Overview

Gertrude R. Schmeidler was among the most prolific and methodologically rigorous experimental parapsychologists of the twentieth century. Her career spanned more than seven decades, during which she conducted hundreds of controlled ESP and psychokinesis (PK) experiments, developed standardized protocols for psi research, and established personality psychology as a central framework for understanding individual differences in psi ability. Her work demonstrated that ESP is not a rare, anomalous phenomenon confined to exceptional individuals, but rather a capacity distributed across the general population and modulated by measurable psychological variables.

Schmeidler’s fundamental contribution was methodological and conceptual: she showed that psi research could be conducted with the same rigor as mainstream experimental psychology, and that individual differences in psi performance could be predicted and explained by personality traits, cognitive styles, and belief systems. This approach transformed parapsychology from a field dominated by anecdotal case studies into one grounded in quantitative, replicable laboratory work. Her influence extended beyond parapsychology itself; her insistence on controlling for personality factors and her development of standardized assessment tools became models for psychological research more broadly.

Life and career

Schmeidler’s entry into parapsychology came through a distinctive intellectual pathway. Early in her career, she collaborated with Gardner Murphy, a prominent psychologist at the City College of New York who had long been interested in psi phenomena. This partnership proved formative. Together, they designed experiments that moved beyond simple hit-or-miss scoring to examine the psychological context in which ESP occurred. Schmeidler’s training in experimental psychology and personality assessment gave her the tools to ask questions that parapsychology had not systematically addressed: not merely “does ESP occur?” but “under what conditions, and in whom?”

Her landmark early work, conducted with Murphy, examined the relationship between belief and ESP performance. In a series of experiments beginning in the 1940s, Schmeidler divided participants into two groups: “sheep” (those who believed ESP was possible) and “goats” (those who were skeptical). The results were striking and consistent: sheep scored significantly above chance on ESP tasks, while goats scored at or below chance.¹⁸ This finding, which became known as the “sheep-goat effect,” established that psychological attitude was not merely a confounding variable to be controlled but a fundamental factor in psi performance itself.

Throughout the 1950s and 1960s, Schmeidler expanded this research program systematically. She investigated the relationship between ESP performance and personality traits measured by standard psychological instruments, including the Rorschach test, the Picture Frustration Study, and various measures of anxiety and creativity.⁹¹⁰¹¹ She published a comprehensive monograph, ESP and Personality Patterns, co-authored with R. A. McConnell, which synthesized years of data and established personality psychology as the dominant framework for understanding individual differences in psi ability.²

In the 1970s and 1980s, Schmeidler’s work became increasingly sophisticated in its use of neurophysiological measures. She collaborated with colleagues to examine the relationship between ESP performance and brain-wave activity, particularly alpha rhythms. In studies with Laurence Lewis, she demonstrated that alpha activity, measured via EEG, showed systematic relationships with ESP success, particularly after feedback training.⁶¹² She also investigated the effects of meditation and breathing instruction on ESP performance, finding that brief training in these techniques could produce significant increases in ESP scores.⁵

Schmeidler’s methodological contributions were equally significant. She developed detailed protocols for controlled ESP research and published a comprehensive guide to research methods in ESP and PK.¹³ Her work on feedback effects (examining how knowledge of results influenced subsequent ESP performance) established feedback as a critical variable in psi research design.⁴ She also conducted pioneering work on precognition, examining whether knowledge of results in precognitive tasks affected scoring patterns.¹⁴

In her later career, Schmeidler continued to publish actively, producing comprehensive reviews of ESP research and comparative analyses of ESP and PK phenomena. A 1994 review of her own experiments conducted between 1978 and 1992 documented the consistency of the sheep-goat effect and other personality-related patterns across hundreds of trials.¹⁵ She also published a detailed examination of PK research, comparing methodological approaches and effect sizes across the literature.¹⁶

Throughout her career, Schmeidler maintained a commitment to studying psi at multiple levels of analysis. In a foundational paper on individual psi experiences, she argued that understanding psi required examining not only aggregate statistical patterns but also the phenomenology of individual psi events, their duration, their accuracy, their relationship to conscious awareness, and the conditions under which they could be identified and potentially controlled.¹⁷ This multi-level approach anticipated contemporary work in consciousness studies and neuroscience.

Research

Personality and individual differences. Schmeidler’s core research program examined how personality traits predicted ESP performance. Her early work with Murphy established the sheep-goat effect, but she went far beyond this initial finding. Using standardized personality assessment tools, she demonstrated that ESP performance correlated with measures of anxiety, creativity, frustration tolerance, and other psychological dimensions.⁹ In one study, she examined Rorschach responses in patients with cerebral concussion, finding systematic relationships between personality patterns evident in the Rorschach and ESP scoring.¹⁰ This work established that psi was not a unitary ability but rather a capacity that varied systematically with measurable psychological characteristics.

Schmeidler’s monograph ESP and Personality Patterns, published in 1958, synthesized data from numerous experiments and established personality psychology as the dominant theoretical framework in parapsychology.¹⁸ The book demonstrated that personality differences could predict ESP performance with reasonable accuracy, and that these relationships held across diverse populations and experimental paradigms. This work influenced an entire generation of parapsychologists to adopt personality-based approaches to psi research.

Cognitive factors and ESP. Beyond personality traits, Schmeidler investigated the relationship between cognitive abilities and ESP performance. She examined the relationship between creativity and ESP, finding that creative individuals showed enhanced ESP performance in some conditions.³ She also investigated the relationship between ESP and memory, proposing that ESP and memory might share underlying cognitive mechanisms. Her research suggested that memory processes could either facilitate or inhibit ESP, depending on the specific conditions of the task.⁷¹⁹

Schmeidler’s work on subliminal perception and ESP explored the boundary between these two phenomena, examining whether ESP might operate through mechanisms similar to those involved in subliminal perception.²⁰ This work was part of her broader effort to integrate psi research with mainstream cognitive psychology, showing that psi phenomena might be understood through the same theoretical frameworks used to explain other aspects of cognition.

