Researching unexplained phenomena: empirical-statistical validity and reliability of the Multivariable Multiaxial Suggestibility Inventory-2 (MMSI-2)

Anomalous phenomena are unexplained occurrences, such as paranormal experiences, that challenge the ontological bases of current scientific knowledge and are considered scientifically impossible. Problematically, some scientific research yields significant statistical results in favor of the existence of telepathy, precognition, mind matter interaction, and mediumship. The current study presents and statistically justifies the Multivariable Multiaxial Suggestibility Inventory-2 (MMSI-2), a new psychological instrument to measure and detect the main psychological explanations for anomalous experiences. A nonprobabilistic sample of 3,224 subjects without a psychiatric history were recruited from the general population of Spain. Exploratory factor analysis (EFA) was used to examine the internal structure of the MMSI-2's 174 items. Direct oblimin and promax oblique rotations were applied as criteria for axis rotation. Cronbach's alpha coefficients and their ordinal transformation were also calculated, and gender-differentiated scales for the raw MMSI-2 scale scores were developed. The first-order factorial solution yielded a total of 16 factors that explained 92.84% of the variance. Of these, 10 corresponded to the psychological variables cited in the background literature, four classified the anomalous phenomena according to their sensory mode, and two represented prototype control scales for this class of psychometric inventory. The higher-order EFA grouped the MMSI-2 scales into four macrofactors that together explained 97.737% of the variance. Satisfactory reliability rates were obtained (alphas 0.8). The full version of the MMSI-2 with 174 items is a valid and reliable psychometric instrument for evaluating anomalous phenomena and the theoretically concomitant psychological variables. Similarly, the scaling of scores can be used in psychological assessment as a screening tool to identify clinically suspected psychological variables.