in head tripPopSci explores the relationship between our brains, our senses, and the strange things that happen between them.
lots of fantasies It is the product of a mismatch in sensory input and is triggered when one sense conflicts with another. (that Appearance It’s just a noisy fan, sound One of the most amazing of these illusions, and one of the easiest to try on your own, is the McGuirk Effect, which is an audiovisual illusion. explained It was written in 1976 by Scottish psychologist Harry McGuirk and his assistant John MacDonald.
When you search on YouTube, you will find many videos About the McGurk effect. Observe the faces of people who speak monosyllables. Normally, Ba-again and again. After a while, the person usually starts saying different syllables. Fa. Many listeners will “hear” the audio change accordingly. But in reality it does nothing of the sort. The sound played remains the same throughout. “Ba! Ba! Ba!
what happened? Michael Beacham, a professor of neurosurgery at the University of Pennsylvania, has spent much of his career studying the McGuirk effect. “That’s what I think about all day, every day,” he laughs.in 2012 paper in diary neuroimageBeauchamp and colleague Audrey Nath looked at the link between effects and neural activity in a region of the brain called the left hemisphere. superior temporal sulcus (STS).
This STS creates a physical bridge between the visual cortex and auditory processing areas (a fact that Beauchamp has demonstrated with 3D printouts of his own brain). One of the many important functions of this brain region is the processing of multisensory audiovisual input. “[The STS] It combines auditory and visual information,” Beecham explains. “That’s why we think it’s important to McGuirk.”
According to a 2012 survey functional MRI Data to study left STS activity in people who experienced the McGuirk effect and compare it with left STS activity in people who did not experience it. Indeed, activity levels increased in the first group. However, Beecham cautions that given the brain’s inherent complexity, this result is not as conclusive as “STS causes the McGuirk effect.” “It won’t be comfortable. [being that definitive] You don’t need a much larger sample size,” he says.
Still, this study suggested one important fact that became the focus of many subsequent studies. “Some people get the McGuirk effect all the time, while others never get it,” says Beecham. “[But] There’s also a whole spectrum in between. We are very confident about this.we have seen [it] To hundreds of people. ”
The existence of this spectrum suggests that the effects, the interplay of vision and hearing in multisensory processing, are more complex and nuanced than many scientists once believed. (This includes McGuirk himself, who claimed that 98% of people experience the full effect all the time, while the remaining 2% never experience it.)
It also suggests that the whole concept of “fantasy” is worth reconsidering. We tend to think that experiencing an optical illusion is a sensory malfunction, meaning that we’re being fooled and, in the process, confronting the limits of our brain’s ability to understand the outside world. But Beecham’s research suggests that the real situation may be more nuanced. Even if auditory and visual information do not match, McGurk’s perceivers integrate it. This may provide an advantage under conditions of high levels of auditory or visual noise, at the cost of being distracted by the McGurk stimulus. ”
This means that, at least in some cases, susceptibility to illusions may be adaptive rather than maladaptive. This is because illusions are ultimately induced by the brain doing its best to make sense of mismatched or contradictory sensory information. This also raises the question of how our neural centers can adapt to changes in the quality of their information. (As someone who has suffered from hearing loss, I have a damaged cochlea in one ear and a dislocated elbow in a childhood basketball game, so I think this idea has personal resonance.) Is the rest of the brain adapting to long-term changes in the reliability of one of our senses?
“This is an interesting question and an open question. We know that the brain is plastic,” he says, and one of his team’s research goals is to find ways to harness this plasticity. He added that there is. “For example, many people’s hearing declines much faster than their vision, so if we can help them adapt better to visual information, that might help.” [compensate for] Hearing loss. “
The degree of brain plasticity in this regard is underscored by another remarkable detail uncovered by Beecham’s research. That means the McGuirk effect could be permanent. “If you watch the same McGuirk Effect clip for too long, you get the illusion that you’re not looking at the screen. Basically, your brain is being rewired. You don’t even need to look at faces anymore. Your brain is Because they’re convinced, ‘Okay, the auditory part is wrong, so let’s follow what the visual part is saying,'” the professor explains.
Again, you can try it yourself. “Go to YouTube,” he says Beauchamp. “clock [one of those] Watch the video for one minute every day for a few days, then listen to it again without watching anything. My prediction is that you’ll still get the McGuirk effect. ”
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