0:02 if you've been hearing about this thing
0:05 a Fantasia This inability to visualize
0:08 to see things in your mind's eye and
0:10 you've also noticed you don't have an
0:12 inner voice when you're reading you
0:14 don't hear a little internal monologue
0:16 reading out the words that you can't
0:19 replay the latest song you've just heard
0:21 you can't remember and
0:24 re-experience the smell of good coffee
0:26 the smell of rain on cement this is
0:29 something called multisensory a Fantasia
0:33 so Fantasia can go beyond just the pure
0:35 visual hello my friends welcome to the
0:38 channel I'm Joel Pearson professor of cognitive
0:39 cognitive
0:41 neuroscience and I'm here to tell you
0:43 about multisensory a Fantasia in some
0:46 recent research we've done looking at
0:48 all the different subgroups of a
0:51 Fantasia and multisensory a Fantasia so
0:54 first up a mini recap if you new to the
0:56 channel if you're new to a Fantasia let
0:58 me tell you first what mental imagery is
1:01 for some people so when some people
1:03 think about what an apple looks like
1:05 what anything looks like they have a
1:07 fleeting conscious sensory like
1:10 experience of what the apple is this is
1:12 absolutely not like holding an apple in
1:14 your hand and looking at it it's nowhere
1:16 near as strong as that perceptual
1:18 experience if you do have imagery you do
1:20 have some kind of experience it's
1:22 fleeting you might see the details you
1:24 might zoom in now some people have a
1:27 much stronger experience I'm describing
1:29 my experience just then some people say
1:32 they experience is almost photol likee
1:34 they can replay a whole movie in their
1:38 Mind's Eye so a Fantasia is a word
1:41 recently given to this blind Mind's Eye
1:43 we've known about a Fantasia for well
1:44 over a hundred years but it's really
1:46 been only the last sort of handful of
1:48 years that it's really been moved into
1:52 the general uh awareness through media
1:54 through new papers new
1:58 Publications so it turns out that a
2:01 Fantasia goes beyond the domain of
2:03 vision just like our sensory experience
2:05 of the world involves all the touch
2:08 smell sounds of course mental imagery if
2:11 you like can also include all those
2:14 senses and hence you can have all these
2:16 different types or subtypes of a
2:18 Fantasia so in a recent paper that we
2:21 did in the in the lab here we sent out
2:23 two different surveys or you like we
2:26 sent out two different uh questionnaires
2:28 to two different groups and this
2:30 questionnaire looks at all all the
2:33 different uh sensory domains of mental
2:35 imagery not just Vision so this is not
2:36 looking at the visual vividness of
2:38 visual imagery it's looking at all the
2:41 different senses about sound taste touch
2:44 so matter sensory across the board and
2:45 everything I going to be talking about
2:46 we sort of replicated it so we ran it in
2:48 one group with a th000 participants and
2:50 then we ran it in another group with a
2:53 th000 participants then what do we do we
2:55 got a number of different what's called
2:57 clustering algorithms and this is sort
3:00 of automated algorithm based way of
3:02 looking at the clustering the grouping
3:04 of the data and there's lots of these
3:07 different clustering algorithms we did
3:08 uh use three different methods to do
3:11 that so the idea here is to see what are
3:15 the natural groupings of people with a
3:18 Fantasia for example are they all just
3:21 pure visual a Fantasia are they all
3:23 multi- sensory maybe they're all just
3:27 pure smell a Fantasia and clustering
3:28 analysis like this is a sort of
3:31 non-biased way to look at the different
3:33 natural groupings so the job of the
3:35 algorithm is to find which groups of
3:37 people naturally cluster together and
3:39 find nice ways of separating those
3:41 without us bringing our bias as
3:44 scientists onto the data so what do we
3:47 find we found there are two main groups
3:49 no matter which clustering algorithm you
3:52 use there are two clear groups and that
3:56 is of course pure visual a Fantasia so
3:59 that's a Fantasia just localized if you
4:01 like to the capacity of vision visual
4:03 information and the other big group
4:05 which according to one of the clustering
4:07 algorithms was almost half of those
4:11 people we tested was full multisensory a
4:14 Fantasia so that's not being able to
4:16 conjure up any sensory experience in any
4:19 of the sensory domains so not being able
4:21 to uh read out loud in your mind not
4:23 being able to replay your favorite tune
