I posted a link to the survey on my Google+ account, and inserted the link at the top of all gwern.net pages; 51 people completed all 11 binary choices (most of them coming from North America & Europe), which seems adequate since the 11 questions are all asking the same question, and 561 responses to one question is quite a few. A few different statistical tests seem applicable: a chi-squared test whether there’s a difference between all the answers, a two-sample test on the averages, and most meaningfully, summing up the responses as a single pair of numbers and doing a binomial test:
I had tried 8 randomized days like the Adderall experiment to see whether I was one of the people whom modafinil energizes during the day. (The other way to use it is to skip sleep, which is my preferred use.) I rarely use it during the day since my initial uses did not impress me subjectively. The experiment was not my best - while it was double-blind randomized, the measurements were subjective, and not a good measure of mental functioning like dual n-back (DNB) scores which I could statistically compare from day to day or against my many previous days of dual n-back scores. Between my high expectation of finding the null result, the poor experiment quality, and the minimal effect it had (eliminating an already rare use), the value of this information was very small.
Microdosing With Psilocybin: Psilocybin, AKA “magic mushrooms”, are naturally occurring fungi, with over 180 different species and research from archaeologist evidence has shown that humans have been using psilocybin mushrooms for over 7,000 years. I’ve personally found microdoses of psilocybin, AKA “magic mushrooms”, to be best for nature immersions, hiking, journaling or self-discovery.  Psilocybin primarily interacts with the serotonin receptors in the brain and has been used in therapeutic settings to treat disorders such as headaches, anxiety, depression, addiction, and obsessive-compulsive disorders (See additional studies here, here, here and here). There is limited data to show any adverse drug interactions with the use of psilocybin, and liver function, blood sugar, and hormonal regulation all appear to be unaffected during consumption (although it is best to avoid alcohol and any serotonin-based antidepressants while taking any psychedelics) (See studies here, here and here). A microdose of psilocybin is generally between 0.2 grams and .5 grams, and I’d highly recommend you start on the low end of the dosage range with these or any of the psychedelics mentioned here.
Alpha Lipoic Acid is a vitamin-like chemical filled with antioxidant properties, that naturally occur in broccoli, spinach, yeast, kidney, liver, and potatoes. The compound is generally prescribed to patients suffering from nerve-related symptoms of diabetes because it helps in preventing damage to the nerve cells and improves the functioning of neurons.
One claim was partially verified in passing by Eliezer Yudkowsky (Supplementing potassium (citrate) hasn’t helped me much, but works dramatically for Anna, Kevin, and Vassar…About the same as drinking a cup of coffee - i.e., it works as a perker-upper, somehow. I’m not sure, since it doesn’t do anything for me except possibly mitigate foot cramps.)
According to Dr. Lisa, "neuro-nutrition is how our internal work translates to the external, for instance how we perform, behave, and use our strength, as opposed to 'dieting' which has an external (aesthetic) goal." An important portion of her research and theories on this matter root from her Mediterranean upbringing. She recalls immediately noticing how drastically different was the Western's culture in regards to food upon her arrival to the U.S. Interestingly enough, a recent study published in the British Medical Journal showed just how stark the difference between these lifestyles are and concluded that the Western lifestyle usually leads to "accelerated aging and increased risk of future dementia." 
I was contacted by the Longecity user lostfalco, and read through some of his writings on the topic. I had never heard of LLLT before, but the mitochondria mechanism didn’t sound impossible (although I wondered whether it made sense at a quantity level14151617), and there was at least some research backing it; more importantly, lostfalco had discovered that devices for LLLT could be obtained as cheap as $15. (Clearly no one will be getting rich off LLLT or affiliate revenue any time soon.) Nor could I think of any way the LLLT could be easily harmful: there were no drugs involved, physical contact was unnecessary, power output was too low to directly damage through heating, and if it had no LLLT-style effect but some sort of circadian effect through hitting photoreceptors, using it in the morning wouldn’t seem to interfere with sleep.
Professor David O Kennedy published a book in 2014 called Plants and the Human Brain. In his book he summarizes the last 15 years of research into cognitive nutrition, including the work he's done with colleagues at the Brain Performance Nutrition Research Center at Northumbria University. It's a great read and a good guide to what sorts of herbs and other plants to include in our weekly diet and it is all based on hard science rather than mere assertion or trendy but unsubstantiated beliefs.
Caffeine keeps you awake, which keeps you coding. It may also be a nootropic, increasing brain-power. Both desirable results. However, it also inhibits vitamin D receptors, and as such decreases the body’s uptake of this-much-needed-vitamin. OK, that’s not so bad, you’re not getting the maximum dose of vitamin D. So what? Well, by itself caffeine may not cause you any problems, but combined with cutting off a major source of the vitamin - the production via sunlight - you’re leaving yourself open to deficiency in double-quick time.
Choosing to take smart drugs is not an effective or long term solution. Smart drugs may help you study faster or keep you awake longer, but they are not your best option. Most of the ADHD medications are based on an amphetamine structure and they are not healthy for your heart or your liver. Also, by taking smart drugs, you are putting yourself at considerable risk for addiction to these substances.
