The Ultimate Thought Experiment Part I: Do Androids Dream of Electric Sheep?

Let’s imagine something crazy.

What if each person in China was ordered to simulate a neuron in a brain, making an enormous “China brain?” Every participant in this grand experiment would be given a two-way radio to communicate with other people, similar to how neurons talk to each other. Some people play the role of “effector neurons,” which control parts of a giant robot, just as motor neurons in our nervous system control bodily movements.

Basically, imagine that the entire nation of China became a giant robot’s brain. What might happen?

The robot’s behavior might be sluggish, but it could, in theory, show behaviors such as walking, fighting, and sleeping. Given that the population of China is equivalent to the number of neurons in the brains of some monkey species (Footnote 1), one might expect the behavior of the robot to be as complex as that of a monkey!

The above scenario was originally posed by philosopher Ned Block in his famous China brain thought experiment. Does the China brain have a real mind? Could a real mind actually emerge from a nation of people acting as neurons in a brain? Or would the Chinese participating in the experiment merely be simulating a mind?

A thought experiment — or Gedankenexperiment, to use the original term coined by Danish physicist Hans Christian Oersted — explores the consequences of an imaginary experiment, often one that cannot be performed in real life for practical or ethical reasons. Thought experiments often channel intuition into problems that are fairly unintuitive by reframing the problem in a new, more familiar context.

“Dick imagines a world in which artificial humans–androids–are denied their apparent humanity…”

But thought experiments are not only tools for scientists and philosophers. Intuitive reframing of intellectual problems using familiar characters or situations is a favorite tool of science fiction writers. Indeed, walk into almost any library or bookstore, and you will find a wonderful collection of Gedankenexperiment by the likes of Philip K. Dick, Arthur C. Clarke, Daniel Keyes, and many other authors.

Years before the China brain thought experiment was formalized by academics, much looser questions of who or what can be called an authentic mind were asked by the prolific science fiction writer Philip K. Dick. In his 1968 novel Do Androids Dream of Electric Sheep?, Dick imagines a world in which artificial humans–androids–are denied their apparent humanity and “retired” by bounty hunters such as the novel’s protagonist, Rick Deckard. Far from being metallic, C-3PO-style robots, the androids of Dick’s novel are flesh and blood entities of synthetic origin. As such, they cannot be distinguished from humans by physiology alone.

The suspense!

In both the novel and the film inspired by the novel, Blade Runner, Deckard uses the fictional Voight-Kampff test to identify androids based on their behavior. The Voight-Kampff test combines physiology and behavior by measuring reflexive pupil dilation in response to empathy-probing questions. In the real world, measurements of pupillary reflexes, known as pupillometry, are being brought to psychiatric clinics to assess emotional and cognitive processing in disorders, such as autism. The Voight-Kampff test may also have been inspired by the Turing test. Proposed by the computer scientist Alan Turing, such a test would determine if an artificial intelligence (AI) program has a mind on the basis of whether its answer to questions can be distinguished from those of humans. Usually, the interrogator is envisaged giving questions and receiving answers through a wall, so that he or she cannot cheat and look at the identity of his or her interlocutor. But the androids of Dick’s world, visually indistinguishable from humans, hide in plain sight. While such manufactured biology might sound absurd, neuroscientists of today are already growing small, isolated brains known as “organoids” in the lab to study disease and development. While lacking the complexity of “real” brains, organoids nonetheless demonstrate that manufactured brains cannot be dismissed as pure science fiction.

“… the best science fiction stories are often powerful thought experiments disguised as films or novels.”

Another clever idea introduced by Dick’s thought experiment is the mood organ, a brain stimulating household appliance that Deckard and his wife, Iran, use to artificially experience different emotions. Similarly, in our world, deep brain stimulation can be used to treat severe mood disorders like depression by stimulating the nucleus accumbens, an important part of the brain’s so called ‘reward circuit‘. But in Dick’s world, brain stimulation can be used to induce any emotion, not just relief from depression or sadness. A concerning moment occurs early in the novel when Iran uses the mood organ to do just the opposite, self-inducing a voluntary state of depression.

As Graham Sleight suggests in the introduction to the 2009 SF Masterworks edition of the novel, Do Androids Dream of Electric Sheep? seems to concern itself with questions of what is fake and what is authentic. Like the China brain thought experiment, Dick’s thought experiment ponders whether a simulation can be genuine, albeit without probing as deeply into the implementation of the simulation.

While science fiction has often been viewed as a cheap form of entertainment, the best science fiction stories are often powerful thought experiments disguised as films or novels. In the upcoming Part II of this series, we’ll explore thought experiments in the Arthur C. Clarke novel and Stanley Kubrick film 2001: A Space Odyssey.




Block, N. (1980). Troubles with functionalism. Readings in philosophy of psychology, 1, 268-305.

Farzin, F., Scaggs, F., Hervey, C., Berry-Kravis, E., & Hessl, D. (2011). Reliability of eye tracking and pupillometry measures in individuals with fragile X syndrome. Journal of autism and developmental disorders, 41(11), 1515-1522.

Graur, S., & Siegle, G. (2013). Pupillary motility: bringing neuroscience to the psychiatry clinic of the future. Current neurology and neuroscience reports, 13(8), 365.

Herculano-Houzel, S. (2009). The human brain in numbers: a linearly scaled-up primate brain. Frontiers in human neuroscience, 3, 31.

Kelava, I., & Lancaster, M. A. (2016). Dishing out mini-brains: Current progress and future prospects in brain organoid research. Developmental Biology, 420(2), 199-209.

Sleight, G. (2009). Introduction. In Dick, P. K., Do Androids Dream of Electric Sheep? (SF Masterworks editon). London, Gollancz.


Footnote 1: The brain of an owl monkey has 1,468 million neurons (Kelava and Lancaster, 2016), comparable to the population of China in 2017 (1,388 million people).

Joel Frohlich

Joel Frohlich is a postdoc studying consciousness in the lab of Martin Monti at UCLA. He is interested in using brain activity recorded with EEG to infer when a person is conscious. Joel earned his PhD from UCLA in 2018 studying EEG markers of neurodevelopmental disorders in the lab of Shafali Jeste. You can also check out Joel's blog Consciousness, Self-Organization, and Neuroscience on Psychology Today. For more about Joel's research and writing, please visit Joel's website at