Experimental Atomic Psychology
Is there any evidence for the atomic hypothesis in psychology, however slender? It certainly doesn’t seem to us that our consciousness is composed of little psychic particles separated in space—the analogue of physical particles. But there is one area in which the hypothesis enjoys some phenomenological support—I mean, the experience we have when we close our eyes in the dark. Our visual field seems populated with tiny dots, light against a dark background, and these dots are visited by edges and blobs that move slowly around. The dots are shaped into primitive forms that seem to seek greater solidity and sharpness, like ghosts of the real world. In this experience, admittedly unusual, our visual field appears granular, corpuscular, pixelated, like a pointillist painting—an assembly of point-like particles. Might this be evidence of an underlying particulate structure operating at the level of the brain, one neuron per point perhaps? I want you to do an experiment: next time you are in bed at night close your eyes and focus on the tiny dots in your visual field, trying to get a sense of their sharpness and clarity. Now open your eyes and gaze into the gloom: vague forms will appear in the darkness, say the shape of an overhead fan. Can you still see the dots? If you are anything like me, you will still see them, but they are slightly less well-defined. The shapes perceived have somehow reduced their phenomenological salience without eliminating them altogether. If you close one eye, you find that the dots gain slightly in salience as the external shape is less clearly perceived. And if you close both eyes again, they come back in all their understated glory. The external form has co-opted what was only vestigially and virtually present in those edges and blobs. It would be possible to replicate this experiment more systematically: assemble a group of subjects and gather reports under varying conditions of illumination, beginning with pitch dark. At what point do the visual pixels disappear from consciousness completely? Is there much intersubjective variation? Can input from another sense interfere with the disappearance? I will venture a hypothesis: pixelation is inversely proportional to form—that is, the greater the perceived form the less the apparent pixelation, and vice versa. At the point of ordinary daytime illumination, pixelation is zero, except perhaps in abnormal conditions. When there is no form to see, as in the closed eyelid condition, the pixelation is at its height; but as forms enter the visual field, even in low illumination, they disappear from view. This is not to say they no longer exist, just that we have no awareness of them. Perhaps blind people have vivid pixelation and their pixels never disappear from view; perhaps hallucinogenic drugs can heighten their presence; perhaps certain diseases cause them to occur in normal vision—these are all empirical questions. We do know there is such a thing as visual snow syndrome, which sounds a lot like pathological pixelation. The idea, then, is that the brain employs two mechanisms in the production of visual percepts: one mechanism generates mental atoms or points; the other mechanism organizes these into visual forms, generally controlled by an external stimulus. The mental atoms are organized into wholes that represent shapes and other qualities. If psychological atomism is true, the same should hold of the other senses, though the atoms may be less accessible to introspection. Taste, for example, operates by way of innumerable receptors that work to create (in conjunction with the brain) gustatory points, the totality of which constitute (say) the taste of pineapple. The taste is not an ontological simple having neither parts nor structure; instead, it is a complex sensation made up of many elements (if you have ever partially lost your sense of taste, you will know what I mean). Then the general hypothesis is that all mental phenomena obey the same basic principles—atoms combining to produce complex mental states. Is there anything analogous to closed-eye vision for thought, i.e., unorganized dots of thought awaiting assembly into a coherent whole? Not that I know of, but it would be worth investigating whether certain kinds of degenerative brain disease produce such effects, e.g., Alzheimer’s disease. What about sleep and dreams in normal humans? Rational thought seems to fall to pieces there. Could drugs have this kind of effect? Surely it would be possible for the brain to cease to be able to put concepts together to form coherent thoughts. Couldn’t concepts themselves break down into parts that refuse to join with other concepts (neurons can clearly lose the ability to connect with other neurons)? Empirical, indeed experimental, work could be done to determine the answer to such questions. It need not be left up to philosophy. So, the atomic hypothesis could be subjected to empirical test, beginning with the bedroom experiment I suggested above. Returning to vision, we can confidently report that the retina and the brain have a pixelated structure–rods and cones in the retina, neurons in the brain—so it is on the cards that the mind itself duplicates this structure. We may not be conscious of it (what biological point would there be in that?) but it may yet be present inconsciousness, hovering just below the surface. Eyelid vision hints at these subterranean depths, and it may be that they exist elsewhere too. It is true that we can’t detect the mental particles by the use of particle accelerators that bombard the mind with supercharged particles and reveal the hidden gems, but we have other ways of determining the fine structure of mental phenomena (such as introspecting our closed-eye visual field). The brain is thus (we conjecture) a synthesizer of basic mental atoms that together form mental life as we experience it. First it manufactures the elementary particles, then it assembles them into mental complexes. What the most elementary particles are is, as they say, a matter for further research. We already know the mind is combinatorial at more coarse-grained levels; atomic psychology simply extends this basic idea down to smaller scales. The search for the elusive mental quark is now on.
 I first discussed mental atomism in “Consciousness, Atomism, and the Ancient Greeks” in Consciousness and its Objects (2004). Research is proceeding slowly.