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There are plenty of so called Audio-Visual-Stimulation (AVS) tools you can buy on the market (used to be called Psychowalkman). They usually claim that it can stimulate brain with sound/visualization to increase mental abilities such as ability to learn, help with sleep problems, headaches and much more.

So I am wondering, does this really work? And by this I mean, is there really ANY such device which can be demonstrated to work? Focus of this question is on the devices themselves, however it might be questionable whether the AVS mechanism works by itself...

I could not find a study that would prove/disprove this. The manufactures usually refer some articles that itself talk about some very specific property of the brain to adapt to audio/visual waves, but I find that weak, since this does not show that what they sell actually utilizes this feature (could be device that randomly creates noise/sound as far as i can tell). They also refer to some celebrities that are using the tool, other thing that seems suspicious. Even if lots of people are claiming it helped them in a way, how do I know it isn't a placebo effect?

So I guess one question is if this can work based on current knowledge? And if yes, does it actually work with devices one can buy?

Edit: Adding examples. First is site http://www.smarterway.com/AVS-MindsEye.html. It states there:

Modern scientific research has verified this phenomenon: brain activity becomes more active or more quiet in response to external rhythms of light and sound.

Another one http://www.mindmachines.com/

Mind Machines specializes in providing theraputic tools for relaxation, enhanced learning, mind power, biofeedback, neurofeedback, high tech meditation and personal achievement.

...

By presenting beats and pulses to the brain, the brain begins to mimic or follow the same frequencies. This process is referred to as entrainment. In essence, these instruments speak to the mind in it’s own language – the language of frequency.

  • Please add some example links and quotes. – Jan Doggen Sep 23 '16 at 17:47
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    Added few, isn't that an advertising though? :) – user35854 Sep 23 '16 at 18:41
  • @Sil is your question about mind machines or AVS? – Mohammad Sakib Arifin Dec 10 '16 at 18:54
  • @MohammadSakibArifin Hm I thought those are two names for the same thing. Is there a difference? – user35854 Dec 11 '16 at 1:04
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    @MohammadSakibArifin To clarify, this question is about the devices, if any such device works this way. So in principle it should be enough to show that AVS works by itself, but it wouldn't surprise me if some of those that are sold are random sound/visual simulations generators (thats why i mention if ANY such device works). I will update the question to clarify this. – user35854 Dec 15 '16 at 10:55
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I read the papers that Mohammad Sakib Arifin cited in this answer but I came to a different conclusion, so I thought I would write another answer.

I found that the "research" on this subject is lacking a controlled, blinded study with a reasonable sample size. Without these basic elements of study design, it's easy to reach wrong conclusions due to effects that have nothing to do with the "treatment", e.g.: placebo effect, subject tries harder on the "post-test" knowing that he was part of the experimental group, researcher gives subject a higher score on a subjective "intelligence" test knowing that she is part of the experimental group...

Therefore, while I cannot definitely say that these devices do not work, I can say that the research I have seen cited in support of their capabilities is suspect.

Here are the papers I looked at (thanks to Mohammad Sakib Arifin), and the problems I found:

In The Impact of Light-Sound Stimulation on Intelligence in Teenagers, there is no mention of what treatment the "control" group got, so it's impossible to say whether the researchers really ruled out the placebo effect. (If the "control" group is just a group who also took the same "intelligence" tests and got no placebo treatment, then they have not ruled out the placebo effect.) Another major issue is that there is no mention of blinding - presumably, the researchers knew which treatment group each subject was in when evaluating their "improvement". This is especially troubling because the instrument used includes subjective components, e.g.

Performance is based not just on the accuracy of the drawings, but also on the examiner's observation of behaviour during the test, including such factors as attention level, self-criticism, and adaptive behavior

Another study, Use of Auditory and Visual Stimulation to Improve Cognitive Abilities in Learning-Disabled Children, was written by a psychologist in private practice, based on her experience with 30 clients. Again, there is no blinding, so the psychologist administering the instrument knows that the child has undergone the treatment (and most likely, also has a financial incentive to consider the treatment successful, because it's her practice!) Worse, there is no control group.

Another, EEG responses to long-term audio–visual stimulation, involved only six subjects, and no control group. The authors of the study note that the treatment was administered in a dim room and subjects sometime fell asleep - something that could, conceivably, also have caused the changes in brain activity that they observed. Without a control group who undergo a "placebo" treatment, it's impossible to tell.

