Prof. Graham Harding, a pioneer in photosensitive epilepsy research, has died at age 81. His recent obituary in The Times aptly described him as a world authority on photosensitive epilepsy. Prof. Harding published more than 350 research papers and co-authored a seminal book on photosensitive epilepsy. He was among the first to recognize the risk of seizures from television and video game graphics.
Perhaps most important of all, he crafted image guidelines that reduce the public’s risk of photosensitive seizures from environmental triggers, and he advocated for safer video games. His own research and studies by others showed that specific, measurable qualities of a flashing or patterned image determine its risk of triggering epileptic seizures in individuals with photosensitive epilepsy. Identifying the risk factors and danger thresholds from the flash interval, and the brightness, size, and color contrast of images enabled him to create guidelines for minimizing the chances of seizures.
The need to protect the public
In 1993, flashing images in a commercial on British TV caused seizures in three viewers the first time it aired. In response, the British regulatory agency for television asked Prof. Harding to draft guidelines to limit the public’s exposure to seizure-provoking television images. Four years later, after the Pokémon incident in Japan, the Japanese government asked him to do the same.
Nearly 700 children had arrived at hospitals in Japan for suspected seizures during a Pokémon cartoon broadcast. Prof. Harding later recalled in an interview, ‘The first I knew of it was when my secretary said, ‘The Japanese embassy is on the phone, 400 children have just had seizures,”’ and shortly afterward he was flown to Japan. Doctors found that 560 of the children had probably experienced seizures; 76 percent of them had never had a seizure previously.
Prof. Harding was clear that seizure warnings on video game packaging and instructions do not provide adequate protection for consumers, citing the 76 percent of Japanese children whose first seizure occurred during the Pokémon cartoon.
While Nintendo, for example, warns that anyone who has had a seizure induced by flashing lights or patterns should consult a doctor before playing a video game, Harding said, that doesn’t protect against a first attack. ″Warnings are good except for people who don’t know they are photosensitive,″ said Harding.
Knight-Ridder Newspapers, December 25, 2002
Ensuring that the guidelines were observed was very time-consuming; he analyzed broadcast video images frame by frame. “Some days I spend four to five hours watching the television,” he said at the time. “It is nice in that it is real applied medical science. Part of my job is stopping people having seizures, so if this is how I do that I don’t really mind.”
With the help of his wife and Cambridge Research Systems, Ltd. he then created the Harding Flash and Pattern Analyzer (FPA) to automate the process, which was nominated for a Royal Television Society technical innovation award in 2001. I have used the FPA many times to check images of video games and music videos.
Prof. Harding received his PhD at the University of Birmingham in electroencephalography (EEG) and psychiatry. He spent 40 years at Aston University in Birmingham, where he headed up the Vision Sciences Department and was the first professor of clinical neurophysiology in the UK. When the department opened a new building in 1987, Prof. Harding hosted the Prince of Wales at the opening ceremony. Although he did not have medical credentials, his contributions to medicine were recognized with membership and then fellowship in the Royal College of Physicians.
Prof. Harding was also one of the developers of guidelines to standardize photic stimulation testing, a diagnostic procedure for identifying photosensitivity, and he wrote about the risk of photosensitive seizures precipitated by wind turbines.
It is hard to overstate Prof. Harding’s influence on the study, diagnosis, and prevention of visually induced seizures.
When you play a game ranked in the GameSpot or New Yorker Top 10 video games of 2017, the chances are about even that you will be exposed to images that could trigger photosensitive seizures. These images, which violate established guidelines for reducing the risk of photosensitive seizures, appear in 6 of the games in a combined Top 10 list. In 7 games these images were not found (some games are on both Top 10 lists).
What are photosensitive seizures?
Photosensitive seizures can occur when people with photosensitive epilepsy are exposed to intense visual stimuli: bright, rapid flashing light and bold patterns with strong contrasts. An unknown segment of the population has photosensitive epilepsy, including people with no history of seizures. It is under-reported and under-diagnosed.
In those who develop the condition, photosensitive epilepsy typically is hidden until the first noticeable seizure occurs in the presence of bright flashing or patterns. Most people with other types of epilepsy are not photosensitive. In other types of epilepsy, seizures are much more unpredictable.
Seizures can be of any type, from tonic-clonic episodes with loss of consciousness to brief absence seizures that can be as subtle as a brief hesitation or stare. Most people do not have photosensitive epilepsy, but many who do are unaware that they have the condition until a they experience a seizure during or after exposure to flashing or patterned images. Some individuals may have seizures that are too subtle to notice.
