Morrison’s Position Selecting Interactionism

Freelance physics-trained philosopher Colin Morrison posits that the direct physical correlate of our subjective experience is the wavefunction of a single rare particle (no doubt of a complex, compound nature), confined within a very small region of the brain (most likely a single neuron) that he calls ‘the cavity.’ Physically, what is confined within that cavity is a very weak solution of this particle, containing only one instance of it. There are likely many other types of particles in this solution. However, what is special about this one is that the cavity is surrounded by detectors for that particle (likely supported on microtubules) that extend over its inner surface and throughout its interior (Morrison, 2016, 2025).

As Jo Edwards puts it in his book review, “Morrison concludes that the only approach consistent with science is to assume that qualia are inherent to the basic dynamic units (in common parlance ‘particles’) that constitute what we loosely call ‘matter’. In other words, he takes a graded panexperientialist view reminiscent of Whitehead. He then argues that the qualia we happen to experience must be those associated with certain ‘particles’ in brain environments that have evolved through natural selection to be well-adapted to providing representations of the outside world. Consciousness does not emerge out of nowhere. The potential for our qualia lies in the basic nature of matter, but it has taken millions of years for arrangements of matter so well suited to representing an outside world to arise through natural selection” (Edwards, 2017).

Particle in the Cavity and Panexperientialism

Morrison proposes that, due to its rarity, measurements of the position of such a particle became first adapted to introduce a limited amount of randomness into our ancestors’ attention-shifting behavior, thereby making a group of them more likely to spot dangers and opportunities since they would not all attend to the same source of information at the same time. At first, he says, such measurements were only adapted to choose between potential targets of attention that were assessed by their brains to have a very high chance of being the most appropriate one (since systems that allowed other targets to be chosen would be prevented by natural selection). However, gradually the system would evolve such that the chance of being the most likely source of info would be correlated with the chance of being selected by a position-measurement of this particle (Morrison, 2016, 2025).

Morrison argues that it would be far easier for the brain to adjust the probabilities of the appearance of the particle at particular detectors than to adjust the wiring. Consequently, position-measurements became hardwired to direct attention to particular locations in the environment (including the physical space occupied by the body); and the intensities of sensory stimuli coming from those locations, together with input from memories and emotion circuitry, became adapted to increase and decrease those probabilities appropriately in real time. The detection of more intense light from a particular direction, for example, often entailed a closer object (and thus a higher priority target of attention). If there were raised levels of acoustic vibrations coming from that direction, that would further increase the chance of a closer object and thus a higher-priority source, and so on. Hence, the sensory intensities were thus adapted to increase the amplitude of the wavefunction for the appearance of the particle at detectors that trigger shifts in attention to the locations in space from which those sensory stimuli originate.

Attention, Qualia, and Subjective Images

Morrison’s explanation for why these variations in the amplitude of the wavefunction form subjective images very closely matching those on the sense organs requires several things. Firstly, it requires that the subjective aspect of intensity of a particular type of qualia be identified with the ‘physical’ quantity of wavefunction amplitude for a particular position. Secondly, it requires one to identify particular types and categories of qualia (colors, sounds, pressures, pains, etc.) with particular ways in which that amplitude is affected. Thus, it is proposed that signals from the visual system were adapted to vary the amplitude of that wavefunction in a way that was quite different from the way in which signals from the auditory system or the somatosensory system vary it (Morrison, 2016).

Regarding the selection pressure that might explain why signals from the visual system became adapted to adjust that amplitude in a way that was different from those from the auditory or somatosensory system, Morrison proposes that the indeterminacy in the position of that quantum particle is caused by a genuine freedom it has to choose its position within the cavity. Its experience of all its possible positions is identified with our sense of our body and the spatial universe around us, and it is the intensities of the qualia in which these possible locations are represented that make it (us) more likely or less likely to select them, which we do by subjectively (not cognitively) centering our experience on these locations.

