody

7:29

who had their opponents sense

7:31

of Deja Vu at least.

7:34

His family and his.is all described

7:37

it as opponents as decency. Now

7:39

the young. That. New

7:41

a psychologist to start my phd at that

7:43

time and I I looked up in the

7:45

books Deja Vu and It's Obama be an

7:47

explanation of why this person's got. Deja.

7:50

Vu and in fact there was.

7:52

There was nothing similar and his

7:54

face was very extreme. subsequently

7:56

revise inside other people that the same

7:59

but for instance when he came to the

8:01

memory technique, he said there was no point doing my

8:03

memory test because he'd already done them all before. He

8:07

said that every conversation was repeating, that he'd

8:09

already met me when I turned up at

8:11

his house to do some research with him.

8:15

He refused to watch television saying that

8:17

everything was repeating on the television. He

8:19

was an engineer and he took, still

8:24

he had subscriptions to scientific

8:26

journals. And I like

8:28

this one the most, you stop reading in scientific journals

8:30

saying that he'd read everything in them already

8:33

before and that's sometimes

8:35

an experience that us scientists

8:37

have anyway in general. So

8:40

his life was very,

8:42

very difficult for his, certainly for

8:45

his wife, she was very patient and was

8:48

very interested in the research and saw the kind of

8:50

philosophical side of things. But it

8:52

was constant torment from the moment he woke

8:55

up, he was saying that he'd already had

8:57

that conversation, that he'd already done all the

8:59

things and the chores he needed to be doing

9:01

in the house. So it really was

9:04

more like being stuck in the

9:06

present moment, more like anything like

9:08

deja vu. So we

9:11

did some research with him and identified

9:13

memory mechanisms and brain mechanisms that were

9:16

involved and that was

9:18

really interesting work and that

9:20

launched my interest in

9:22

deja vu. But of course

9:25

it took me a bit of time to

9:27

realize but that's not actually what deja vu

9:29

is when we have deja vu. When we

9:31

have deja vu we are

9:33

aware that we're having a deja vu. So

9:35

he was not aware that he was, that

9:39

he had this kind of problem. So one of

9:41

the things is why I used to ask him,

9:43

it's like okay if you've watched his TV program

9:45

before can you tell me what's going to happen

9:47

next? And his response was very

9:49

canny. He used to reply well how should

9:51

I know what happens next? I've got a

9:53

memory problem. So he was

9:56

kind of aware that he had Difficulties

9:59

with his memory. Was not aware

10:01

that he had this constant feeding, the

10:03

repetition that his life was reputed. Say

10:05

again that the hamsters converge a month.

10:07

Deja Vu is cause for us. Deja

10:09

Vu is this conflict the sense that

10:12

it's feel like it's the media but

10:14

I know it's not. and we think

10:16

with with him and the other patients

10:18

who who has similar all of whom

10:20

have had this kind of dementia passing

10:23

them have been older adults is very

10:25

bay laughs and they've all had this

10:27

kind of permanent census. too many out

10:29

in. New set of being able

10:31

to reject the sense of familiarity. A

10:35

Something false, an erroneous,

10:37

And these patients actually accept it and

10:39

then kind of work with it and

10:41

in by the sits in that details

10:43

to and and someone said for so

10:45

it it didn't Very interesting case. It's

10:47

not lost my interest in Deja Vu,

10:49

but I think that the most if

10:51

one thinks it's to underline marriage is

10:53

it's not Deja Vu. and I actually

10:55

regret ever using the word Deja Vu.

10:57

but that's. Not. Times where describes

11:00

it the the carrots and the ducks. It

11:02

in both they write a disguise of fun.

11:05

At does your view. On

11:07

and then you asked about epilepsy

11:09

epilepsy at my interest in athletic

11:11

him a bit afterwards. The

11:14

only kind of scientists scientific

11:16

studies of Deja Vu for

11:19

maybe a hundred years were

11:21

within the domain of of

11:23

the study of epilepsy. So

11:25

it's long been known that

11:27

certain people, not everybody and.

11:30

Send. People with with

11:32

epilepsy report Deja Vu

11:34

which is associated with

11:37

and seizure activity so

11:39

before. For. A.