The seizure reduction guidelines test
Guidelines for seizure reduction originated in 1994, when the UK adopted technical guidelines to accommodate TV viewers with photosensitive epilepsy. These guidelines, based on studies by photosensitive epilepsy experts, outline the characteristics of flash rates and spatial patterns that typically trigger seizures in people with photosensitive epilepsy. They were later updated and some have been adopted by the World Wide Web Consortium (WC3), the international group that produces website standards for all types of applications, and the International Telecommunication Union.
The guidelines define criteria for photosensitive seizure risk involving:
- flash rate greater than 3 per second and less than 60
- stripes and geometric patterns with high contrast
- large areas of very bright (“saturated”) red
- any of the above problem images taking up more than one quarter of the total screen area
Visuals adhering to these guidelines are unlikely to provoke seizures in 97% of people with photosensitive epilepsy.
Testing video games for compliance with guidelines
Although most games carry seizure warnings, not all games contain the types of images that can bring on seizures. The warnings are not specific to the content of a given game, so consumers who pay attention to the warning don’t know whether it pertains to the game they are about to use. So I test them.
I tested the games using downloaded clips of gameplay that I loaded into an application called the Harding Flash and Pattern Analyzer. The FPA is widely used by TV producers and networks in the UK—including by the BBC—to reduce the risk of seizures from material on broadcast TV, and is used by some game studios. It examines video sequences frame by frame for very specific and measurable image qualities that research shows can trigger seizures.
What do a pineapple playing tennis and a grape going for a ride have in common? Two things: 1) They’re currently appearing in Google’s Olympics-themed iOS and Android Doodle Fruit Games app, and 2) viewing them in Google’s video promoting the app could give you a seizure.
For the next two weeks while the game app is available, Google is promoting it with a zippy, fast-paced trailer. Visitors watching the trailer see rapidly moving images images that could provoke seizures in anyone with a condition known as photosensitive epilepsy. I tested the trailer for its risk of inducing seizures and found two segments–involving the aforementioned pineapple and grape–with a flashing effect that could trigger photosensitive seizures. From what I can tell, the problem images appear only in the trailer and not in the games app itself–unless they appear only after players achieve a high score that I didn’t reach.
What is photosensitive epilepsy?
Photosensitive epilepsy is more common than is generally known, and researchers agree it is probably underestimated. People with the condition have epileptic seizures triggered by lights or images that flash faster than three times per second.
It gained some notoriety after a Pokémon cartoon shown on Japanese TV in 1997 sent nearly 600 children to emergency rooms with seizure symptoms. The condition had already been extensively studied and researchers had drawn up guidelines for reducing the seizure risk from video images, but at the time Japan did not protect TV viewers from problem images.
Who is affected by photosensitive epilepsy?
The vast majority of those with “regular” epilepsy are not affected by visual stimuli. But photosensitive epilepsy may be harder to detect and is underrecognized by the public and by doctors. You may be susceptible to photosensitive seizures and not even realize it since:
- Photosensitive epilepsy typically doesn’t develop until adolescence.
- It can occur in people with no history of seizures. Of Japanese children affected by the Pokémon cartoon, 76 percent had never before experienced a seizure.
- People with other forms of epilepsy are routinely tested for photosensitive epilepsy, but the condition may be most common in individuals who don’t have any other type of seizures. These people are very unlikely to be screened for it.
You can already be experiencing seizures and not know it.
- Not all seizures involve complete loss of consciousness, falling, or body movement observable by others. Such major events, known as generalized seizures, occurred in less than half of the Pokémon-affected children.
- Because consciousness is altered at the time, a person having a seizure often has no memory of it.
Even if you have no visible symptoms of a seizure, there can be lingering after-effects that include fatigue, sleep, learning, and memory problems, mood irregularities, among others.
How the media and entertainment industry can reduce seizure risk
More than 20 years ago, researchers studying photosensitive epilepsy defined the factors, in particular the flash frequency, that are most likely to provoke visually induced seizures.The UK has required all TV content to conform to seizure-reduction guidelines since 1994, and Japan enacted similar regulations following the Pokémon incident. To date, no other countries have done this, but a United Nations-affiliated agency did adopt recommendations for reducing photosensitive seizure provocation from television. Meanwhile, of course, interactive media have become a much bigger part of our lives than television, and the same guidelines for reducing seizures from TV should be adapted to the internet.
