Published in 1992, in Skeptical Inquirer 16
Why do so many people
believe in psychic phenomena? Because they have psychic experiences.
And why do they have psychic experiences? Because such experiences are
an inevitable consequence of the way we think. I suggest that, like
visual illusions, they are the price we pay for a generally very effective
relationship with a massively complex world.
The latest Gallup poll (Gallup and Newport
1991) shows that about a third of Americans believe in telepathy and
about a quarter claim to have experienced it themselves. Rather fewer
have experienced clairvoyance or psychokinesis (PK), but still the numbers
are very high and have not been decreasing over the years. Previous
surveys have found similar results and also that the most common reason
for belief in the paranormal is personal experience (Palmer 1979; Blackmore
A "psychic experience" is here defined
as any experience interpreted by the experient as requiring a psychic
or paranormal interpretation. The question of whether such a hypothesis
is required is not addressed. Rather we are attempting to understand
how such experiences come about even if no genuinely paranormal phenomena
occur. It should be noted that many experimental studies of psi (such
as guessing long strings of targets) do not produce psychic experiences
in this sense, although they may produce evidence of the paranormal.
Others (such as ganzfeld studies and remote viewing, perhaps) do, but
the experience is a separate issue from the question of statistical
significance or evidence for psi. We are here concerned with experience
and belief, not the evidence for psi.
My hypothesis is that psychic experiences are
comparable to visual illusions. The experience is real enough, but its
origin lies in internal processes, not peculiarities in the observable
world. Like visual illusions they arise from cognitive processes that
are usually appropriate but under certain circumstances give rise to
the wrong answer. In other words, they are a price we pay for using
In the case of vision, illusions arise when,
for example, depth is seen in two-dimensional figures and constancy
mechanisms give the answer that would be correct for real depth. The
equivalent in the case of psychic experiences may be the illusion that
a cause is operating and an explanation is required when in fact none
is. In other words, psychic experiences are illusions of causality.
I shall discuss five types of illusion.
1. Illusions of Connection
Experiences of telepathy, clairvoyance, and
precognition imply a coincidence that is "too good to be just chance."
This is so whether the experience involves dreaming about a persons
death and that person dies within a few hours, feeling the urge to pick
up ones partner from the station and in fact he was stranded and
needed help, or betting on a horse that later wins a race.
Some peoples response to such events
is to say, "That was just a chance coincidence"; while others
is to say, "That cannot be chance." In the latter case the
person will then look for a causal explanation for the coincidence.
If none can be found, a "cause," such as ESP, may be invoked.
Alternatively, some kind of noncausal but meaningful connection may
be sought, such as Jungs "acausal connecting principle"
There are two possible types of error that
may be made here. First, people may treat connected events as chance
coincidences, thereby missing real connections between events and failing
to look for explanations. Second, they may treat chance events as connected
and seek for explanations where none is required. In the real world
of inadequate information and complex interactions one would expect
errors of both types to occur. It is the latter type that, I suggest,
gives rise to experiences of ESP.
This is comparable to classical signal-detection
theory. Figure 1 shows two distributions. For any given stimulus strength
there could be just noise or noise plus a signal. At low signal-to-noise
ratios, it is not possible to be a perfect detector. Mistakes are inevitable
and may be either in missing a true signal or in thinking there is a
signal when there is not. I am suggesting that believers in the paranormal
(called "sheep" in psychological parlance) are more likely
to make the latter kind of error than are disbelievers (called "goats").
In signal-detection theory, this is described in terms of a variable
criterion. As the payoffs change, people may use a different criterion,
making more of one kind of error and fewer of another. Their sensitivity
(d) may not change when their criterion does (see Figure 2). It
is not a question of right and wrong but of which kind of error you
would rather make, given you have to make some.
One prediction of this approach is that those
people who more frequently look for explanations of chance coincidences
are more likely to have psychic experiences. Therefore, sheep should
be those who underestimate the probability of chance coincidences.
It has long been known that probability judgments
can be extremely inaccurate. Kahneman and Tversky (1973) have explored
some of the heuristics, such as "representativeness" and "availability,"
that people find coincidences surprising (Fall 1982; Falk and McGregor
1983) Adding specific but superfluous detail can make coincidences seem
more surprising, and things that happen to subjects themselves seem
more surprising to them than the same things happening to other people.
Diaconis and Mosteller (1989) have reviewed some ways of studying the
psychology of coincidences and have provided models for calculating
There is, however, little research relating
these misjudgments to belief in the paranormal or to having psychic
experiences. Blackmore and Troscianko (1985) found that sheep performed
worse than goats on a variety of probability tasks. For example, in
questions testing for responsiveness to sample size, sheep did significantly
worse than goats. The well-known birthday question was asked: How many
people would you need to have at a party to have a 50:50 chance that
two have the same birthday? (See Diaconis and Mosteller 1989 for a general
model for this type of question.) As predicted, goats got the answer
right significantly more often than sheep.
Subjects also played a coin-tossing computer
game and were asked to guess how many hits they would be likely to get
by chance. The correct answer, 10 hits in 20 trials, seems to be rather
obvious. However, the sheep gave a significantly lower mean estimate
of only 7.9, while goats gave a more accurate estimate of 9.6.
