Precognition (from the Latin præ-,“before,” + cognitio, “acquiring knowledge”), is usually filed under esoteric pseudoscience. There are scientific articles on precognition, but pointing this out often results in the rare admission that scientific journals’ peer review can be flawed badly, so badly that complete nonsense gets all the way through the long process. The latter is very true but seldom admitted. All this is a cultural phenomenon, a question of belonging; naïve scientism wants to lynch you for mentioning clairvoyance but discussing time travel is fine, go figure.
Ray Hyman, a noted critic (!) of anything paranormal, remarked:
“the contemporary ganzfeld experiments display methodological and statistical sophistication well above previous parapsychological research. Despite better controls and careful use of statistical inference, the investigators seem to be getting significant results that do not appear to derive from the more obvious flaws of previous research.” 
I personally have zero tolerance for pseusoscience and a track record of actively fighting against scientific fraud in academia, with my publications and with this science column. Studies on precognition have reached a level of scientific rigorousness that leaves a serious skeptic only the option to engage properly on at least the same level.
One often encountered immediate reaction against precognition is that such can never be science at all because it is ill-defined. Another interesting aspect is that precognition should be especially difficult to detect by a scientific method that demands large numbers of repetitions. Let us discuss these and a few closely related aspects like the “general decline effect” in detail.
1) Is Precognition merely inconsistent Terminology?
Precognition would be a form of “extrasensory perception” (ESP). “Extrasensory Perception” is the title of a 1934 book written by the botanist turned psychologist Joseph Banks Rhine. It discusses Duke University research on whether there is perception by something other than the known senses. “Extrasensory perception” is misleading terminology. Given any aspect X that is perceived, the perception of X can be studied and findings published as “Discovery of an X-Sense”. That sense may not be based on easily accessible sensors like our eyes for example, but once perception exists, that sensing is sufficient to have a sense. Hard to isolate neural circuits could conceivably be the sensors. Partially because of these issues, a better term than “ESP” is “paranormal” or “psi”.
Now what about precognition? I see a flowerpot falling from a balcony above me. I step aside because my brain calculates and perhaps shows to my inner eyes that the heavy pot will fall into the place otherwise occupied by me. My brain’s prediction turns out spot-on correct and the pot falls into that spot – boom. I saw that coming, but this is prediction, not precognition. In fact, precognition is negatively defined somewhat like ESP, namely as paranormal successful foretelling, an above chance prediction that cannot be explained as mere prediction on the basis of what we know (could not otherwise be anticipated through any known inferential process).
Precognition denotes above chance prediction of future events whose mechanism is not understood, thus paranormal. Once we understand the mechanism, precognition, if such existed, would turn into merely yet another way of prediction and perhaps become normal. The big question is of course: Does any such paranormal thing exist at all?
2) Why has Precognition not shown up clearly in Science?
There are scientific studies like D.J. Bem’s “Feeling the Future” , which apparently shows precognition with statistical significance (of course - there is the possibility of fraud). However, well done studies are so rare that one cannot claim precognition has been shown to exist scientifically. Why?
2.1) Cosmic Habituation or General Decline Effect
Researchers find new phenomena all the time and with much higher significance. Most (!) of these phenomena, even those in the so called “hard sciences”, disappear over time with further studies. They cannot be reproduced with the same significance, which slowly decreases over time. This is sometimes called “decline effect”, a term shaped by Joseph B. Rhine and first found in the very field of precognition studies, where it describes something else though as we will discuss below.
This effect of that “The Truth Wears Off” (J. Lehrer) has also been called “cosmic habituation” by Jonathan Schooler, who saw his celebrated phenomenon of “verbal overshadowing” entirely disappear over the years. We will call this henceforth the “general decline effect” instead of the somewhat silly “cosmic habituation”. One cannot stress enough that this effect is found in all sciences. Especially nowadays, general decline of significance is often followed by science eventually supporting the opposite of the originally discovered effect.
These problems with the scientific method generally imply that a few sporadic studies discovering some phenomenon never prove its existence conclusively. This sounds like criticism of psi studies, but can also read as a defense! In uncontroversial fields, the general decline effect is mostly due to confirmation bias by the researchers and publishing bias in favor of positive results.
Except for perhaps confirmation bias, the aspects to do with publishing culture do not explain why precognition suffers a strong decline effect during studies (the proper decline effect discussed below). This topic is extremely difficult to publish anyway, so the general decline effect that occurs over several studies due to publishing bias is not applicable. You cannot count immediate refutations that are obviously done fast and under pressure to produce null results (also, a perverted form of Bayesian updating is increasingly used to combat undesired science, for example in order to counter the Bem study). In this particular field, namely precognition, not positive results, but null results are strongly preferred right from the start.