  • Nice explanation. I found seven studies regarding AVS and all of them agreed that it works even though most them had no control group differentiating placebo and other effects. I reached the conclusion that it works because I couldn't find any study that says the contrary. – Mohammad Sakib Arifin Dec 17 '16 at 9:02
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    @MohammadSakibArifin To be honor I think it is better to stay unconvinced/undecided until there is sufficient evidence to prove or disprove this, otherwise we would have to believe everything by default and only stop believing after there is something contrary, which seems strange (by definition we would believe everything at first). In this case I think there is not yet a satisfactory answer, no one has proved/disproved this, so we don't know whether it is working so I would like to keep this open. Still though I'd like to divide the bounty for the effort, but not sure if that is doable :o – user35854 Dec 17 '16 at 11:27
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Do Audio-Visual-Stimulation/Psychowalkman/Mind Machine devices work?

Various scientific studies indicate that Audio Visual Stimulation does work. According to this paper, several studies have shown that Audio Visual Stimulation improves IQ, behaviour, attention, impulsiveness, hyperactivity, anxiety, depression, ODD and reading level.

Attention Deficit Disorder (ADD) and Attention Deficit Hyperactivity Disorder (ADHD) are unique attentional disorders which primarily involve slowed frontal brain wave activity and hypo-perfusion of cerebral blood flow in the frontal regions, particularly during tasks such as reading.

A variety of disorders, such as anxiety, depression and Oppositional Defiant Disorder (ODD), are often co-morbid with ADD, thus creating a plethora of complications in treatment procedures. Audio-Visual Entrainment (AVE) lends itself well for the treatment of ADD/ADHD. AVE exerts a major wide spread influence over the cortex in terms of dominant frequency. AVE has also been shown to produce dramatic increases in cerebral blood flow.

Several studies involving the use of AVE in the treatment of ADD/ADHD and its related disorders have been completed. AVE as a treatment modality for ADD/ADHD has produced wide-spread improvements including secondary improvements in IQ, behaviour, attention, impulsiveness, hyperactivity, anxiety, depression, ODD and reading level. In particular, AVE has proven itself to be an effective and affordable treatment of special-needs children within a school setting.

This study says:

These days mind power techniques are very effective to stimulate the cognitive aspects of an individual. These techniques could be very much effective for the teenagers to achieve their goals in the life because today is the world of competition and every individual wants to go for higher profiles. So this path of Light-Sound stimulation seems to be the best for the teenagers.

A sample of 120 students was selected from teenage group i.e. 13 to 19 years of both sexes belonging to middle socio-economic status by purposive random sampling technique. The experimental condition was further divided into three experimental groups and was administered three different treatments of mind power techniques i.e. sound, light and light-sound through mind power music and mind machines.

The scores of Intelligence showed a significant difference between the entire experimental groups and control group. The maximum score was observed for Light-Sound stimulation followed by light and sound stimulation.

I found some other studies (this, this and this) that also says AVS works.

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    You have not yet cited a single controlled study, i.e. one with a control group. You seem to be just searching for any "study" that confirms what you want to find (that it works), and then citing it without actually reading and understanding it (as in the totally irrelevant "visual search improvements in hemianopic patients" study), and without evaluating potential flaws in the study design that could compromise the conclusions. – ff524 Dec 15 '16 at 10:11
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    I think this answer needs improving, not the question. This answer makes the claim that audio-visual stimulation works by citing (1) a study that is completely irrelevant because the treatment it describes is nothing like the audio-visual stimulation referenced in the question, and (2) some studies with small sample sizes and no control groups, without noting these deficiencies. – ff524 Dec 15 '16 at 10:20
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    An honest answer might say something like: "These studies have found some effects following treatment with AVS, but their conclusions have not been validated in a study with a control group, so it is impossible to rule out placebo effect or other experimental conditions as the reason for the treatment 'working'." Then go on to cite only the studies that are actually about the thing described in the question. – ff524 Dec 15 '16 at 10:21
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    That "The Impact of Light-Sound Stimulation on Intelligence in Teenagers" study is really bad junk science. They claim to have a control group, but they don't say what "placebo" treatment is administered to the control group. I suspect there was none, so they have not ruled out placebo effect. Worse, there is no mention of blinding, and the instrument they use to measure "intelligence" includes subjective assessments by the person administering the test, who presumably knew what treatment group the subject was in. Not good! – ff524 Dec 16 '16 at 19:19
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    Here is a critical review: ncbi.nlm.nih.gov/pubmedhealth/PMH0027030 "The authors concluded that preliminary evidence suggested that brainwave entrapment was an effective therapeutic tool, but further research was required. The evidence presented appeared to justify the recommendation for further research. In view of the lack of controlled evidence and problems with methodology and reporting in the review, the authors’ conclusions regarding efficacy did not appear reliable." – TsSkTo Dec 16 '16 at 19:22

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