11:43

Maybe just the during

11:45

a seizure activity and

11:48

and. As a

11:50

result, if we wanted to

11:52

research. Deja. Vu. They seem

11:54

like a very helpful to the people

11:56

to help us better understand what's what's

11:58

going on. Certainly for some

12:01

people with epilepsy, does your boot clinically

12:03

relevant because they can signal that they

12:05

are about to have a seizure? Mr

12:08

something Any to know about. Good.

12:11

But also a press wants you to

12:13

better understand Hiv. With with those people,

12:15

at least Deja Vu appears to be

12:18

more frequent and more predictable, so that

12:20

helps us get a handle on what's

12:22

going on in from Deja Vu. And.

12:25

Unlike the patience with dementia, we

12:27

do believe that there's no difference

12:29

between the days of your experience

12:32

by people with and without epilepsy.

12:34

It's it's very similar kind of

12:36

thing, except you might imagine that

12:38

things epilepsy. It's it's it's tutor.

12:41

That. New I know communications an

12:43

electrical activity which isn't in some

12:46

white and disrupt his. But

12:49

that's not bad at the same case fans

12:51

for us necessary although that is a that's

12:53

a story where we need bomb be set.

12:57

Up There is sort of the opposite of

12:59

Deja Vu, right? Which is cause I'm a

13:01

vote now that something that you've never experienced

13:03

I can you tell us a little bit

13:05

more about. What that

13:07

is? the term I believe is

13:09

not that widely known on, but

13:11

people recognize the sensation. Yeah.

13:14

So. Exactly when

13:16

we do questionnaires on on jenny do

13:18

we have to help people understand will

13:20

what it will, the it's were trying

13:22

to talk about and and a half

13:24

happily. People. Do understand

13:26

and identified as experience so

13:28

yummy. Do it happens in

13:30

daily life? Ah most frequently

13:32

something flights and spelling. Ah,

13:35

and using words So you may have had

13:37

this experience. I definitely have had it. Where

13:40

you're using a word and all of a

13:42

sudden. Even the you know

13:44

the word is spelled rights and you've

13:46

produced it correctly. This.

13:49

Something wrong and seals. it

13:51

feels like it's not right so once i

13:53

had it to the would guess i was

13:56

using the woods is an unknown of a

13:58

sudden recycled this this isn't how It

14:04

seems pretty common for words, at least that seems

14:06

to be the most common version, but when

14:08

I talk to people about it, and again I'll

14:10

talk about my own experience and hope that

14:12

I'm not the only person to have had such

14:15

things, I once had it quite profoundly, looking

14:17

at my father's face. And

14:19

it was like, well, this is, it was

14:21

like I knew it was my father, there was no

14:23

way in which I didn't recognise him, but

14:25

I was looking at him thinking, well, that's

14:27

really, there's something strange about

14:29

this, it's a strange kind of

14:31

idea that that is my father,

14:35

and it's almost like you see your

14:37

father's face with fresh eyes, you come

14:39

to something fresh, and you have this

14:41

kind of sense of novelty,

14:43

like you're seeing something for the first time,

14:45

even though you know it's your father, and

14:48

there's no question

14:50

that you wouldn't recognise him, it's

14:52

more like the recognition seems strange

14:54

in some way. So in

14:57

Xianmizhu, just like with Deja Vu,

15:01

they are opposites, but the key

15:04

experience is this experience

15:06

of strangeness and a

15:08

conflict between two evaluations. So

15:11

the conflict in Deja Vu is that you

15:15

know it's new, it's something you've

15:17

never talked about before, or a place you've

15:19

never been before, but somehow it feels like

15:22

it's familiar, and then you

15:24

have the opposite, with Xianmizhu, the opposite

15:26

being that you know

15:29

very well that this is a word that you've

15:31

used and you can write it

15:33

perfectly well, but somehow it looks

15:35

strange or it looks wrong, or you have to

15:37

double check what you're doing, and exactly the same

15:40

with people's faces. And

15:44

it goes on, Akira Okona, who's

15:46

my main partner in crime with

15:48

this research work that we do together, he

15:51

says he's had Xianmizhu

15:54

for driving, to the extent that

15:56

he was really unsure

15:58

of what he was doing. was doing and

16:00

what pedal was doing what in the car.