Feedback and learning in ESP. A significant portion of Schmeidler’s research examined how feedback (knowledge of results) affected ESP performance. In a series of experiments with Laurence Lewis, she demonstrated that feedback could enhance ESP scoring in subsequent trials, particularly when the feedback indicated success.⁴ She also found that the relationship between feedback and ESP performance was modulated by personality factors; some individuals benefited more from feedback than others.²¹ This work suggested that ESP performance could be improved through training and feedback, opening the possibility of applied uses of psi ability.

Neurophysiological correlates of ESP. In the 1970s, Schmeidler began investigating the relationship between brain-wave activity and ESP performance. Working with colleagues including Laurence Lewis and Michael Maher, she conducted EEG studies examining alpha rhythms during ESP tasks. Her findings indicated that alpha activity showed systematic relationships with ESP success, particularly after feedback training.⁶ She also found that mood changes following alpha feedback training correlated with subsequent ESP performance.¹² Additionally, she investigated cerebral lateralization effects in ESP processing, examining whether ESP information was processed differently by the left and right hemispheres.²²

Meditation and altered states. Schmeidler conducted pioneering research on the relationship between meditation and ESP performance. In one notable study, she found that brief instruction in meditation and breathing techniques produced significant increases in ESP scores.⁵ This work suggested that altered states of consciousness, induced through relatively simple techniques, could enhance psi ability. The findings anticipated later research on the relationship between meditation, mindfulness, and psi phenomena.

Psychokinesis research. While best known for her ESP work, Schmeidler also conducted systematic research on psychokinesis. She published a comprehensive review comparing ESP and PK research, examining methodological similarities and differences, and evaluating the evidence for PK effects.¹⁶ She also published a detailed examination of research findings in psychokinesis, discussing the current state of the evidence and methodological challenges in PK research.²³

Field investigations and spontaneous cases. Schmeidler’s research was not confined to the laboratory. She conducted field investigations of allegedly haunted locations, using both sensitive individuals and control groups to examine claims of paranormal activity. In one notable study, she conducted a quantitative investigation of a “haunted house,” examining whether sensitives reported more paranormal phenomena than controls.²⁴²⁵ She also analyzed proxy sessions with mediums, examining the accuracy of information obtained through mediumistic channels.²⁶

Methodological development. Throughout her career, Schmeidler was deeply concerned with methodological rigor. She published a comprehensive guide to research methods in ESP and PK, detailing protocols for controlled experiments, discussing sources of error and bias, and providing practical guidance for researchers.¹³ Her work on precognition included detailed analysis of scoring reliability and the statistical methods appropriate for evaluating precognitive data.²⁷ She also contributed to discussions of how to evaluate the accuracy of parapsychological information, examining the relationship between hit rates and information content.²⁸

Influence and reception

Schmeidler’s influence on parapsychology has been profound and enduring. Her demonstration of the sheep-goat effect established that psychological factors were central to understanding psi phenomena, fundamentally shifting the field’s theoretical orientation. Rather than viewing psi as a rare, anomalous ability confined to exceptional individuals, her work showed that psi was a distributed capacity present in the general population and modulated by measurable psychological variables. This reframing made psi research more amenable to systematic psychological investigation and opened new avenues for understanding the mechanisms underlying psi phenomena.

Her methodological contributions were equally significant. By insisting on the use of standardized personality assessment tools, controlled experimental designs, and quantitative analysis, Schmeidler elevated the standards of rigor in parapsychology. Her detailed protocols for ESP research became models for laboratories worldwide. Her work demonstrated that psi research could be conducted with the same methodological sophistication as mainstream experimental psychology, lending credibility to the field and attracting researchers trained in rigorous experimental methods.

Schmeidler’s integration of psi research with mainstream psychology was particularly influential. By examining relationships between ESP and established psychological constructs (personality traits, cognitive abilities, emotional states, brain-wave activity) she showed that psi phenomena were not isolated anomalies but rather aspects of normal psychological functioning. This approach made psi research relevant to psychologists and neuroscientists who might otherwise have dismissed parapsychology as outside the bounds of legitimate science.

Her work on individual psi experiences and the need for multi-level analysis anticipated contemporary approaches in consciousness studies and neuroscience. Her argument that understanding psi required examining phenomena at multiple levels of analysis (from aggregate statistical patterns to individual phenomenological experiences) remains relevant to current research on consciousness and anomalous cognition.

Schmeidler’s prolific publication record, spanning more than seven decades and including hundreds of experimental reports, methodological papers, and comprehensive reviews, established her as the most extensively published parapsychologist of her era. Her 1994 review of her own experiments conducted between 1978 and 1992 documented the consistency of her findings across hundreds of trials, providing compelling evidence for the reliability of personality-related patterns in ESP performance.¹⁵

Her work has continued to be cited and built upon by contemporary researchers. The sheep-goat effect remains one of the most robust and frequently replicated findings in parapsychology. Her personality-based approach to understanding psi has influenced research on individual differences in anomalous cognition, and her methodological standards continue to guide experimental design in parapsychology laboratories.

Beyond parapsychology proper, Schmeidler’s work has influenced research on the relationship between personality and perception, the effects of feedback on learning, and the relationship between altered states of consciousness and cognitive performance. Her insistence on rigorous methodology and her integration of psi research with mainstream psychology have made her work relevant to researchers in diverse fields.