[bOR_]

So.. how do we know for a fact that in parapsychology the null hypothesis should always be true?

We do not understand how it could work, but to therefore say that whenever we label some experiment as falling under the school of parapsychology, any significant results must be a fluke.. that is almost analogous to saying that any deviation from newtons' prediction of planet movements must be due to measurement errors.

In my opinion such a mindset is a sure way to hinder scientific progress: it heavily favors finding acceptable truths.

[gort]

"The problem is that the mechanical principles that govern each particle of our bodies (and of the things around us) already specify how each of us behaves as a whole. But in that case, there is no room for the ghostlike component to have any influence - if it did so, it would have to make some of the particles sometimes violate the principles that all particles are always observed to obey whenever we check carefully."

- Gary Drescher, Good and Real, chapter 2.1: The Case against Ghosts

At the very least it's highly likely that the positive results of parapsychology, or the vast bulk of them, are due to the sort of statistical problems that plague other sciences as well. I cannot, of course, say it's 100% certain.

[bOR_]

The mechanical principles that are referred to are our theories about those mechanical principles. They may be very accurate in describing them, but they are not 'fact'.

I think the new age / hippies / spiritual / mysticism explanation is that the moment you do an experiment in which consciousness is heavily involved, you are going to see violations of the principles that work soundly when there is noone exerting whatever the name of this consciousness-force is upon particles.

Anyway, to plead my case ;), there is this thing called the sheep-goat effect. People that belief they can exert an influence ("the sheep") tend to do better in parapsychological effects than people that do not belief. Worse even, people that do not belief in parapsychological effects ("the goats") tend to do worse than random. This effect has been reported and studied for over 60 years now (see first source)

I'm not sure how to explain the sheep-goat effect in terms of statistically slacking methods. From a 'the null hypothesis is always true in parapsychology' point of view, there should be no difference between believers and nonbelievers, so both groups should have an equal chance in performing better than the other group. The skeptics also have a problem explaining this one (see second source).

Source: http://findarticles.com/p/articles/mi_m2320/is_1_68/ai_n1369... http://www.skepdic.com/sheep-goat.html

p.s. love the name sheep-goat effect ;).

[jongraehl]

If you think the causation proceeds from:

believes in ESP -> reproducibly performs slightly above chance when doing ESP tasks

doesn't believe in ESP -> reproducibly performs slightly below chance (which should be impossible if the experiment is designed properly)

on the basis of some correlation, then you're wrong. A rational person would consider the other direction to be more likely.

Clearly having been told that you perform slightly better than chance when gamely trying to be psychic, would incline a person to profess more belief in ESP. But some individuals will always experience slightly above or below mean (since variance isn't 0).

What's funny is that people who believe in ESP because they feel they personally have experienced too many mystical things to accept as coincidence, mostly just miscalculate the odds of "things like that" happening to them. There are 10^15 (just a guess) possible coincidences that you'd notice and claim as noteworthy (i.e. odds of that happening are just 1 in a billion!), over your life, and most people don't appreciate the facility we have for recognizing things that align between e.g. our thoughts and others' in the same environment, our dreams and the possible events of our everyday life, our dreams and others' dreams, etc.

Of course, 1 in N people really are exposed to 1 in N better than chance past evidence of ESP. The beautiful thing is, if they're honest and firewall off those past coincidences, and perform new experiments without bias, they're almost certain to disillusion themselves. But people who have a belief tend to cherish and protect it.

And that's really all there is to belief in ESP.

[bOR_]

I understood that people were asked beforehand about their beliefs. Afterwards would indeed be silly, and I would have been very surprised if 60 years of peer review would not have caught that.

Just checked the two links I pasted earlier. The second link (skeptics dictionary) quotes:

    The expression dates back to 1942 and Gertrude Schmeidler, 
    a professor of psychology at City University of New York. She 
    asked her students whether they believed in psi *before* 
    giving them an ESP card test. 

So your explanation doesn't hold here. People were asked first, and then tested.

[xiaoma]

Has this result been replicable over the past 60 years?

[bOR_]

Many times, apparently (see recent articles). There's just no explanation except fraud or misformed experiments that fits well with our current scientific understanding of the world, and those shouldn't be invoked just to keep your comfortable world-image :).