2.2) Precognition needs Future Influence
Many hold the impossibility of any form of influence from the future as a dogma. For them, precognition does not show up because it does not exist, period. This may be, but one must still test and prove to people scientifically that certain claims cannot be scientifically supported. This is best done by avoiding all dogma, else the appearance of science being establishment conspiracy against the truth is nourished and snake oil flies of the shelves even faster.
The dogma is, as dogmas usually are, quite unfounded. Future Influence has been seriously discussed by established scientists. Wheeler’s and Feynman’s “absorber theory” includes advanced waves coming from the future on equal footing with retarded effects (“retarded” signifying after the cause). Quantum interference can be interpreted as future influence (quantum physics is time symmetric, so inverting usual explanations about interfering histories is already proving this, but there is more to this as will be discussed in a future post).
Many skeptics construe the mentioning of “quantum” as indication of “woo”. They may not appreciate that classical physics (read: non relativistic and pre-quantum) is trivially without future influence. The naïve “real world-box being changed by time” concept is the very core of classical physics. Future influence is strictly modern physics and needs quantum concepts.
Once there is a physical mechanism, any minute physical effect, evolutionary selection is expected to tap into the physical effectiveness eventually. Quantum interference along molecules is used by plant chlorophyll to harvest light. Quantum effects have been shown to be exploited by birds’ sensing earth’s magnetic field in ways that were previously thought impossible (see discussion of surprising quantum biology). The necessary quantum entanglement should (according to established knowledge) be immediately destroyed in warm macroscopic systems like bird brains.
2.3) Precognition may Necessitate Strong Emotions – the proper Decline Effect
The following factors correlate with positive scores in Ganzfeld experiments: Belief in psi; prior psi experiences, practicing forms of meditation (yoga), creativity/artistic ability, emotional closeness between sender and receiver, extraverts rather than introverts. Insisting on that the scientific method is better served by selecting subjects randomly is obviously counterproductive; that such studies nevertheless find significant effects the more significant.
In all the reported cases of precognition, successful “media” are always extremely motivated to participate. Strong emotions float about whenever test subjects perform especially well. The latter may be due to biased reporting, i.e. the emotions are interpreted as especially strong in the light of the just gotten streak of correct predictions. Nevertheless, rather than being and ad hoc excuse, emotions have all along been said to be involved in precognition, which is often premonition (affective apprehension) or presentiment, both signifying effect from future events that is perceived as emotion.
Even assuming it exists, precognition is a feeble effect. If it is indeed coming about via emotions, there is an obvious problem: Studies that want to increase significance must repeat the same experiment over and over again. Repetition kills emotions, positive as well as negative. You do not fall on the floor laughing after hearing the same joke a hundred times. Recalling a tragic personal loss again and again is one way to overcome emotional involvement; psychotherapy exploits this. This could be the proper “decline effect” in its original meaning.
Joseph B. Rhine reported this proper decline effect in the 1930s. An undergraduate, Adam Linzmayer, guessed cards that were not yet revealed to him with a hit rate far above chance. There are five different cards in a Zener deck (see picture below), thus chance would be a 20 percent hit rate. He had three streaks of guessing nine cards in a row, which has a one in two million chance already if it occurs just once. Yet repeated testing again and again for thousands of times wore him down and he lost the talent. So did many other subjects; it always happens this way in these studies, and it is not explained away by an initial chance fluctuation towards positive results slowly drowning in the large numbers, a so called “regression to the mean”. The latter would have different detailed statistics and would be the same for fluctuations into the opposite direction, but people who are phenomenally bad at guessing never show up.
In 2004, also Jonathan Schooler found a remarkable decline effect during precognition studies. The latter was not biased towards finding precognition! He did not embark on that study to find precognition but in order to find the decline effect. And he found that one, maybe “because he desired to find it”, but his finding of precognition along with it is not falling to confirmation bias. Schooler would have been perfectly happy if he had found the decline effect for phenomenally below chance guessing. However, subjects guessed correctly above chance.
The neat thing is that recent studies keep emotion constantly inside the experiment, for example by using sexually explicit images. Sexual images get people probably as often more excited over time than that they habituate. Moreover, sex or threat relating emotions are evolutionarily especially important. Bem found the strongest effects with the sexually explicit images involving studies.
2.4) The next time in this series I add an extremely speculative idea: The influence of belief. Quantum physics will play a major role, but not in any way that would need David Bohm (the later pseudoscientists, not the early scientist), Michael Talbot’s holographic nonsense, or any of the other usual suspects (Stapp, ... ).
 Ray Hyman: "Evaluation of Program on Anomalous Mental Phenomena." The Journal of Parapsychology (December 1995) [Note: This journal publishes a lot of nonsense!]
 Daryl J. Bem: “Feeling the Future: Experimental Evidence for Anomalous Retroactive Influences on Cognition and Affect.” Journal of Personality and Social Psychology, 100, 407-425 (2011) [Note: Quoting peer reviewed research does not imply any commitment toward the truth of the research.]