As with all psi phenomena, there is wide disagreement and controversy within the sciences and even within parapsychology as to the existence of precognition and the validity or interpretation of precognition related experiments (see Parapsychology).
Throughout history there have been many people who have claimed to have precognitive abilities, and the gift of prophecy is a common feature of many religions. Just as prevalent are anecdotal accounts from the general populace of precognitions, such as someone "knowing" who is on the other end of a ringing telephone before they answer it, or having a dream of unusual clarity with elements of content that later turn out to be events that actually occur. While anecdotal accounts do not provide scientific proof of precognition, such common experiences continue to motivate research into such phenomena.
Experimental research of precognition began at least as early as the work of J. B. Rhine, and eventually came to be his preferred mode of conducting his tests. This was a variation of his famous card-guessing experiments in which the subject was asked to record his guess of the entire order of a card deck before the deck was shuffled. Precognitive experiments have since been studied in a variety of formats by various parapsychologists, for example by the remote viewing researchers, and at the Princeton Engineering Anomalous Research center (PEAR).
Sometimes evidence suggesting precognition has appeared in unexpected places as well. One line of research began with the work of swedish psychologist Holger Klintman in the early 1980s (who was not a parapsychologist, at least not to begin with). He was investigating reaction times in a Stroop task, in which a color block is displayed to a subject followed by the printed name of a color and the subject is asked to say whether the name matches the color displayed. As with most Stroop task studies, there is significant variation in reaction times depending on whether there is a match or not (slower for a mismatch). Klintman was interested in more precise measurements, so he decided to measure the time required for each step, assuming that the reaction time to recognize the color of the color block (RT1) (before the color name was displayed) could be used as a baseline for the subsequent measurement of the reaction time to indicate a match with the color name subsequently displayed (RT2). Since the name displayed was chosen by a random number generator and only after the color block identification was made, he expected a uniform measurement for RT1. Instead he found that RT1 varied more than expected and moreover correlated with whether the subsequent name displayed was a match (slower for a mismatch). After checking for conventional explanations, i.e. apparatus calibration, etc, he considered the possiblity of a precognitive effect, and so he designed a series of experiments to test this hypothesis, with positive results which he published in 1983 in the European Journal of Parapsychology. Subjects were generally unaware that their reaction times showed this behavior.
In 1997 parapsychologist Dean Radin designed a new series of automated experiments to test for presentiment. In these experiments, subjects are monitored for biophysical parameters such as galvanic skin response, blood volume at the extremeties, etc, and then presented randomly with photographs which have either a "calm" content (e.g. landscapes, still life, etc), or an "emotional" content (erotic or violent). Within predicted parameters, the experiment showed positive results that for some subjects there was a correlation between the content of the picture (calm vs. emotional) and a subject's measurements in the several-second interval preceding the presentation of the photo. The experiment's design is fairly secure in that the system is automated and double-blind, and the subject's measured reactions do not involve conscious responses.
There is ongoing criticism and debate of all these results in the literature.
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3 See also
anomalous cognition, time travel, pseudoscience, and James Randi's $1,000,000 Challenge.