Nav: Home

People 'hear' flashes due to disinhibited flow of signals around the brain, suggests study

March 27, 2019

A synaesthesia-like effect in which people 'hear' silent flashes or movement, such as in popular 'noisy GIFs' and memes, could be due to a reduction of inhibition of signals that travel between visual and auditory areas of the brain, according to a new study led by researchers at City, University of London.

The study is the first to provide insight into the brain mechanisms underpinning such auditory sensations also known as a 'visually-evoked auditory response' (aka vEAR or 'visual ear').

Whilst one theory is that areas of the brain responsible for visual and auditory processing normally compete, this research suggests that they may actually cooperate in people who report visual ear.

It was also found that musicians taking part in the study were significantly more likely to report experiencing visual ear than non-musician participants. This could be because musical training may promote joint attention to both the sound of music and the sight of the coordinated movements of the conductor or other musicians.

Dr Elliot Freeman, Principal Investigator on the study and a Senior Lecturer in Psychology at the University said:

"We already knew that some people hear what they see. Car indicator lights, flashing neon shop signs, and people's movements as they walk may all trigger an auditory sensation.

"Our latest study reveals normally-occurring individual differences in how our senses of vision and hearing interact.

"We found that people with 'visual ears' can use both senses together to see and also 'hear' silent motion, while for others hearing is inhibited when watching such visual sequences."

Some neuroscientists believe visual-ear may be a type of synaesthesia, with other examples including music, letters or numbers that can evoke perceptions of colour. However, visual ear appears to be the most prevalent, with as many as 20% of people reporting some experiences of it compared to 4.4 per cent for other types.

The condition has received more attention due to the recent, viral popularity of the 'skipping pylon GIF', and other 'noisy GIFs' depicting silent motion, which in some people evoke very vivid visual ear sensations.

To shed light on what may be going on in the brain when people view such content, the researchers applied a weak alternating current to participants' scalps, using a technique called transcranial Alternating Current Stimulation (tACS), to explore how the visual and auditory parts of the brain interact in those who experience visual ear and those who don't.

The first experiment of the study included 36 healthy participants, including 16 classical musicians from the London Royal College of Music. All were shown auditory and visual 'Morse code' sequences, while electrical simulation (tACS) was applied to either the back of the head (visual areas of the brain) or the sides (auditory areas) using 'alpha-frequency' tACS stimulation. Participants were then classified as visual or non-visual ear depending on whether they reported 'hearing' the silent flashes.

The researchers found that in non-visual ear participants, alpha-frequency stimulation to auditory areas significantly reduced auditory performance but improved visual performance, while the opposite pattern was found for the same frequency of stimulation to visual areas (poorer vision, better audition).

This reciprocal pattern suggests a competitive interaction between visual and auditory brain areas with each normally inhibiting the performance of the other.

However these interactions were strikingly absent in visual ear participants, suggesting that their auditory and visual areas were not competing but cooperating with each other.

A second experiment was conducted to see whether even people without conscious awareness of 'visual ear' sometimes use their auditory brain areas to make purely visual judgements. It found that this might indeed be the case for some, where stimulation to auditory areas of the brain affected accuracy of visual judgements almost as much as stimulating visual areas.

Taken together, the results of these experiments support a popular theory that some kinds of synaesthesia may depend on a disinhibition of pre-existing neural cross-connections between sensory brain areas that are normally inactive. When these connections are disinhibited this may result in conscious awareness of visual ear and other synaesthetic phenomena.

Dr Freeman said:

"We were also interested to find that, on average, participants with visual ear performed better on both visual and auditory tasks than those without. Perhaps their audio-visual cooperation benefits performance because more of the brain is engaged in processing visual stimuli.

"Such cooperation might also benefit musical performance, explaining why so many of the musicians we tested reported experiencing visual ear."
-end-
The study was published in the Journal of Cognitive Neuroscience.

Dr Freeman is continuing his research in this field with a new online questionnaire, which anyone can complete as a participant.

