The ganzfeld procedure is a mild sensory isolation technique that was first introduced into experimental psychology during the 1930s and subsequently adapted by parapsychologists to test for the existence of psi--anomalous processes of information or energy transfer such as telepathy or other forms of extrasensory perception that are currently unexplained in terms of known physical or biological mechanisms. Parapsychologists developed the ganzfeld procedure, in part, because they had become dissatisfied the card-guessing methods for testing ESP pioneered by J. (...) B. Rhine at Duke University in the 1930s. In particular, they believed that the repetitive forced-choice procedure in which a participant repeatedly attempts to select the correct "target" symbol from a set of fixed-alternatives failed to capture the circumstances that characterize reported instances of psi in everyday life. (shrink)

This paper reviews the debate over the evidence for ESP provided by experiments using the ganzfeld technique, a simple method used to induce a mild altered state of consciousness. The quantitative literature review technique called meta-analysis has played a prominent role in this controversy. The first question addressed by the reviewer is whether the data establish that ESP in the ganzfeld is replicable. Issues discussed include the effect of multiple analyses, the 'file-drawer' problem and statistical errors. The second (...) question asks, if the effect is real, can it be explained by methodological artifacts? Potential flaws discussed include sensory leakage, problems of randomization and participant fraud. The reviewer's first conclusion is that the aggregate database does provide evidence for a genuine psi effect. However, heterogeneity of results across experimenters indicates that the phenomenon is not easily replicable. The second conclusion is that conventional alternative explanations offered for the observed results tend to be conceivable, but even critics sometimes agree that they are implausible. (shrink)

This paper presents a brief review of the debate between parapsychologists and skeptics regarding the issue of replication in experimental tests of extrasensory perception (ESP) using a sensory reduction technique known as ganzfeld. The review is followed by a basic assessment of 59 ganzfeld ESP studies reported in the period following the publication of a stringent set of methodological guidelines and recommendations by R. Hyman and C. Honorton in 1986. The assessment indicates that these 59 studies have a (...) combined hit rate of approximately 30%, which is significantly above the chance expected hit rate of 25%. A comparison of the hit rates across four ganzfeld meta-analyses, as well as across fifteen laboratories, seems to further indicate replication of the ganzfeld ESP effect by a broad group of independent researchers. Keywords: extrasensory perception (ESP)—ganzfeld—meta-analysis—psi—parapsychology. (shrink)

The first premise of Schellenberg’s particularity argument reads, “If a subject S perceives a particular α, then S discriminates and singles out α” (2018: 25). But this is false if seeing a ganzfeld is possible (i.e., a homogeneous field without any particulars to discriminate). In response, Schellenberg argues that seeing a ganzfeld is impossible by appealing to the ganzfeld effect (viz. hallucinatory experiences caused by ganzfeld exposure) exclusively as a ‘sense of blindness’. I present two challenges (...) for this line of reasoning. The first concerns the need to account for the long delay before blindness is reported (if it is reported at all) and the second concerns the need to be consistent with potential causes of ganzfeld hallucinations (in general, not exclusive to the sense of blindness). I show how Schellenberg’s particularity argument can meet the first challenge but struggles to meet the second. I present evidence based on considerations related to sensory deprivation and that follow from the predictive processing theory of cognition, which describes seeing a ganzfeld as the cause of ganzfeld hallucinations. If correct, this means that you can see a homogeneous field, and thus we ought to be skeptical of the soundness of Schellenberg’s particularity argument. I conclude with a possible strategy for rehabilitating the particularity argument that reconceptualizes perceptual experience as fundamentally multimodal, constituted by both exteroceptive and interoceptive sensation. (shrink)

The existence of psi—anomalous processes of information transfer such as telepathy or clairvoyance—continues to be controversial. Earlier meta-analyses of studies using the ganzfeld procedure appeared to provide replicable evidence for psi (D. J. Bem & C. Honorton, 1994), but a follow-up meta-analysis of 30 more recent ganzfeld studies did not (J. Milton & R. Wiseman, 1999). When 10 new studies published after the Milton-Wiseman cutoff date are added to their database, the overall ganzfeld effect again becomes significant, (...) but the mean effect size is still smaller than those from the original studies. Ratings of all 40 studies by 3 independent raters reveal that the effect size achieved by a replication is significantly correlated with the degree to which it adhered to the standard ganzfeld protocol. Standard replications yield significant effect sizes comparable with those obtained in the past. (shrink)

This paper examines the impact that recent advances in clinical neurology, introspectionist psychology and neuroscience have upon the philosophical psycho?neural Identity Theory. Topics covered include (i) the nature and properties of phenomenal consciousness based on a study of the ?basic? visual field, i.e. that obtained in the complete dark, the Ganzfeld, and during recovery from occipital lobe injuries; (ii) the nature of the ?body?image? of neurology and its relation to the physical body; (iii) Descartes? error in choosing extension in (...) space as the criterion for distinguishing the physical and the mental; (iv) the technical distinction between sensing and perceiving; (v) why phenomenal Direct Realism is incorrect whereas epistemic DR and the representative theory are correct; (vi) the ontological and topological status of phenomenal space and physical space. This leads to considerations of the current ?binding problems? in neuroscience; the role of the brain mechanisms that construct the sensory fields of phenomenal consciousness; the ?homunculus? fallacy; the key difference between epistemic and non?epistemic perception as revealed by brain injury studies; and how the brain codes information, contrasting topological and vectorial coding, with particular reference to the binding problem. My conclusion is that the Identity Theory is incompatible with the scientific evidence from an integrated approach to modern introspectionist psychology, clinical neurology, and neuroscience. However, Cartesian Dualism is even more incompatible with the evidence. This leaves only two viable theories. The first is Bohr's theory of brain?consciousness complementarity. The second is the Broad?Price?Smythies theory of extension, which is a topological theory of the relation between phenomenal space and physical space. (shrink)

