Has experimental psychology proven that consciousness causes the collapse of the wave function?
Reading | Experimental Psychology
Richard Lucido, PhD | 2025-08-15
Dr. Lucido argues that his psychology experiments, entailing subliminal suggestions—priming—of subjects, corroborates the ‘consciousness causes collapse’ interpretation of quantum mechanics. Here he makes his case in an accessible manner. So what do you think? Is he on to something significant here?
Contemporary psychology views consciousness as the inner life of an individual, their subjective experiences, which is created and maintained by its neurobiological underpinnings. It is a relatively recent evolutionary adaptation that is found in humans and other animals with sufficiently complex neurobiological structure to support it. It is most likely epiphenomenal, existing without causal power, or at best explains a smaller part of our behavior than what can be accounted for by automatic neural processes [1-3]. In short, it is a relatively small thing, even within the sphere of the individual human. However, at the other end of the academic spectrum, lies a simple 97-year-old hypothesis in the foundations of physics [4] which, if true, would force a reappraisal of consciousness’s place in nature. It would take it from being a small part of psychology, to having a fundamental role in the nature of reality itself. Because of this, the validation or falsification of this hypothesis is just as important to the field of psychology as it is to physics, and its evaluation as described in this essay will rely primarily on methods from mainstream experimental psychology.
Interpretations of Quantum Mechanics
Quantum Mechanics yields the most accurate predictions that physical science has ever produced. The mathematical procedures work as they are and require no changes. However, these methods appear to force the abandonment of classical concepts such as direct causation, locality, and objective realism [5-8]. Exactly what gets abandoned depends on which interpretation of quantum mechanics is applied. In the standard orthodoxy, the Copenhagen Interpretation, particles exist in a state of superposition, an undifferentiated collection of all possible states described by Schrodinger’s wave function, until the act of measurement, at which time the superposition collapses into only one of these possible states in a probabilistic manner. The Copenhagen Interpretation is silent on what actually constitutes an act of measurement or on how or why it collapses the wave function.
Despite being the standard orthodoxy, the Copenhagen Interpretation and the notion of superposition are far from universally accepted [9]. Other interpretations of quantum mechanics have emerged that contest the reality of the superposition. For example, the Many Worlds Interpretation [10] holds that the wavefunction never collapses; rather, the universe bifurcates every time a measurement is taken on a quantum system and that all the possibilities are actually realized. Other interpretations maintain that nonlocal hidden variables determine the results of each measurement [11,12], or that the collapse of the wave function is a spontaneous—yet objective—process where collapse does not occur upon the interaction with a physical measurement device [13].
Perhaps the boldest interpretation of quantum mechanics lies in the augmentation to the Copenhagen Interpretation suggested in 1932 by John von Neumann [4] and latter advocated for by Eugene Wigner [14]. This interpretation holds that there is no clear physical end to the superposition, and that the mathematics allows for the collapse of the wave function to be placed anywhere on the causal chain from the physical measurement device all the way to the experimenter’s subjective perception. In other words, when a particle in superposition interacts with a physical measurement device, it is reasonable to conclude that both the particle under consideration along with the physical measurement device itself are existing in a state of superposition until they are observed by the experimenter. The only clear place to draw the line of collapse is at the point where a physical system interacts with consciousness, something that is outside of the physical reality governed by quantum mechanics. This has subsequently become known as the Consciousness Causes Collapse (CCC) interpretation.
It is a common refrain that the many interpretations of quantum mechanics are currently untestable against each other. However, recent research using subliminal priming suggests that this may no longer be the case. Four separate experiments have been conducted utilizing a subliminal priming methodology to test the CCC interpretation of quantum mechanics [15-17]. The results of these experiments provide empirical support for both the reality of the superposition and the notion that the collapse of the wavefunction occurs upon human observation of the measurement result, rather than the previous interaction of the quantum phenomenon with a physical measurement device.
Subliminal priming in experimental psychology
In experimental psychology, the term priming refers to an effect where exposure to one stimulus influences a person’s response to another stimulus. For example, a positive word such as “happy” is recognized and responded to faster after the word “joy” as compared to a negative word such as “sad” or “pain.” The word “up” is responded to faster following a prime such as “high” or “top” as opposed to “bottom” or “low.” The primes work by getting you to lean mentally in a particular direction, so when you have to respond to something that is already in that direction you can do so faster, while it takes you longer than normal to respond to something in the opposite direction. Psychologists have been exploiting these reliable reaction-time effects for decades as a multipurpose research tool. In recent years, these methods have even been used to prime subjects subliminally [18-20]. In such research, subjects are flashed primes (such as a word or a symbol) on a computer screen for a length of time that is just below the duration that can be consciously experienced (about 50 milliseconds). Despite subjects reporting to not be aware of seeing the primes, they demonstrated shorter reaction times responding to stimuli that were congruent with the primes than to incongruent stimuli. Their brains processed the meaning of the primes and began to react to them even though they were not aware of it. The primes were processed unconsciously.
Testing the ‘Consciousness Causes Collapse’ interpretation
In 2023, an experiment was conducted that used subliminal priming to test the CCC interpretation of quantum mechanics [15]. In this study, a Geiger counter was placed next to a local source of radioactive decay. A series of primes were then derived directly from the frequency of the Geiger counter clicks without having any interaction with a conscious observer. Therefore, the direction of the primes, and consequently whether they were congruent or incongruent with the stimulus, were entirely determined by the state of the quantum phenomena. However, since the Geiger counter output had yet to be exposed to conscious observation, according to the CCC, the primes derived from that output should have not yet collapsed into definite states. They should still be in a state of superposition, a state that is not yet specified, and a prime in a state of superposition should not have the same effect on reaction time as would a prime that has already collapsed into a definite state, as it could be neither congruent nor incongruent with the prime.
