The Ganzfeld Experiments: Sensory Deprivation, Psi, and the Search for Telepathy

An in-depth exploration of one of parapsychology's most rigorous and debated research programs

Introduction: The Problem of Signal and Noise

Among all the experimental protocols developed in the long history of psychical research, few have proven as enduring, as methodologically refined, or as controversially productive as the Ganzfeld technique. The word itself is German, meaning "total field" or "whole field," and it refers to a state of perceptual homogeneity — a condition in which the sensory system, deprived of structured input, is believed by some researchers to open itself to subtler forms of information transfer. For decades, parapsychologists have used this procedure to investigate the possibility of telepathy and clairvoyance under controlled laboratory conditions, generating a body of literature that remains fiercely disputed and yet stubbornly resistant to easy dismissal.

The central idea is both elegant and counterintuitive: that the noise of ordinary sensory experience may actively suppress the reception of psi signals, and that by reducing that noise to near zero, researchers might amplify whatever faint channel of anomalous communication exists between minds. Whether or not such a channel exists at all is, of course, the central question — one that the Ganzfeld program has spent more than fifty years attempting to answer.

Historical Background: From Gestalt Psychology to Parapsychology

The Ganzfeld effect was not invented by parapsychologists. Its origins lie in the academic study of perception, particularly within the tradition of Gestalt psychology in the early twentieth century. The German psychologist Wolfgang Metzger, working in the 1930s, was among the first to systematically describe what happens when the visual field is flooded with uniform, undifferentiated light. Rather than seeing nothing, subjects experienced vivid hallucinations, phosphene-like visual phenomena, and profound alterations in their sense of depth and space. The brain, it seemed, could not sustain a state of true perceptual blankness — deprived of structure, it began generating its own.

This observation caught the attention of Charles Honorton, a young American parapsychologist working at the Maimonides Medical Center in Brooklyn during the late 1960s. Honorton had been deeply involved in the dream telepathy studies being conducted there by Montague Ullman and Stanley Krippner, in which sleeping subjects were monitored for REM activity while distant "senders" attempted to transmit images into their dreams. Those studies had produced suggestive results, but dreams were notoriously difficult to control and standardize. Honorton began to wonder whether the altered state of consciousness produced by dreaming might be mimicked in a waking subject through sensory reduction, making the Ganzfeld procedure not merely a perceptual experiment but a potential gateway to anomalous cognition.

Honorton's insight drew on a broader theoretical model that had been gaining traction in parapsychology — the idea, sometimes called the "noise reduction model," that psi signals are weak and easily overwhelmed by the constant bombardment of ordinary sensory and cognitive processing. If this were true, then reducing that processing to a minimum might allow the signal to emerge from the background. The Ganzfeld, with its capacity to produce a reliable and replicable altered state in ordinary laboratory subjects without the use of drugs or sleep, seemed an ideal vehicle for testing this hypothesis.

The Standard Protocol: How a Ganzfeld Session Works

The basic Ganzfeld procedure has remained largely consistent across decades of research, though it has been refined and elaborated in numerous ways. In its standard form, it involves two participants: a "receiver" and a "sender," housed in separate, acoustically isolated rooms. The receiver is prepared for the session through a process of progressive relaxation, typically guided by a recorded voice leading them through a systematic release of muscular tension and mental activity. This relaxation phase usually lasts between ten and fifteen minutes and is considered essential for inducing the receptive mental state that the procedure depends upon.

Once relaxed, the receiver is placed in a condition of sensory attenuation. Halved ping-pong balls — translucent and smooth — are taped over their eyes, and a source of diffuse red or white light is directed at their face, flooding the visual field with uniform illumination. Because the ping-pong ball halves eliminate any sharp edges or structures in the visual environment, the brain rapidly loses its ability to track or fixate on external objects. Within minutes, most subjects report the characteristic visual phenomena associated with the Ganzfeld state: swirling colors, geometric patterns, and eventually more complex imagery ranging from abstract shapes to fully formed scenes and figures.

Simultaneously, the receiver wears headphones through which white noise or pink noise is played continuously, masking any ambient sounds and filling the auditory field with the same kind of undifferentiated input that the ping-pong balls provide for vision. The combined effect is a thorough reduction of patterned sensory input across the dominant sensory channels, inducing a mild but reliable altered state that many subjects describe as dreamlike, hypnagogic, or reminiscent of deep meditation.

