This is the Hermann grid illusion. It’s a very well-known and simple optical illusion. When you look at the intersections of the white lines, you see illusory dark blobs.
The standard explanation for this has to do with retinal ganglion cells. These cells pool information from several rod and cone cells in the retina and transmit it to the brain. The area each ganglion cell collects information from is called its receptive field. In the middle of each receptive field, light stimulates the ganglion cell, causing it to fire more frequently. However, on the periphery, light has a paradoxical opposite effect: the more light hits the peripheral receptive field, the less the ganglion cell fires. The theory goes that, at the intersections, more of the peripheral receptive field is stimulated than elsewhere, and so the ganglion cell is inhibited, and the area appears darker. Here’s an illustration of this:
This would also explain why, when looking directly at the intersections up close, you don’t see the dark blobs, but they start to appear in the peripheral vision, and as you move back. This is because the receptive fields are much smaller in the fovea, the center of the eye. Here’s an illustration of that:
The conventional explanation is wrong. A recent counterexample shows why:
If you make the lines wavy, the illusion disappears completely. As you can see, this should not, according to the conventional hypothesis, change the illusion:
But it does, and so it appears that there’s something else going on. What, exactly, is still a mystery. The Hermann illusion, discovered almost 150 years ago, isn’t quite ready to let its secret go.
That it is in fact not impossible to express the degree and kind of blurring of all variables in one perfectly clear concept follows at once from the fact that Q.M. as a matter of fact has and uses such an instrument, the so-called wave function or psi-function, also called system vector. Much more is to be said about it further on. That it is an abstract, unintuitive mathematical construct is a scruple that almost always surfaces against new aids to thought and that carries no great message. At all events it is an imagined entity that images the blurring of all variables at every moment just as clearly and faithfully as does the classical model its sharp numerical values. Its equation of motion too, the law of its time variation, so long as the system is left undisturbed, lags not one iota, in clarity and determinacy, behind the equations of motion of the classical model. So the latter could be straight-forwardly replaced by the psi-function, so long as the blurring is confined to atomic scale, not open to direct control. In fact the function has provided quite intuitive and convenient ideas, for instance the “cloud of negative electricity” around the nucleus, etc. But serious misgivings arise if one notices that the uncertainty affects macroscopically tangible and visible things, for which the term “blurring” seems simply wrong. (…)
One can even set up quite ridiculous cases. A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer which shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.
It is typical of these cases that an indeterminacy originally restricted to the atomic domain becomes transformed into macroscopic indeterminacy, which can then be resolved by direct observation. That prevents us from so naively accepting as valid a “blurred model” for representing reality. In itself it would not embody anything unclear or contradictory. There is a difference between a shaky or out-of-focus photograph and a snapshot of clouds and fog banks.
If you’re reading this blog, you’ve most certainly heard of the Higgs particle, that elusive thing the Large Hadron Collider is trying to find. But do you have any understanding of what it is, other than a vague notion that it has something to do with particles having mass? I can’t say I really had, but here’s a helpful FAQ.
On February 9, 1913, a unique procession of meteors was observed from Canada, parts of the US, and in one case, off the coast of Brazil. Several streams of brilliant meteors were seen moving relatively slowly across the sky; the event lasted too long for a regular meteor sighting, but too short for a regular meteor shower, and moreover, the meteors did not, like showers, radiate from a single point in the sky. Most of North America was cloudy that day, so out of the millions of potential observers, only hundred-odd reports were made, mostly from remote locations, but there is no doubt that it happened. The meteors were accompanied by a trembling sound.
Comparing eyewitness reports and making calculations of possible trajectories, scientists have proposed a remarkable possibility: that this event, called by some the Cyrillid meteor shower, was a short-lived natural satellite of the Earth. (This view is not undisputed.) Natural satellites, especially bigger ones, are more conventionally called moons. If this hypothesis is true, the most likely explanation for the 1913 event is that some small celestial object, after however many round-trips around the Sun, got caught in orbit around the Earth, for a brief while giving us a second, tiny moon, until it broke apart into a brilliant procession of meteors.
Science should be open. If you support that sentiment, this initiative is good news. It is a call for researchers to declare a boycott of Elsevier, one of the largest publishers of scientific journals in the world. Elsevier makes enormous profits off the free labor of scientists all over the world. Scientists do the research, write the papers, do the editing and peer-review, and then the paper gets published by an Elsevier journal, earning the middleman enormous profit. In order to protect its business model, which consists of adding literally nothing worthwhile to science or the general public, Elsevier forces libraries to buy bundles of their journals, rather than just the journals they want or need. At the same time, they make every effort to restrict the free flow of scientific knowledge, supporting laws like SOPA, PIPA, and the Research Works Act, which seeks to prohibit open access mandates to publicly funded research.
