Overview

May’s investigation of precognition and presentiment represents a systematic effort to identify and characterize physiological correlates of anomalous anticipation. Rather than treating precognition as a purely cognitive or subjective phenomenon, he approached it as a measurable autonomic response that could be detected through psychophysiological methods. This approach shifted the focus from anecdotal reports to controlled laboratory experiments where stimulus timing could be precisely controlled and physiological responses objectively recorded.

Central to May’s work is the distinction between precognition (knowledge of future events) and presentiment, the physiological anticipation of those events. While precognition implies conscious or unconscious awareness, presentiment describes the body’s apparent ability to respond to stimuli before they occur. May’s research has primarily focused on presentiment as a measurable phenomenon, examining whether the autonomic nervous system exhibits differential responses to future emotional versus neutral stimuli.

May’s theoretical perspective suggests that precognition may be more fundamental than other forms of psi. Rather than viewing remote viewing, psychokinesis, or other phenomena as independent mechanisms, he has proposed that precognition could underlie apparent instances of these other abilities, with organisms unconsciously selecting actions or information based on future outcomes.

Skin conductance and presentiment

One of May’s most significant contributions to presentiment research involves the use of skin conductance as a dependent measure. Working with collaborators, he conducted experiments in which participants were exposed to randomly selected stimuli (some emotionally arousing and others neutral) while their skin conductance was continuously monitored. The critical innovation was examining whether skin conductance responses occurred in the prestimulus period, before the stimulus was presented.

In a landmark study, May and Spottiswoode examined skin conductance responses to acoustic startle stimuli.¹ Participants heard 20 stimuli per session, with a 50% probability of receiving an audio startle or a silent control. Stimulus type was determined by a true random generator only moments before presentation. The researchers found a significant effect in the proportions of 3-second epochs prior to stimuli in which skin conductance responses occurred. The effect size was modest but statistically significant, with a Z-score of 3.27 and p-value of 5.43 × 10⁻⁴.

Importantly, May and Spottiswoode systematically examined potential artifacts that could explain their results. They considered whether idiosyncratic responses to stimuli, amplitude outliers, or other methodological confounds could account for the prestimulus effect. By using audio startle stimuli rather than photographs, they avoided the problem of individual differences in emotional responses to pictorial content. Their analysis demonstrated that significant prestimulus effects could be detected even without relying on average-based epoch analyses, which are sensitive to outliers.

A notable finding was the correlation between prestimulus response magnitude and participant lability, the tendency toward physiological variability. Participants with higher lability showed stronger prestimulus skin conductance responses, suggesting that individual differences in autonomic reactivity may predict susceptibility to presentiment effects.¹

May extended this work to examine anomalous anticipatory skin conductance responses to acoustic stimuli in additional experiments.⁴ These studies further documented the phenomenon and explored potential mechanisms underlying the anticipatory response. The consistency of findings across multiple experiments and stimulus types strengthened the case that presentiment represents a genuine physiological phenomenon rather than a methodological artifact.

The multiphasic model of precognition

To account for the temporal dynamics and individual variability observed in precognitive and presentiment research, May and Marwaha developed the multiphasic model of precognition.³ This model proposes that precognitive processing occurs through multiple phases, each with distinct temporal and phenomenological characteristics. Rather than treating precognition as a unitary phenomenon, the multiphasic approach recognizes that different aspects of future information may be accessed through different mechanisms or at different times.

The multiphasic model provides a framework for understanding why precognitive effects vary in magnitude and consistency across experiments and individuals. Some phases of precognitive processing may be more robust or more easily detected than others. The model also accounts for the observation that presentiment effects, while statistically significant, typically show modest effect sizes, they represent one component of a more complex system of anomalous anticipation.

This theoretical development reflects May’s broader approach to understanding psi phenomena: rather than seeking a single mechanism or explanation, he has worked to develop models that accommodate the empirical complexity observed in laboratory data. The multiphasic model suggests that precognition is not a simple, all-or-nothing ability but rather a multifaceted process involving different temporal phases and potentially different neural or physiological substrates.

Theoretical implications

May has proposed that precognition may be the fundamental form of psi, with other apparent psi phenomena potentially reducible to precognitive mechanisms.² This perspective suggests that what appears to be direct influence on physical systems (psychokinesis) or direct access to distant information (remote viewing) might instead reflect unconscious precognitive selection. An organism might unconsciously “know” which action will lead to a desired outcome and select that action, creating the appearance of direct influence. Similarly, remote viewing success might reflect precognitive access to information about which target will be selected, rather than simultaneous perception of a distant location.

This theoretical framework has implications for how we interpret experimental results across different psi domains. If precognition is indeed fundamental, then improving our understanding of precognitive mechanisms could illuminate the nature of other psi phenomena. Conversely, the modest effect sizes typically observed in precognition research suggest that if other psi phenomena are precognitive in nature, they may operate through similarly subtle mechanisms.

May’s emphasis on physiological markers of precognition also reflects a broader theoretical commitment: that psi phenomena, while anomalous from the perspective of conventional physics, are nonetheless biological phenomena that should be detectable through standard psychophysiological methods. The autonomic nervous system, which evolved to respond to immediate threats and opportunities, may retain the capacity to respond to future threats and opportunities, a capacity that could have provided evolutionary advantages to organisms capable of detecting imminent danger or opportunity.

Methodological considerations

May’s work on precognition and presentiment has been characterized by careful attention to methodological detail and artifact control. In developing protocols for studying presentiment, he and his colleagues have worked to eliminate or account for potential confounds that could produce false positive results.

One key methodological innovation involved the use of true random number generators to determine stimulus type, ensuring that stimulus selection could not be influenced by experimenter bias, participant expectations, or any systematic pattern. By determining stimulus type only moments before presentation, May ensured that participants could not unconsciously perceive cues about upcoming stimuli through conventional sensory channels.

May also developed specific protocols for data collection and analysis in precognition research.⁵ These protocols were designed to maximize the sensitivity of experiments to genuine precognitive effects while minimizing the risk of detecting artifacts or statistical flukes. The emphasis on standardized protocols reflects May’s recognition that reproducibility and methodological consistency are essential for establishing the reality of precognitive phenomena.

In examining the quality of precognitive remote viewing performance, May investigated how well precognitive accuracy could be improved through refined analytical techniques.⁶ This work addressed the practical question of whether precognitive remote viewing could be developed into a reliable operational capability, while also providing insights into the factors that enhance or limit precognitive accuracy.

Throughout his research on precognition and presentiment, May has maintained a commitment to transparency regarding both positive findings and null results. His systematic examination of potential artifacts and alternative explanations reflects the scientific principle that extraordinary claims require extraordinary evidence. While his findings suggest that precognition and presentiment are real phenomena worthy of serious investigation, he has consistently acknowledged the modest effect sizes and the need for continued research to fully understand these phenomena.