Susan Blackmore's In Search of the Light is a very rewarding glimpse into the mind of one of CSICOP's leading skeptics, as her views evolved from absolute belief to skepticism of the paranormal.
Blackmore founded a paranormal club in college, earned her PhD in paranormal psychology, taught the first college course in England on the paranormal., was a member of paranormal societies for her entire adult life, and was even solicited to write a book on OBEs by the London society. Her own OBE remains a compelling motive for all her efforts.
Her skepticism grew gradually. It had its origin in the remarkably poor reasoning and experimental design that she saw in so much paranormal literature. She was determined to change this, and diligently pursue careful experimental design in her own studies.
The primary subject she studied was telepathy, which is the most common subject of psi studies. She found that the few times she got non-random results, she became convinced it was the result of a design error in her procedures. In an effort to determine why others were getting significant results, she examined the historical record of the field. Many of the most spectacular recorded psi successes appear to her to have been the result of fraud. Her co-researchers she found generally did not follow as careful a process of experimental design as she did. Even in the OBE field, she found that the documentation did not seem to support the assumptions - the same individual is cited for the claims of OBE communication (rather than clear statements and dates from both the traveler and observer), etc.
The consequence of her increasing skepticism is unfortunate, as she herself illustrated with an example. An elderly man wrote her of a premonition he had had, which caused him to put his daughter on a train rather than aircraft. The subsequent crash of the plane killed all aboard. She did not have independent confirmation of any of the facts (frequency of premonitions, etc), but wrote to the daughter. The daughter said her father was imagining it all, that he just wanted to save money by using the train, and that the crash has only injured one stewardess. Blackmore took this as confirmation of selective memory on the father's part, until the Civil Aviation Board confirmed the date and 100% fatality rate of the plane crash. Blackmore admits this confirmed her own biases.
But recognition of her own biases did not prevent her reaching conclusions unsupported by the facts. This comes through in reading her analysis of the Gansfield experiments - in which telepathy is tested while the recipient is immersed in white noise with vision blocked. Unlike all others, these have an ~60% success rate in showing statistical significance. Blackmore then tried to test for the "file drawer" effect, where only successful studies are published, while the failures are buried. She found that ~2/3 of all studies had actually been published, and that the 1/3 unpublished had about the same success rate as the published ones (she documented her findings in a peer-reviewed publication).
Despite this, she continued in her skepticism. She investigated the lab of the most respected researcher in the field, observed a dozen tests, which ran over 50% hits (25% would be a null effect), which was typical of the labs success. She then postulated a complex cheating procedure which could possibly bias the result, which would require the photo-selector to know all four of the photos of the multiple photo sets, and know the personality of the recipient, and guess which photo the recipient would most likely pick, then discretely cheat the random-selection process. The speculation was wildly improbable, and I at least cannot imagine anyone knowing someone else well enough to produce a significant bias that way. While investigating the possibility of such cheating, she did witness one unrelated deviation from proper experimental procedure, and found a few discarded photo-selection envelopes around the lab consistent with her cheating hypothesis. The one procedure violation was a problem, but it was only one out of a dozen, and the consistent results for the others matched the labs reported data. The cheating she hypothesised would have been apparent in the tests she witnessed, and did not happen while she was there. The proper conclusion would be that the lab occasionally violated the test protocol, but for the vast bulk of the tests it was followed rigorously. Instead, she asserts its results are questionable, and should be dismissed from the literature.
So, in order to validate her own new preconception that psi is not valid, she has published slanders on the reputation of the most rigorous experimentalist in the field, and dismissed her own failure to refute the Gansfeld results with the file-drawer effect. This leap to an inappropriate conclusion, and slander on the character of someone she considered a friend, is unfortunately typical of the behavior of CSICOP skeptics, whom she has now joined.
Similarly, she declares the small but statistically significant effect seen in dice-rolling experiments to be most likely experimental error, with no evidence to support her claim. She also declares that psi plays no role in OBE experiences, despite it being claimed in over 50% of the of the cases she cited in her own book on the subject.
Throughout the book, she notes that parapsychology is badly defined, characterized by a negative definition that it exists when all physical processes have been dismissed. She is correct that this definition is flawed. Experiments should be designed to test a hypothesis, which is a positive assertion, and should be definitive between a specific hypothesis and a competing one (experimental bias, self-deception, or whatever the skeptics might propose).
But she herself continues to use this flawed definition, and takes it to absurd extremes in that she basically requires parapsychologists to prove they are not cheating. This is a virtually impossible standard to meet. It is, unfortunately, the standard the CSICOP uses - if there is ANY possible alternative explanation, no matter how far-fetched, or unsupported by anything but speculation, they, and Blackmore, will dismiss all claims of the paranormal.
Regardless, the book is well-written, is very instructive for why a hard-headed true believer became a skeptic, and is in any event an excellent first-person narrative to show how scientists minds should work.
Postscript to the review: Blackmore has made much of her early history of failed parapsychology experiments, both in this book and in her lectures and quotes to newspapers as a spokesperson for CSICOP. But a review of her published data shows she had an ~30% success rate in showing statistical significance in her psi studies. She asserts that "poor experimental design" caused the successes, and that the "better design" of the tests which do not show significance. However there are several major problems with her explanation. Peer review of her experiments has not shown ANY significant difference in the quality of the protocols between her successes and failures. Since a 95% confidence level of significance can randomly occur ~5% of the time due to data noise, her 30% success rate is actually pretty phenomenal, and is fairly typical of the rate shown by other parapsychology researchers (para phenomenon are time-intensive to test for, and collecting enough data to show statistical significance is difficult on the low/no budget such studies are done with - the lack of statistical significance in most published work is due to the generally below-optimum sample sizes tested). Her describing her own tests as "failing to discover psi" as she does repeatedly, and ascribing any "apparent" successes to poor experimental design, as she does, are both falsehoods in describing her own work. Since it was not her own data, as she asserts in this autobiography, this leaves as a mystery what REALLY lead Blackmore to drift away from advocacy to one of the most outspoken critics of parapsychology.
The other reviews here all cite this as a triumph of scientific objectivity over shoddy science -- but when Blackmore's own dishonesty shows up in characterizing her own work, and in falsely smearing a friend's professional reputation -- which side of this controversy is really the objective one, and which the shoddy? I strongly reccommend Chris CArter's "Parapsychology and the Skeptics" for a more trustworthy score sheet on the good guys and bad here.