Imagine you're watching a basketball game. Your favorite team is wearing white and the other team is in black. In the midst of the action, someone in a dark gorilla suit calmly walks to the center of the court, waves to the crowd, then walks off the court. Do you think you would notice this peculiar event? Most people might say yes. Most people would be wrong.

Our perceptual system unconsciously filters out the vast majority of information available to us. Because of this filtering process, we actually experience only a tiny trickle of information, by some estimates a trillionth of what is actually out there. And yet from that trickle our minds construct what we expect to see. So when we pay attention to our favorite white-shirted basketball team, the likelihood of clearly seeing darker objects moving about is substantially reduced. That includes even obvious objects, like gorillas. Psychologists call this phenomenon "inattentional blindness," and it's just one of many ways in which our prior beliefs, interests and expectations shape the way we perceive the world and cause us to overlook the obvious.

Because of these blind spots, some common aspects of human experience literally cannot be seen by those who've spent decades embedded within the Western scientific worldview. That worldview, like any set of cultural beliefs inculcated from childhood, acts like the blinders they put on skittish horses to keep them calm. Between the blinders we see with exceptional clarity, but seeing beyond the blinders is not only exceedingly difficult, after a while it's easy to forget that your vision is restricted.

An important class of human experience that these blinders exclude is psychic phenomena, those commonly reported spooky experiences, such as telepathy and clairvoyance, that suggest we are deeply interconnected in ways that transcend the ordinary senses and our everyday notions of space and time.

Exclusion of these phenomena creates a Catch 22: Human experiences credibly reported throughout history, across all cultures, and at all educational levels, repeatedly tell us that psychic phenomena exist. But Big Science -- especially as portrayed in prominent newspapers and popular magazines like Scientific American -- says it doesn't.

Well then, is this gorilla in the basketball game, or not? One way to find out is to study the question using the highly effective tools of science while leaving the worldview assumptions behind. That way we can study the question without prejudice, like watching a basketball game without preferring either the white or black team. Neutral observers are much more likely to spot a gorilla, if one is indeed present.

This form of investigation has been going on for over a century, and despite official denials, the jury is in: Some psychic phenomena do exist. But like blindingly obvious gorillas, not everyone can see them. (Actually, like the majority of the general public, many scientists do have these experiences, but as in the parable of the Emperor's New Clothes, fledgling science students quickly learn in college that it is not politically expedient to talk about it.)

Here's an example of not seeing. In the July/August 2008 issue of the Skeptical Inquirer (the Playboy of the enthusiastic debunker), neuroscientist Amir Raz and psychologist Ray Hyman describe their impressions of an invitation-only scientific meeting held on "anomalous cognition" at the University of British Columbia (UBC) in July 2007. Anomalous cognition is a neutral euphemism for psychic or "psi" phenomena, one that avoids the connotation of séances and ghostbusting associated with the touchy p-words. I was a co-organizer of the UBC meeting. Sixty prominent scientists and physicians were invited to the meeting, including a couple of Nobel Laureates, representing a variety of disciplines and perspectives.

Not surprisingly, given the skeptical focus of the magazine in which their essays appeared, Raz and Hyman both concluded that they were not persuaded by what they heard at the meeting, that nothing interesting was going on, and that the scientific pursuit of anomalous cognition is akin to a misguided search for the Tooth Fairy (Raz's term).

Now, let me preface what I'm about to say by first noting that I respect Raz's and Hyman's opinions and I'm glad that they attended the UBC meeting. There is always room for critical debate in science; as President Dubya once said in another context, "Bring it on." But what I am concerned about is that sometimes holding a fruitful debate stalls before it can get off the ground because one side regards the topic as fantasy. And so to make a point I'll be ruthless in pointing out problems with these two authors' opinions.

One of Raz's principal complaints was that he would "be curious to see compelling scientific demonstrations of psi (i.e., a string of multiple successful experiments by several independent investigators producing lawful and replicable outcomes). Alas, I have found none to date."

When I first read that statement I felt like I increasingly do these days when driving past a gas station. What did that sign say? A gallon of gas costs what? Didn't we discuss several classes of repeatable experiments at the UBC meeting? For example, I presented an overview of "presentiment" experiments, an unconscious precognitive effect that has been independently and successfully replicated numerous times. (Nearly all of the 20 experiments I'm aware of to date have produced results in the predicted direction, and of those 10 were independently statistically significant.)

And among researchers who have closely studied the psi literature, the vast majority have little doubt that something interesting is going on, something not easily attributable to chance or to any known conventional artifacts. These effects are in principle no more difficult to demonstrate than the efficacy of new pharmaceutical drugs or medical procedures. Such effects tend to be small in magnitude, they are highly reactive to the psychosocial context and other environmental factors, and they take substantial amounts of careful data collection to overcome the statistical noise generated by dozens of poorly understood interactive factors. But they are real, and they are repeatable in the laboratory.