While the receiver is undergoing this experience, the sender — located in a separate room with no sensory connection to the receiver — is shown a randomly selected target. In the classic design, targets were photographs or short video clips chosen from a pool of images spanning a wide range of content: natural scenes, human activities, artworks, abstract compositions, and so forth. The sender is instructed to concentrate on the target as intently as possible, sometimes employing active visualization techniques, sometimes simply holding the image in mind while attempting to transmit it to the receiver.

Throughout the session, which typically lasts between twenty and thirty minutes, the receiver speaks aloud in a continuous stream of consciousness, describing whatever thoughts, images, feelings, and impressions arise in their awareness. This monologue is recorded and may also be monitored in real time by the experimenter. At the end of the session, the receiver is brought out of the Ganzfeld state and presented with a set of four images — one of which is the actual target, and three of which are decoys drawn from the same pool. Without being told which image was the target, the receiver rates each one for its correspondence to their Ganzfeld impressions, and selects the one they consider most likely to have been the sender's focus.

Under chance conditions, a correct selection would be expected in one out of four trials — a hit rate of 25 percent. The question that decades of Ganzfeld research have attempted to answer is whether the actual hit rate, aggregated across many subjects and many studies, significantly exceeds this chance baseline.

The First Wave: Honorton's Meta-Analysis and the Hyman Debate

By the early 1980s, a sufficient number of Ganzfeld studies had accumulated in the parapsychological literature to permit a formal statistical synthesis. Charles Honorton undertook this analysis, examining 28 studies from ten different laboratories involving 835 subjects. His results, published in 1985, reported an overall hit rate of approximately 38 percent — substantially and statistically significantly above the 25 percent expected by chance. Honorton argued that this effect was robust across independent laboratories and experimenters, suggesting that the results could not be easily attributed to the idiosyncratic practices of any single research group.

This claim was met with immediate and detailed scrutiny from Ray Hyman, a cognitive psychologist and longtime skeptic of parapsychological claims. Hyman conducted his own analysis of the same database and concluded that the studies were riddled with methodological flaws sufficient to explain the positive results without invoking telepathy. His criticisms centered on several issues: inadequate randomization procedures for target selection, sensory leakage between sender and receiver rooms that might have allowed subtle cues to pass, inadequate blinding of experimenters who knew which target had been selected, and multiple analysis problems including the selective reporting of significant results.

The resulting exchange between Honorton and Hyman became one of the most detailed and consequential debates in the history of parapsychology. What made it unusual was its civility and its rigor: both men took each other's arguments seriously, and both acknowledged that certain of the criticisms were valid while contesting others. The outcome of this extended dialogue was a joint communiqué, published in 1986, in which Honorton and Hyman agreed on a set of minimal methodological standards that future Ganzfeld research would need to meet in order to be considered credible. These standards addressed randomization, target selection, sender-receiver isolation, experimenter blinding, and statistical analysis protocols.

This negotiated framework for future research was itself a significant development, representing an unusually productive collision between parapsychological research and mainstream scientific skepticism. The agreed-upon standards formed the basis for what would become the "autoganzfeld" program — a technologically upgraded version of the procedure designed to eliminate the specific flaws that Hyman had identified.

The Autoganzfeld: Technology in Service of Rigor

Working at the Psychophysical Research Laboratories in Princeton, New Jersey, Honorton and his colleagues developed an automated version of the Ganzfeld procedure that replaced human judgment with computer control at every stage of the process where bias might otherwise intrude. The autoganzfeld, as it came to be known, represented a major methodological advance over earlier studies.

In the autoganzfeld protocol, target selection was handled entirely by computer, with random number generation determining which of a large pool of videotaped clips would be assigned to any given session. The clips themselves — short segments drawn from films, nature documentaries, and artistic works — were stored in a secure library and presented to the sender via a monitor in an isolated room. The selection process was completely inaccessible to any human participant or experimenter until after the receiver had completed their session and made their judgment.

The rooms used in the autoganzfeld studies were built to professional acoustic isolation standards, ensuring that no sounds from the sender's room could reach the receiver. Electromagnetic shielding further reduced the possibility of inadvertent signal leakage. The receiver's verbal report was recorded but not monitored in real time by anyone who knew the target, eliminating the possibility that subtle cues from an experimenter might guide the receiver's responses. At the judging stage, the receiver was presented with all four options simultaneously on a video monitor and asked to rank and rate them; again, the experimenter present at this stage had no knowledge of which clip had been the target.

