The Speed of Implicit (Unconscious) Neural Processing

Brain functioning reflects a dynamic interaction between the need for both speed and response flexibility. Our expanded cortex and the government of neural systems which comprise it, allow us a vast amount of response flexibility. But compared to our basic reflexes and more primitive processing systems, conscious processing is extremely slow. I just Googled the word “consciousness” and received 1,230,000,000 results in 0.39 seconds; less time than it took me to type the word and press return. Although it’s hard to imagine how this is possible, what is clear is that the pace of my moment-to-moment experience, and Google’s processing speed, differ by many orders of magnitude. I don’t know how the processing speed of our brain compares to Google, but the evidence suggests that it runs on a considerably faster clock than our conscious experience. The evolutionary balance between speed and response flexibility has resulted in a nervous system which abides by several different clocks.

In situations where response speed is vital, our fast systems are in charge. The startle reflex and the orienting response, for example, operate much faster than conscious awareness. When we are startled by an unexpected touch or pull our hand off a hot surface, we become consciously aware of our actions well after they’ve occurred. These reflexes are processed within the spinal cord and don’t involve the cortex; conscious processing would take up too much precious time in reacting to these kinds of environmental dangers.

Conscious awareness runs on the nervous system’s slowest clock, involving input from multiple systems as well as the need to synthesize and grasp their significance. This means that, in many ways, our nervous systems construct our experience before rolling it out for consciousness awareness. While it takes approximately 500–600 milliseconds for an experience to register in conscious awareness, the amygdala can react to a potential threat in less than 50 milliseconds. This means that by the time we have become consciously aware of a threatening situation, it has already been processed and reacted to by our more primitive neural networks. Instinct, implicit memories organized by past learning, and physiological arousal all precede conscious awareness.

Ninety percent of the activation within our cerebral cortex is in response to other internal processing. This is how our temperamental predispositions, unconscious needs, and our accumulated memories from the past participate in the creation of our present experiences. This mechanism accounts for the phenomena of transference, projection, implicit bias, and the attribution errors studied by social psychology. A major challenge to human consciousness is that this implicit and largely unconscious construction of human awareness is experienced as if it is completely about the external environment. This leads us to experience our personal construction of reality as objective truth, and lead us to defend it to ourselves and others as such. This half-second between neural activation and the construction of experience is the soil of our core beliefs, both adaptive and maladaptive. Much of psychotherapy is involved with subjecting these “truths” to conscious evaluation.

Think of a military veteran many years after combat, who still ducks when he hears a car backfire or runs for cover as a news helicopter flies overhead. Or a client who experienced a loss of a parent during childhood who, as an adult, is perfectly capable of starting new relationships. Yet, at a certain point, increasing intimacy and feelings of dependency may trigger implicit memories of anticipated abandonment leading him to flee from a potentially healthy relationship (Koukkou & Lehmann, 2006: Rholes et al., 2016). The impulse to run, driven by implicit memories embedded in primitive brain circuitry, might be overpowering and inescapable. The underlying reasons for these “irrational” behaviors based on implicit memories have been brilliantly described by Christopher Bollas (1987) as the “unthought known.”

The brain’s implicit processing creates a social-emotional background which shapes our thoughts, feelings, and behaviors and constructs our experience of self, others, and the world in the present moment (Nomura et al., 2003; Wiens, 2006). Because all of this implicit processing runs faster than conscious awareness, we experience it as if it is happening in the present and believe we are seeing reality and acting of our own free-will. The illusion of free will has obvious survival advantages, foremost of which is the confidence and assertiveness we need for challenging situations. The downside of this strategy is when we become so sure of our erroneous personal beliefs that we are unable to consider more adaptive alternatives.

Openness to questioning one’s assumptions, especially when they are incorrect and self-defeating, is a key predictor of positive outcome in psychotherapy. Once clients begin to understand that what they assumed to be reality is actually a product of the past conditioning of their brains and minds, they either flee from therapy or become fascinated. We attempt to get our clients to question their thoughts, beliefs, and assumptions and to make as much of the output of their implicit processing available for conscious consideration and reconsideration.  Attachment schemas, transference, and self-esteem are all examples of implicit memories that shape and distort conscious awareness. These very patterns of unconscious processing led Freud to develop a therapeutic context that supported an exploration of the unconscious. Psychotherapy encourages being skeptical of the perceived realities of our brains, a sound strategy that we share with research scientists and Buddhist monks.