One SCFA in particular, called propionic acid, has been identified as a driver for abnormal behaviour that is related to both ADHD and the autism spectrum. This SCFA can alter metabolic and immune pathways, as well as gene expression, which can affect the functionality of the brain cells and their receptivity to neurotransmitters, as well as their ability to regenerate and regulate inflammatory responses. Certain strains of pathogenic bacteria, such as clostridia, have been implicated in producing large amounts of propionic acid. This strain of bacteria is naturally present in the gut, however, an overgrowth can occur when good bacteria levels are compromised and/or there is an acute infection. In addition, processed wheat and dairy products often contain propionic acid as a food preservative in the form of calcium propionate.
The chemical Huperzine-A (Examine.com) is extracted from a moss. It is an acetylcholinesterase inhibitor (instead of forcing out more acetylcholine like the -racetams, it prevents acetylcholine from breaking down). My experience report: One for the null hypothesis files - Huperzine-A did nothing for me. Unlike piracetam or fish oil, after a full bottle (Source Naturals, 120 pills at 200μg each), I noticed no side-effects, no mental improvements of any kind, and no changes in DNB scores from straight Huperzine-A.
The AC-11 that Marcus mentioned for health is an extract from the Amazon jungle vine una de gato, and has been shown in laboratory and clinical trials to encourage DNA repair. The Mucuna pruriens he named for motivation is a legume that's a concentrated source of L-Dopa, which the body converts to the neurotransmitter dopamine. The Huperzia serrata Marcus selected for hunting is the same substance that induces lucid dreaming. This seems appropriate. While I felt the Alpha Brain helped my hunting, maybe I was dreaming. Or maybe a dream state of mind is good for hunting.
Absorption of nicotine across biological membranes depends on pH. Nicotine is a weak base with a pKa of 8.0 (Fowler, 1954). In its ionized state, such as in acidic environments, nicotine does not rapidly cross membranes…About 80 to 90% of inhaled nicotine is absorbed during smoking as assessed using C14-nicotine (Armitage et al., 1975). The efficacy of absorption of nicotine from environmental smoke in nonsmoking women has been measured to be 60 to 80% (Iwase et al., 1991)…The various formulations of nicotine replacement therapy (NRT), such as nicotine gum, transdermal patch, nasal spray, inhaler, sublingual tablets, and lozenges, are buffered to alkaline pH to facilitate the absorption of nicotine through cell membranes. Absorption of nicotine from all NRTs is slower and the increase in nicotine blood levels more gradual than from smoking (Table 1). This slow increase in blood and especially brain levels results in low abuse liability of NRTs (Henningfield and Keenan, 1993; West et al., 2000). Only nasal spray provides a rapid delivery of nicotine that is closer to the rate of nicotine delivery achieved with smoking (Sutherland et al., 1992; Gourlay and Benowitz, 1997; Guthrie et al., 1999). The absolute dose of nicotine absorbed systemically from nicotine gum is much less than the nicotine content of the gum, in part, because considerable nicotine is swallowed with subsequent first-pass metabolism (Benowitz et al., 1987). Some nicotine is also retained in chewed gum. A portion of the nicotine dose is swallowed and subjected to first-pass metabolism when using other NRTs, inhaler, sublingual tablets, nasal spray, and lozenges (Johansson et al., 1991; Bergstrom et al., 1995; Lunell et al., 1996; Molander and Lunell, 2001; Choi et al., 2003). Bioavailability for these products with absorption mainly through the mucosa of the oral cavity and a considerable swallowed portion is about 50 to 80% (Table 1)…Nicotine is poorly absorbed from the stomach because it is protonated (ionized) in the acidic gastric fluid, but is well absorbed in the small intestine, which has a more alkaline pH and a large surface area. Following the administration of nicotine capsules or nicotine in solution, peak concentrations are reached in about 1 h (Benowitz et al., 1991; Zins et al., 1997; Dempsey et al., 2004). The oral bioavailability of nicotine is about 20 to 45% (Benowitz et al., 1991; Compton et al., 1997; Zins et al., 1997). Oral bioavailability is incomplete because of the hepatic first-pass metabolism. Also the bioavailability after colonic (enema) administration of nicotine (examined as a potential therapy for ulcerative colitis) is low, around 15 to 25%, presumably due to hepatic first-pass metabolism (Zins et al., 1997). Cotinine is much more polar than nicotine, is metabolized more slowly, and undergoes little, if any, first-pass metabolism after oral dosing (Benowitz et al., 1983b; De Schepper et al., 1987; Zevin et al., 1997).
Systematic reviews and meta-analyses of clinical human research using low doses of certain central nervous system stimulants found enhanced cognition in healthy people.[21][22][23] In particular, the classes of stimulants that demonstrate cognition-enhancing effects in humans act as direct agonists or indirect agonists of dopamine receptor D1, adrenoceptor A2, or both types of receptor in the prefrontal cortex.[21][22][24][25] Relatively high doses of stimulants cause cognitive deficits.[24][25]