The World Wide Web Consortium (WC3), the international group that produces website accessibility standards for all types of applications, now includes guidelines for reducing the risk of visually triggered seizures. But incorporating such standards into private industry applications and sites is a hugely complex and time-consuming process.
The United States Department of Justice has been considering since 2010 the complexities of creating regulations ensuring access by the disabled to public and private websites. The DOJ announced this spring that rules governing private websites have been delayed until 2018 at the earliest.
In 19901, after a few consumer lawsuits were filed due to seizures, game developers began including a seizure warning that has kept consumers from filing or winning such lawsuits. Although most game documentation and packaging contain a seizure warning, not all games contain seizure-provoking visuals. Consumers don’t know which games actually have potentially harmful sequences and largely ignore the warnings.
How you can prevent photosensitive seizures
If you’re susceptible, even a brief exposure of a few seconds to flashing can be enough to bring on a seizure. If you know that you are vulnerable to these seizures, there are some precautions doctors recommend to avoid being triggered:
- When possible, avoid situations and stimuli that are likely to be provocative, including emergency lights, electronic billboards, video games, light shows, flickering fluorescent lights, fireworks, animé and other fast-moving cartoons
- Wear blue-colored glasses, which filter out the most provocative light frequencies. Most opticians can make these inexpensively.
- In the presence of flashing light, cover one eye.
- Increase your distance if possible from the flashing image–so, for example, stay at least 6 feet from your TV screen, and don’t play video games up close.
- Don’t play when fatigued or sleep-deprived.
- Take frequent breaks during prolonged exposure–although this won’t always help if you are triggered in a matter of seconds.
Testing for visuals that can provoke seizures
I tested the trailer using an industry-standard application called the Harding Flash and Pattern Analyzer that detects image sequences that can trigger photosensitive seizures. It is based on algorithms devised by Graham Harding, one of the world’s leading experts on photosensitive epilepsy. The application is widely used by producers and networks in the UK—including by the BBC—to reduce the risk of seizures from material on broadcast TV. The analyzer examines video sequences frame by frame for very specific and measurable image qualities that researchers have found can trigger seizures.
Seizures from video shown on TV about 2012 Olympics logo
This is not the first time that Olympics-themed promotional visuals have placed viewers at risk of seizures. A promotional video for the logo of 2012 London Olympics logo shown on British TV news in 2007 resulted in seizures in some viewers. It had not undergone the required testing that would have alerted producers to the problem prior to broadcast.
According to a Reddit post, a game that I’ve said “passed the seizure test” triggered a seizure. Recently the same game—Hearthstone—could have been implicated in a professional gamer’s seizure that happened during a live stream. What’s going on?
I write about games I’ve tested to alert readers to the games that don’t meet internationally recognized image safety guidelines. But I don’t want to create undeserved confidence that a game that passed the seizure test will be safe for anyone with photosensitive epilepsy.
Ian Hamilton, a user interface designer who specializes in and advocates for game accessibility, clarifies the role of testing this way:
“Passing the Harding test doesn’t mean that a game is safe. It means ‘reasonably safe’ because common triggers have been avoided. Something that gets a ‘pass’ can still absolutely cause seizures.”
I regularly write that your experience may differ, that I’m not trained in quality assurance, that I test excerpts of game play, and that health and lifestyle variables affect every individual’s vulnerability to seizures at any given time. Still, the meaning of my findings could be misleading without an understanding of the limitations of the seizure test itself:
- the pass/fail guidelines aren’t expected to prevent seizures in all individuals
- the test was designed for TV images, not video games
What the Pass/Fail guidelines mean
The guidelines originated in 1994, when the UK’s agency for regulating TV broadcasting (now known as Ofcom) inserted into its code of standards some technical guidelines to accommodate viewers with photosensitive epilepsy. These guidelines, based on studies of photosensitive epilepsy and consultation with Prof. Graham Harding and other photosensitive epilepsy experts, detail flash rates and spatial patterns that typically trigger seizures in people with photosensitive epilepsy. Specifications regarding saturated red images were added later, after the 1997 Pokémon incident in Japan.
Some compromises in the guidelines were made for the sake of practicality. Criteria for acceptable images (commonly referred to as the Harding test) were developed with the understanding that they would realistically protect most individuals with photosensitive epilepsy, but not all. For example, the guidelines permit images that flash at a rate of up to 3 times per second because flash at that frequency affects only 3 percent of photosensitive individuals. UK regulators decided that was “an acceptably small risk.”