The reason this works is that these are prestigious journals that everyone uses. If one researcher refuses to participate, it’s little more than a nuisance to their fellow scientists. If many people announce their unwillingness to participate in this scheme, however, maybe real progress can be made. Elsevier is only part of the problem, but it is probably wise to focus on one specific company to begin with.
Alternatives to the commercial journals—which, again, to emphasize, do not actually make any money for the benefit of scientists or science—already exist. Open access to scientific papers and data will make science more democratic, and likely more efficient as well. It will also benefit the general public. When I write about science on this blog, I try to rely on primary sources, but often, they are behind paywalls, and I can’t afford to spend hundreds of dollars to purchase access to papers only to write a free blog. If science is open access, that means people like you and me don’t need to rely on people affiliated with research institutions or with sufficient economic means to interpret science for us. We can do it ourselves.
In the scientific limelight, that is. Sort of. In the 1950s and 60s, there was a great deal of optimism about the potential of psychedelic drugs for therapeutic use. Drugs like LSD and psilocybin, the active substance in magic mushrooms, were touted as the cure for everything from depression and unhappy relationships to serious crime. As the hippie era wound down and these drugs were made illegal, the scientific investigation of these substances ground to a halt. It’s possible to speculate, discuss and editorialize a lot about the hows and whys of this, but since this is not a politics blog, we’ll skip straight to the chase. After decades of little in the way of scientific research on psychedelics, it seems that they’re on their way back.
Psilocybin has seen mainstreamcoverage recently due to two fresh-off-the-presses new studies. One looked at the brains of people tripping on psilocybin, using fMRI scanning, and found something surprising: the vivid, hallucinatory state of mind isn’t caused by increased activity in the brain, but decreased activity in a few key areas. These included the anterior and posterior cingulate cortex and the medial prefrontal cortex, which are believed to function to coordinate our mental worlds into neat narratives we can understand. Feelings of ego or the sense of self are also related to these areas, and they’re overactive in depressed or anxious people. As others have pointed out, this seems to fit with what Aldous Huxley, author and mescaline enthusiast, theorized all the way back in 1954:
But in so far as we are animals, our business is at all costs to survive. To make biological survival possible, Mind at Large has to be funneled through the reducing valve of the brain and nervous system. What comes out at the other end is a measly trickle of the kind of consciousness which will help us to stay alive on the surface of this Particular planet. To formulate and express the contents of this reduced awareness, man has invented and endlessly elaborated those symbol-systems and implicit philosophies which we call languages. (…)
That which, in the language of religion, is called “this world” is the universe of reduced awareness, expressed, and, as it were, petrified by language. The various “other worlds,” with which human beings erratically make contact are so many elements in the totality of the awareness belonging to Mind at Large. Most people, most of the time, know only what comes through the reducing valve and is consecrated as genuinely real by the local language. Certain persons, however, seem to be born with a kind of by-pass that circumvents the reducing valve. In others temporary by-passes may be acquired either spontaneously, or as the result of deliberate “spiritual exercises,” or through hypnosis, or by means of drugs. Through these permanent or temporary by-passes there flows, not indeed the perception “of everything that is happening everywhere in the universe” (for the by-pass does not abolish the reducing valve, which still excludes the total content of Mind at Large), but something more than, and above and something different from, the carefully selected utilitarian material which our narrowed, individual minds regard as a complete, or at least sufficient, picture of reality.
That study had some implications for treatment of depression and anxiety, but the other study making the rounds looks at this more directly. It looked at how the increased ability to visualize during a psychedelic trip could be used to reinforce positive autobiographical memories. Healthy volunteers reported more vivid recollections on psilocybin than on placebo, and vividness was positively correlated with subjective well-being on follow-up. Brain imaging also appeared to support the subjects’ reports of vivid activation of memories. While hardly conclusive, these two studies are grounds for optimism, and should lead to further studies on psilocybin’s potential as a therapeutic tool.