Honorton ran 354 sessions across 11 series between 1983 and 1989 using this automated procedure. The results showed a hit rate of 32 percent — above chance at a level of statistical significance that, by conventional scientific standards, would be considered strong evidence of a genuine effect. The effect appeared consistent across different series and different experimenters. Honorton published these results in 1990 in collaboration with Diane Ferrari, and the data attracted considerable attention both within parapsychology and in the broader scientific community.

The Bem and Honorton Paper: Parapsychology Enters the Mainstream

A pivotal moment in the history of Ganzfeld research came in 1994, when Daryl Bem — a prominent social psychologist at Cornell University with no prior involvement in parapsychology — co-authored a paper with Honorton in the prestigious Psychological Bulletin, one of the most highly regarded journals in academic psychology. The paper, titled "Does psi exist? Replicable evidence for an anomalous process of information transfer," presented a comprehensive review of the Ganzfeld database and argued that the evidence met conventional scientific standards for accepting the reality of a novel phenomenon.

Bem's involvement was significant for several reasons. His reputation as a mainstream psychologist lent credibility to the research in quarters that would have dismissed a paper authored solely by parapsychologists. His writing was technically sophisticated and closely argued, making it difficult to dismiss on superficial grounds. And the venue — Psychological Bulletin — ensured that the paper would be read and taken seriously by a large audience of professional psychologists who would otherwise never have engaged with parapsychological literature.

The paper reported an overall effect size across the Ganzfeld database that was modest but consistent, and it included a careful analysis of potential artifacts and confounds. It also highlighted several internal patterns in the data that were difficult to explain by simple statistical artifact: for example, the finding that subjects who had prior experience with meditation or other contemplative practices performed significantly better than those without such experience, as did subjects who described themselves as believers in psi. These secondary findings were consistent with the noise reduction model and added a layer of interpretive complexity to the basic hit rate results.

The paper was published alongside a commentary from Ray Hyman and a reply from Bem and Honorton, creating a structured scientific exchange that allowed the debate's main lines to be aired in a single venue. Hyman maintained his skepticism but acknowledged that the autoganzfeld studies had addressed many of the methodological problems he had identified in the earlier database. His remaining criticisms focused on issues of multiple analysis, publication bias, and the absence of a convincing theoretical mechanism for the claimed effect.

The Replication Problem: What Happened Next

The Bem and Honorton paper generated a wave of replication attempts, and here the history becomes considerably more complicated. A number of independent laboratories undertook Ganzfeld studies in the years following the paper's publication, and their results were inconsistent in ways that created new interpretive difficulties.

Some laboratories reported positive results broadly consistent with the earlier database. Others, including several with strong methodological credentials, reported chance-level performance or effects that fell short of statistical significance. A meta-analysis conducted by Julie Milton and Richard Wiseman in 1999, covering 30 studies conducted after the Bem-Honorton paper and meeting the methodological standards Honorton and Hyman had jointly specified, found no significant overall effect. This was a serious challenge, since a genuine psi effect should, in principle, be replicable under adequate conditions.

The response from parapsychologists was multifaceted. Some argued that the Milton-Wiseman database included studies of insufficiently high quality, and that restricting the analysis to studies meeting stricter criteria restored the positive effect. Others suggested that the variable results across laboratories reflected genuine variability in the psi-conducive conditions of different research environments — a claim that, while theoretically plausible, is difficult to operationalize in a way that does not risk circularity.

A subsequent meta-analysis by Daryl Bem, John Palmer, and Richard Broughton, published in 2001, examined a larger and differently defined database and reported a significant overall effect. The methodological argument about which studies to include and how to weight them has continued ever since, with different analysts reaching different conclusions depending on their inclusion criteria and their assessments of study quality.

Autoganzfeld Studies at the University of Edinburgh

Among the most important replication programs to follow the autoganzfeld work was that conducted at the Koestler Parapsychology Unit at the University of Edinburgh — one of the few academic institutions in the world to maintain a formally constituted research program in parapsychology. The Edinburgh group undertook a series of Ganzfeld studies using protocols closely modeled on the autoganzfeld design, with careful attention to the methodological standards that had been established through the Honorton-Hyman dialogue.