4:26 not being able to re-experience the
4:28 taste of some yummy food or coffee or
4:32 wine um but also touch movement extends
4:34 to all the different sort of Senses so
4:37 that's multisensory a Fantasia and it
4:39 turns out that almost half of the people
4:42 we tested of those 2,000 had that
4:44 multisensory a Fantasia so they the two
4:47 groups pure Visual and what's called
4:50 multisensory a Fantasia now as you drill
4:52 down in the data we saw other groups but
4:55 very small groups for example one of the
4:57 small groups was about 5% of the
4:59 participants had what we call somatus
5:03 sensory intact so they had a Fantasia on
5:05 all the other senses except when it came
5:07 to somata sensory the internal
5:09 Sensations their body their feelings if
5:11 you feel hungry full you could describe
5:14 as physical Sensations um were intact
5:15 everything else gone so they could
5:17 imagine that internal feeling that
5:19 feeling of full things related to their
5:21 body so that was about 5% of the
5:25 populations we tested auditory intact we
5:28 saw in about 4% of the groups we tested
5:30 so again that's a Fantasia and all the
5:33 other sensory domains no visualization
5:37 capacity no smell no taste but auditory
5:41 sounds was fairly normal so we saw that
5:44 about 5% of the top populations we
5:46 tested so what's interesting here is as
5:48 you drill down you find very smaller and
5:51 smaller groups of very specific uh
5:55 patterns of a Fantasia so as you get to
5:57 1% and Below 1% we did find these very
6:00 small groups in sort of almost all the
6:03 categories and all the um having one
6:05 sense of imagery but not the others so
6:08 what does this tell us about a Fantasia
6:10 in general and this inability to
6:12 visualize and how it relates to all the
6:15 senses well it paints a very interesting
6:17 picture it really tells us that it's
6:21 really bespoke that a fantas is very
6:23 bespoke and it's very different across
6:25 different people and so the general
6:27 experience of this internal model of the
6:29 world the internal virtual reality
6:31 simulator you have in your head is going
6:33 to be very different from one person to
6:35 the next one of the other really
6:36 interesting things I found about this
6:40 study was that there is no perceptual
6:42 equivalent if you think about it for a
6:46 moment so with imagery you can be blind
6:48 if you like across all the sensory
6:51 domains does that ever happen in terms
6:53 of perception can you think of anyone
6:56 you've ever come across who is blind de cannot
6:57 cannot
7:01 taste uh can cannot smell cannot feel in
7:03 their skin that just I don't think that
7:06 ever existed so it tells us something
7:09 that you can have full multisensory a
7:12 Fantasia but you can't really have full
7:14 multisensory sensory blindness or
7:17 perceptual blindness so this thing
7:20 exists in the mind or with imagery but
7:23 not with perception and that is a
7:24 striking difference between perception
7:26 and imagery and that tells us something
7:28 that's really fascinating I think what
7:30 does it tell us why is it fasc fting
7:32 well it suggests that imagery these
7:34 internal experiences are different to
7:37 perception they might be controlled by
7:40 one overall arching Factor whereas
7:43 perception that's probably not the case
7:45 to the degree it is with imagery so
7:47 whenever we find differences between
7:48 imagery and perception that's really
7:50 interesting because it shows us how
7:52 these systems are different in the brain
7:55 tells us more about a Fantasia more
7:57 about understanding the condition and
7:59 potentially more about switching imagery
8:01 on in people if that's what they want
8:03 not everyone wants that so which of
8:05 these senses do you think you have do
8:07 you not have let me know in the comments
8:08 I'd love to hear from you do you think
8:11 you have full multisensory a Fantasia or
8:14 do you have a very unusual specific kind
8:16 I've heard things from people that say
8:18 they can imagine everything but they
8:21 can't imagine faces for example we
8:22 haven't had a chance to study that yet
8:25 but is there some very unusual form of a
8:27 Fantasia you think you might have I
8:28 would love to hear about it and so would
8:30 the uh the community so the other so
8:33 please share in the comments we'd really
8:35 appreciate that so thanks for watching
8:39 stay curious stay imagery conscious keep
8:41 trying to imagine represent the world in
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