Further research is called for here. It would
be interesting to test whether sheep and goats differ in the probability
they assign to various kinds of coincidences happening both in laboratory
tests and in assessing probabilities of real-world events.
2. Illusions of Control
Where the coincidence is between a persons
own action and an event external to them, the same effect may be at
work but the assumed cause will be personal control; or in the context
of psi, it will be PK. This has been called the "illusion of control"
by Langer (1975). Sheep have been found to show a greater illusion of
control than goats in a psi task (Ayeroff and Abelson 1976, Jones et
al. 1977; Benassi et al. 1979).
One might argue that if PK occurs then the
perception of personal control in such tasks is not an illusion. This
is less likely, given that no PK was found in these experiments. However,
to rule out this as an explanation for the difference, Blackmore and
Troscianko (1985) used a covert psi task. There was no evidence of PK
and a greater illusion of control for sheep than for goats.
3. Illusions of Pattern and Randomness
Pattern and randomness cannot be unambiguously
distinguished. In a long enough series of events, any combination or
string of events is likely to occur by chance. However, the process
of extracting pattern from noise is central to all sensory processes.
As in the case of coincidences two kinds of error can occur. One is
the failure to detect patterns that are there; the second is the tendency
to see patterns that are not there. We are arguing that the second type
of error will make people search for a cause and that, since there is
no cause they may turn to paranormal explanations.
This predicts that people who make this type
of error are more likely to have psychic experiences (or experiences
they interpret as psychic) and hence to believe in the paranormal.
It has long been known that people are bad
at judging randomness. In particular, when asked to generate a string
of random numbers (subjective random generation, or SRG), people typically
give far fewer repetitions of the same digit than would be expected
by chance (see reviews by Budescu 1987 and Wagenaar 1972). This is related
to the "Gamblers Fallacy," whereby some people think
that a long string of reds must be followed by black. ESP experiments
are often equivalent to SRG and show the same bias.
Blackmore and Troscianko (1985) found no differences
between sheep and goats in SRG for strings of digits 1 to 5 or in the
ability of sheep and goats to discriminate random sequences from biased
ones. However, Brugger, Landis, and Regard (1990) did. They argued that
the same variables affect ESP scoring and SRG in the same directionvariables
like task duration, stimulant and depressant drugs, and age. They even
suggest that many laboratory ESP findings may be explained by correspondences
between target sequences and human biases. Although there is some evidence
for this in studies giving immediate feedback (Gatlin 1979; Tart 1979),
this cannot easily explain results obtained without feedback and with
adequate target randomization.
They tested the relationship to belief in the
paranormal in three experiments. SRG was studied in a telepathy experiment
with five symbols to choose from. Sheep produced significantly fewer
repetitions than goats did. Subjects intermediate in belief gave intermediate
repetitions. There was no evidence of ESP occurring and no sheep-goat
effect (i.e., sheep did not do better at the ESP test).
In a second experiment, SRG was studied in
mimicking the roll of dice (6 choices). The same effect was found. Third,
subjects were shown dice sequences with different numbers of repetitions
and asked which was more likely to appear first by chance. Of course
all strings were equally likely to occur, but subjects tended to choose
the string with fewer repetitions. Sheep did so more than goats, and
the intermediate group was in between. These results appear t be highly
consistent and to show the expected greater bias in sheep.
To test this further, Katherine Galaud, at
Bristol University, carried out an experiment to compare SRG for different
numbers of choices. It might be argued that most people could predict
or calculate likely sequences when only two choices are involved but
that the real world typically involves multiple choices and low probabilities.
Perhaps SRG would be even less random when more choices are possible.
Furthermore, difference between sheep and goats may be more extreme
where more choices are available. This experiment studied the variation
in results with different numbers of choices available.
One hundred twenty students were given the
Belief in the Paranormal Scale (BPS) (Jones, Russell, and Nickel 1977),
a randomness questionnaire, and a probability questionnaire The probability
questionnaire consisted of three questions based on the "taxi problem"
(Kahneman and Tversky 1972) manipulated to give correct answers of 20,
40, and 80 percent. The randomness questionnaire asked subjects to generate
strings of random numbers, choosing from the digits 1 to 2, 1 to 4,
or 1 to 8, with expected numbers of repetitions being 12, 6, and 3,
respectively. No differences were found between sheep, goats, and intermediates
(Blackmore, Galaud, and Walker, in press).
There are two differences between this experiment
and Bruggers that might account for the different results. One
is that Brugger et al. timed the generation of digits with a metronome.
It could be that, given time to think about randomness, people can to
some extent compensate for their biases and that untimed and unpressured
responses like those in the present experiment cannot reveal them. However,
it could also be argued that in real-life situations there is not usually
time pressure. Another difference is that they used only one question
on ESP to divide subjects into sheep, goats, and intermediates. Further
experiments now under way at Bristol are trying to find out if these
factors are responsible.
4. Illusions of Form
Object recognition can entail the same two
types of error. A conservative approach means missing interesting forms
that are there. A less cautious approach means seeing things that are
not. Possibly, those people who are more likely to see forms when none
is present are also more likely to see apparitions or ghosts or to seek
paranormal explanations when none is required.
