The PRF has had a number of delightful individuals serve on its research staff over the years, and in this blog entry, we wish to take a moment to fondly remember one of them that we lost late last year: Muriel Gold Roll, who passed away on October 5, 2018, in Chapel Hill, North Carolina. Aside from being a devoted mother and grandmother, Muriel was known for having earned a number of academic achievements in her long life, and for her volunteer service at the Nasher Museum of Art in Durham (see her obituary, published in the Raleigh News & Observer on October 13 - an electronic copy can be found by clicking here). But relatively few people are likely to be aware that at one time, Muriel had made some valuable contributions to parapsychological research, as well.
One of her contributions was her direct involvement in the extensive series of experimental tests for psychic ability that the PRF had conducted with Sean Lalsingh Harribance throughout the early 1970s. Initially recognized for his reported accuracy in the psychic readings he would give to people in his native West Indies island community of Trinidad, Sean came to the United States at the end of the 1960s to be formally tested for extrasensory perception (ESP) by the Foundation for Research on the Nature of Man (now known as the Rhine Research Center), and later by the PRF, in North Carolina. Since Sean was used to actively applying his abilities toward psychically gathering information relating to the personal lives of the clients who came to him for a reading, the PRF had looked to make one particular aspect of this situation adaptable to an experimental setting by designing a series of tests which utilized a specially-made set of 10 photo-cards as the ESP target material. Each card bore the portrait photo of a certain individual on its face, and without seeing it, Sean would be asked to try and psychically determine whether the individual shown on the card was male or female, with a 50% probability of him being correct. 
Acting as one of the experimenters, Muriel had carefully prepared the photo-cards prior to each test, thoroughly shuffling up their order before laying them out in a row on a table and carefully concealing them from sight underneath an opaque cardboard shield and a thickly-folded blanket. Once she'd prepared them, Muriel quickly exited the test room before Sean was brought in by another experimenter to gather his psychic impressions about the individuals shown on each of the concealed cards. Out of a total of 1,840 card test trials, Sean's impressions were found to be correct 1,066 times, amounting to an accuracy percentage of 57.9% (see the graph below) .
Graphical summary showing the accuracy percentages (with associated 95% confidence intervals) obtained by Sean Harribance in the photo-card test series involving Muriel Roll as an experimenter (Ref. 1). Tests 2 & 3 in the series have been excluded due to possible issues with sensory shielding (see Note 2). The red horizontal line at 50% indicates the chance-expected level of accuracy. The far right-hand percentage marked "All" represents Sean's accuracy combined across all the tests in the series.
While a difference of 7.9% from the chance-expected 50% may sound small, this turns out to be a highly significant difference by statistical standards, being associated with an odds ratio greater than a million to one (z = 6.78, binomial p = 6 x e-12).
Later on, Muriel took part as an experimenter in a shorter series of ESP tests with Sean, recording Sean's verbal impressions as he gave psychic readings to individual volunteers who'd been concealed from his direct view by being placed in a separate, non-adjacent room.  Although his overall results were not as statistically high as in the photo-card series, Sean was still able to achieve notable success in these tests, with odds greater than 50 to one against chance. 