The Edinburgh results were mixed. Some series yielded significant hit rates, while others did not. The overall effect across the Edinburgh database was positive but modest, and researchers there have been notably candid about the difficulties of achieving consistent replication. Work by researchers including Robin Fife, Caroline Watt, and others at Edinburgh has contributed substantially to the field's understanding of which procedural variables may moderate the Ganzfeld effect, including factors such as experimenter effects, the relationship between sender and receiver, and the nature of the target materials used.

The Edinburgh group has also been at the forefront of examining possible artifactual explanations for positive Ganzfeld results. Studies examining sensory leakage, statistical artifacts, and the role of demand characteristics have generally not found these explanations sufficient to account for the positive results, while also not conclusively establishing the presence of a genuine anomalous effect. The honest complexity of the Edinburgh work stands as a model of how parapsychological research can be conducted with genuine scientific rigor.

The Noise Reduction Model and Theoretical Interpretations

Underlying the Ganzfeld procedure is a theoretical framework that has evolved considerably since Honorton's early formulations. The noise reduction model, in its basic form, proposes that psi — whatever its ultimate nature — operates as a weak signal that is normally swamped by the continuous processing demands of ordinary sensory and cognitive activity. The Ganzfeld reduces this activity, and in doing so potentially allows the psi signal to achieve threshold and enter awareness.

This model draws implicitly on information-theoretic concepts, treating the mind as a signal-processing system with a finite capacity that, when occupied with ordinary sensory traffic, has little bandwidth available for anomalous channels. The analogy is sometimes made to radio reception: a station may be broadcasting continuously, but it will not be heard if the listener is in a noisy environment or tuned to the wrong frequency. Reducing environmental noise, or shifting the mind's attentional "tuning," may improve reception.

More elaborate theoretical frameworks have been proposed to explain why the Ganzfeld state specifically might be conducive to psi. Some researchers have noted the similarity between the hypnagogic state — the transitional condition between waking and sleeping, characterized by vivid involuntary imagery — and the phenomenology reported by Ganzfeld subjects. The hypnagogic state is associated with decreased prefrontal regulatory activity and increased spontaneous activity in visual and associative cortical areas, and it has long been associated in folk tradition and in some experimental work with heightened psychic sensitivity.

Others have drawn on quantum mechanical interpretations of consciousness, suggesting that quantum nonlocality might provide a mechanism for the kind of instantaneous, non-signal-mediated information transfer that psi would require. These proposals remain highly speculative and are contested even within parapsychology, but they represent a genuine effort to situate the Ganzfeld findings within a broader scientific framework rather than simply asserting their reality without mechanistic explanation.

A different approach focuses not on the physics of information transfer but on the phenomenology of the Ganzfeld state itself. Researchers including Stanley Krippner and Cheryl Alexander have emphasized the importance of the imagery that arises during the Ganzfeld experience, arguing that this imagery is not random noise but has a structure that may reflect the receiver's scanning of information from multiple sources — including, potentially, the sender's mental content. On this view, the Ganzfeld state does not so much open a new channel as it removes interference from a channel that is always present but normally suppressed.

Individual Differences and Moderating Variables

One of the most consistently replicated findings across the Ganzfeld literature is that not all subjects perform equally. Several individual difference variables have been reported to predict Ganzfeld performance with some consistency, and their patterns are theoretically suggestive even if none of them constitutes proof of psi.

Belief in the existence of psi — operationalized through questionnaire measures such as the Sheep-Goat Scale developed by Gertrude Schmeidler — has been associated with better Ganzfeld performance in a number of studies, a finding consistent with the broader "sheep-goat effect" observed across many domains of parapsychological research. Whether this reflects a genuine causal relationship, a motivational or attitudinal effect on the quality of the receiver's engagement, or an artifact of some kind remains unclear.

Experience with meditation, relaxation practices, and other forms of contemplative training has emerged as one of the more robust predictors of Ganzfeld success. In a series of studies conducted by Honorton and replicated by other researchers, subjects with prior meditation experience showed significantly higher hit rates than those without. This finding is theoretically coherent with the noise reduction model, since meditation training presumably enhances the subject's ability to achieve and maintain the quiet, receptive mental state that the Ganzfeld procedure is designed to induce.

