When it comes to the emphasis on accessibility features, Apple, which stands "at the intersection of technology and the liberal arts," can be said to lead the pack among manufacturers. A month before WWDC, Apple teased a batch of new accessibility features for Global Accessibility Awareness Day (May 16th), including eye tracking, vehicle motion alerts, dimming flickering lights, and music haptics, all of which can be conveniently turned on and off in the newly revamped Control Center.

In addition to the "eye tracking" feature, which can be inferred to be related to the development of Apple Vision Pro, another feature that is likely to garner attention is the "vehicle motion alerts," which are said to potentially alleviate motion sickness discomfort. After all, in modern society, more or less everyone has been troubled by car, boat, or airplane sickness at some point.

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In today's article, we will discuss what "motion sickness" is, how to treat it, and whether this new feature can be effective.

What is motion sickness: A literal explanation

Motion sickness (motion sickness) may seem unfamiliar at first glance, but when it comes to car or boat sickness, it's a common topic. Even if you haven't had a profound personal experience, you've probably seen people around you suffer from car sickness, and you've heard about various folk remedies to prevent it.

The earliest descriptions of motion sickness can be traced back to 400 BC, when people first considered seasickness as a kind of plague. Readers interested in this history can refer to this article:

Related reading: A Historical View of Motion Sickness—A Plague at Sea and on Land, Also with Military Impact

In current undergraduate medical textbooks, motion sickness is classified as peripheral vertigo (vestibular vertigo), which is the "dizziness" in motion sickness.

Motion sickness: It is caused by mechanical stimulation of the inner ear's labyrinth when riding in a car, ship, or airplane, leading to vestibular dysfunction. It is often accompanied by symptoms such as nausea, vomiting, pale complexion, and cold sweats.People's Medical Publishing House, "Diagnostics" 9th Edition

Firstly, dizziness has a clear definition, which is stated in the 8th Edition of "Neurology" as follows:

Dizziness (vertigo) is a sensation of motion or position illusion, causing a distortion in the cortical response of the relationship between a person and their surrounding environment, resulting in feelings of rotation, tilting, and undulation.

It can be caused by many different reasons. For instance, in daily life, one might feel dizzy due to lack of breath and cerebral hypoxia, skipping breakfast and experiencing low blood sugar, high blood pressure, or low blood pressure. Feeling lightheaded and unsteady, without a sense of rotation or swaying of oneself or the external environment, these are categorized as 'non-vestibular system dizziness' and are generally described as 'dizziness' (dizziness).

Today's main focus, motion sickness, belongs to the opposite category of vestibular system dizziness (vertigo), and further细分, it is the peripheral vertigo mentioned above, with typical manifestations including a sense of rotation, swaying, and movement.

"Diagnostics" provides further explanation for why people feel dizzy:

The human body transmits information about body position through vision, proprioception, and vestibular organs via sensory nerves into the central nervous system, integrates it to make judgments about position, and then sends out adjustments through motor nerves to maintain balance. Any functional abnormality in any of these input links can lead to incorrect judgments and result in dizziness.

In layman's terms, the human body processes the visual information seen by the eyes, the body's position and movement sensed by the body, and the balance sensations felt by the vestibular organs in the inner ear (including the semicircular canals, utricle, and saccule), all of which are transmitted to the brain for processing, thereby judging motion status and regulating limb movement, allowing us to walk steadily.

This is also the reason why normal people do not feel dizzy while walking: we move forward with our legs, the scenery seen by our eyes moves backward, the skin feels the wind blowing backward, and the vestibular organs in the inner ear sense the forward acceleration, all of which point to a consistent conclusion in the brain: we are walking forward, so we do not feel dizzy. In other words, when the brain misjudges, the person is not moving, but the brain thinks the person is running, jumping, or rotating, and the person becomes dizzy.The term "motion" in motion sickness specifies the context in which it occurs, that is, during movement. This "movement" refers to the process of relative position change in the human body, which is motion, or at least one of the aforementioned three senses "feels" that we have changed position. Therefore, to be more precise, this "motion" is the mismatched process between the motion we see, the motion sensed by the vestibular system, and the motion of proprioception.

