• Windows to the soul: Pupils reveal 'apha

    From ScienceDaily@1:317/3 to All on Wed Apr 20 22:30:50 2022
    Windows to the soul: Pupils reveal 'aphantasia' -- the absence of visual imagination

    Date:
    April 20, 2022
    Source:
    University of New South Wales
    Summary:
    Picture this, if you will: Aphantasia can be detected with an
    eye-opening look into our pupils.



    FULL STORY ========================================================================== Visual imagination -- or rather, the lack of it -- can be verified by
    measuring pupil dilation, thereby providing the first physiological
    evidence of aphantasia, new research shows.


    ==========================================================================
    The study, led by researchers from UNSW Sydney and published in eLife,
    found that the pupils of people with aphantasia did not respond when asked
    to imagine dark and light objects, while those withoutaphantasia did.

    To first gauge the pupillary reflex of non-aphantasic people, the
    researchers sought 42 study participants, self-reported as having a
    visual imagination, and fitted them with glasses to track their eye
    movements and pupil sizes.

    Participants were then exposed to bright or dark shapes against a grey background, which predictably evoked pupillary constriction in response
    to bright shapes (comparable to looking up at a bright sky) and pupillary dilation in response to dark shapes (after switching a light off).

    Next, to test visual imagery -- the mind's capacity to visualise
    objects - - participants were asked to simply imagine those same light
    or dark shapes (with their eyes open, for their pupils to be tracked)
    and subsequently report the 'vividness' of that imagery.

    The researchers found that even in response to imagined bright and
    dark shapes, the participants' pupils still constricted and dilated appropriately, a pupillary response that was larger in those reporting
    greater imagery vividness.



    ==========================================================================
    "The pupillary reflex is an adaption that optimises the amount of light
    hitting the retina," says Professor Joel Pearson, senior author on the
    paper. "And while it was already known that imagined objects can evoke so-called 'endogenous' changes in pupil size, we were surprised to
    see more dramatic changes in those reporting more vivid imagery. This
    really is the first biological, objective test for imagery vividness."
    Testing for a lack of imagination Finally, with the link between visual
    imagery and pupillary response established, the researchers sought to
    test the effect in aphantasic individuals. The researchers repeated the
    study with 18 participants self- reporting aphantasia.

    Exposing participants to bright and dark shapes, the researchers found
    that aphantasic individuals exhibited the same pupillary response as
    the general population: constriction to bright, dilation to dark.

    However, during the study's second component where participants were asked
    to visualise those same shapes, the pupillary response of aphantasic individuals did not significantly differ in response to imagined dark
    versus imagined bright objects.



    ==========================================================================
    "One of the problems with many existing methods to measure imagery is
    that they are subjective, that is to say they rely on people being able
    to accurately assess their own imagery. Our results show an exciting
    new objective method to measure visual imagery," says Prof Pearson,
    "and the first physiological evidence of aphantasia. With over 1.3
    million Australians thought to have aphantasia, and 400 million more internationally, we are now close to an objective physiological test, like
    a blood test, to see if someone truly has it." To ensure the aphantasic participants were really attempting imagery, the researchers included
    a further experimental condition, requesting aphantasic individuals to visualise four shapes, instead of one.

    While the pupils of those with aphantasia showed no difference when
    imagining light versus dark objects, they did show a difference imagining
    one versus four objects, suggesting more mental effort, thereby negating
    an explanation of non- participation by aphantasic individuals.

    "Our pupils are known to get larger when we are doing a more difficult
    task," says Lachlan Kay, PhD candidate in the Future Minds Lab,
    UNSW. "Imagining four objects simultaneously is more difficult than
    imagining just one. The pupils of those with aphantasia dilated when
    they imagined four shapes compared to one, but did not change based
    on the whether the shapes were bright or dark. This indicated that
    the participants with aphantasia were indeed trying to imagine in this experiment, just not in a visual way." "The aphantasic pupil response to
    the four objects condition is also a really exciting finding," adds Prof Pearson, "because for the first time we have strong biological evidence
    that those with aphantasia are really trying to create a mental image,
    putting to rest claims that they may simply not be attempting to create
    a mental image." "These findings are also really interesting in regard
    to memory and aphantasia," said Dr Rebecca Keogh, Postdoctoral research
    fellow based at Macquarie University and another author of the study. "Our previous work has shown that aphantasic individuals are able to perform
    visual working memory tasks, remembering many images for a short period
    of time, without using visual imagery.

    "These findings further highlight the wide variability of the human mind
    that can often remain hidden until we ask someone about their internal experiences or invent new ways to measure the mind. It reminds us that
    just because I remember or visualise something one way, doesn't mean
    everyone does." What's next for aphantasia research? A look into the
    future...

    Next, Prof Pearson and his team at the Future Minds Lab plan to
    investigate how this new method could be scaled up and run online to allow
    a global, efficient and objective measurement of imagery and aphantasia.

    "This really is an exciting time. We are very close to having objective, reliable tests for extreme imagery, aphantasia and hyperphantasia
    (extremely strong visual imagery) that could be scaled up to run online
    for millions of people everywhere," says Prof Pearson.

    "We know that thinking in pictures or not affects the number of details
    in lifelong memories, how emotional we get when reading, and how we hold
    things in short term memory. This new method will allow us to understand
    the brain mechanisms of extreme imagery and the global implications for
    how we think, make decisions and feel."

    ========================================================================== Story Source: Materials provided by
    University_of_New_South_Wales. Original written by Jesse Hawley. Note:
    Content may be edited for style and length.


    ========================================================================== Journal Reference:
    1. Rebecca Keogh, Lachlan Kay, Thomas Andrillon, Joel Pearson. The
    pupillary
    light response as a physiological index of aphantasia, sensory and
    phenomenological imagery strength. eLife, 2022; 11 DOI: 10.7554/
    eLife.72484 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220420092150.htm

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