In 1979 Robert G. Jahn, Dean of the Princeton School of Engineering and Applied Sciences and a leading plasma propulsion researcher for NASA, set up a laboratory in the basement of his engineering building dedicated to the question whether human consciousness can physically and measurably influence electronic random number generators: the Princeton Engineering Anomalies Research Lab, PEAR for short. What began as an undergraduate side project grew into the largest institutional micro-psychokinesis study in the world: 28 years of operation, around 2.5 million individual trials, a combined statistic with Z-scores beyond Z = 7, and a closure in 2007 that made the front pages of the New York Times.
Who was Robert Jahn?
Robert G. Jahn (1930–2017) was no fringe researcher. He earned his PhD in physics at Princeton in 1955, stayed on as an aerospace engineer, and became Dean of the School of Engineering and Applied Sciences in 1971. His main field: electric propulsion for spaceflight – ion thrusters, plasma physics. He advised NASA and the US Department of Defense, was a Fellow of the American Institute of Aeronautics and Astronautics, and had written a substantial standard textbook on plasma physics well before PEAR.
At his side, from 1979, was Brenda Dunne, a developmental psychologist with prior experience in psi research at the University of Chicago. She became Laboratory Manager and remained for all 28 years the methodological and analytical half of the project. Without this combination – an engineering dean with institutional standing and a psychologist with study-design experience – PEAR would not have been possible.
The undergraduate thesis that grew into an institution
The starting point in 1976/77 was a senior thesis by a Princeton engineering student who wanted to investigate the influence of human intention on electronic random number generators. Jahn, initially sceptical, agreed to supervise because the methodological question interested him. The results were statistically small but consistent – strong enough that Jahn decided to pursue the topic systematically. PEAR was formally established in 1979, initially funded out of Princeton resources, later largely by the McDonnell family (James S. McDonnell, the founder of McDonnell Aircraft) and other foundations.
Random Event Generators: quantum noise as experimental setup
PEAR's main instrument was the REG – a Random Event Generator. At its core, an electronic circuit that produces a binary random sequence from the quantum noise of a Zener diode or a resistor. The device generates 200 binary events ("0" or "1") per second. Over a minute that adds up to 12,000 bits. Statistically one expects on average 6,000 ones; real deviations normally lie within a narrow band around the standard deviation.
The test subject – in PEAR jargon the "operator" – sits without physical contact in front of the device and tries, by pure mental intention, to shift the expected value of the bit sum in a pre-specified direction: upwards (more ones), downwards (more zeros), or as a control with no intention. Over a quarter of a century, this added up to more than 100 different operators, several generator types, and around 2.5 million individual trials.
The finding is not spectacular in size, but in consistency. On average the bit sum in intentioned trials shifts by about 1 to 2 parts in 10,000 in the desired direction. That is tiny. But accumulated over 2.5 million trials it yields an overall Z-statistic in the region of Z ≈ 7 – a chance probability somewhere between 10⁻¹¹ and 10⁻¹². Conventional explanations fail against that number: device drift would not be intention-dependent, statistical artefacts would not be reproducible across three decades.
Random Mechanical Cascade: 9,000 balls and the Galton board
Alongside the purely electronic REG, PEAR built a second, visually striking instrument: the Random Mechanical Cascade. A wall-sized apparatus in which roughly 9,000 small polystyrene balls fall through an array of 330 staggered pins and pile up in 19 collecting bins to form a Gaussian distribution – a giant Galton board. The task for operators: try mentally to shift the distribution to the left or right.
The results were statistically significant. Across all runs there were shifts correlated with the intended direction – a small effect, but a clean signal. The machine was later donated by PEAR to the Technorama in Winterthur (Switzerland), where it has been preserved as a public science exhibit.
Remote Perception: the Princeton variant
The third major research strand picked up the remote viewing work of Targ and Puthoff at SRI, which later grew into the CIA's Stargate programme. PEAR built its own, methodologically tightened version: Precognitive Remote Perception. An "agent" travelled to a randomly chosen location; a "percipient" at another location was asked to describe the place at the same time, or earlier. The descriptions were coded into standardised descriptors and judged by blinded raters.
Here too, across several hundred trials, statistically clear excess hits emerged. The PEAR protocol was methodologically tighter than the early SRI trials – with blinded judging and mechanised descriptor evaluation.
Operator signatures
One of the most peculiar observations from PEAR concerned not the mean of the data but the individuality of operators. Over the years it turned out that individual operators produced strikingly consistent personal "signatures". Some reliably pushed the REG upwards, others reliably downwards – even when their stated intention was the opposite. Some only showed the effect under particular emotional conditions. These signatures remained stable over years.
