Image Above – The Canadian Jay or Whiskey Jack, a very proactive bird.
Two models of psychology from the 1990s recently caught my attention. They posit an idea about human personality that seems to resonate with the reading I have been doing on the trait of high sensitivity.
The models hypothesize that there is a sub-group of humans who are sensitive in a very specific way. They are more in tune with two environmental conditions; one negative and the other positive. The negative conditions are ones that have a high potential for risk. They are refereed to as “risk-promoting” conditions. The positive conditions are ones that promote personal development, dubbed “development-enhancing” conditions.
Susan Cain in Quiet quotes research that introverts are risk sensitive, while extroverts are reward sensitive.
The 1990s models are called the “Biological Sensitivity to Context Theory” (BSCT) developed by W.T. Boyce and B.J. Ellis; and the “Differential Susceptibility Theory” (DST) developed by Jay Belsky and Michael Pluess.
These models suggest that for many species two types of basic personalities exist: Reactive and Proactive.
Reactive personalities are good at deeply processing experiences to find or uncover connections in the data, larger patterns, and relationships of meaning. This provides these individuals with a survival advantage for long term planning and acquisition of resources within known territory.
Proactive personalities seek strong stimulus and tolerate risk in order to be the first to discover an advantage in new and hostile environment.
Reactive personalities tend to play a long game, while proactive personalities use their quick assessment skills to react quickly and secure resources before others.
The negative environmental conditions labeled “risk promoting” do not cause undue concern to Proactive types. They learn to seek out these environments as places they can test and hone their skills. As they get better at assessing, avoiding, and reducing risks, they are rewarded with more and more resources and territory that was underutilized because of the risks involved.
“Development enhancing” environments refers to conditions like a loving stable family, economic stability, and predictable and stable cultural norms. Reactive personalities do better in all aspects of life than proactive types when they grow up in development enhancing environments. They are said to respond disproportionately better than proactive types to these conditions.
In practice this means that Reactive types appreciate and thrive in stable predictable environments and succeed to a greater degree than proactive types after significant development takes place in their life. Proactive types benefit from growing up in stable healthy environments too, but much earlier in their life they push out into challenging, difficult, dangerous, and hostile environments seeking rewards and success while they develop.
Both strategies have been selected for in the course of the evolution of life because both strategies are effective, depending on the conditions at any given time.
During times of low competition or when resources are plentiful, Reactive types build stability and stores, and more complex biological and social systems to support their family, pack, group, or community. In times of scarcity and challenge Proactive types show their prowess by finding untapped opportunities for themselves and their group.
For Reactive types, when the world is hostile, unpredictable, and unstable, or when resources are scarce and competition is high, they are not very successful. The negativity bias protects them during such times and evidence suggests that social factors can profoundly impact their physiological adaptation to these environments.
Paradox: Without nurture, rats learn and remember better
Research conducted by Michael Meaney and colleagues showed that rats who provided lower than usual maternal care produced measurable changes in their pup’s brains and nervous systems.
Specifically pups who received low levels of maternal licking and grooming had higher corticosterone levels, shorter dendritic branch lengths, and lower spine density in hippocampal neurons.
The agent of change is methyl groups. In rats when parents experience stress they pay less attention to their pups. This increases the amount of methyl groups in each pup’s body, making it more likely that they’ll bind to susceptible spots in the genome. One such spot is on an area of the genome that promotes production of receptors for estrogen, which is associated with maternal care. Fewer estrogen receptors mean less oxytocin and lower maternal investment, which feeds back into increased stress for their offspring, triggering a feedback loop. Stressed mom rats give less attention and their daughters, who feel less need to give attention, and the pattern continues.
This all sounds pretty bad and has caused many theorists to generalize. It seems likely that many mammals who do not give their children enough attachment-support will produce neurologically anxious children. In human terms we call it neglect and it is considered a serious matter.
But anxiety has an upside. The high corticosterone, short dendritic, low spine hippocampal celled rat pups were better at learning and memory than well-licked rats under stress. (Champagne et al., 2008).