[tel]

A rational person would consider the other direction to be more likely

You're, I think, making that conclusion based off the prevailing knowledge that ESP isn't true. A rational person seeking to learn if it is or isn't would still attempt to consider causality in the direction the op stated and otherwise be guilty of irrationality.

Some individuals will always experience slightly above or below mean (since variance isn't 0)

By my understanding of the standard ESP experiment the observation you state there would be evidence against the null hypothesis, evidence stating that there is some external factor tied to personal identity which changes your ability (for better or worse) to guess the identity of these cards. If the both experiment was perfectly designed and ESP totally impossible you'd expect that over time no one would have an edge on anyone else in their ability to guess these cards.

But people who have a belief tend to cherish and protect it

Much as you're doing now with the counterbelief?

(Disclaimer: I personally strongly don't believe in ESP. I also don't believe it's worth spending my own time on it. Finally, I do believe that if you're going to spend time on it you should do it carefully because it is clear that if there is an effect it's going to be something highly unexpected and subtle because most of the expectable and obvious things have been tested)

[pmichaud]

I just wrote an essay that supports what you said:

http://www.petermichaud.com/essays/dont-reject-your-experien...

We HAVE to assume "out there" stuff has some objective underpinning, or we commit the same sin as invoking God, but in mirror image.

[Confusion]

Assuming there is an "out there" is unwarranted. As Nietzsche famously stated, "God is dead". He didn't mean the Christian god: he meant every objectivist philosophy. There is just the world with us immersed in it. It is not even wrong to attempt to describe the world in objective terms, separate from ourselves.

[gort]

If there's no truth to the matter of what's out there or how the world is, then I invite you to leave your 10th floor apartment via the window some time. After all, there's nothing out there that makes this dangerous.

[Confusion]

Truth cannot be out there—cannot exist independently of the human mind—because sentences cannot so exist, or be out there. The world is out there, but descriptions of the world are not. Only descriptions of the world can be true or false. The world on its own—unaided by the describing activities of humans—cannot.

-- Richard Rorty

The point is not that the world does not behave in consistent ways: the point is that if you assume there is some objective truth 'out there', you are bound to sometimes end up with 'wrong' conclusions, because truth is only in us, because 'truth' is not an attribute that 'what is out there' has.

[Eliezer]

http://yudkowsky.net/rational/the-simple-truth

[Confusion]

I'm not advocating abandoning the notion of 'truth'. It's certainly not up for grabs either. I side firmly with the pragmatism of Rorty: I only care about the 'truths' that I think help me and others survive and be happy.

[bOR_]

I agree to what you say :). Had pretty much the same line of thinking myself.

Coming from biology: I know our brains are complex machines, and highly skilled and skewed pattern recognizers, and that therefore many things can be explained in terms of subconsciously picking up signals, or just plain coincidence.

Still, some of my experiences (knowing where someone's attention is at, or feeling flow of energy between bodies) seem to suggest that we can experience more than just the input of our five physical sensory organs. And rather than ignoring these more esoteric senses, I try to use them in a practical sense - as a source of information. Maybe I'm making stuff up ;), but so far my life is more fun allowing for the possibility of these esoteric senses to exist, than going for a purely material world.

[JulianMorrison]

"Fact" doesn't mean p==1 (an unreachable goal) it means p approximates 1, less some insignificant minuscule slice of the pie within which live all the mad implausibilities you might think up - but which Occam's razor forbids.

[bOR_]

Occam's razor is frequently misused. It is not a law, and using it to forbid something that cannot easily be explained is counterproductive. Occams Razor works nicely when deciding whether to use a linear or a nonlinear function to describe some mathematical relationship, but beyond mathematics, what of two things is 'simpler' can be highly subjective.

P.S. I think the whole topic of this thread is sort of not within Hackers' News interest (just peeked at the guidelines). Calling it quits for now.

[JulianMorrison]

Occam's Razor has a non-mathematical history, but it parallels the recently discovered mathematics behind "Inductive inference" (http://en.wikipedia.org/wiki/Inductive_inference) and the AIXI model of a provably optimal learning system.