Scientists Can Make People Hallucinate Using Flickering Image

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Scientists Can Make People Hallucinate Using Flickering Image
Hallucinations can range from simple geometric shapes, such as blobs, lines and hexagons, to seeing animals, people or insects.

Credit: VAlex /

How can we measure the mind? When you ask someone what they’re thinking about, what they tell you is not necessarily the truth. This doesn’t mean they’re lying. It means many environmental, social and personal influences can change what someone tells us.

If I put on a white lab coat, suit or t-shirt and ask you a bunch of questions, what I wear will change what you say. This was demonstrated in the famous Milgrim experiments in the 1960s, which showed the power of perceived authority to control others’ behaviours. People want to be liked, or give a certain impression. This is commonly referred to as impression management and is one of the hardest obstacles to overcome in scientific research.

Neuroscientists have made notable advances in measuring the anatomy of the brain and its regions at different scales. But they’ve made few big advances in measuring the mind, which is what people think, feel and experience. The mind is notoriously difficult to measure; but it needs to be done as it will aid development of new treatments for mental and neurological disorders.

Out-of-control mental imagery and hallucinations are good examples of mental health symptoms that are difficult to measure accurately in science and medicine. Our study published this week shows a new method to induce and measure visual hallucinations in anyone at any time.

These findings open the door to a new avenue of research. We can now study visual hallucinations in the lab using anyone as a subject.

Hallucinations are commonly associated with disorders such as schizophrenia and Parkinson’s disease. But healthy people can also have visual hallucinations after taking drugs, being sleep deprived or suffering migraines, just to name a few conditions.

Generally, hallucinations are defined as an involuntary perception-like experience in the absence of an appropriate direct stimulus. To put it more simply, seeing or hearing something that isn’t there. Hallucinations can range from simple geometric shapes, such as blobs, lines and hexagons, to seeing animals, people or insects.

These involuntary experiences are thought to come about when spontaneous changes in the brain temporarily hijack vision and attention, but the exact causes and underlying mechanisms aren’t fully understood. The best way to understand these things, is to induce a hallucination and observe it in a laboratory.

We have known for more than 200 years that flickering light at particular frequencies can cause almost anyone to experience hallucinations. But the unpredictability, complexity and personal nature of these make them difficult to measure scientifically without having to rely on verbal descriptions. Their changing content, including colours and changing shapes, add to the difficulty.

The simple breakthrough in our research was to reduce hallucinations from flickering lights to a solitary dimension: grey blobs. To do this, rather than flashing random lights or a full computer or TV screen on and off, we flickered a doughnut ring shape instead.

To our surprise, when we did this, we no longer saw lots of different shapes and colours but just grey blobs. By reliably stabilising the hallucination in this way, we could start to objectively investigate its underlying mechanisms.

Under the right viewing conditions, you may experience light grey blobs (that are not physically presented in the movie) appearing around the flickering annulus.

Under the right viewing conditions, you may experience light grey blobs (that are not physically presented in the movie) appearing around the flickering annulus.

Credit: eLife,

Our study’s participant volunteers were university students with no history of migraines or psychiatric disorders. They watched the image of a plain white ring flicker on and off around ten times per second against a black background. All of them reported seeing pale grey blobs appear in the ring and rotate around it, first in one direction and then the other.

To measure the hallucinations, we placed a second ring marked with permanent perceptual grey blobs (not hallucinated) inside the white ring and then flickered this ring again. This allowed people to simultaneously look at hallucinated and perceptual blobs and make a simple comparison.

We showed a range of blobs of different perceptual strengths. The participants then stated whether the hallucinated blobs were lighter or darker than the real blobs. Their answers helped us calculate the equivalent point in strength or contrast between perception and hallucinations.

We used behavioural science techniques to demonstrate that the hallucinations were arising inside the visual cortex. We did this by showing volunteers two flickering rings – one for each eye, displayed out of synchrony. So when one ring was presented, the other was removed, so they alternated between the two eyes.

These lights were flashing about 2.5 times per second — a relatively slow rate, which normally doesn’t induce strong hallucinations. But the volunteers were experiencing hallucinations consistent with lights flashing about five times per second. The signals from the two eyes were being combined in the brain to create a stronger and faster hallucination.

This combination of the signals from the two eyes really only happens in the visual cortex, not in the eye, or other early processing areas of the brain that receive visual input before it gets to the cortex.

Further reading: Some people can’t see, but still think they can: here’s how the brain controls our vision.

Currently, we are testing this new method for inducing and measuring hallucinations in people with neurological disorders to reveal more about how clinical hallucinations are experienced and processed in the brain.

If we can discover the underlying mechanisms of visual hallucinations, this will give us targets to focus treatments on. We hope this new technique will open the doors to new avenues of research, not only shedding light on the foundations of human consciousness, but also helping to develop innovative new treatments for those suffering from hallucinations.

Joel Pearson giving a talk on creating tools to measure the mindJoel Pearson, Associate professor, UNSW Australia

This article was originally published on The Conversation. Read the original article.

Twins Conjoined at Head Now Separated: What Causes Rare Condition?

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Twins Conjoined at Head Now Separated: What Causes Rare Condition?

Does Your ‘Self’ Have a Soul?

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Does Your ‘Self’ Have a Soul?

How to Watch China Launch Its Longest Manned Space Mission Tonight

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How to Watch China Launch Its Longest Manned Space Mission Tonight
Photo: AP

Today, China is set to launch its longest manned spacecraft mission at 7:30pm ET (2330 GMT) from the Gobi Desert and you can watch it live right here.

Two men, Jing Haipeng, 49, and Chen Dong, 37, have been given the task of testing out the life support system of China’s Tiangong 2 space station. The Shenzhou-11 “Heavenly Vessel” will ride into orbit, dock with the station and the crew will spend 30 days conducting experiments aboard.

This will be Jing Haipeng’s third flight and he will celebrate his 50th birthday in space.

Chen Dong told assembled reporters at a press conference that their tests will “focus on improving our ability to handle emergencies in orbit, medical first aid, mutual rescue capabilities and space experiments.” They will also be bringing three experiments that were designed by middle school students from Hong Kong. One experiment will involve testing silkworms in micro-gravity.

China has increased the ambitions of its space program considerably in recent years and mostly focused on near-Earth space exploration but that is expected to change soon. Its last manned mission, Shenzou 10, took place in 2013 and lasted for 15 days. The country has plans to send a probe to Mars and potentially put another man on the moon. In the near-term, Zhang Yulin, an official with the space program and the Central Military Commission, told reporters that they plan to send spacecraft further than 400km and increase their frequency. He said, “Spacecraft launches won’t be like now, one every few years, instead there will be several each year.”

The Tiangong space stations are just a precursor to China’s ultimate goal of putting a permanent 20-ton space station into orbit 2022, two-years before the International Space Station will be retired.

Unfortunately, Congress has banned NASA from working with China on its space program due to national security concerns. Joan Johnson-Freese, a professor at the Naval War College, specializes in space programs and space security. She warns that “If the US does not change its policies very soon and begin to work with China in space, it will lose whatever leverage it might have in shaping Chinese space plans for the future.”

You can watch the live stream below at 7:30pm ET on Sunday, October 16th. If something goes wrong with that stream you can also see it here.

[BBC, Reuters, CNN]

Gizmodo weekend editor