The Multidisciplinary Association for Psychedelic Studies is funding a bunch of different studies, especially focusing on psychedelic-assisted therapy for patients with posttraumatic stress disorder in war veterans and for anxiety associated with terminal illness. There was a good story about therapy aided by MDMA (ecstasy) in Oprah Magazine (of all places). In 2002, a paper was published in Science that claimed to show that MDMA was severely neurotoxic. It turned out that the study, which had been done on monkeys, had used methamphetamine, and not MDMA, and thus had to be retracted.
Finally, there is ibogaine, a substance found in the iboga root and traditionally used for its visionary effects by the Bwiti tribe of Gabon. Ibogaine has a great potential as a treatment for substance addiction. Around the world, there exist treatment centers with varying degrees of official sanctioning and legality. In rats, ibogaine inhibits cocaine self-administration. In humans, it has proven effective in treating opiate withdrawal. Ibogaine’s mechanism of action is complex and little understood. It may work by somehow “resetting” cognitive or behavioral patterns associated with bad habits, not limited to substance abuse, but much more research is needed to make this notion precise.
Major pharmaceutical manufacturers remain uninterested in psychedelic research. The substances are, after all, illegal, but perhaps more importantly, the patents are expired, and the suggested treatments recommend administering the drug a limited number of times. In other words, psychedelic treatments are unlikely to be very profitable.
In science, experiments are often double-blind, that is, neither subjects nor experimenters know which one of the possible conditions the subject is in. This is to prevent the unconscious expectations of either subjects or experimenters from influencing the outcome. Doyen attempted to replicate the 1996 findings, but devised a very strict protocol to ensure that the experiment was indeed double-blind, as expected. This experiment failed to reproduce the original findings. No one showed evidence of priming. However, Doyen then did another experiment, this time manipulating the experimenters’ expectations. Half of the experimenters were told to expect that the primed subjects would walk more slowly. The other half were told the subjects would walk faster. Lo and behold, that is exactly what Doyen observed. When the experimenters expected primed subjects to walk faster, they did; when they expected them to walk slower, they walked slower. (The actual measuring of walking time was done automatically using infrared sensors.)
The priming was real, but it had nothing to do with the unrelated word-task. It was all about what was going on in the experimenters’ heads, and how the subjects picked up on it and acted accordingly. Which, as Ed Yong points out, isn’t so different from Clever Hans, the horse who mastered arithmetic.
Wolbachia is a very common and very interesting group of bacteria. It infects insects and arthropods, living inside their cells, and is known for modifying the reproduction of host species in a variety of ways. It may play a role in rapid speciation, lateral gene transfer, and has potential as a vector in genetic engineering.
Some of the ways Wolbachia modifies reproduction:
It spreads from mother to offspring. The mechanism is pretty clever: Wolbachia causes what is known as cytoplasmic incompatibility. Basically, infected eggs are compatible with infected and uninfected sperm, but uninfected eggs are only compatible with uninfected sperm. Thus infected eggs have more options, and the infection spreads through the population.
Parthenogenesis. This is what you see above in the wasp eggs. Parthenogenesis means reproduction without fertilization. The bacteria cause an egg to develop into a female wasp without being fertilized by wasp sperm. The bacteria accumulate in the end of the egg that will develop into reproductive organs.
Feminization of genetic males. Wolbachia can make genetically male offspring into sterile or fertile females. This is to Wolbachia’s advantage, since it spreads through the maternal line. For example, in the woodlouse, Wolbachia supresses an androgenic gland, and genetic males become fertile females.
Selective killing of males. Wolbachia can also straight-up kill males, making sure that females survive to bring the parasite into the offspring.
Wolbachia can also cause bidirectional incompatibility. This may lead to rapid speciation. For example, Nasonia is a wasp genus consisting of three sibling species. They can’t reproduce with each other, and each species has its own strain of Wolbachia. It is, however, unclear which one preceded the other.
Vertical gene transfer is the usual, parent to offspring. Gene transfer outside parent-to-offspring is called lateral gene transfer. It’s uncommon to see lateral gene transfer between prokaryotes and multicellular eukaryotes, but scientists have found evidence of gene transfer between Wolbachia and insect as well as roundworm species. Some species had the entire Wolbachia genome embedded in their own.
Finally, there’s the potential for using these bacteria in biological control. Genetic engineers prefer to piggyback on nature: that way is a lot easier. Genetically modified Wolbachia can potentially be used to control insects that carry diseases like Malaria, either by transferring genes that make the carriers unable to carry the parasite, or by using Wolbachia’s manipulation of reproduction to reduce the fertility of the insect population.