Notes to editors

  1. To speak to Dr Elliot Freeman or for a copy of the study, please contact Shamim Quadir, Senior Communications Officer at City, University of London on shamim.quadir@city.ac.uk or 0207 040 8782.
  2. Watch the 'skipping pylon GIF': https://twitter.com/LisaDeBruine/status/937105553968566272
  3. Watch the 'Bam Bam from the Flinstones' GIF: https://twitter.com/chrisfassnidge/status/939133452053557248
  4. Read the peer-reviewed research:
    Christopher Fassnidge, Danny Ball, Zainab Kazaz, Synøve Knudsen, Anthony Tipple, Elliot Freeman (in press). Hearing through your eyes: neural basis of audiovisual cross-activation, revealed by transcranial alternating current stimulation. Journal of Cognitive Neuroscience
  5. Link to Dr Elliot Freeman's new questionnaire on visual ear: https://cityunilondon.eu.qualtrics.com/jfe/form/SV_1XrRAjC74ScbklT


About City, University of London

City, University of London is a global institution committed to academic excellence, with a focus on business and the professions and an enviable central London location.

It is the top higher education institution in London for student satisfaction (The Complete University Guide), is ranked 18th overall in the United Kingdom (Guardian University Guide) and is among the top five per cent of universities in the world (Times Higher Education World Rankings).

City has around 19,500 students (46% at postgraduate level) from more than 150 countries and staff from over 75 countries. More than 130,000 former students from over 180 countries are members of the City Alumni Network. City's academic range is broadly-based with world-leading strengths in business; law; health sciences; mathematics; computer science; engineering; social sciences; and the arts including journalism and music.

The University's history dates from 1894, with the foundation of the Northampton Institute on what is now the main part of City's campus. In 1966, City was granted University status by Royal Charter and the Lord Mayor of London became its Chancellor. In September 2016, City joined the University of London federation and HRH the Princess Royal became City's Chancellor. Professor Sir Paul Curran has been Vice-Chancellor and President of City since 2010.

City University London

Related Brain Articles:

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.
Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.
Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.
Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.
BRAIN Initiative tool may transform how scientists study brain structure and function
Researchers have developed a high-tech support system that can keep a large mammalian brain from rapidly decomposing in the hours after death, enabling study of certain molecular and cellular functions.
Wiring diagram of the brain provides a clearer picture of brain scan data
In a study published today in the journal BRAIN, neuroscientists led by Michael D.
Blue Brain Project releases first-ever digital 3D brain cell atlas
The Blue Brain Cell Atlas is like ''going from hand-drawn maps to Google Earth'' -- providing previously unavailable information on major cell types, numbers and positions in all 737 brain regions.
Landmark study reveals no benefit to costly and risky brain cooling after brain injury
A landmark study, led by Monash University researchers, has definitively found that the practice of cooling the body and brain in patients who have recently received a severe traumatic brain injury, has no impact on the patient's long-term outcome.
Brain cells called astrocytes have unexpected role in brain 'plasticity'
Researchers from the Salk Institute have shown that astrocytes -- long-overlooked supportive cells in the brain -- help to enable the brain's plasticity, a new role for astrocytes that was not previously known.
Largest brain study of 62,454 scans identifies drivers of brain aging
In the largest known brain imaging study, scientists from Amen Clinics (Costa Mesa, CA), Google, John's Hopkins University, University of California, Los Angeles and the University of California, San Francisco evaluated 62,454 brain SPECT (single photon emission computed tomography) scans of more than 30,000 individuals from 9 months old to 105 years of age to investigate factors that accelerate brain aging.
More Brain News and Brain Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Teaching For Better Humans 2.0
More than test scores or good grades–what do kids need for the future? This hour, TED speakers explore how to help children grow into better humans, both during and after this time of crisis. Guests include educators Richard Culatta and Liz Kleinrock, psychologist Thomas Curran, and writer Jacqueline Woodson.
Now Playing: Science for the People

#556 The Power of Friendship
It's 2020 and times are tough. Maybe some of us are learning about social distancing the hard way. Maybe we just are all a little anxious. No matter what, we could probably use a friend. But what is a friend, exactly? And why do we need them so much? This week host Bethany Brookshire speaks with Lydia Denworth, author of the new book "Friendship: The Evolution, Biology, and Extraordinary Power of Life's Fundamental Bond". This episode is hosted by Bethany Brookshire, science writer from Science News.
Now Playing: Radiolab

Space
One of the most consistent questions we get at the show is from parents who want to know which episodes are kid-friendly and which aren't. So today, we're releasing a separate feed, Radiolab for Kids. To kick it off, we're rerunning an all-time favorite episode: Space. In the 60's, space exploration was an American obsession. This hour, we chart the path from romance to increasing cynicism. We begin with Ann Druyan, widow of Carl Sagan, with a story about the Voyager expedition, true love, and a golden record that travels through space. And astrophysicist Neil de Grasse Tyson explains the Coepernican Principle, and just how insignificant we are. Support Radiolab today at Radiolab.org/donate.