Experimenter effects and the remote detection of staring

Journal of Parapsychology, The, Sept, 1997 by Richard Wiseman, Marilyn Schlitz

. . . the experimenter effect is the most important challenge facing modern experimental parapsychology. It may be that we will not be able to make too much progress in other areas of the field until the puzzle of the experimenter effect is solved. (Palmer, 1986, pp. 220-221.)

The apparent detection of an unseen gaze (i.e., the feeling of being stared at, only to turn around and discover somebody looking directly at you) is a common type of ostensible paranormal experience, with between 68% and 94% of the population reporting having experienced the phenomenon at least once (Braud, Shafer, & Andrews, 1993a; Coover, 1913).

Some parapsychologists have attempted to assess whether this experience is based, at least in part, on genuine psi ability. Such studies use two participants: a "sender" and a "receiver." These individuals are isolated from one another, but in such a way that the sender can see the receiver. Early experiments had the sender sitting behind the receiver (Coover, 1913; Poortman, 1959; Titchener, 1898); some later studies have used one-way mirrors (Peterson, 1978) or a closed-circuit television system (Braud, Shafer, & Andrews, 1993a, 1993b; Williams, 1983). The experimental session in this type of study is divided into two sets of randomly ordered "stare" and "non-stare" trials. During stare trials the sender directs his/her attention toward the receiver; during non-stare trials the sender directs his/her attention away from the receiver. Either during or after each trial a response is made by the receiver. In early studies, the receivers made verbal guesses as to whether they believed they had been stared at; later studies have measured receivers' electrodermal, activity (EDA) throughout each trial. A number of studies have obtained statistically significant differences between responses to stare and non-stare trials and in a recent review of this work, Braud, Shafer, and Andrews (1993b) concluded:

We hope other investigators will attempt to replicate these studies. We recommend the design as one that is straightforward, has already yielded consistent positive results, and addresses a very familiar psi manifestation in a manner that is readily communicable and understandable to the experimental participants and to the public at large. (p. 408)

Both authors of the present paper previously attempted to replicate this staring effect. The first author (R. W.) is a skeptic regarding the claims of parapsychology who wished to discover whether he could replicate the effect in his own laboratory. The second author (M. S.) is a psi proponent who has previously carried out many parapsychological studies, frequently obtaining positive findings. The staring experiments carried out by R. W. showed no evidence of psychic functioning (Wiseman & Smith, 1994; Wiseman, Smith, Freedman, Wasserman, & Hurst, 1995). M. S.'s study, on the other hand, yielded significant results (Schlitz & LaBerge, 1997).

Such "experimenter effects" are common within parapsychology and are open to several competing interpretations (see Palmer, 1989a, 1989b). For example, M. S.'s study may have contained an experimental artifact absent from R. W.'s procedure. Alternatively, M. S. may have worked with more psychically gifted participants than R. W. had, or may have been more skilled at eliciting participants' psi ability. It is also possible that M. S. and R. W. created desired results via their own psi abilities, or fraud. Little previous research has attempted to evaluate these competing hypotheses. This is unfortunate, because it is clearly important to establish why experimenter effects occur, both in terms of assessing past psi research and attempting to replicate studies in the future. For these reasons, the authors agreed to carry out a joint study in the hope of learning why our original studies obtained such dramatically different results.

METHOD

Design

Our joint study required M. S. and R. W. to act as separate experimenters for two different sets of trials. The two sets of trials were carried out at the same time (early October, 1995) and in the same location (R. W.'s laboratory at the University of Hertfordshire in the U.K.). In addition, the experimenters used the same equipment, drew subjects from the same subject pool, and employed exactly the same methodological procedures. The only real difference between the trials was that one set was carried out by M. S. and the other set was run by R. W. We were curious to discover if, under these conditions, we would continue to obtain significantly different results. Each study had one independent variable with two levels - stare and non-stare. The dependent variables were the receivers' EDA during the experimental session and their responses to a "belief-in-psi" questionnaire.

Participants

Thirty-two subjects (10 males and 22 females; mean age of 25.72, age range 18 - 49) acted as receivers. Thirty of these were undergraduate psychology students studying at the University of Hertfordshire. The remaining two were the authors' colleagues. M. S. and R. W. acted in a dual capacity as both experimenter and sender.