16:03

And yeah, scary.

16:06

It's a little scary. Well, he

16:08

pulled over, he was he's a sensible

16:10

chap. But when when when those things

16:12

happen, they're very, very rare. But again,

16:15

that's another kind of piece

16:18

of evidence as to what's happening

16:20

in Xamadu because driving is a

16:23

very fluent automatic behavior. And

16:26

we find in the lab, the easiest way

16:28

to generate Xamadu is by another very fluent

16:30

automatic behavior, which is writing. And we

16:32

ask people to repeatedly

16:35

write the same words until

16:37

they feel pretty strange about

16:39

the word. And that's the

16:41

work for which we won the

16:44

Ig Nobel Prize, because it's a pretty strange thing

16:46

to do. And in fact, it's,

16:50

it's based when we designed experiment, it

16:52

was based on my experience of punishment

16:54

at school where I had to write

16:56

lines and write the same sentence over

16:58

and over again, I will not talk

17:00

in French class. I think it was

17:02

like I remember. And I realized

17:04

that writing this sentence over and over

17:06

again, I must have been about 12 really

17:08

made me feel strange. It wasn't an

17:10

unpleasant sensation, but it was

17:12

very strange. So, yeah, I

17:15

guess, nearly 20

17:17

years later, I came to the idea all

17:19

that that could be a cool way of

17:22

invoking these strange sensations,

17:24

these conflicts between familiarity and lack

17:26

of familiar. So you

17:29

can instigate one

17:31

Xamadu, but can you in a lab instigate

17:33

Deja Vu? I mean, how do you study

17:35

it since it's such a fleeting

17:38

subjective thing? Yeah,

17:40

that's a good question. So the

17:43

first thing is, is that

17:46

Deja Vu

17:48

took a little bit of time to get

17:50

going as an experimental concern. And

17:54

I think there's

17:56

two reasons for that. The first

17:58

reason is that subjective experiences kind

18:00

of fell out of grace in

18:02

psychology. But

18:04

since the 1980s, we've been able to,

18:07

you know, tackle the subjective experiences head

18:09

on. But that's kind of a historical

18:11

note. The second issue is

18:13

we were kind of waiting for a theoretical

18:15

entity that might be useful

18:18

to better understand deja vu, because it

18:21

didn't seem easy to classify what deja

18:23

vu was. In the title, it's deja

18:25

vu, it's about vision. So we tend

18:27

to think it's about what we

18:29

see in perception, but in fact, the

18:32

best theoretical entity is familiarity.

18:35

So familiarity is

18:37

supposed to be like a memory

18:40

process, which we know quite

18:42

a lot about. So you

18:44

can have familiarity for context, which

18:48

may just feel like you know about them

18:50

without really being able to retrieve too much

18:52

about them. So

18:55

the examples I like are things like when

18:59

you're a child, you were very familiar

19:01

with a concept, let's say like a

19:03

home computer. You had a home computer

19:05

for five years and it was called

19:07

an acorn electron. And

19:10

then 20, 30 years later in your life, you might encounter

19:14

something like that acorn electron in a different

19:16

concept. It's now the name of a rock

19:18

group or something like that. And

19:20

what you may find is familiarity.