Muriel had also served as the principal experimenter in a series of tests aimed at determining whether Sean might be capable of mentally affecting the roll of dice using psychokinetic (PK, or "mind over matter") ability.  During each tests, six dice enclosed inside a clear plastic tube were randomly tossed about as the tube was made to rotate around in a circular motion by an electric motor belt. Sitting quietly with his hands folded, Sean would focus his attention upon the tumbling dice, trying to make a certain predefined target number (between 1 and 6) come up on each of their faces through the exertion of his mental will. After the tube had fully rotated around twice, Muriel would shut off the electric motor and record the number showing on each of the die faces as the tube (and the dice) came to a halt. Out of 14,040 total dice rolls, she'd found that 2,701 of them ended up matching the target number that Sean was aiming for, resulting in an accuracy percentage of 19.2% (whereas 16.7% would be expected by chance, on average). Again, while a difference of 2.5% over chance expectation sounds quite small, this turns out to be a highly significant difference statistically, amounting to odds of about a quadrillion to one! (z = 8.18, with a p = 1.68 x e-16) 
In addition to her contribution to the PRF's experimental work, Muriel had offered some useful insight into some rather unique historical cases of spontaneous psychic experience that have appeared in the psychical research literature. Particularly notable in this regard is her review of the book Immortality Proved by the Testimony of Sense, written by theologian Abraham Cummings in 1826.  This book chronicled the spirit-related phenomena apparently witnessed on multiple occasions by small groups of people in the local community around Sullivan, Maine, in the period between 1800 and 1806. These phenomena included knocks, raps, hearing a phantom voice, and seeing a bright mass of white light, which were thought by most witnesses (including Cummings) to be due to the discarnate spirit of Captain George Butler's deceased first wife. But upon carefully examining the witness accounts reported in the text, Muriel noticed that a number of these phenomena actually seemed to take place in relatively close proximity to Captain Butler's second wife. Further noting how similar these phenomena were to the kinds of large-scale PK-related occurrences reportedly observed in Spiritualistic seances, Muriel suggested that physical mediumship on the part of a living agent (the captain's second wife, in this case) could be another way to possibly account for them, as an alternate to the discarnate spirit hypothesis. Among the factors noted by Muriel to be consistent with this alternate possibility were the second wife's relative closeness to the phenomena, her apparent signs of fatigue following an occurrence (something that a number of physical mediums have also seemingly displayed following their efforts to produce large-scale PK ), and the suggestive clustering of the occurrences around certain circumstances in her life. Speaking about the ultimate value of the case itself, Muriel eventually concluded that:
From the historical point of view, the account of the Butler apparition provides a record of how a psychical case was investigated one hundred and fifty years ago [from the time of her review]. It is also worth noting that several details that are now conventional features of the seance probably made their debut on the American scene with this case [seeing how it pre-dated by several years the rise of the Spiritualism movement in America, starting with the rapping phenomena reported around the Fox sisters in 1848; see Ref. 9]. Aside from these features, it is an intrinsically interesting account of ostensible parapsychological phenomena. [7, p. 409]
For all of her contributions to the study of psychic phenomena during her time with us, the PRF remains immensely grateful to Muriel Gold Roll. We were honored to have had her as part of our staff, and we will miss her.
References & Notes:
 Stump, J. P., Roll, W. G., & Roll, M. (1970). Some exploratory forced-choice ESP experiments with Lalsingh Harribance. Journal of the American Society for Psychical Research, 64, pp. 421 - 431.
 This statistical result excludes 252 test trials (comprising all of Series 2 & 3 in Ref. 1) in which the cards were concealed only by the folded blanket, which by itself may not have sufficiently guarded against visual cues, in some cases.
 Roll, W. G., Morris, R. L., Damgaard, J. A., Klein, J., & Roll, M. (1973). Free verbal response experiments with Lalsingh Harribance. Journal of the American Society for Psychical Research, 67, 197 - 207.
 As a relative value for comparison, odds of 20 to one are the typical standard for results to be considered statistically significant in most psychological experiments.
 Roll, M. (1971). Some recent dice-throwing studies with Lalsingh Harribance. In W. G. Roll, R. L. Morris, & J. D. Morris (Eds.) Proceedings of the Parapsychological Association No. 8 (pp. 19 - 20). Durham, NC: Parapsychological Association, Inc.
 A detailed overview of the various ESP and PK experiments conducted with Sean Harribance can be found in a special review chapter on this work that appears in Broderick, D., & Goertzel, B. (Eds.) (2015). Evidence for Psi: Thirteen Empirical Research Reports (pp. 102 - 137). Jefferson, NC: McFarland & Company, Inc.
 Roll, M. (1969). A nineteenth-century matchmaking apparition: Comments on Abraham Cummings' Immortality Proved by the Testimony of Sense. Journal of the American Society for Psychical Research, 63, 396 - 409.
 Reinsel, R. (2004). Physical mediumship, macro-PK, and the autonomic nervous system. Proceedings of Presented Papers: The Parapsychological Association 47th Annual Convention (pp. 314 - 315). Durham, NC: Parapsychological Association, Inc.
 Weisberg, B. (2004). Talking to the Dead: Kate and Maggie Fox and the Rise of Spiritualism. San Francisco, CA: HarperSanFrancisco.