As for "sickness," those who have experienced car or sea sickness have a lot to say about it, with symptoms such as nausea and vomiting, dizziness, and a general sense of discomfort. Referring to a set of diagnostic criteria for motion sickness published in the Journal of Vestibular Research in 2021, common symptom clusters include:

Nausea and/or gastrointestinal dysfunction

Thermoregulatory disorder

Changes in the state of arousal

Vertigo and/or a sensation of spinning

Headache and/or ocular pressure

Annotations: Nausea and/or gastrointestinal discomfort may include a feeling of wanting to vomit, actual vomiting, retching, upper abdominal/stomach discomfort/sensation of discomfort, increased salivation and/or changes in appetite, and belching or the urge to defecate. Thermoregulatory disorder may include sweating/cold sweats, stickiness, flushing, warmth, and paleness. Changes in the state of arousal may include drowsiness, fatigue, tiredness, and difficulty concentrating. Vertigo and/or a sensation of spinning may include these symptoms as well as disorientation, fainting, and visual motion illusions. Headache and/or ocular pressure may include headaches, a feeling of fullness in the head, ocular pressure, difficulty focusing, or visual blurring. Visual blurring may also occur in cases of vertigo.

When physical motion or visual motion triggers the aforementioned signs and symptoms, and these symptoms intensify with prolonged duration, gradually subside after stopping the motion, and traceably disappear, and there are no other diseases of organs and systems, motion sickness can be considered for diagnosis.

How does motion sickness occur?The etiology of motion sickness has not yet reached a definitive conclusion, and there are several theories within the academic community. Here, I will synthesize and list some of the more representative ones:

Sensory Conflict Theory

This is the most common theory and is the most directly related to the mechanism of dizziness. It posits that motion sickness occurs because of a conflict between what our brain expects and what our visual, vestibular, and proprioceptive senses actually input. To illustrate with the most common example of car sickness, our vestibular organs in the inner ear sense that we are moving forward, but most of what our eyes see is stationary, and our bodies are sitting still—we are not moving. This contradiction creates a "motion illusion," leading to dizziness.

Isn't it straightforward? We can further support this with examples. For instance, modern people often read on their phones or tablets while in moving vehicles, ships, or aircraft. The content displayed on these devices is mostly static or at least does not change with the motion of the vehicle or vessel. Therefore, even those who are not prone to car or sea sickness can experience motion sickness if they read or use devices for extended periods.

Conversely, we often say that "passengers get car sick, but drivers do not," because the driver's attention is focused on the road ahead, and what they see matches what they should see while moving. During driving, there are actions such as stepping on the gas or brakes, turning the steering wheel, and shifting gears that are in sync with the "motion." The brain perceives little or no conflict among these senses, which largely determines that the likelihood of a driver experiencing car sickness is much lower than that of a passenger.

In this light, motion sickness seems to be a result of human evolution not keeping pace with the changes in the material world. After all, in the ancient times when our ancestors evolved from hominids to modern Homo sapiens, they relied on their legs for traveling and hunting, without the mismatch between what they saw and what they felt.

Speculatively, future humans might gradually become accustomed to the sensory conflicts experienced during transportation and no longer fear motion sickness.

However, regrettably, the pace of human evolution is clearly far slower than that of technological development. In addition to the long-standing phenomena of car and sea sickness, with the advent of 3D first-person games, VR headsets, and other technologies, a new manifestation of motion sickness, known as 3D sickness, has also emerged. It is currently categorized under visually induced motion sickness (VIMS), specifically referring to the motion sickness induced by the use of certain head-mounted virtual reality displays, simulators, or screen viewing.According to the sensory conflict theory, 3D motion sickness is also quite understandable, and it actually has a somewhat opposite flavor to car sickness: the images we see through the screen change rapidly, and our vision tells our brain that our body is in motion, but proprioception and balance sense both convey the signal of "stillness." This conflict leads to an illusion and thus causes dizziness. The emergence of this type of visually induced motion sickness has even led scholars to revise the diagnostic criteria for motion sickness.