19:23

You may have this wow, that

19:25

rings some bells, that means something to me, that

19:27

net concept. And

19:30

so familiarity is kind of one of

19:32

the cornerstones of how memory works in

19:34

daily life. And we

19:36

think it operates like when you hear this

19:38

acorn electron kind of idea, you're like, oh,

19:40

okay, well, that feels

19:43

familiar to me. Well, why? And then you

19:45

can coordinate your memory processes to

19:47

try and research things in memory. So

19:51

given that you know that this

19:53

entity familiarity exists, that's

19:55

really what we can pin

19:58

adagea root research on. I'm

20:00

here to cut

20:02

a long story short, I think there's

20:05

some really elegant experiments which

20:07

are done which kind of provoked Deja Vu in

20:09

the lab and I can really praise these experiments

20:11

and say how elegant and wonderful I think they

20:13

are because in fact I'm not responsible for any

20:16

of them but Anne Cleary

20:19

who's done a lot of

20:21

research on Deja Vu, she's used, I

20:24

think my favorite experiment of hers uses

20:27

virtual reality and what she does is

20:29

she provokes this sense of familiarity

20:32

by using some similarity

20:36

and since the 19th century that one

20:38

of the ideas about what causes Deja

20:40

Vu is a similarity between something you've

20:42

encountered previously in your life and something

20:44

which you encounter now where

20:47

you can't identify that

20:49

source of familiarity. So in the

20:51

daily life you

20:53

might go into your friend's flat for the

20:55

first time, your friend's apartment for the first

20:57

time and the layout of

21:00

the apartment is such that there's the window

21:02

in front of you and the fireplace to

21:04

the left of you and the sofa and

21:06

the TV and in fact that configuration matches

21:08

exactly something that you've already seen

21:11

before in your life. You can't

21:13

remember what it is but that's enough to

21:15

provoke this sense of familiarity. So

21:17

Anne Cleary she's looked at that in virtual

21:19

reality because it's quite easy to set up

21:22

those kinds of things in experimental situations and

21:25

like that she can do,

21:27

she can provoke feelings of Deja

21:30

Vu and people report freely

21:33

that they've had Deja Vu

21:35

or something like it generated in her experiments.

21:38

So that's really neat and then she's taken

21:41

that in lots of other different directions and

21:43

then the other series of experiments which is

21:46

similar are run by Akira O'Connor

21:48

and he's used

21:51

pretty much as a similar technique but

21:53

with words and his thing

21:55

is all about generating the conflict which is

21:57

in Deja Vu. So he

22:00

He does this really neat thing.

22:04

He asked people to learn lists of words, which

22:06

is something we do. It's our bread and butter,

22:08

that's what I'm paid to do mostly. He

22:11

gets people to learn lists of words, and

22:16

for each word they have to learn, they

22:19

have to note down the first letter of the

22:21

word. So they're doing something at the

22:23

same time as looking at the word, and he keeps

22:25

the note of that, and he uses that with them

22:27

later when he tests them. So

22:29

there's this neat effect,

22:32

which we see often in memory experiments,

22:34

which is if you learn a set

22:36

of related information, it will give you

22:39

a false memory and strong

22:41

familiarity for something that you haven't learned.

22:44

So if I give you a list of words to learn,

22:46

which is like doze,

22:48

rest, blanket, bed,

22:51

snore, pillow, tired,

22:54

et cetera, and then a bit

22:56

later on I show you the word sleep. You'll

22:58

think that you've seen the word sleep now, I

23:00

didn't give you the word sleep.

