Friday, January 7, 2011

Psychic Powers!

Every so often there's excitement about possible scientific evidence of extrasensory perception (ESP).  But then attempts to replicate the findings fail, or critical flaws in the experiments are discovered.  So over the years, most of these results have been disproved and discredited.   

Claims of psychic powers are nothing
new, but proof has been lacking...

However, now there's compelling new evidence from a study published in a prestigious scientific journal and led by Daryl Bem, a well-respected psychologist at Cornell University.  In their article entitled Feeling the Future, the authors claim to demonstrate "anomalous retroactive influences on cognition and affect."  Translation: proof of ESP.  

Not surprisingly, this article is attracting a lot of attention.  I'll give a brief summary and then point out some of the major criticisms.  I'll also throw in some info about other ways we can "sense" the future. 

Evidence for ESP?

In an effort to be as convincing as possible, Bem and his colleagues took an ambitious approach to their study -- they performed 9 different experiments using more than 1000 subjects, employing a variety of techniques all in search of one thing: "retroactive influence."  That is, ANY evidence that a person's response in the present can be influenced by something that hasn't happened yet.  

Is there porn behind this curtain?
Subjects were able to predict this
better than chance.
Here's an example of one of their experiments.  Subjects were shown two identical curtains on a computer screen, and they had to predict which one had a picture behind it.  After they made their choice, the computer would randomly assign one curtain to contain a picture and the other to simply hide a blank screen.  The subject's chosen curtain would then open, revealing whether or not they were correct.  

If the subjects were guessing completely at random, you'd expect them to pick the correct curtain 50% of the time.  However, when the curtain hid an explicit erotic image, subjects guessed correctly 53.1% of the time -- significantly better than chance.  Interestingly, this was only the case for highly erotic pictures, not for negative or neutral ones.  The researchers' interpretation is that something about highly arousing images enables people to sense their presence in advance.  

Test performance was retroactively
improved by studying.
In another experiment, the researchers examined whether performance on a test can be improved by studying afterwardsSubjects were asked to memorize a list of words and were then tested for recall.  After that, a random subset of the words was chosen and the subjects reviewed those words only.  Amazingly, it turned out that recall was better for that specific subset of words.  Even though the words weren't selected and reviewed until after the test!


If the results of Bem's study are true, it means that information from the future can somehow travel backwards in time to influence the decision-making process.  That would be a real breakthrough.  And the concept is not totally without precedent, at least in the world of quantum mechanics (I'll have more to say about this in future posts!).

Daryl Bem, psychology professor
and author of the recent study
But now the question: is it really true?  That's highly debatable.  Several critics have described how the researchers committed many serious statistical errors that throw all the findings into question.  These problems include: combining results of tests that wouldn't be statistically significant on their own, post-hoc selection of specific groups that demonstrated stronger results, use of inappropriate tests of significance, and arguing for different hypotheses than the ones the experiments were designed to test.  This doesn't necessarily mean the results are wrong, but it certainly weakens their claims and demands more rigorous follow-up studies. 

"Feeling" without knowing

So when it comes to sensing something before it happens, time-reversed information transfer may or may not be the answer.  But what about other ways of predicting the future?  People often refer to a "gut feeling" or "sense of foreboding" that they experience prior to an event.  Unlike pure ESP, this is a very real and well-documented phenomenon.  The explanation isn't quite as exciting... but it's fascinating nonetheless. 

The underlying story is that your brain is doing a lot more "thinking" than you think it is.  There's an incredible amount of information processing that happens without our awareness.  Here are two simple but really interesting examples:

Drawings by a person with hemineglect.  Information from
the neglected half of space, although inaccessible to their
awareness, can still influence their thoughts & actions.

1.  By recording a person's brain activity while they're performing a simple choice task, you can actually tell what decision they're going to make BEFORE they think they've decided.  That is, the brain already knows, and that knowledge only later rises to the level of conscious awareness.

2.  People with hemineglect (a loss of awareness of one side of space, usually caused by damage to the right hemisphere of the brain) can intuitively process information from the "neglected" area.   If you show a person with left-sided neglect a picture of two houses - #1 being normal and #2 having burning flames on the left side - they'll tell you that they'd prefer to live in house #1.   Even though they say there's no difference between the two houses.  And they have no idea why they've chosen house #1.   It's just a "feeling."

Sensing the future

Those examples aren't exactly like telling the future, but they help illustrate the basis of premonitions.  Having a feeling that something is about to happen may seem like an inexplicable psychic phenomenon, but it almost always has a basis in the present reality.  Subtle cues or information allow the brain to make a reasonable prediction, even though we're not directly aware it's happening.  This processing occurs at a subconscious or preconscious level.  Sometimes we're never able to identify what the cues were (like for the person with hemineglect).  Other times we can identify the cues in retrospect.   This is especially the case for people who have a lot of experience in a particular area, so that they can "know" something without consciously thinking about it (e.g. a nurse sensing that something is wrong with a patient, or a police officer sensing imminent danger). 

Of course in some cases there's truly no prior information at all.  But apparent "ESP" in these situations most likely reflects a retrospectively-biased interpretation of something that's pure coincidence.  We're surrounded by irrelevent cues that can trigger vague "gut feelings."  When this occurs and nothing notable happens, we don't give it a second thought.  But if by random chance something DOES happen, then we assign great significance to it after the fact.  

Even when we have a reality-based sense of foreboding (as described above), there's still plenty of post-hoc bias.  We might recall having a specific prediction rather than a vague feeling, or the strength of that feeling might become inflated in our memories.

In conclusion, do we really have psychic powers?  Is ESP real?  The jury's still out and probably will be for a long time.  But the belief produces great stories, and the possibility is producing some pretty fascinating science. 

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