Real and repeatable, and yet what Raz meant by a "compelling" demonstration does not exist for him, at least not yet. When one regards evidence from a position where the claimed phenomenon is viewed as exceedingly unlikely, like a gorilla on a basketball court, then the evidence required to change one's mind must be super-powerful. Not merely a string of successful experiments by independent investigators, as Raz calls for, but effects that are robust enough to be easily repeatable by anyone, anywhere, any time, and highly stable over long periods of time. And better yet, the effect should be predicted by a theory that doesn't do much violence to orthodox dogma about how the world works.

This is what I call the "UFO landing on the White House lawn" type of evidence. Alas, such robust evidence is rarely available when dealing with phenomena at the bleeding edge of the known. And it's true that the evidence for psi today does not quite achieve the status of a Special News Bulletin interrupting the season finale of Lost by reporting a UFO landing on the White House lawn (would anyone believe such a story, even if it were true?). Instead, the evidence available today for psi is more like a formation of UFOs repeatedly flying over the US Capitol, captured on film and spotted simultaneously by radar, jet pilots, and hundreds of witnesses on the ground. Well, surely that would convince a few people.

Oh, wait. Such a UFO sighting actually did occur in Washington DC in 1952. All the major newspapers carried the story. But who remembers that today?

Perhaps Ray Hyman does. Hyman earned his PhD in 1953 at John Hopkins University, near Washington DC. Today, Hyman is a retired psychology professor who has been one of the premier academic critics of parapsychology for over 50 years. In his essay in Skeptical Inquirer, his major complaint was the lack of easy repeatability of psi effects. To support his claim he cited "a psi proponent reported a meta-analysis of [a class of telepathy experiments] with an average effect size that significantly differed from zero with odds of more than a trillion to one while another meta-analysis ... concluded that the average effect size was consistent with zero." (A meta-analysis is a quantitative review of many similar experiments.) He bolstered this assertion by citing a few parapsychologists who have acknowledged difficulties in producing "UFO on the White House lawn" form of evidence. From this viewpoint, he concluded that parapsychology does not deserve serious scientific attention. He's been repeating this opinion for 50 years.

Except there's a small problem. The parapsychologists mentioned by Hyman were expressing well known difficulties in producing robust repeatable effects on demand. But none of them doubt that the preponderance of evidence strongly indicates the presence of genuine anomalies. Hyman's selective reporting is akin to dismissing as worthless a clearly visible formation of UFOs flying over the US Capitol, because of a stubborn insistence that the only acceptable data are UFOs landing on the White House lawn precisely at high noon, followed by alien pilots emerging from their crafts, offering tea and biscuits to the President and Vice President of the United States, and then soberly shooting the VP in the face with a projectile weapon (due to regarding that act as a sign of diplomatic friendship, having unfortunately misinterpreted a news story regarding the Vice President's shooting his friend in the face -- but I digress).

There's another problem, one more substantial. Hyman's damning denouement was that not all meta-analyses of telepathy experiments were judged to be positive. By mentioning the meta-analysis where the "average effect size was consistent with zero," he reinforced his contention that telepathy experiments are slippery and unrepeatable, and not to be trusted. The study he cited appeared in a 1999 publication by British psychologists Julie Milton from the University of Edinburgh and Richard Wiseman from the University of Hertfordshire. They analyzed a selected subset of telepathy experiments, ended up with a positive but statistically non-significant result, and then quite reasonably concluded that nothing interesting was going on. Well, as I said, there's always room for debate. Except when conclusions are based on a mistake. It turns out that their analysis was miscalculated.

Jessica Utts, a professor of statistics at the University of California at Irvine, explained at the UBC meeting that Milton and Wiseman had employed a technique that underestimated the actual telepathy effect. If they had used the same (simpler and more powerful) technique employed in all of the other published telepathy meta-analyses, they would have reached the same conclusion that everyone else did: There is indeed significant positive and repeatable evidence for telepathy obtained under controlled laboratory conditions.

Hyman was in the audience during Utts' presentation. I don't know why he choose to ignore her analysis, although if he had acknowledged it that would have neutralized his own arguments. So perhaps its exclusion is not so puzzling.

Speculations aside, one thing is crystal clear: It can take a White House lawn party to overcome one's long-held beliefs, so if nothing obviously wrong can be found in a reported experiment, skeptics will still worry if the experiment was conducted by "believers," because they imagine that believers would not be as rigorously careful as "non-believers." Indeed, fervent skeptics are quite vocal in asserting that non-believers cannot get the same results in these experiments. Unfortunately, the fact is that skeptics hardly ever conduct these studies, and on the scant occasions when they do, they rarely publish them in sufficient detail to evaluate the results. So we really don't know whether the suspicion is justified or not.