23:03

So that's like a kind of false memory paradigm,

23:05

but what you have for the word sleep is

23:09

familiarity. So what

23:11

Akira did, which is really novel, was

23:13

he did that kind of experiment, which

23:15

is fairly standard in experimental psychology, but

23:18

the new thing he did was to ask

23:20

people to look at

23:22

the numbers of words that could start to

23:25

be the certain letter. So at

23:27

the same time as presenting them with the word

23:29

sleep, he also presented them with the information that

23:31

no words that they actually saw in the list

23:33

began with an S. So

23:36

that is exactly like the conflict that's

23:38

inherent in deja vu. And

23:41

I think that's a really neat demonstration

23:44

of really what's going on. It's like that,

23:46

it's like that world, sleep feels familiar, yes,

23:48

yes, I've encountered that before, but hang on,

23:50

it's impossible. And so people

23:52

identify that as being like deja

23:54

vu. So are there

23:56

brain imaging studies that help you to

23:58

understand what's going on? on in people's

24:00

brains when they're having these

24:02

experiences? Yeah, so

24:05

that's a good question. In healthy

24:08

subjects, Akira has done

24:10

that work as well. So we know that

24:13

when people are having something like

24:15

a deja vu experience, that it's

24:17

the prefrontal cortex, which

24:20

is activated. And the prefrontal

24:22

cortex is proposed to

24:25

be involved in this kind

24:27

of detection of conflict. And

24:30

it's kind of a higher order system

24:32

which kind of watches what's going on

24:34

beneath it, if you see what I

24:36

mean. So it's there to control and

24:38

coordinate what's happening in memory. So

24:41

that's consistent with this kind

24:45

of aspect which is about

24:47

detecting conflict and your relationship with your

24:49

memory rather than memory itself. That's

24:53

one kind of avenue of

24:55

research. There's not a

24:57

lot of neuroimaging research done on

24:59

healthy populations. What

25:01

there's more of is kind of classic

25:04

neuropsychology. It's a good old

25:06

neuropsychology on volunteers

25:09

who are very keen to help us

25:11

on research who have epilepsy,

25:14

for instance, or even

25:17

acquired brain injury. And

25:19

those people with deja vu, we can

25:21

converge on the fact that there's definitely

25:25

implication of the

25:28

temporal nodes and the areas

25:30

which we know are responsible for memory. And

25:33

the particular

25:36

zone is the

25:38

zone which is described as

25:40

being para-hypotemple. So the hippocampus

25:42

is what we teach our

25:44

students in the first year

25:47

of the undergraduate degrees that is

25:49

the area which is responsible for memory. But

25:52

just outside that area

25:54

in the brain, just connected to it,

25:56

is another zone which is

25:58

responsible for familiarity. So

26:02

it's no surprise that this intense sensation

26:04

of familiarity is associated to

26:06

activation in that area.

26:09

And we've actually known that for quite

26:11

a long time because of the the

26:14

studies of the pioneering studies in epilepsy

26:16

trying to understand different kinds

26:18

of epileptic focus and the changes

26:20

that people experience in daily life

26:22

with those things. So

26:24

there's kind of two zones that

26:27

are involved. It would

26:29

be the the temporal lobes for

26:31

this kind of familiarity part and

26:33

then the prefrontal cortex which is

26:35

in some way monitoring

26:38

what's going on in the temporal lobes.

26:40

So we can imagine those two different

26:43

zones are involved. It

26:45

seems that there are a number of these

26:48

types of experiences that you study that are

26:50

all related. There's also deja-reve for example which

26:52

has to do with dreaming. Yeah. Can you

26:54

explain what some of these others are and

26:56

how they're related? Yeah. I think there's

27:02

almost a jokey response to this

27:04

which I like to point out

27:07

that some researchers in deja vu

27:09

have tried to discover in

27:12

quotation marks as many different forms of deja

27:14

vu that exist as possible. And for me

27:16

certainly living in France it seems like they're

27:18

just running through their French past particulates that

27:20

they've learnt. So you can

27:22

imagine that deja vu, deja vecout,

27:25

deja-reve which is to have

27:28

already dreamt and

27:30

we can go on and on. The

27:32

deja sonti which is

27:35

already felt and

27:38

some researchers who

27:40

are not motivated by the same scientific

27:42

concerns as me would

27:45

identify really 20, 30 different

27:47

types of deja

27:50

vu. Deja-reve is

27:52

something which is beginning to

27:54

gather scientific interest and we think it

27:57

would be distinct from deja vu and

27:59

it's is

28:01

this sensation of having

28:04

already dreamt something or experiencing something

28:06

which feels to you like you'd

28:09

already experienced it in a dream.

