The science of negativity bias and survival.
Stages in the evolution of man. Increase in size and ‘more convoluted’ brain as evolution progresses.
To make stuffs clear, let’s take a quick look at the facts about the brain.
Evolution of human brain:
“The triune brain”
The triune brain is a model of the evolution of the vertebrate forebrain and behavior, proposed by the American physician and neuroscientist Paul D. MacLean. MacLean originally formulated his model in the 1960s and propounded it at length in his 1990 book The Triune Brain in Evolution. The triune brain consists of the reptilian complex, the paleomammalian complex (limbic system), and the neomammalian complex (neocortex), viewed as structures sequentially added to the forebrain in the course of evolution. However, this hypothesis is no longer espoused by the majority of comparative neuroscientists in the post-2000 era. Some scientists regard this hypothesis as neither completely acceptable nor rejectable. However it offers simple insights on understanding the brains function.
Triune brain proposed by MacLean showing reptilian, mammalian and human neocortex.
Functions of each complex:
The reptilian complex:
- Brainstem, cerebellum, hypothalamus
- Reactive and reflexive
- Avoids hazards
The mammalian complex:
- Limbic system, cingulate, early cortex
- Memory, emotion, social behaviour
- Approach rewards
The human brain:
- Massive cerebral cortex
- Abstract thought, language, cooperative planning and empathy
- Attach to “us”
Three goal directed systems in brain:
The analogy to ‘carrots’ and ‘sticks:’
Avoid “sticks”, threats, penalties and pain. Approach “carrots, ” opportunity, rewards and pleasure. Attach to us, proximity, bonds and feeling close. Each system can draw on the other two for it’s ends.
Reptiles and fish avoid and approach. Mammals and birds attach as well- especially primates and humans. Mammals and birds have bigger brains than reptiles and fish. Thus, more approach behaviour have possibly resulted in bigger brains. The more social the primate species, the more bigger the cortex.
Since the first hominids began making tools approximately 2.5 million years ago, the brain has roughly tripled in its size, much of its build-out devoted to social functions (eg. cooperative planning, empathy and language). The growing brain needed a longer childhood, which required greater pair bonding and band cohesion.
A key component of the reactive mode is a focus on scanning for, reacting to, storing and retrieving negative stimuli– the negativity bias.
Sticks: natural hazards, predators and social aggression and pain (physical and psychological).
Carrots: food, sex, shelter, social support, pleasure (physical and psychological).
During evolution, avoiding “sticks” usually had more effect on survival than approaching “carrots.”
Urgency: Sticks, usually, must be dealt with immediately, while carrots allow a longer approach.
Impact: Sticks usually determine mortality, carrots not; if you fail to get a carrot today, you’ll likely have a chance at a carrot tomorrow, but if you fail to avoid a stick today – whap! -no more carrots forever.
With negativity bias, the avoid systems hijacks the approach and attach systems inhibiting them or using them for its ends.
Survival and the negative stimuli:
Negative stimuli produces greater body arousal than positive ones. Pain can be produced everywhere whereas pleasure is circumscribed. In short, negative stimuli produces greater brainwave responses, amygdala-hippocampal system flags negative responses more prominently in memory.
Like Velcro for negative stimuli and Teflon for positive stimuli
Negative stimuli command more attention than positive ones. They are less common and thus more informative. They are perceived more easily and quickly. Reaction times are faster for angry faces than happy ones.Empathy is elicited more for negative experiences. Learning based on punishment is generally faster. Strong dislikes are acquired more quickly than strong likes.
In nature: multiple chances to learn how to approach rewards but, no chances for trial-and-error learning about dangers.
There’s also a positive bias for positive stimuli that are rare (eg. Heroic acts, exceptional ability).
Thus, negative opinion about a person shapes the opinion most. In health, parenting and relationships, absence of negativity greatly matters more than the presence of positive.