The introduction to the guidelines states that their purpose is “reducing the risk of exposure to potentially harmful stimuli.” It also concedes that even when broadcasting images that comply with the guidelines,
“it is…impossible to eliminate the risk of television causing convulsions in viewers with photosensitive epilepsy.”
Applying TV guidelines to video games
There are no formal guidelines for reducing the seizure risk from video games. A 2005 consensus paper by experts on photosensitive seizures acknowledges that additional work would be required first on the existing guidelines for TV. In the meantime, it is reasonable to use the television guidelines since the impact of screen images on the visual system is the same.
The biggest challenge in applying TV specifications to video games is explained in the consensus paper:
“These principles are easier to apply in the case of fixed media (for example, a prerecorded TV show), which can be analyzed frame-by-frame. Interactive media, such as video games, may afford essentially limitless pathways through the game, depending on user actions. Therefore …in the case of video games, the consensus recommendations apply to typical pathways of play but cannot cover every eventuality of play.”**
Reducing risk going forward
In sum, a game that fails the Harding test is best avoided by those with photosensitive epilepsy. A game that passes is less likely to act as a trigger. Despite all the qualifiers, I believe there’s value in reminding people that seizures can happen to anybody, that certain video games can trigger them, and that you can lessen the risk by selecting games without lots of flash and patterns. Other strategies to lessen the risk of photosensitive seizures can be found here and here.
Tip of the hat to Ian, who suggested that I avoid the word “safe” when describing games that have passed the test. I also will be revising my prior posts to do some rewording.
Gamer’s seizure on live stream
Here’s a reminder that seizures can happen to anyone. A professional gamer known as Lothar had a seizure recently during his live feed while playing Hearthstone on Twitch. Lothar apparently has no history of seizures and the seizure may or may not have any connection to Hearthstone. In updates about his condition and hospital stay, Lothar didn’t mention photosensitive epilepsy nor has he said he’s been advised to limit his gameplay.
For the record, Lothar is also a body builder—he’s obviously a guy who has enjoyed good health and takes good care of himself. Lothar has a large and caring following and has been receiving lots of well wishes as he recovers. Why do I mention this incident here? Viewing the incident (you can find it on YouTube) and seeing how it affected so many fans who care about him reinforced for me the seriousness of seizures and the importance of preventing those that are preventable.
When the Duke and Duchess of Cambridge arrived at their New York hotel this week, it was big news. Did you catch the squeals of delight from the crowd and the flicker of so many cameras flashing? The arrival scene was featured on a number of American news programs.
How it was seen in the UK
This same New York arrival scene was shown in the UK as well—but with an important difference.
Rapid-fire flash photography from the swarm of media creates a strobe-like effect on the image, which is known to trigger seizures in some people. In the US this material is broadcast despite the seizure risk.
But for more than 20 years, TV programs and commercials flashing at frequencies that can provoke seizures have been barred from broadcast in the UK. An exception to the regulation is made for breaking news coverage, where potentially seizure-inducing material is allowed to air if accompanied by a warning. These regulations were put in place after a noodle commercial triggered seizures in several British viewers.
Out of curiosity I tested a video clip of that New York sidewalk scene to see if the flash freqency falls into the category of a seizure hazard. I used an application called the Harding Flash and Pattern Analyzer (below) that assesses video sequences for seizure safety. The clip did in fact exceed flash safety limits for people vulnerable to visually induced seizures. Folks in the UK at least got an on-screen warning, which perhaps gives susceptible viewers a chance to avert their eyes.
What happens when American TV programs are shown in the UK?
TV programs and music videos imported to Great Britain from the US (and other countries) need to be tested first, then modified to comply with the British seizure safety mandate. An engineer in a London post-production studio who does this compliance work shared with me that a popular US crime series had nearly 150 violations of seizure safety guidelines in a single episode. Where is the consumer lobby for seizure-safe TV programming in this country? Anybody?
A new definition of epilepsy published this week affirms that photosensitive and other reflex seizures qualify as “real” epilepsy. This clarification may eventually help increase awareness of seizures from video games and other electronic media.
Although reflex seizures have long been included in official classification schemes of epileptic seizures, they don’t fit cleanly into established categories of seizure types and epilepsy syndromes. In neurology training they are typically mentioned only briefly. And typically they are taken too lightly by doctors using the prevailing diagnostic criteria for epilepsy: at least two unprovoked seizures at least 24 hours apart.
