Nicholas Rose and Susan Blackmore
Department of Psychology
University of the West of England
Bristol BS16 2JP
Blackmore and Rose (1997) suggested a link between psi and a person’s tendency to confuse reality and imagination, and reported an experiment that examined two hypotheses. The first was that people may misinterpret their own imagination as reality; leading them to conclude that a psychic phenomenon has occurred when in fact it has not. In this case we would expect believers in the paranormal to be more likely to confuse reality and imagination. The second proposed that the confusion between reality and imagination is itself psi-conducive – as though psi can somehow sneak into the uncertainty gap.
Subjects were shown slides, half of which showed common objects with labels underneath, and the others just labels. For the latter they were asked to imagine the objects named. Some were shown once and some three times. Over the following two weeks, subjects were asked to describe, draw and answer questions about all the objects. By the end of the experiment we expected that many of them would have been confused into thinking that they actually saw some objects that, in fact, they had only imagined (i.e. false memories).
Psi targets were pictures of half of the imagined objects (randomly selected for each subject) and were concealed in envelopes during the first session. The analysis compared the number of false memories on targets (hits) with the number on non-targets (misses) for each subject. Belief was measured using the Revised Paranormal Belief Scale (Tobacyk, 1988) and scores were correlated with the number of false memories for each subject.
The technique used in Blackmore and Rose (1997) successfully induced false memories in many subjects. That is they said that they had seen an object when they had actually imagined it. 8 subjects made a total of 12 errors of this kind. A significant psi effect was found. That is, there were more false memories for target objects (ESP hits) than for non-target objects (ESP misses) (t=2.25, 32df, p=0.032, 2-tailed). Using Cohen’s d (Rosenthal, 1984), the effect size was 0.80. We predicted a correlation between the number of false memories and PBS score. However, no such correlation was found (rs = 0.069, n=32, p=0.70). Neither was there any correlation between total errors (regardless of type) and BPS score (rs = 0.046, n=33, p=0.80).
In this research brief we report two further experiments carried out using the same technique. The first is an exact replication of the original experiment designed to see whether the apparent psi effect could be repeated. The second used a modified design in an attempt to increase the number of false memories obtained.
In the first experiment 26 psychology students took part, and 13 subjects made a total of only 19 false memory errors. There were 10 hits and 9 misses, which is non-significant (t=0.25, 12df, p=0.808, 2-tailed). No correlation was found between the number of false memories and BPS score (rs = -0.134, n=25, p=0.53).
Problems with this experiment included the low numbers of subjects completing all phases and the low numbers of false memories produced. We completed a further study (not reported here) in which subjects were tested individually with the stimuli presented by computer. We measured the time they took to draw and describe the objects and the time taken to recall which objects they had seen in the final session. From the results of all these experiments we designed the final classroom study as follows.
Time limits previously imposed on the tests were removed. Subjects’ data were included if they had attended only one of the intermediate sessions and the time between the first and last session was increased from three weeks to two months.
82 psychology students took part. The number of false memories improved; 60 subjects made a total of 148 false memory errors. There were 73 false memories for target objects (hits) and 75 false memories for non-target objects (misses); a non-significant difference (t=-0.22, 81df, p=0.829). Once again, no correlation between PBS score and false memory was found (rs = -0.178, n=81, p=0.11).
The modified classroom design used in this experiment appears an ethical and effective method for producing false memories. The failure to replicate the original psi result was disappointing, and having reviewed the possible causes the most parsimonius explanation for the original result appears to be chance. Our second hypothesis, that believers in the paranormal might make more false memory errors, was not confirmed in any of the experiments. Whilst this may, in part, be due to the well documented weaknesses of the Tobacyk (1988) scale, the results suggest that there is no relationship. However, these findings do not rule out the possibility that believers in the paranormal may be more likely to have false memory for ostensibly paranormal events.
Blackmore, S.J. and Rose, N.J. (1997) Reality and imagination: A psi-conducive confusion? Journal of Parapsychology. 61, 321-335.
Tobacyk,J. (1988) A Revised Paranormal Belief Scale. Unpublished Manuscript, Louisiana Tech University, Ruston, LA.
With thanks to the Perrott-Warrick fund for their financial assistance to this research, and to Kerry Grey who assisted with running one of the experiments.