For a control condition, the experimenter directly observed only half of the primes. The participants’ response times to stimulus items preceded by these “observed” primes populated the observed condition, and response times to items preceded by primes that had yet to be observed populated the unobserved condition. It was hypothesized that these observed primes, having collapsed into a definite state, would affect the participants’ reaction times as they have done in previous research. However, the primes that remained unobserved should still be in a state of superposition, and should not have the same effect on reaction time as the primes that were previously exposed to observation.
In this study, the participants responded to 928 items overall (464 in the observed condition and 464 in the unobserved condition). The primes were found to affect the participants’ response times in the observed condition, but not in the unobserved condition. These results appeared to support the CCC interpretation of quantum mechanics. A follow up study [16] using similar methodology replicated the results in that the magnitude of the effect of the primes in the observed condition was much greater than it was in the unobserved condition. Finally, two additional experiments were conducted in 2025 that further replicated and expanded on the results of the original study [17]. In total, across the four experiments, participants responded to 4,201 items overall (2,099 in the observed condition and 2,102 in the Unobserved Condition). This resulted in a weighted effect more than twice as large in the observed condition as in the unobserved condition [21]. Due to the size of this difference and the large number of items, the probability of obtaining this cumulative result by chance was calculated to be approximately one in a million.
If consciousness caused collapse…
If von Neumann’s hypothesis is correct, and consciousness collapses the wavefunction, the implications for physics, psychology, and philosophy are significant. The prima facia implication for physics would be that the state of superposition, the coexistence of mutually exclusive phenomena, is an ontically valid notion. In other words, the wavefunction cannot be thought of as a mathematical approximation of the reality between measurements. The ontic reality of the superposition would negate the assumption that physical particles have an objective and independent persistence in time. Therefore, in a very literal sense, the math would become the reality. Also, since these studies provide evidence that both the superposition and the notion of collapse are real, interpretations of quantum mechanics that hold that the wavefunction never collapses, such as the popular Many Worlds and the Pilot Wave Interpretations, would be inconsistent with this evidence.
The implication for psychology is that consciousness has a role in nature that is vastly larger than what is commonly realized. If the wavefunction collapses upon the observation of a conscious observer, then it plays a fundamental role in the workings of physical reality. How the discipline of psychology thinks about consciousness, its origins, and its role in affecting our behavior will need to be revised. Consciousness studies would move from a small branch of psychology, which is itself a small branch of biology, to the center trunk of the tree on which the natural world is understood.
Lastly, the prima facia implication for philosophy would be that serious consideration would be owed to the possibility that metaphysical idealism, the idea that the primary constituent of reality is consciousness, may be the most reasonable metaphysical position. If consciousness causes collapse than physical reality does not exist independently of consciousness. If this is the case, at the very least, if physics is not independent of consciousness, then physicalism (the notion that all is physical) becomes an untenable position. However, we can easily go further: if consciousness causes the wavefunction to collapse, this would mean that physical reality is rendered as it is observed. That brings us to the doorstep of the idealist George Berkley’s famous 18th-century dictum, “to be is to be perceived” [22].
Conclusions
More work in this area would be needed to gain increased confidence in the results so far obtained. However, a jumping-off point has been established that may hopefully generate further experimental investigation. If idealism is the correct metaphysical hypothesis, then it would certainly make sense that the validation of the CCC would rely on experimental designs that employ methods from psychology. How could it not? It may also make sense to explain physics’ lack of progress in quantum foundations in terms of physicists’ understandable antipathy towards the CCC, the outgrowth of which may have prevented the use of outside methods to test physical hypotheses.
However, to be fair, from the physicalist’s perspective, if physicalism were true it would make no sense to use psychology to test a physical hypothesis related to the foundations of quantum mechanics. And for those with an a priori commitment to physicalism, it would be easy to dismiss the preceding experimental results as being obviously false for that reason alone. Therefore, the best way to address this may be to build the body of empirical evidence to a degree that prohibits dismissal. The methods are there. Using subliminal priming, or perhaps some other research paradigm, the methods of experimental psychology appear to be providing the pathway by which this metaphysical question can be transformed into an empirical one.
References
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[14] Wigner EP. Remarks on the mind-body question. In: Good IJ, ed. The Scientist Speculates. London, UK: Heinemann; 1961.
[15] Lucido, R. J. (2023). Testing the consciousness causes collapse interpretation of quantum mechanics using subliminal primes derived from random fluctuations in radioactive decay. Journal of Consciosuness Exploration and Research; 14(3):185-94. https://jcer.com/index.php/jcj/article/view/1057
[16] Lucido, R. J. (2024). Replication of results from a test of the consciousness causes collapse interpretation of quantum mechanics using subliminal priming methodology. Journal of Consciousness Exploration and Research;15(3):229-239. https://www.testingtheccc.com/uploads
[17] Lucido, R. J. (2025). Do Cats Collapse the Wave Function? Confronting the Measurement Problem with Subliminal Priming. Journal of NeuroPhilosophy, 4(1). https://doi.org/10.5281/zenodo.15003998
[18] Greenwald, A. G., Abrams, R. L., Naccache, L., & Dehaene, S. (2003). Long-term semantic memory versus contextual memory in unconscious number processing. Journal of experimental psychology. Learning, memory, and cognition, 29(2), 235–247. https://doi.org/10.1037/0278-7393.29.2.235
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[21] Lucido, R. J. (2025). A weighted analysis of four experimental tests of the consciousness causes collapse interpretation of quantum mechanics. Unpublished Data Analysis. http://dx.doi.org/10.13140/RG.2.2.18902.56645
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