However, Morrison also proposes that there is another influence biasing those subjective choices besides the intensity aspect of qualia: a tendency to shift our subjective attention between similar qualia. If so, there would be an advantage, Morrison argues, for organisms in which the same frequency of visual (or auditory) stimulus generated the same qualia, and in which different frequencies of the same stimulus generated qualia that blended. That is because surfaces that reflect the same frequencies of light (or emit the same frequencies of sound) are often part of the same object or similar objects. By shifting attention more often between such locations, the brain is able to quickly gather useful data about the abundance or size of such an object before its attention gets shifted onto something else (Morrison, 2016).

Morrison points out that it is very hard to distinguish this subjective centering of experience from the objective brain-determined shift in attention that follows when, after measuring the position of our particle, the brain readjusts the amplitude of its wavefunction by uniformly increasing that amplitude in the region surrounding the position we selected. This ‘attention spotlight’ evolved because it was more beneficial for our ancestors if the attention of individuals remained focused on nearby points in space for a time long enough for their brains to make a reasonably reliable assessment of what was there.

By increasing the amplitude of the wavefunction for those nearby locations of the quantum particle, the brain could ensure that most individuals maintained attention in this usually beneficial manner. Of course, the brain could simply have evolved to disallow further measurements of the particle’s position to influence attention until the necessary assessment was made. But if it did this, it would lose the randomness that made it possible for a distracted individual to alert the group to a sudden danger or opportunity. The advantage for our ancestors of allowing that little bit of randomness is thus why we have this subjective ‘attention spotlight,’ and according to this theory, it also explains how those variations in subjective intensity evolved to have a form very like the patterns of stimulus intensity on our sense organs.

The most important requirement in forming those subjective images is that the quantum particle detectors that direct the organism’s attention to adjacent points in space always be adjacent to each other. This is not guaranteed by the selection pressures so far considered. However, according to Morrison, the advantage for organisms of maintaining attention in a particular neighborhood long enough for a reliable assessment to be made can explain it. That is because increasing the wavefunction’s amplitude for one position is bound to cause some accidental increase for neighboring locations too. That would not be a problem if measurements of the particle at those locations directed attention to nearby locations in external space because the data gathered from those external locations is still likely to make a useful contribution to the brain’s assessment of what is there.

However, the further they direct the organism’s attention away from its current focus, the more likely they are to cause a detrimental shift in attention—a shift that stops the brain from gathering data from a particular location before a reasonable assessment of its significance is made. Hence, the system is bound to evolve until adjacent detectors trigger shifts in attention to adjacent positions in space, thereby allowing the sensory-based variations in the quantum particle’s wavefunction to form images very like the patterns of stimuli on the sense organs that gave rise to them.

Valence, Binding, and Micropsychism

As for the valence aspect of our experience, like the qualia-type aspect, it is also given a subjective explanation that is still looking for a physical correlate. Morrison’s proposal is that unpleasantness increases the randomness by making the particle more likely to be found far from its previous location while not removing its tendency to be found at a location where it experiences similar qualia. More randomness of this limited type was beneficial when deterministic behavior was causing damage. Pleasantness, in contrast, reduces its tendency to be found far from its previous location, thereby reducing the frequency at which the organism is randomly distracted by this system. Such a reduction would be restricted by natural selection to prolonging circumstances that improved our ancestors’ chances of passing on their genes to future generations.

Moreover, Morrison contends that the binding problem is solved by his theory's requirement that certain qualia are always felt to be connected—particularly those contributing to the amplitude of his particle’s wavefunction at the same location in space and time, but probably also instances of precisely the same quale-type (as in hue of color or pitch of sound). The theory, he says, leads to a micropsychist view, as all particles are likely consciousnesses that, by choosing their position, are really positioning a tiny subjective effect in the experience of all others. The experience of each particle is thus the cumulative effect of all the others. He concludes that, as we are almost certainly a molecule rather than anything elementary and yet possess a single position-determining consciousness, further consciousnesses, in certain circumstances, can come into being (Morrison, 2016, 2025).