Because reflex seizures, by definition, are provoked by specific triggers, there’s confusion and most doctors have been reluctant to diagnose epilepsy in people whose epileptic seizures require an environmental provocation. The authors of the new definition paper acknowledge this:
“Under limits of the current definition, [a] patient might have photosensitive epilepsy, yet not be considered to have epilepsy because the seizures are provoked by lights…People with reflex epilepsies previously have been disenfranchised by the requirement that seizures be unprovoked. The inclusion of reflex epilepsy syndromes in a practical clinical definition of epilepsy now brings these individuals into the epilepsy community.”
Diagnostic criteria under the new definition now include at least two unprovoked or reflex seizures at least 24 hours apart. The new definition also allows an epilepsy diagnosis after a single seizure–either unprovoked or reflex–if there is a high probability of recurrence.
I’ve written previously about the inconsistency inherent in using the criterion of “unprovoked” to diagnose epilepsy in people whose seizures happen only in response to sensory triggers such as flashing light. This thinking (along with the assumption that photosensitive epilepsy is very rare) has led to marginalization of reflex seizures in the research community and among clinicians as well. Marginalization means doctors have been underdiagnosing reflex epilepsy, researchers seeking funding pursue other topics to study, and the public and public policy makers are largely unaware of the public health issue of photosensitive seizures.
The practical clinical definition was developed by a 19-member multinational task force of the International League Against Epilepsy (ILAE), incorporating input from hundreds of other clinicians, researchers, patients, and other interested parties. I’m more than pleased that the ILAE is choosing to make it clear that reflex epilepsy deserves the same respect as other forms of the disease (the new definition paper characterizes epilepsy as a disease rather than a disorder). It’s fortunate that the chair of the ILAE task force that produced the new definition is Robert Fisher, MD, PhD of Stanford, lead author of the 2005 consensus paper describing seizures from visual stimulation as “a serious public health problem.” No doubt Dr. Fisher’s appreciation of the magnitude of the problem was instrumental in ensuring that the task force addressed it.
Not all epileptologists agree with all aspects of the new epilepsy definition–and Epilepsia has given them a voice as well, publishing half a dozen commentaries, all of which are available free online. I contributed a piece as well, providing a patient/family perspective.
Of course, it remains to be seen how long it will take for neurologists to shift their attitudes and diagnostic practices regarding reflex epilepsy. Perhaps the inclusion of reflex seizures in the epilepsy definition will help dispell the idea that reflex seizures are rare.
Gaming fans who object to the concept of seizure-safe games have some major misconceptions about how their favorite games would look after seizure-inducing visuals are removed.
I’ve seen people in online forums threaten to stop their game subscription if the game’s images are made safe. These folks are assuming that making safety modifications to the graphics will mean “neutering” the game experience in a way that ruins their enjoyment. In fact, very minor changes to images, which can be pretty hard to detect, are often all that’s needed.
Thanks to extensive research that defined the characteristics of images that induce seizures, it’s possible to make small changes that interrupt any such seizure-generating sequences. For example, after changes are made to some video frames, the flash interval–more than 3 flashes per second–which can lead to a seizure in people with photosensitive epilepsy, no longer induces seizures.
Want some proof?
NOTE: For those with visual sensitivity, before you click on the upcoming link to side-by-side videos, know that you should be able to view the page safely because the problem images aren’t very large. If you’d prefer not to risk it, you might want to step back farther from your screen or cover the left side of your screen, because that’s where the problem images are.
Now click to see the side-by-side images of a music video running in its original form (with safety violations) and after modifications were made to comply with seizure safety guidelines (in the UK, they’re requirements, not guidelines). The changes are very subtle! Can you find them? As you’ll see in the modified version, even visual sequences that contain some flashes and quick cuts can therefore pass the safety test. Basically, portions of some flashing sequences (9 instances) have been altered or removed, which does little to change the overall viewing experience. Edits to the video that allowed it to be broadcast were done within a single day by London-based post-production firm Vanderquest Limited.
Readers familiar with the Harding Flash and Pattern Analyzer that I routinely use to test video material for seizure safety will recognize the HFPA results shown beneath both versions of the music video. Although the original, uncorrected official version could not be broadcast in the UK due to regulations barring seizure-inducing material from being shown there, it lives on on YouTube.
Imagine these types of edits to the user interface of a video game. Exactly how do they ruin the gaming experience?! Or artistic expression?