Toxin hypothesis

This hypothesis suggests that motion sickness is actually an evolutionary achievement. Unlike the public's focus on "dizziness," this hypothesis seems to pay more attention to the manifestation of "nausea and vomiting." Essentially, it is a protective mechanism (in fact, vomiting itself is indeed a physiological mechanism to protect the body from harmful substances), and car sickness is just an accidental byproduct that emerged with the advent of modern transportation and first-person games.

The basis of this hypothesis is that the sensory input integration caused by the use of modern transportation tools produces illusions similar to the neurological effects caused by poisoning in ancient times. That is to say, a long time ago, although there was no experience like riding in a car that could cause a conflict between vision and vestibular sensation, consuming spoiled meat, toxic plants, and rotten fruit, the toxins within would cause prehistoric humans to experience conflicts between vision, vestibular sensation, and proprioception. Therefore, when such sensations reoccur, the alarm goes off: "Eaten something wrong! Need to expel it immediately!" The fastest and most effective way is vomiting.

This hypothesis is supported by some observational results, such as the fact that people who are prone to car sickness are more likely to vomit under the stimulation of other factors (such as chemotherapy and real toxins) than those who are not prone to car sickness, but it has also been questioned.

Nystagmus hypothesis

This hypothesis is slightly more complex than the previous two and involves some relationships between the eyes and brain nerves. I have summarized the following three main specific mechanisms, hoping to help you understand.

The relationship between the vestibular system and eye movement:

The vestibular system in the inner ear can sense the movement of the head (mainly rotation and acceleration). This type of input is closely linked to the eye movement control system, also known as the "vestibulo-ocular reflex." In simple terms, when the vestibular system detects our head movement, it triggers eye movement to ensure the stability of the field of vision, which is somewhat like a gimbal.Semicircular Canal Vestibulo-Ocular Reflex

Abnormal eye movements:

Under the precondition of motion sickness, a conflict between information from the vestibular system and vision may lead to abnormal eye movements, specifically nystagmus. It is generally believed that these abnormal eye movements can interfere with the stability and processing of vision, which may be the cause of the sensation of the world spinning and the subsequent symptoms of motion sickness.

Brain processing of conflicting information:

When such conflicting information is processed and integrated in the brain, it may cause discomfort, nausea, and vomiting.

Although this hypothesis is complex, it can explain many phenomena that existing theories cannot, such as patients with inner ear labyrinthine dysfunction not experiencing car sickness, similar symptoms of motion sickness occurring with rapid head shaking, and the effectiveness of many drugs that suppress eye movements in inhibiting the symptoms of motion sickness.

Is the ultimate answer just a coincidence?

In recent years, some have also proposed the possibility that motion sickness exists simply because the pathways mediating vestibular signal transmission and those mediating nausea and vomiting are anatomically close, that is, there is a "vestibular-vomiting link." In simple terms, when there is a vestibular conflict, it is easy to trigger nausea and vomiting.

Obviously, we are not that fragile, so scholars have speculated that there should be a threshold that evolved gradually with the invention of early boats around 3000-5000 years ago and the domestication of animals for riding. This threshold ensures that discomfort does not occur with sensory-motor conflicts of this degree, meaning that activities below this threshold, such as walking, running, or short-distance rafting and horse riding, do not result in motion sickness.In the current era where long-lasting and fast-paced modes of motion are prevalent, this threshold can only sustain the level of conflict for a few minutes before exceeding it and triggering nausea and vomiting.