In a second experiment at Bristol, carried
out by Catherine Walker (Blackmore, Galaud, and Walker, in press), we
tested this and a related question. If sheep are more willing to see
forms in noisy displays, is this an error compared with goats, or are
goats more likely to miss forms that are present. This is the familiar
question of accuracy versus criterion. Sheep might simply have a lower
criterion for seeing forms than goats, with the same accuracy for discriminating
forms, or they may actually make more errors altogether.
Fifty subjects were given the Belief in the
Paranormal Scale and tested on an object-identification task. The stimuli
consisted of four sets of seven pictures each; ranging from barely identifiable
blobs to clear outline shapes (see Figure 3). The final shapes were
two leaves, a bird, a fish and an axe. They were presented for 10 milliseconds
each, with a mask of black dots on a white background shown between
presentations. The four least identifiable stimuli were shown first,
progressing through the series with the four at each level being randomized
for order. The subjects were asked whether they could see any shape;
and, if they could, what shape it was.
It was predicted that sheep would report seeing
forms earlier in the series than goats but would not be any more accurate
in identifying the forms. In other words, they would have a lower criterion
for identification. This is exactly what was found. BPS scores did not
correlate with the number of pictures correctly identified but did correlate
closely with the number of incorrect identifications and the tendency
to say there was a shape but not identify it. In other words, the sheep
were more likely to make wrong guesses but were no worse at detecting
the pictures that were there. Goats, although willing to say there was
a shape, were less willing than sheep to guess at identifying it.
This confirms that sheep are more likely to
claim to see identifiable forms in ambiguous stimuli, but there are
many possible reasons for this. For example, creativity may correlate
with belief in the paranormal and with tendency to see forms. Whatever
the origins of the tendency, the findings fit with the idea that
paranormal belief may be encouraged in those who more often see form
5. Illusions of Memory
In addition to all the processes above, selective
memory may make coincidences appear to occur more often than they do
in fact occur. Hintzman, Asher, and Stern (1978) demonstrated selective
remembering of meaningfully related events. Fischhoff and Beyth (1975)
showed that people misremember their previous predictions to conform
with what actually happened.
We might predict that people who are particularly
prone to such memory effects are more likely to seek paranormal explanations
and therefore to have psychic experiences and believe in the paranormal.
If so, these effects would be greater for sheep than for goats, but
this has not been tested.
The popularity of fortune-tellers may also
depend to some extent on selective memory. Selective recall of meaningful
coincidences and true statements about the person will add to the Barnum
effect, or the tendency to accept certain kinds of personality readings
as true of oneself but not of others (Dickson and Kelly 1985). If this
is so we would expect the people who frequent fortune-tellers to be
more prone to this kind of selective memory. Again this has not been
tested, but a project is now underway at Bristol to investigate it.
Five types of psychic illusion have been explored.
They may be the basis for many spontaneous psychic experiences that
generate belief in the paranormal. The tendency for sheep to show many
of these effects to a greater extent than goats tends to confirm this
This conclusion does not apply to many kinds
of psi experiments, especially those giving no feedback and using sound
randomization techniques. It therefore has no bearing on the issue of
whether any laboratory experiments provide evidence for psi. Also in
life outside the lab these processes may operate to produce psychic
experiences and belief in the paranormal quite independently of whether
genuinely paranormal phenomena ever occur.
These findings are therefore not so much evidence
against the occurrence of paranormal phenomena as a suggestion that
we should expect to find a high incidence of psychic experiences and
widespread belief in the paranormal whether or not psychic phenomena
The Nature of Skepticism
The whole basis of this approach is that human
beings, in trying to make sense of their world, must make mistakes.
On the one hand, they miss things that are there and, on the other,
invent things that are not. This applies as much to simple signals as
to complex correlations and to scientific theories as well as to perceptual
ones. I have tried to show some of these in Figure 4.
In everyday life the equivalent of the sheep
is someone who will see something interesting in everything. The problem
is that they may be seeing things that are not there. The equivalent
of the goat is someone who needs lots of evidence before seeing or experiencing
anything. They are likely to miss out on a lot of fun!
Similarly, in science the equivalent of the
sheep is someone who enjoys every crazy theory and follows every faint
lead. The problem is that they may easily be following a false lead.
The equivalent of the goat is someone who takes no interest in wacky
theories and sticks only to the conventional. They may be safe but are
likely to miss the really exciting new theory when it comes along.
You takes your choice and with it the consequencesfun
or boredom, fear of failure or love of novelty. But what of skepticism?
I do not think the true skeptic is the goat. The true skeptic does not
always stick to one end of the spectrum but can shift criteria as the
circumstances demand. The true skeptic is as skeptical of the goat who
denies everything as of the sheep who embraces everything (as is John
Palmers  "progressive skeptic"). True skeptics
can drop their fear of looking silly or curtail their love of the novel
as appropriate; can apply caution or stick their neck out according
to their understanding of the issues. The true skeptic is not the ultimate
goat but something more like a flying horse.
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