Creative individuals — defined variously as professional artists, musicians, or actors, or as those scoring high on psychometric measures of creativity — have also shown elevated Ganzfeld performance in several studies. A series of studies conducted with students at the Juilliard School in New York found particularly high hit rates among music and theater students, results that have been replicated in other samples of creative individuals. The theoretical connection between creativity and psi remains somewhat obscure, but some researchers have suggested that both may involve enhanced access to pre-reflective or non-analytical cognitive processing — the kind of associative, imagery-rich mental activity that the Ganzfeld is designed to facilitate.

The relationship between sender and receiver has also emerged as a potentially significant variable. Several studies have found higher hit rates when the sender and receiver are personally acquainted, friends, or in a close relationship, compared to pairs of strangers. This finding resonates with anecdotal reports of spontaneous psi experiences, which overwhelmingly tend to occur between emotionally bonded individuals, and with theoretical perspectives that emphasize the role of emotional connection in facilitating anomalous information transfer.

Skeptical Analyses and Alternative Explanations

The Ganzfeld literature has been subjected to sustained skeptical scrutiny, and the criticisms that have been raised deserve serious consideration. Beyond the methodological issues identified by Hyman in the early 1980s, several other potential sources of artifact have been proposed and investigated.

Publication bias — the tendency for positive results to be submitted and accepted for publication while negative results remain in file drawers — is a pervasive problem in experimental psychology that has particular relevance for parapsychology, where the stakes of a positive finding are unusually high and the field's journals may be especially susceptible to the selection effects that drive positive results into print. Various statistical techniques have been developed to estimate the number of null results that would need to exist in file drawers to reduce a meta-analytic effect to nonsignificance, and while these analyses have generally suggested that implausibly large numbers of null studies would be required to explain the Ganzfeld results, such analyses cannot rule out publication bias entirely.

Sensory leakage — the possibility that subtle cues allow the receiver or experimenter to infer the identity of the target without any anomalous process being involved — has been a consistent concern. The autoganzfeld design addressed many of the obvious routes for such leakage, but critics have suggested that acoustic and electromagnetic isolation may not be complete in practice, and that experimenter effects may operate in ways that are genuinely difficult to control. Studies in which the experimenter is completely blind to the target from selection through judging have generally continued to show positive effects, but the possibility of subtle uncontrolled cueing cannot be entirely excluded.

The "optional stopping" problem — the possibility that experimenters may terminate a series of trials when a significant result has been achieved rather than running a predetermined number of sessions — is another potential artifact that has been raised. The autoganzfeld protocol addressed this by specifying the number of sessions in advance, but earlier studies may have been vulnerable to this issue.

Susan Blackmore, a psychologist who spent many years attempting to replicate Ganzfeld effects and consistently failing to do so, has offered a more general critique: that the positive results in the database reflect not psi but the cumulative operation of small and individually innocent methodological imperfections, each of which adds a small upward bias to the hit rate. On this view, no single identifiable flaw is responsible for the effect; rather, it emerges from the combined action of many subtle influences that become visible only when studies are aggregated across a large database.

The Ganzfeld and Neuroscience: Brain States and Psi

A relatively recent development in Ganzfeld research has been the incorporation of neuroimaging and electrophysiological methods, reflecting the broader turn in parapsychology toward biological and neuroscientific frameworks. If the Ganzfeld state is genuinely conducive to psi, it may be associated with identifiable neural characteristics that distinguish it from ordinary waking consciousness, and those characteristics might provide clues about the neural mechanisms through which anomalous information transfer could operate — or might reveal that the state is simply a known variety of altered consciousness without any special psi-relevant properties.

EEG studies of subjects in the Ganzfeld state have generally confirmed that it is associated with increased slow-wave activity — particularly in the alpha and theta frequency bands — relative to ordinary waking consciousness. Alpha activity is typically associated with relaxed, unfocused awareness, while theta activity is characteristic of the hypnagogic state and light sleep. These findings are consistent with subjects' phenomenological reports and with the theoretical claim that the Ganzfeld produces a distinctive altered state rather than simply a mild relaxation response.

More directly relevant to the psi question are studies that have attempted to correlate neural activity in the receiver with the content of the target material being concentrated upon by the sender. A small number of studies have reported correlations between specific features of the receiver's EEG — such as power in particular frequency bands at particular scalp locations — and characteristics of the target, but these findings are preliminary and have not been replicated with sufficient consistency to support strong conclusions.