Summary

We can observe that these hypotheses are not mutually exclusive but rather serve as complementary roles. Most of them attempt to explain why the inconsistency between the motion seen and the motion sensed by the vestibular system when riding in a vehicle, on a boat, or playing 3D first-person games leads to dizziness and nausea. It is evident that their starting point is the "discrepancy between what is seen and what is felt by the body," which is also the starting point for most alleviation methods.

Why do some people get car sick while others do not?

Firstly, it can be明确的 is that almost everyone can potentially develop motion sickness under strong enough stimuli, meaning that unless one suffers from diseases such as vestibular disorders mentioned earlier that lead to abnormal vestibular function, modern humans are all susceptible to car sickness.

Even so, the susceptibility and severity of motion sickness show very obvious individual differences. Previous research has indicated that only a small portion of people are highly sensitive to motion sickness. Friends who want to check if they belong to the susceptible group and to what extent can take this motion sickness susceptibility questionnaire.

Since the pathogenesis is not yet clear, it is difficult to analyze from the source who is prone to car sickness. The existing patterns are mostly summarized through epidemiological means. After reading the relevant literature, I have summarized the following points for reference:

The susceptibility to motion sickness changes with age. It is mainly reflected in the fact that infants and young children are not prone to car sickness before the age of 2, after which the susceptibility to motion sickness increases, reaching its peak between the ages of 7 and 12, and then gradually decreases with adulthood. Overall, as age increases, susceptibility tends to decrease, although a few people may be the opposite. The evidence for this conclusion is limited because older people may reduce such activities due to a self-perception of being prone to car sickness, thus leading to fewer reports. VIMS (motion sickness in 3D) is more common among older people, which also supports the view that there is no correlation between car sickness and 3D sickness.

There is no sufficient evidence to indicate a gender difference in the susceptibility to motion sickness. Objectively, the incidence of symptoms such as vomiting and nausea is higher in females during motion sickness, but there is still a lack of medical evidence to support gender differences. Scholars believe that this difference may be related to the variability of gender bias. Even though the incidence of VIMS is slightly higher in the female population, it is not caused by gender but by other factors, such as the fact that females generally have a smaller interpupillary distance than males.

The susceptibility to motion sickness among descendants of Asian ancestry is higher than that among Europeans or African descendants, and this difference still exists among Asian children born in the United States, which may support the idea that there is a genetic component to motion sickness susceptibility.Motion sickness has a genetic component, and a large-scale genome-wide association study involving 80,494 individuals with car sickness has identified 35 single nucleotide polymorphisms (SNPs) at a genome-wide significant level that can be used to predict susceptibility to motion sickness. In other words, some consumer-level genetic tests might report that 'you are prone to car sickness.'

People with certain medical conditions may have a different susceptibility to motion sickness compared to those without these conditions. For instance, individuals with migraines are more likely to experience car sickness. Patients with structural vestibular disorders such as vestibular neuritis, bilateral vestibulopathy, and vestibular migraines may have an increased or decreased susceptibility to motion sickness.

How to alleviate or treat motion sickness?

Believe that friends who have read this far now have a more systematic understanding of motion sickness than before. However, I guess how to deal with motion sickness is what everyone is more concerned about.

Dealing with motion sickness from 3D experiences is relatively straightforward; one can simply stop playing the game when feeling unwell. Although complaints about being forced to miss out on gaming masterpieces are often seen, more common are the inescapable experiences of car and boat sickness in daily life. Current methods that can help alleviate symptoms of car and boat sickness can generally be divided into pharmacological and non-pharmacological approaches, with the latter often referred to as behavioral countermeasures.

In this section, I will list some measures supported by evidence-based medicine, and more suggestions are welcome in the comments section for everyone to contribute and enrich the discussion. Since the pathophysiological mechanisms of motion sickness have not been fully elucidated, it is not surprising that there are effective 'folk remedies.'

