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Consciousness as Afterthought

The brain scans input subconsciously and then thinks about some of it.

I get a lot of questions in Quora about neuroscience, because neuroscience is what I do. A recent question prompted this post. The question was: "Does all thinking originate in subconscious thinking?" This is a provocative question. It gets to the heart of the matter: What is the default mode of brain operation, conscious or subconscious?

Semantic Confusion

Much of the confusion about consciousness arises because words fail us. We have poor definitions for the usual words: conscious, unconscious, subconscious, non-conscious. Before I attempt an answer to my Quora question, let me establish some background about terminology. First, the currency of thought is patterns of nerve impulse activity constrained by flowing in and through defined circuits of linked neurons. The impulse thought patterns that occur in primitive circuitry, like spinal segments and neuroendocrine circuits, are considered non-conscious thoughts because we can never be consciously aware of what those circuits are doing. We can, for example, use instruments to measure our blood pressure, but on its own the brain can never detect that consciously.

Perhaps the most common kind of thought is that which occurs all the time, even when asleep, that we are not aware of. These days, scholars like to call this "unconscious" thinking. But coma is clearly an unconscious state, and there often is little electrical activity that reflects thought. That is why a more useful term in this context is "subconscious," a term popularized by Freud. That is probably why the term has fallen into disuse. Too many of Freud's ideas have been discredited. But not his idea of subconsciousness.

Consciousness Is Not the Same as Being Awake

Reflect on your own perceptual experiences. Every time you are consciously aware of something, you were attending to it. True, you can be awake without being conscious (as in the gorilla in the basketball game). This means that we have to make a careful distinction between wakefulness and consciousness. They are not synonymous. You can't be conscious if you are not awake, but being awake does not assure consciousness of non-attended objects. Wakefulness is generated out of excitatory activity of the brainstem reticular formation acting on the neocortex. The mechanisms of consciousness have not been established, but they likely involve coherent nerve impulse activity in distributed circuitry.

The phylogenetic perspective argues for unconsciousness as the default mode of thinking, inasmuch as lower animals are not likely to have conscious thought, yet their behavior clearly indicates that they are awake and their brains are "thinking." Also, we know from studies of infants that behavioral signs of consciousness are rare and only emerge as the brain matures. It is clear that much human thinking occurs below the level of conscious awareness.

The many scholars who claim that humans have no free will use the assumption of subconscious thinking to defend their stance against free will. They came to this conclusion from experiments that indicate that all willed action is generated subconsciously and only recognized later in consciousness. The experiments and the interpretation are flawed, as I explain in my book on free will.

To help defend the stance that free will is an illusion, the proponents go further to argue that consciousness is just an observer, like a movie patron in a theatre. You can watch what is happening but can't do anything about it. Thus, they construct the specious circular argument that you can’t have free will because free will requires consciousness by definition, and consciousness can’t do anything. How convenient! This absurd notion, held by academics who are not as smart as they think they are, assumes that all our conscious thinking is basically irrelevant. They assume that the neural activity of conscious thought cannot influence neural activity in other parts of the brain, even though they have to admit that the neurons that mediate conscious thought are functionally connected with the other parts of brain. By these connections, conscious thought can, for example, explicitly evaluate the meaning of stimuli, or order certain muscles to contract, or force mental effort to memorize, or change our emotional state and visceral functions in light of reason or mindfulness meditation, and so on. The circuitry of consciousness is not in a pickle jar outside the brain. It is inextricably bound to other brain circuits.

I certainly don't mean to dignify the anti-free-will position by describing it. However, debunking that position opens the door to reconsider the possible relationship between subconscious and conscious thought. Suppose conscious thought is an afterthought, but not in the restricted sense prescribed by the anti-free will crowd. Just because subconscious thought can lead to conscious thought does not mean that conscious thought has no action of its own. When we consciously think about what we have recognized in consciousness, all that thinking is, by definition, conscious. Conscious thought can consider options explicitly. It can reason. It can set goals, plan, command action, evaluate consequences of action, and adjust programming as needed. Subconscious thinking can do that too. Most likely the two modes of thinking work in potentially synergistic ways, though it seems clear that conscious thought can veto subconscious impulses and bad ideas.

Consciousness as Selective Attention

Have you seen the YouTube video of a pickup basketball game? The video instructs viewers to count how many times one of the teams pass the ball. Viewers are so focused on the task that many of them fail to see a man in a gorilla suit walk into the game, do a little chest pounding, then walk off the court. The point is that the eyes and subconscious mind saw the gorilla, but not the conscious mind. The same phenomena has been confirmed in another context. The phenomenon is labeled by psychologists as "inattentional blindness." In other words, we are only conscious of targets of our attention.

Like all biological systems, brains are stimulus-response systems. Humans have unique ways to respond to stimuli and experience, in that our brains selectively identify the information content, evaluate it in terms of available optional responses, then determine an appropriate response. Both subconscious and conscious thought can be involved, but conscious thought only operates on attended targets.

W. R. Klemm
Suggestion that we consciously think about something only after it has registered subconsciously.
Source: W. R. Klemm

Scanning for Meaningful Impulse Pattern

While it is clear that conscious brains think, it may be useful to consider that consciousness is also a scanning mechanism. We don't know how such scanning is enabled by wakefulness, but we do know that the awake brain generates more regular oscillations of impulse activity. These oscillations arise in many localized subnetworks throughout the cortex, occurring at varying frequencies and extent of synchrony among other generators. Intracellular recordings of neurons reveal that one or a few spikes are generated each time the membrane depolarizes. Oscillation is a built-in feature of neural circuits which commonly oscillate because impulse output re-enters the circuitry that generates it. Increasing the frequency of oscillation increases the total impulse discharge because there are more depolarizations per unit of time. This increases the informational throughput in the network. Likewise, the degree to which multiple oscillators synchronize to share data modulates impulse throughput throughout linked circuits.

Perhaps the oscillation itself is the scanning mechanism. As novel or particularly relevant input enters an oscillating circuit, that circuit’s own impulse firing pattern may be disrupted, or it may reset, change frequency, or alter its time-locking to other subnetworks. Enhanced time-locking among circuits could have the magnifying intensity effect that seems to be required in selective conscious attention. The carrying capacity for information is limited, because only subsets of networks in the global workspace synchronously engage at any one moment. This is one way to improve the signal-to-noise ratio of neural circuit processing.

Perhaps conscious thought is the afterthought of this scanning once it latches onto a subconscious thought that compels attention. Such a mechanism has great biological advantage in that it is a way for brain to scan through a noisy stimulus- and thought-world to identify signals that are salient for appropriate and selective processing and response. Once the target is captured in consciousness, conscious neural activity evaluates the salient signals and determines what to do about it and directs useful action. Taken in this light, I answer a tentative yes to my Quora questioner who wanted to know if all thinking originates in subconscious thinking.


Klemm, W. R. (2014). Mental Biology: The New Science of How the Brain and Mind Relate. New York: Prometheus.

Klemm, W. R. (2016). Making a Scientific Case for Conscious Agency and Free Will. New York: Academic Press. The original basketball game example of the invisible gorilla. A confirmation of the invisible gorilla in another context.