28:13

In epileptic patients it's a bit

28:15

of a

28:18

different concern I think because

28:20

it seems that there might be kind

28:23

of reactivation of material that was indeed

28:25

experienced as part of a dream. I

28:29

think with the people that I work

28:31

with when I talk about Deja Vadhi

28:34

I think and I remember thinking this myself

28:36

before I started psychology, Deja

28:38

who's pretty weird and when you have it

28:41

you're trying to explain to yourself why

28:43

it is that you find

28:46

something familiar and I

28:48

think without wanting to kind of trick yourself

28:51

you nonetheless think that well a pretty

28:53

good bet is that I dreamt something

28:55

like this and now I'm encountering it

28:58

again and it seems to be like

29:00

a natural interpretation of this sense

29:03

of familiarity that you are now encountering something

29:05

that you already can't. That's

29:08

an idea that's entered into kind

29:11

of popular thought because that was Jung's idea

29:13

of what

29:15

Deja Vadhi was and Freud and Jung both

29:17

thought that there was kind of this aspect

29:19

of the unconscious and the dream state which

29:21

was related to Deja

29:24

Vu. I think we just need more

29:26

research but there's I mean there's data

29:29

that shows that there's definitely something going

29:31

on. People who remember their dreams are

29:34

more likely to have Deja Vu and

29:36

that's the finding that's been replicated for

29:38

in across

29:41

different research labs and in different studies

29:43

so there seems to be something going

29:46

on between me and I'm

29:48

not quite prepared to say what that is

29:50

yet but it's certainly something very interesting. And

29:53

then for the other types of Deja Vu I

29:56

try not to proliferate the different types of

29:59

Deja Vu. I think my

30:01

job is to generate plausible accounts

30:03

of deja vu based on

30:05

the memory systems. And

30:07

I think there might be a weaker form,

30:10

which is more about familiarity, and a stronger

30:12

form, which is more about really

30:14

believing that you can remember something,

30:16

which might give you the feeling

30:18

that you are about to predict

30:20

what's about to happen next. So

30:23

not everybody, we think in

30:25

our question, there's about 20% of the time when you

30:28

have deja vu, you also have the feeling that you

30:30

can predict what's going to happen next. I

30:32

think we need to start looking at that

30:34

aspect of things as well, because that might be

30:36

a stronger different form of deja vu than the

30:39

form where you just have a vague sensation of

30:41

familiarity. People who regularly

30:43

listen to this podcast probably know that

30:45

I have a particular fascination with odd

30:48

psychological syndromes. And

30:50

there is another one that is, it sounds

30:53

like it might be related to jamais

30:55

vu, which is Capgrass syndrome, where people

30:57

don't recognize their own loved ones. I

30:59

think that they are strangers. Is

31:02

this an extreme version of jamais vu, or

31:04

is it something else totally? I

31:07

am very pleased you asked

31:09

that, because I think that's

31:12

possible. I

31:14

think that's one way of looking at it. And

31:18

I think you and I share the same kind

31:21

of passions for psychology, because

31:23

I think having worked

31:25

with all kinds of people, with

31:27

all kinds of psychological and

31:30

cognitive difficulties, I

31:32

really believe that there's nothing that unusual

31:34

that you can experience in

31:37

terms of psychological disturbance, like in

31:39

Capgrass, which doesn't have

31:41

an equivalent in our own daily lives.

31:44

I think it's more severe

31:47

and more problematic and debilitating.

31:51

But yes, I think the jamais vu

31:53

thing, we can give people

31:55

jamais vu with faces. You

31:57

do it with famous faces and you can just...

32:00

saturate the face and people just have to

32:02

repeatedly look at the same face. And

32:04

eventually it will begin to feel a

32:06

bit different. So we know that inducing

32:10

Xianmue Wu is all about this kind of

32:12

idea of repetition of things that are very

32:14

automatic. And indeed

32:16

our research goal was to try

32:18

and understand the

32:21

link between Xianmue Wu and that

32:23

sensation that, OK, it looks real,

32:25

but it's not real. I mean,

32:27

that sounds exactly like a delusion

32:29

that you know it. In

32:33

fact, it's not so much that you know, you

32:35

accept that person as being, as looking

32:38

like your husband,

32:40

but you don't

32:43

feel that that's your husband. So

32:49

it's almost exactly the same thing. It's the

32:51

difference between a perception, which is a perception

32:53

of a face that looks like my husband

32:56

and then the internal feeling, which is a

32:58

belly, doesn't feel like my husband. It's

33:00

not right, it's something that's not right. So,

33:03

yeah, it's

33:06

definitely something

33:08

we'd like to work more on. But

33:11

if I don't get to do work

33:13

and to elucidate like concretely what the

33:16

relationship between those two things is, I

33:18

think it's important for this story that

33:21

we are, all of us, each of us,

33:23

living a kind of

33:25

relationship with our perceptual systems and our

33:28

cognitive systems. And

33:30

when Deja Vu and Xianmue Wu happen, they're

33:32

a little reminder of the

33:35

fact that it doesn't always run that smoothly.