Before getting too creative, let's be practical. Motion sickness can be such an uncomfortable experience, so is it necessary to seek medical help?

When should one see a doctor?

When citing the diagnostic criteria for motion sickness in the previous text, in addition to the common symptom clusters, there is a key sentence: one gets sick when riding in a car/boat, the sickness increases with continued riding, and it stops once off the car/boat.

Generally speaking, since stopping activities that cause positional illusions will stop the discomfort of motion sickness, there is no need to seek medical attention in most cases. After all, who would knowingly continue to endure vomiting and dehydration, or risk fainting, without trying to take a break? Especially in today's developed transportation systems, if boats are not an option, one can choose other modes of travel like airplanes and high-speed trains, which have a lower likelihood of inducing motion sickness.However, if one is compelled to endure motion sickness without the benefit of anti-motion sickness medication and experiences severe vomiting, it is crucial to seek medical attention for rehydration and electrolyte replenishment after the episode to prevent serious imbalances.

Of course, there are exceptions, as not all dizziness is caused by motion sickness. How can one determine if they are an exception? One can observe the onset and severity of the discomfort. For instance, if discomfort or the most severe symptoms occur immediately upon sitting in a vehicle or within 30 seconds of starting the car, or if one becomes disoriented and nauseous within minutes of playing Apex Legends, these symptoms may not align with the diagnostic criteria for motion sickness. In such cases of car or boat travel, vestibular disorders should be considered, and for 3D-induced dizziness, oculomotor or visual-vestibular disorders should be considered, necessitating a specialized medical evaluation.

However, the phenomenon of feeling dizzy as soon as one gets in a vehicle could also be an inherent anxiety response or a conditioned reflex, where past experiences of motion sickness have created a classical conditioning through visual and olfactory cues in the context of the situation. This is more common in older individuals. Nevertheless, very strong stimuli can rapidly induce symptoms in highly sensitive individuals, so extreme cases are a different matter.

What medications can be chosen?

Personally, I do not recommend immediately turning to medication. On one hand, all medications have side effects, such as causing fatigue or drowsiness, and there is a risk of abuse. On the other hand, considering the use of medication before a trip even begins may contribute to the anxiety response or conditioned reflex mentioned earlier, as the psychological suggestion that one will feel dizzy as soon as they get in a vehicle can itself trigger motion sickness symptoms, and the effectiveness of the medication may be diminished.

However, when faced with the necessity of taking medication as described earlier, it becomes very necessary. This article, "Neurophysiology and Treatment of Motion Sickness," introduces common types of anti-motion sickness drugs, their indications, dosages, and side effects, translated here for easy reference.

Note: This article does not constitute any medical advice, including but not limited to the listing of anti-motion sickness medications here. Since most of these drugs come with significant side effects, if medication is needed, please consult a qualified pharmacist or physician and follow the prescription instructions.

CategoriesIndications

Dosage

Method of Use

Adverse Reactions

Anticholinergic Drugs

Scopolamine

Motion Sickness (Carsickness, Seasickness)

Transdermal Patch 1.5 mg/patch

For prevention, apply 6-8 hours before exposure, effective for up to 72 hours

Common: Dry mouth and dryness of the mouth, mydriasis with photosensitivity. Rare: Impaired vision, drowsiness, headache, sedation.Rare: Acute angle-closure glaucoma, confusion, contact dermatitis, unilateral mydriasis, urinary retention.

Antihistamines (listed in order of increasing sedative potential)

Cinnarizine plus Diphenhydramine

Vertigo of various causes

20 mg Cinnarizine/40 mg Diphenhydramine orally

Acute treatment, three times a day, not to exceed 4 weeks

Common: Somnolence, headache, dry mouth, stomachache.

Uncommon: Paresthesia, memory loss, tinnitus, tremor, hyperesthesia, convulsions, indigestion, nausea, diarrhea, sweating, rash.

Rare: Urinary retention.

