The human mind goes through significant, identifiable stages on its path to maturity. The age at which a stage occurs, the particular physical changes, and the personal experiences unique to that age affect the final shape of our adult mind.
Both physical changes and behavioral insights indicate that we go through certain stages with critical periods on our road to mental maturity.
The brain more than doubles in weight the first year (Figure 14.1) and triples by the second year, then grows at a much slower rate, but with a regular pattern, until about age 20, remaining relatively constant in size until the 50s, after which there is a slow decline. This later age period is marked by changes not considered in the Mental Construction framework.
We are experiencing the world throughout the years of brain growth. Those lessons, formed with less cortical volume, continue forward and underlie our adult thoughts.
Critical Periods of Learning
At particular times in the path to our full mental capabilities, certain tasks must be mastered. If the opportunity is missed, the task cannot be mastered later, no matter one’s effort. A prime example is the ability to see. If an infant has an operation removing cataracts after the first two years of life, despite the optical information to the brain then being unimpeded, the critical period has passed and the child never learns to use sight as an input.
Language acquisition provides a critical period example in the mental realm. Children deprived of experiencing communication, like those few found locked into isolation rooms or feral children, do not develop language skills if it continues beyond age 10. If it ends earlier, they can develop rudimentary skills, but not facility.
Psychological skills, like friendliness, trust-worthiness, and self-assurance do not have such stark critical periods. These social skills are more subtle, harder to measure, and can be overridden by higher levels of cognition. However, these skills are being developed while the brain proceeds through a sequence of stages fixing the output from one area of the brain to another. Soft skills (psychological and social skills) once set become harder, though not impossible) to change when the myelination stage moves to another area of the brain.
MyelinationIn the physical arena, we note the routine pattern of myelination, which marks the completion of basic categorization of neurological connections in local modules of the brain. Myelination is the process of coating connections between more distant modules of the brain. This permits the learned categories to be shuttled easily and preferentially between modules. R. Douglas Fields in The Other Brain (p 282) describes the routine progress of myelin pathways as follows:
There is a curious pattern in the way myelination proceeds in the human brain after birth: the last regions of the brain to become fully myelinated are those involved in higher-level cognitive function. In the human brain, myelination proceeds in a slow wave from the back of the cerebral cortex (shirt collar) to the front (forehead) as we reach adulthood.
In a broad stroke, we develop categories in visual images first (the occipital lobe is in the rear of the brain above the shirt collar). Next, categories from hearing develop and are hooked together with visual categories. At that point, myelination continues across the top of the brain, where the bodily sensations arrive to the motor area, where bodily movement is controlled. Finally, myelination completes in mid-to-late 20s with delivery of fully categorized information about our environment, situation, and knowledge of our past to the prefrontal lobe, site of our executive functions.
Stages in development are widely accepted and provide a typical approach in psychological and educational studies. Maslow’s Pyramid of Needs is broadest at what I have termed 3S Imperatives. Kohlberg’s Moral Development highlights that our morals shift over the years, with Erikson’s tasks of social development concomitantly occurring (Classic Stages of Individual Development).
Although development proceeds by stages, everyone does not achieve the same level of mastery, which becomes the basis for the next stage. Some people may be stymied as a child which distorts their mental development as a youngster and beyond.
Here, Mental Construction is concerned with the stages that precede the emergence of a mature adult mind.
The stages leading to mature adult thinking, listed in Figure 14.2, combine both biological changes and individual experiences of new types during the stages. The ages in this table are evocative rather than hard-and-fast rules. Each stage has specific physical changes, typical experiences and challenges which one meets with an ethical stance. Also each stage has internal resources that the prior stages have developed.
Ethics are basic. If it feels good, we want it to start or continue. If it feels bad, we want it to stop.
Newborns have strong muscles which they don’t know how to use. That is one of their first challenges, learning to control their muscles to do their bidding. In addition to growing, human infants must develop the understanding of the relation between their internal state and their body movements.Click for more
By the age of five, our hippocampus has developed sufficiently that long-term memory has come online.
The coating of its axons with myelin, a biological stage, between initial sensation and our reaction has been completed. This marks a significant stability in our assessment of external sense data to primitive internal worldview.Click for more
Around the age of seven, we gain a new sense of self as the limbic system, our emotional system, completes its early maturation.
The biologically-controlled myelin sheaths connections between separate areas of the brain occurs. The capacity for situations and behaviors to satisfy or not our needs, goals, and fears are attached (learning) to occurrences, actions, and relationships with our internal worldview.Click for more
Sexual priority of choices.
The biological changes marking the start of this stage are commonly known as puberty. Although the changes are overtly physical, there is fundamental mental aspect too. The interest in sex becomes a primary filter through which we evaluate the world and situations around us.Click for more
Physically mature, yet emotional choices are still developing
Superficially, by this life stage, one has completed their physical growth. If you are dissatisfied with your body, it’s time to exercise and adjust your diet, because the hormones and genetic factors have completed their basic outline of your physical appearance. Neurologically, senses and memory have completed their baseline preparation. The paths between the earlier modules and the initial decision sites of the prefrontal lobe are still being established (myelinated).Click for more
You have the power of firm beliefs and a loss of ability to change.
Myelination, the sheathing of axons cementing your idiosyncratic connections between your personal worldview and the executive areas of the frontal lobes, is finally complete. You think rapidly on a conscious level, deciding whether current situations are attractive for your goals and desires. If not, you consider other options available to you.Click for more
Myelination marks the fixing of one’s preferred output from one brain module to another. In addition to speeding thoughts, it introduces rigidity into the internal worldview. It becomes more difficult to change or adjust to new situations. Thus, we typically resort to forcing new circumstances into categories based on previous situations rather than adding new categories.
Let’s consider the sources of thoughts and their net result—cognition.