Consciousness alterations can be experienced during unstructured, monotonous stimuli. These effects have not been linked to particular cognitive operations; individual differences in response to such stimulation remain poorly understood. We examined the role of hypnotizability and dissociative tendencies in mind-wandering during a sensory homogenization procedure . We expected that the influence of ganzfeld on MW would be more pronounced among highly hypnotizable individuals , particularly those high in dissociative tendencies. High and low hypnotizables, also stratified by dissociation, completed the (...) sustained attention to response task during ganzfeld and control conditions. High dissociative highs made more commission errors during ganzfeld, suggesting increased MW, whereas the other groups displayed the opposite pattern. Increases in commission errors from the control condition to ganzfeld were associated with more alterations in consciousness and negative affect, but only among highs. Sensory homogenization had opposite effects on MW depending on the interaction of hypnotizability and dissociation. (shrink)

Flickering light induces visual hallucinations in human observers. Despite a long history of the phenomenon, little is known about the dependence of flicker-induced subjective impressions on the flicker frequency. We investigate this question using Ganzfeld stimulation and an experimental paradigm combining a continuous frequency scan with a focus on re-occurring, whole percepts. On the single-subject level, we find a high degree of frequency stability of percepts. To generalize across subjects, we apply two rating systems, a set of complex percept (...) classes derived from subjects’ reports and an enumeration of elementary percept features, and determine distributions of occurrences over flicker frequency. We observe a stronger frequency specificity for complex percept classes than elementary percept features. Comparing the similarity relations among percept categories to those among frequency profiles, we observe that though percepts are preferentially induced by particular frequencies, the frequency does not unambiguously determine the experienced percept. (shrink)

Previous studies have shown that misperceptions and illusory experiences can occur if sensory stimulation is withdrawn or becomes invariant even for short periods of time. Using a perceptual deprivation paradigm, we created a monotonous audiovisual environment and asked participants to verbally report any auditory, visual or body-related phenomena they experienced. The data (analysed using a variant of interpretative phenomenological analysis) revealed two main themes: (1) reported sensory phenomena have different spatial characteristics ranging from simple percepts to the feeling of immersion (...) in a complex multisensory environment and (2) the active contribution of the perceiver where participants report engaging in exploratory processes even when there is nothing to find. Detailed analysis of the qualitative data further showed that participants who reported more perceptual phenomena were more likely to report internal bodily sensations, move more during the experiment and score higher on the Revised Hallucination Scale than those reporting fewer percepts explicitly linking perceptual deprivation to somatic phenomena. The results demonstrate how the variety of sensory experiences induced by perceptual deprivation can give further insight into the factors mediating conscious awareness and may suggest ways in which the brain imposes meaning on the environment under invariant sensory conditions. (shrink)

Although the question 'Does psi exist?' has become a recurrent and intransigent problem for psychological science, seen from a historical and social context, there appear to be reasons as to why no determined effort has been made to resolve the question. The sporadic exchanges from parapsychologists and critics appear only to reinforce the status quo: At most, it is agreed that some form of 'anomaly' has been established but there is no consensus about its nature. Yet such a defeatist stance (...) shies away from the long tradition of research into spontaneous phenomena, as well as experimental research with dreams and hypnosis, all of which suggests that, if psi is real, it is not just an anomaly but has true information content and dynamic effects. This work is briefly reviewed and then, since much of the current controversy has centred on the ganzfeld technique, this is used as an example of the issues involved. The ganzfeld induces sleep-onset imagery during which randomly selected film clips are viewed by a sender as a source of psi-mediated information to be incorporated into the imagery. Our current development of the ganzfeld technique, known as the digital autoganzfeld, takes the work beyond 'anomaly status' since it enables real-time recordings to be made of apparently high-quality psi as it enters consciousness. Initial findings from this illustrate the complexity of the phenomena and the need for more adventurous designs in order to stimulate theory development. There is no doubt that technology now exists which would enable us to resolve the issues raised. Whether the area turns out to be a mixture of rampant fraud, artefact and subjective validation or to present genuine phenomena, a resolution of the issue may be seen as having unwanted implications for psychology -- which may be one of the factors explaining why the controversy is left to continue as it is, unresolved. New questions are needed which take into account the natural context in which psi appears to occur, along with the support needed to reach clear answers. (shrink)

Precognition is an anomaly in information transmission and interpretation. Extant literature suggests that paranormal beliefs and gender may have significant influences on this unknown information process. This study examines the effects of these two factors, including their interactions, on precognition performance by employing the Bayesian Mindsponge Framework (BMF) analytics. Using Bayesian analysis on secondary data of 60 participants, we found that men may have higher chances to score a hit in a precognition task compared to women. Interestingly, stronger beliefs in (...) the paranormal may decrease the success probability in performing precognition tasks. Considering the interactions between the two factors, the effect of paranormal beliefs on precognition task performance is stronger in men than women. Using mindsponge-based reasoning, we argue that paranormal beliefs may increase the interference of imagination in the reception of hypothetical precognitive information. Women tend to rely more on intuition, which may lessen the interference effect of imagination on hypothetical psi reception. Based on the findings, we suggest that researchers should be careful when assessing participants’ psi potential for experiments. We also demonstrate some advantages of utilizing the BMF in parapsychological research. (shrink)