DiphenhydramineNausea and vomiting due to various causes; motion sickness

50-100 milligrams as a single oral dose, up to a maximum of 300 milligrams per day; intravenous injection 62-186 milligrams per day; intramuscular injection 100-300 milligrams per day (up to a maximum of 400 milligrams). Reduce the dose for children, and it should not be given to children under 3 years old.

For prevention, the first dose should be taken 0.5-1 hour before travel. Regularly spaced doses daily.

Very common: drowsiness, dizziness, muscle weakness.

Common: restlessness, excitement, insomnia, anxiety or tremors, blurred vision, increased intraocular pressure, tachycardia, constipation, diarrhea, nausea, vomiting, stomach pain, dry mouth and nasal mucosa, nasal congestion, urinary retention.

Diclofenac

Nausea, vomiting, sleep disturbances

50 mg/day

Short-term therapy, 30 minutes before bedtime.

Risk of addiction, development of tolerance.Very common: Somnolence; reduced concentration the day after sleep deprivation; dizziness and muscle weakness.

Common: Headache, gastrointestinal symptoms (nausea, vomiting, diarrhea) and anticholinergic effects (such as dry mouth, constipation, gastroesophageal reflux, blurred vision, or difficulty urinating).

Promethazine

Nausea and vomiting

Individualized dosing, starting dose 20-30 mg/day, increasing the dose by 10 mg (up to 100 mg/day). For children and adolescents under 18 years of age, it should be used in emergency situations.

Reserve medication, not for first use; initial dose at night; if the dose is increased, also use in the morning and at noon.

Very common: Sedation, anticholinergic effects, extrapyramidal symptoms.

Non-pharmacological interventions: Habituation and short-term behavioral adjustments

When it comes to behavioral strategies, it might come as a slight surprise that habituation is the most reliable method for dealing with motion sickness. Corresponding to short-term behavioral adjustments such as changing body posture or shifting visual attention, habituation can also be defined as a 'long-term measure'. The high reliability of habituation is not only in comparison to short-term adjustments but is even more effective than anti-motion sickness medications.

Regrettably, the habituation mentioned here is not the commonly said 'you won't get dizzy if you ride more often'. This approach is mostly used by the military because pilots are prohibited from using anti-motion sickness medications with side effects. The best-known habituation program is called 'motion sickness desensitization', which involves repeated exposure to the same provocative motion and can reduce motion sickness over time. The key characteristics of this program include:Concentrated and intense stimulation (stimulation with intervals exceeding one week can hinder habituation formation)

Using graded stimulation helps to recover and schedule more sessions, and also helps to avoid opposite sensitization

Positive mental attitude

Overall, habituation, although with a reliability as high as 85%, is not necessary for most people to receive such high-intensity stimulation, nor is it necessary. Such a program is prepared for pilots and astronauts. If there is a real need, it is inevitable, such as the habituation training of "artificial gravity short-arm rotors", which is specially prepared for astronauts, aiming to reduce motion sickness during space flight.

Of course, there are also some simpler programs now. For example, in the laboratory, it has been found that allowing subjects to receive visual-vestibular interaction stimulation can reduce their susceptibility to motion sickness in the long term when taking a bus, but it has not yet entered a mature clinical program.

Common short-term behavioral adjustments

Compared with the time-consuming and not very pleasant habituation, short-term behavioral adjustments should be more acceptable. Most of these programs do not have the rigorous data support like habituation, and they are basically based on consensus and individual cases. Individual differences may be quite large, and more attempts are needed.

For example, the most common advice is: when sitting in a car, look out of the window with both eyes, and let the vision obtain a stable external horizon reference, which can effectively reduce the occurrence of motion sickness. Usually, looking at the horizon in the direction of the car's progress is more useful. It is worth mentioning that it must be real vision, and real-time images cannot take effect.