That is methodologically tricky and interpretively fascinating. It turns the REG experiment into a more individual-psychological question – not unlike the Pauli effect discussion within 1930s quantum physics.
"We measure small effects across very many trials. That is precisely the scientific standard modern particle physics uses. No one disputes the Higgs boson because its signal is small."
— Sense of Robert Jahn, in lectures during the 1990s
Methodological battles: Bösch, Steinkamp, Boller 2006
In 2006 a meta-analysis by Bösch, Steinkamp and Boller appeared in the Psychological Bulletin, one of the most prestigious journals in psychology. It included 380 studies and 1.5 billion individual trials – a large share of them from PEAR – and reached a contradictory result: yes, there is a statistically significant overall effect; but it is so small and stands in such clear inverse correlation with study size that it is probably explained by publication bias.
PEAR replied in the same issue, in a paper by Dobyns, Dunne, Jahn and Nelson: the postulated inverse correlation did not hold up in their own data; large individual studies continued to yield significant effects. The dispute remained unresolved. But what it shows: PEAR was not fringe research operating below the radar; it was being seriously dissected by one of the most important journals in psychology.
The 2007 closure
On 10 February 2007 the New York Times ran a long article by Benedict Carey: "After 28 Years, Princeton Will End ESP Studies". Jahn, by then 77, announced the end of the laboratory. The official reason: the programme had answered its essential questions; further replications would add nothing fundamentally new; younger researchers should continue the work elsewhere. The unstated reason: institutional fatigue. Princeton had never openly welcomed the lab, only tolerated it; no successor in the engineering department was in sight.
The closure was a media moment. The NYT piece described the lab as "shabby" – worn-out computers, sagging sofas. But it also described it as what it was: a research programme conducted seriously for 28 years at one of the best universities in the world.
ICRL – PEAR's afterlife
Jahn and Dunne had founded the International Consciousness Research Laboratories (ICRL) already in 1996, more than a decade before the closure – as a catch-net structure. There the work continues to this day, now detached from Princeton and in a network of additional researchers. Robert Jahn died on 15 November 2017; Brenda Dunne led the ICRL on after his death.
The two key books – Margins of Reality (1987) and Consciousness and the Source of Reality (2011) – summarise the theoretical work: consciousness and matter not as two separate domains but as complementary aspects of one physical reality. PEAR thereby stands in the same line as the unus-mundus concept from the Pauli–Jung correspondence.
What PEAR means for us
- Institutional credibility. 28 years at a top engineering faculty, led by its own Dean, with genuine external funding. That is not "esoterica at the margin" but research within mainstream academic surroundings.
- Quantum randomness as a measuring tool. PEAR achieved something that Rhine with his dice could not yet do: examine experimentally the relation between consciousness and genuinely quantum-mechanical randomness. The line leads directly to Pauli's speculations about quantum non-locality and synchronicity.
- Effect size is not everything. 1–2 parts in 10,000 sounds like nothing. Aggregated over 2.5 million trials it is Z ≈ 7 – more firmly established than most clinical trials published in The Lancet.
- Continuity. The line Rhine (1930) → PEAR (1979) → ICRL (today) is an almost century-long experimental tradition that has never been interrupted. Anyone claiming psi research is "long since refuted" is ignoring this body of data.
PEAR did not prove that consciousness changes matter. It delivered something more modest and at the same time bigger: a statistical finding that conventional explanations struggle to account for – and that maintained pressure on the standard assumption "psyche and matter are separate" for three decades. Anyone who takes the data seriously cannot avoid asking the consciousness question differently from how mainstream neuroscience asks it today. See also our pieces on consciousness and the brain and on majority vs. expert opinion.
Sources
- Robert G. Jahn & Brenda J. Dunne: Margins of Reality. The Role of Consciousness in the Physical World. Harcourt Brace Jovanovich, San Diego 1987 (reprint ICRL 2009).
- Robert G. Jahn & Brenda J. Dunne: Consciousness and the Source of Reality. ICRL Press, Princeton 2011.
- Holger Bösch, Fiona Steinkamp & Emil Boller: Examining Psychokinesis. The Interaction of Human Intention with Random Number Generators – A Meta-Analysis. Psychological Bulletin 132 (4), 2006, pp. 497–523.
- York H. Dobyns, Brenda J. Dunne, Robert G. Jahn & Roger D. Nelson: The MegaREG Experiment. Journal of Scientific Exploration 18 (2), 2004.
- Benedict Carey: After 28 Years, Princeton Will End ESP Studies. New York Times, 10 February 2007.
- Journal of Scientific Exploration – PEAR archive from 1987, online.