The Ganzfeld in the Broader Context of Consciousness Research

Whatever one concludes about the psi hypothesis, the Ganzfeld procedure has made genuine contributions to the scientific understanding of altered states of consciousness. The careful documentation of the phenomenology that subjects experience — the characteristic progression from diffuse visual noise through structured imagery to sometimes elaborate and detailed scenes — has provided a reliable and reproducible window into the processes by which the brain generates experience in the absence of external input.

These observations intersect with broader research programs in the neuroscience of consciousness, including work on sensory deprivation, flotation tank experiences, and the phenomenology of hallucination in clinical and non-clinical populations. The Ganzfeld state occupies a distinctive position in the spectrum of altered states: it is mild enough to be routinely induced in normal subjects without distress, stable enough to persist for extended periods, and rich enough in phenomenological content to support detailed self-report. These properties make it a useful tool for consciousness research independent of any psi claims.

Some researchers have drawn connections between Ganzfeld phenomenology and the experiences reported in near-death episodes, sensory deprivation experiments, and certain stages of meditation. The dissolution of the boundary between self and environment that many Ganzfeld subjects report resonates with the phenomenology of mystical experience more broadly, suggesting that the procedure may be tapping into a mode of consciousness with deep evolutionary and cultural roots rather than simply producing a trivial artifact of reduced sensory input.

Where the Research Stands Today

The Ganzfeld database now spans more than four decades of research conducted across multiple laboratories, continents, and research traditions. The overall picture is one of a modest but persistent anomaly: a hit rate that consistently runs a few percentage points above what chance would predict, that resists straightforward methodological debunking, and that remains without a convincing conventional explanation. At the same time, the effect has proven frustratingly difficult to replicate in a controlled and systematic way, and the absence of a plausible mechanism continues to make it difficult for mainstream science to engage with the findings on their own terms.

The Ganzfeld program has also shaped parapsychology as a discipline in important ways. The Honorton-Hyman exchange established a template for productive engagement between parapsychological researchers and mainstream scientific critics — one characterized by mutual rigor rather than mutual dismissal. The methodological standards developed through that exchange, and operationalized in the autoganzfeld design, have raised the overall quality of experimental work in the field. And the incorporation of quantitative meta-analytic methods has provided a framework for aggregating results across studies in a way that allows the cumulative evidence to be assessed with some degree of rigor.

Contemporary researchers continue to investigate Ganzfeld effects, with increasing attention to individual differences, to the role of the sender-receiver relationship, and to the integration of neuroimaging methods. The question of whether a genuine anomaly exists remains open, as do the deeper questions of what such an anomaly would mean for our understanding of mind, consciousness, and the nature of information.

Conclusion: An Unresolved Experiment

The Ganzfeld experiments occupy a peculiar position in the landscape of scientific inquiry. They are too methodologically sophisticated to dismiss as mere anecdote or self-deception. They are too inconsistently replicated to be accepted as established science. They are too persistently present in the literature to be ignored. And they are too theoretically challenging — requiring, if genuine, a fundamental revision of our understanding of how information can travel between minds — to be absorbed into existing frameworks without great difficulty.

What the Ganzfeld program has achieved, beyond any particular claim about telepathy or clairvoyance, is a serious demonstration that questions about the boundaries of mind can be investigated with rigor and precision, and that the results of such investigations deserve to be taken seriously rather than dismissed on a priori grounds. Whether the modest excess of hits observed across the Ganzfeld database reflects a genuine anomaly in nature, a subtle artifact of experimental procedure, or something else entirely — some interaction between expectation, altered consciousness, and the remarkable flexibility of human perception — remains, as of this writing, genuinely unknown.

That uncertainty is uncomfortable. It is also, perhaps, precisely where the most interesting science lives.

References and further reading: Bem, D.J., & Honorton, C. (1994). Does psi exist? Psychological Bulletin, 115(1), 4–18. | Honorton, C. (1985). Meta-analysis of psi Ganzfeld research. Journal of Parapsychology, 49, 51–91. | Milton, J., & Wiseman, R. (1999). Does psi exist? Lack of replication of an anomalous process of information transfer. Psychological Bulletin, 125(4), 387–391. | Storm, L., Tressoldi, P.E., & Di Risio, L. (2010). Meta-analysis of free-response studies, 1992–2008. Psychological Bulletin, 136(4), 471–485.