These researches further demonstrated that the enhanced learning under stressful conditions was increased in tandem with other behaviors such as defensive behaviors, accelerated sexual maturation and increased sexual behavior. In this context, neglect itself can be regarded as a mechanism through which rat parents, inadvertently perhaps, guide their offspring’s development toward optimal survival and reproductive strategies under conditions of adversity.
Contrary to previous assumptions, diminished licking and grooming is not “poor maternal care” but rather a mechanism in mammalian evolution that prepares offspring for ecological conditions that requires more vigilance, learning, sexual activity, and memory.
I think there is enough evidence to suggest that Reactive individuals match the biology and genetic profile of individuals who received less metaphorical “licking” but is it the explanatory mechanism, a correlation, or a separate factor? I know a few people who had similar upbringings to my own, but they are proactive, appearing not to have developed a reactive nature.
If maternal attention is explanatory, then human subjects who are neglected should be more defensive, more anxious, more sexually active, and more adept at learning and remembering under stressful conditions. These are very general parameters, and might express differently in the highly complex human organism. For example, I would be interested to know if “sexual activity” might manifest in more complex mammals as an attachment style that is more anxious.
At the moment, I’m not aware of any research directed at teasing out these questions.
For most of my life, my tendency to hesitate, contemplate, ruminate, and perseverate, made me the target of criticism from my more proactive teachers, friends, and colleagues. I came to believe I was different from them, less well adapted to success in our action-oriented culture, especially when compared to proactive types.
Proactive people love phrases like, “the early bird gets the worm,” “he who hesitates is lost,” “strike while the iron is hot,” “actions speak louder than words,” and “a rolling stone gathers no moss.” There are dozens of such platitudes lauding the virtue of action, decisiveness, and speed.
I speculate that North America and other frontier areas draw proactive types seeking opportunity; and the closer to the frontier you are, the more likely you are to be surrounded by this type.
Thinking about a Hypothesis
It is tempting to think that Proactive people are less anxious because they received lots of attachment support as children, while Reactive people like myself are more anxious because our attachment support was lower.
The advantage of the reactive brain is that it enhances vigilance and learning. Reactive people are drawn to environments that feel safe and allow for time to think and consider what to do next. The key word there is consider.
Not only do Reactive types consider how to avoid danger, this ability allows them to be considerate of others. It is Jordan Peterson’s theory that we wake up to good and evil by feeling pain ourselves. We know how to hurt others, and know when others are hurting because we have been there.
The Reactive type sounds a lot like someone with SPS the academic term for the trait behind a HSP. Wikipedia says, “Sensory processing sensitivity (SPS) is a temperamental or personality trait involving “an increased sensitivity of the central nervous system and a deeper cognitive processing of physical, social and emotional stimuli.” The trait is characterized by “a tendency to ‘pause to check’ in novel situations, greater sensitivity to subtle stimuli, and the engagement of deeper cognitive processing strategies for employing coping actions, all of which is driven by heightened emotional reactivity, both positive and negative.”
I’m currently looking for a theoretical framework to explain the relationship of the 1990s models with SPS or HSP and uncover how much is nature vs nurture.
Susan Cain quotes research to suggest that introversion, at least, is a trait hard wired in many species.
Dr. Michael Pleuss considered Proactive and Reactive to be related to sensitivity. 
My current belief is that sensitivity is the separate and interacting variable, with introversion and extraversion determining which sensitive types become proactive or reactive.
Introverted SPS are reactive where as extroverted non-SPS folks are the adventurers out there exploring the frontiers (proactive).
Please contact me if you are aware of research related to this topic, I’m keen to develop my understanding of this topic.
 Boyce, W. Differential Susceptibility of the Developing Brain to Contextual Adversity and Stress. Neuropsychopharmacol 41, 142–162 (2016). https://doi.org/10.1038/npp.2015.294 https://www.nature.com/articles/npp2015294#citeas
 Pluess, M. (2015). Individual Differences in Environmental Sensitivity. Child Development Perspectives, 9(3), 138-143.