In addition to looking, breathing is also very important. Regular and active abdominal deep breathing has been proven to improve the tolerance to motion sickness stimulation, and the effect can reach half of the standard anti-motion sickness drugs, and it takes effect quickly without side effects. The specific mechanism is still unclear, and it is speculated that it may be related to the mutual inhibition radiation between respiration and vomiting. In addition, supplementing oxygen can reduce motion sickness in patients during ambulance transportation, but it is ineffective for normal healthy individuals. However, opening windows for ventilation is effective, which is also a method to reduce sensory conflict, and it can also reduce the possibility of inducing vomiting due to smelling bad odors. In addition to breathing, smokers can also effectively prevent car sickness by quitting smoking temporarily.

In addition, actions such as closing your eyes and resting, lying flat can also help reduce sensory conflict and alleviate discomfort. So the common saying, if you are car sick, sleep before getting sick, and wake up when you arrive, is also a clever way.Additionally, there are many other methods that are claimed to be effective against motion sickness, such as acupuncture and acupressure, but there is currently no clear evidence from evidence-based medicine to support these claims.

As for the impact of diet on motion sickness, there is no consensus— for example, one study suggests that a diet rich in protein can suppress the occurrence of motion sickness, while another study advises avoiding high-protein or dairy products before flying to reduce the likelihood of air sickness.

Is ginger effective?

Ginger has long been used as an alternative to medication for preventing motion sickness in folk medicine. A double-blind randomized controlled trial in 2002 revealed the effects of ginger, which can effectively alleviate the nausea caused by motion sickness, prolong the latency period of nausea, and shorten the recovery time. The specific mechanism of action may be the inhibition of the release of vasospasm substances, stabilization of gastric slow waves, and reduction of the rapid increase in gastric activity caused by circular movements such as turning during motion, thus preventing and treating symptoms of vomiting.

It can be affirmed that ginger has more than just a placebo effect. However, its effect is not directly related to the vestibular organs, so it may not be able to alleviate the symptoms of dizziness.

Are vehicle motion cues effective?

From this, we can return to the beginning— Apple's new accessibility feature in iOS 18, 'Vehicle Motion Cues,' is specifically presented as follows: By using sensors such as the gyroscope and accelerometer within the device to determine whether the user is using the device in a moving vehicle, variable-sized dots are displayed on the edge of the screen. These dots move with the vehicle's speed, acceleration, and direction. At the same time, because the dots are displayed on the edge of the screen, they do not affect the user's viewing of the main content on the screen.

In principle, it can indeed provide additional visual information consistent with the vehicle's motion state to the eyes while using an iPhone/iPad to view (relatively stationary) content. From the perspective of sensory conflict causing positional illusions, such additional information may indeed help our brain reduce judgment errors caused by conflicts between vision and vestibular senses, thereby alleviating the occurrence of motion sickness.

However, since this feature is rare in similar devices, there are currently no reports or large-scale trials on the effectiveness of similar features. It is essentially similar to the short-term behavioral adjustments mentioned earlier. Apple itself is also very cautious in its wording for this feature, noting 'may help' in the guidance page for the new feature. Whether it is effective for specific individuals still needs to be tested personally.Finally, regarding this new feature, my suggestion is that it is well worth turning on. Firstly, the new control center allows for quick activation and deactivation without having to delve into multi-layered settings menus each time; secondly, it uses sensors to determine whether the vehicle is in motion, automatically displaying animated dots without affecting everyday use; lastly, the placebo effect may actually be more powerful in alleviating motion sickness discomfort than you might imagine.

It has been a while since I last wrote a light science piece related to real life, and it is the opportunity of Apple's new assistive feature that has allowed me to systematically learn about motion sickness. I hope that after reading this article, you will have a new understanding of motion sickness, and you can confidently discuss it after the 'Motion Vehicle Prompt' feature goes live and sparks widespread debate. Or, when you foresee someone around you suffering from car sickness, you can recall some phrases from this article, which would be very good.