Tag Archives: amygdala

Introversion and Extraversion Starts with Your Genes and Shows in Your Brain

Susan Cain

Susan Cain

Introverts seem to be experiencing an increasingly “level playing field” in work and social environments after Susan Cain’s best-selling book celebrating “the power of introverts in a world that can’t stop talking.”

Hans Eysenck

Hans Eysenck

University of London’s Hans Eysenck provided one of the first physiological explanations of this duality after Carl Jung’s introduction to “psychological types.”

The subjective experience of introversion and extraversion is measured by the Big Five personality dimensions, developed by Robert McRae and Paul Costa, then of the National Institutes of Health, in addition to the widely-used yet psychometrically-criticized Myers-Briggs Type Indicator. 

Eysenck's Three-Factor Theory of Personality

Eysenck’s Three-Factor Theory of Personality

Observable behaviors associated with extraversion include positive emotions, assertiveness, sociability and talkativeness with energetic engagement in work and social contexts.

In contrast, external manifestations of introversion are lower social engagement and energy, and less need for external social stimulation than extraverts, with a quieter, more deliberate style.

Robert McCrae

Robert McCrae

These behaviors are at least partially based on individuals’ genetic profiles, leading to differing brain activity associated with introverted and extraverted thinking and behavior.

Paul Costa

Paul Costa

Eysenck posited that extraverts and introverts differ in their levels of cortical arousal:  Introverts, he suggested, have a higher baseline level of arousal than extraverts, so need less external stimulation.

In contrast, he hypothesized that extraverts seek external stimulation because they have a lower baseline level of cortical arousal.

Yasuyuki Taki

Yasuyuki Taki

Differences in brain structure and function among introverts and extraverts was analyzed by Yasuyuki Taki’s team at Tohoku University, including collaborators  Benjamin Thyreau, Shigeo Kinomura, Kazunori Sato, Ryoi Goto, Kai Wu, Ryuta Kawashima, and Hiroshi Fukuda. 

The evaluated whether personality traits measured on a revised Big Five inventory (Revised NEO Personality Inventory – NEO-PI-R) were related cortical gray matter volume, measured by brain magnetic resonance images (MRI) for more than 270 healthy volunteers over 6 years.

Colin DeYoung

Colin DeYoung

Likewise, University of Minnesota’s Colin DeYoung, Jacob Hirsh of University of Toronto, The Mind Research Institute’s Matthew Shane, and Yale’s Xenophon Papademetris, Nallakkandi  Rajeevan, and Jeremy Gray used a similar method to conclude that behavioral and subjective extraversion was positively correlated with orbitofrontal cortex metabolism and increased cerebral volume of the medial orbitofrontal cortex in 116 adults. 

Michael X. Cohen

Michael X. Cohen

Extraversion has been correlated with sensitivity to rewards and to the brain’s dopamine system, so University of Amsterdam’s Michael X. Cohen and team investigated the brain’s dopamine-based reward system.

He collaborated with Jennifer Young, Jong-Min Baek, Christopher Kessler, and Charan Ranganath of University of California, Davis to demonstrate the connection among trait extraversion, the A1 allele on the dopamine D2 receptor gene, and “extraverted” activity in the brain’s reward system during a gambling task.

Charan Ranganath

Charan Ranganath

Participants received rewards either immediately following a behavioral response or after a 7.5 second “anticipation” interval.
The research team monitored differing fMRI brain activity in the amygdala, which processes emotional stimuli and triggers excitement, and in the nucleus accumbens, which pushes people to seek rewards, novelty and risks.

Brain activation patterns were related to individual differences in extraversion and presence of the A1 allele on the dopamine D2 receptor gene.
Neural pathways differed for extraverts and introverts, validating anecdotal observations that these personality styles are distinctly different, even deep inside the brain and genes.

Many introverts adopt extraverted behaviors in work and social situations, and a remaining question is how fMRI patterns differ for introverts displaying uncharacteristic extraverted behaviors in contrast to people with trait extraversion.

-*How easily can you adopt your non-dominant personality style when you need to display introversion or extraversion behaviors?

-*What tactics enable you to adopt your less-preferred personality style?

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Beware of Seeking, Acting on Advice When Anxious, Sad

Just as wise grandmothers advise, it’s best to avoid decisions when upset, anxious, or sad.

Maurice Schweitzer

Maurice Schweitzer

Maurice Schweitzer and Alison Wood Brooks of Wharton and Harvard Business School’s Francesca Gino validated Grandmother Wisdom in eight experiments that demonstrated anxiety’s impact on lowering self-confidence, impairing information processing, and impeding ability to distinguish advice from neutral advisors and those with a conflict of interest.

Alison Wood Brooks

Alison Wood Brooks

They found that people experiencing anxiety tend to seek advice and act on it, but they are less able to differentiate poor advice from valid recommendations, and these results are applicable to making decisions about crucial medical treatment, financial investments, or even guidance counseling.

Francesca Gino

Francesca Gino

The team evoked anxious feeling among volunteers by presenting potentially frightening film clips and music, and asked them to judge a person’s weight based on a photograph or number of coins in a jar or solve a complex math problem.

Participants were offered money for correct judgments, and the opportunity to receive advice from others when they were uncertain.
Those who heard the scary music or saw the alarming film clip rated themselves as less confident of their decision, and were more likely to ask others for advice.
These effects were not observed when volunteers were shown a film clip that could provoke anger.

Schweitzer, Brooks, and Gino concluded that people vary in their receptivity to advice based on:

  • Advisor’s characteristics, such as expertise, consistent with Cialdini’s observation

    Robert Cialdini

    Robert Cialdini

  • Perceived difficulty of the decision
  • Decision maker’s emotional state when receiving advice

The researchers advised decision-makers to:

  • Monitor their internal states for anxiety
  • Use feedback from multiple sources when making important decisions
  • Work toward developing increased self-confidence
  • Evoke calm state, often possible with systematic breathing or mindful attention and equanimity
Catherine Hartley

Catherine Hartley

Catherine Hartley, then of New York University and Elizabeth Phelps of New York University contributed to the neuroeconomic analysis of anxiety’s impact on decision- making when they reported that brain structures responsible for regulating fear and anxiety are also involved in economic decision-making under uncertain conditions.

Elizabeth Phelps

Elizabeth Phelps

Specifically, the amygdala is crucial in learning, experiencing, and regulating both fear and anxiety and it is also implicated in decision-making in situations of potential loss.
The prefrontal cortex is specialized in controlling fear and is also involved in decisions containing risk elements.

Hartley and Phelps suggest that techniques for altering fear and anxiety may also improve economic decisions-making.

Rajagopal Raganathan

Rajagopal Raganathan

Rajagopal Raghunathan, then of New York University and Michel Tuan Pham of Columbia University demonstrated the same connection between anxiety and making decisions about gambling and job selection.

Michel Tuan Pham

Michel Tuan Pham

They conducted three experiments and found that sad individuals select high risk / high-reward gambling and job options, whereas anxious individuals are biased in favor of low-risk / low-reward options.

Raghunathan and Pham posit that anxiety tends to motivate people to reduce uncertainty whereas sadness moves people to replace rewards.
They suggest suggesting two different decision biases related to mood states.

Raghunathan and Pham add to Schweitzer, Brooks, and Gino’s recommendations for mitigating decision bias:

  • “Monitor feelings”
  • Consider alternate options
  • Speculate on future moods and preferences if each option were selected: “What would I feel better about . . .?

-*How do you mitigate the potential decision bias when anxious or sad?

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