That is, until recently. In 2005 two keenly skeptical psychologists, Edward Delgado-Romero from the University of Georgia and George Howard from the University of Notre Dame, conducted the same type of telepathy experiment under consideration here. To their chagrin, they not only obtained a significant positive outcome after conducting a series of eight studies, but their results were perfectly in alignment with the earlier meta-analytic estimates. That is, based on thousands of previous trials, it is possible to estimate the "hit rate" one should get when running a standard telepathy experiment. Delgado-Romero and Howards obtained exactly that value. To their credit, they published their results.

But their article also included an astounding twist: They ended up rejecting their own experimental evidence based on a single additional study they conducted, which they based on an ad hoc, untested design they proposed, and which ultimately resulted in a statistically significant negative outcome! Strong negative outcomes are just as important statistically speaking, and just as unlikely to occur by chance, as strong positive outcomes. Both indicate that something interesting is going on.

Another way of illustrating the invisibility of gorillas is by revealing an asymmetry in how psi experiments are reported in newspapers. In January 2008, newspapers around the world hailed the first conclusive test for telepathy conducted by two Harvard University researchers. According to the Boston Globe: "Brain scan tests fail to support validity of ESP. Research on parapsychology is largely taboo in academia, but two Harvard scientists recently set out to settle, once and for all, the age-old question: Is extrasensory perception, or ESP, real? Their sophisticated experiment answers: No, at least, not as far as they can tell using high-tech brain scanners to detect neural evidence of it."

Finally. Once and for all. A sophisticated magnetic resonance imaging brainscanner was used (technically, an fMRI), for the first time, to answer this age-old question. The high-tech "no" answer seems conclusive unless you read the actual article, which reported that one of 16 tests conducted showed a stupendously significant outcome exactly in alignment with what was predicted if psi were real. But the authors then took pains to explain why that result was probably an artifact, and so the newspapers didn't mention that one intriguing outcome. (It also makes one question why they employed an experimental design which allowed positive results to be explained away so easily.)

But the study was conducted at Harvard, for goodness sake, so surely that's the last word on ESP. After all, for the first time ever Harvard scientists used one of those expensive and mysterious fMRI brainscanners to peer deep inside the brain, and they didn't see any psi in there. End of story, no?

Well, no. Was this really the first psi study conducted using an fMRI? No, it wasn't even the second such study. Or the third. Or fourth. Or fifth. It was the sixth. And all of the earlier experiments, all conducted since 2000, showed significant evidence for psi effects. Somehow the newspapers overlooked this, despite the fact that most of those studies are freely available in an instant via PubMed.gov, the National Institutes of Health massive online bibliography of scientific articles related to health and healing.

I could continue along the same vein ad nauseum when it comes to how scientific evidence for psi is often ignored or distorted beyond recognition. Unfortunately, there are countless other tales of ignoring other invisible gorillas at the frontiers of knowledge. They include serious scientific arguments that global warming is not being caused by human activities, analyses suggesting that HIV does not cause AIDS, repeatable electrochemical-nuclear reactions once known as "cold-fusion," credible reports of UFOs, and so on. All of these ideas encounter strong sociopolitical resistance in academia, so credible counter-arguments are difficult to locate and even more difficult to discuss in scientific forums unless you have a phalanx of beefy bodyguards watching your back. One of the best sources of information about these "frontier" science topics is the Journal of Scientific Exploration, a peer-reviewed multidisciplinary journal published by the Society for Scientific Exploration.

Without belaboring the point, such tales expose a skeleton in the closet of Big Science. From the popular perspective, science is portrayed as a flawlessly rational enterprise, where accumulating evidence slowly but surely overcomes stubborn skepticism. In reality, science is like any other human activity, and as such, emotions always trump reason. There is as least as much pig-headedness and motivated inattention in science as in politics and religion.

Given the non-rational skeleton, will mainstream science ever be prepared to admit that psychic phenomena warrants serious investigation? I believe the answer is yes. Acceptance someday is inevitable. We are dealing with human experiences reported since the dawn of human history, experiences that do not go away in tightly controlled laboratory tests using the most sophisticated experimental tools and designs. So some of these phenomena will eventually become integrated into the mainstream. Exactly when I cannot say. Perhaps one to five decades.

Will this happen because the accumulated data will overwhelm skepticism? Probably not. As Max Planck, the physicist who dreamt up the idea of the "quantum" in quantum mechanics, once wrote, "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it." Some of the 60 participants at the UBC meeting represented that younger generation, and while a handful of the older crowd are certain to remain mulishly skeptical to their deaths, based on the written opinions of many of the participants collected before, during and after the meeting, it was clear that the majority were more open to anomalous cognition after the meeting than they were before. I expect that trend to continue, and then one day a threshold will be crossed, and on that day some of the invisible gorillas in our midst will become a bit easier to see. The very next day no one will remember that this topic was once considered controversial.

Debunker wrote: Modern Science cant account for a lot things (yet), but that is still no excuse to jump to a Supernatural conclusion. Very sloppy and irresponsible of these people to even consider it.