33:37

We are sometimes mistaken. And the

33:39

reason why Deja Vu is so interesting

33:43

is because it's infrequent and it's

33:45

rare, but it feels really, really

33:47

weird. And if you

33:49

imagine being stuck with sensations like

33:51

that, which you can't kind

33:54

of reason with, that you can't reject or that you

33:56

can't justify, then I think you have a little window

33:59

in your head. into how it

34:01

is to be living with something like Tap

34:31

Nobody's done much direct asking of

34:33

children about their experiences of deja

34:35

vu. It's more retrospective questionnaires and

34:38

it seems like the

34:41

scientific literature says you don't get

34:43

deja vu until you're about 10

34:45

years old. And

34:48

that's again a nice bit of data

34:50

to try and understand what deja vu

34:52

is and we're working

34:54

on the idea that deja

34:56

vu is metacognitive and as I say it's

34:58

a sign that you're able to kind of

35:01

reflect upon your memory and maybe

35:03

not be overly trusting of your memory. So

35:05

we say it was a good thing. So

35:09

the research that we've got ongoing is simply

35:11

to look at when people

35:13

get deja vu. We've got some interesting

35:15

preliminary findings which look like deja vu

35:18

runs in families, not because

35:20

it's genetic. I don't think I'm going to get

35:22

a prize for finding out that deja vu is

35:24

genetic. I

35:27

think that's relatively unlikely. I think a simple

35:29

explanation is there are people that talk about

35:31

their experiences and have a label to give

35:34

to those experiences. And

35:36

there are people that, families that don't so

35:38

much talk about those things, but certainly it

35:40

runs in families. The more the

35:43

parents have it, the more the children have it. That's

35:45

pretty nice. And

35:47

what we would ultimately like to do

35:50

is to

35:52

kind of standard tests of metacognitive

35:55

abilities and thinking skills and

35:57

see if, according to our

36:00

paper, prediction, people who had deja

36:02

vu or people who had deja

36:04

vu earlier, children, they would be

36:06

more metacognitively aware of other kinds of

36:09

cognitive systems and how their memory works

36:11

and things like that. We were kind

36:13

of really pushing this angle

36:16

that deja vu is fact checking that

36:18

it's something good and it's something useful.

36:21

So one project would be to

36:23

look at that and then you can imagine it

36:25

would just be helpful to start talking to children

36:27

about not just deja

36:29

vu and deja vu also, but

36:32

the tip of the tongue experience. These

36:34

are all kind of metacognitive

36:37

experiences, which are relationships with your own

36:39

memory and your own cognitive systems. And

36:42

I think if teachers and educators are

36:44

talking about this kind of things, it's

36:47

gonna help children in general

36:49

with their learning and education and things like that.

36:53

And then I think

36:55

the second big project that we've got going on

36:57

that we're just going to start is, I

37:00

don't believe that these things are just

37:02

quirks. I don't think they're just random

37:04

events, which are meaningless. I think they

37:06

are infrequent and they

37:08

speak to the kind of complexity

37:11

and sensitivity of the human cognitive

37:14

system. And I

37:16

think now we have smartphone technology and

37:18

things like that, we could be much

37:21

better at collecting examples

37:24

and frequency of these

37:26

experiences. And I think that those might

37:29

be clinically useful. And

37:31

my experience of working with deja vu is that

37:34

people don't much do

37:37

research on it, partly because nobody

37:40

much asks people about their experiences

37:42

with those things. And I think we

37:44

could be asking much more about people's subjective

37:47

experiences in daily life, with the

37:49

hopes of better understanding, psychological

37:52

distress, but also just the

37:54

rich range of human experience.

37:56

So with

37:58

neurologists, I'm hoping to have like

38:00

a very broad section of all these kinds

38:03

of subjective experiences and see how frequently they

38:05

occur and what they mean to people. This

38:08

is all really fascinating. I want to thank you

38:10

for joining me. It's been real interesting talking to

38:12

you. Thank you very much. Thank

38:15

you very much for having me. It's been a pleasure for me

38:17

too. You can find

38:19

previous episodes of Speaking of

38:21

Psychology on our website at

38:23

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38:41

of Psychology is produced by Lee Weinerman.

38:44

Our sound editor is Chris Condayan. Thank

38:46

you for listening. For the American Psychological

38:48

Association, I'm Kim Meese.