Definition: Humans have a cognitive limit of approximately 150 people with which they can maintain personal relationships.
Insight: The number (150) has remained relatively constant throughout history, geography, or activity.
Insight: Dunbar argues that this is directly related the the physical size of the neocortex, the part of the human brain responsible for conscious though, logic, and language.
Insight: Organisations should not consist of groups of people in the smallest networks of more than 150 - many organisations use this number as the guide to the maximum number for the efficiency of teams, groups, and departments.
Reference: Origin: The work of evolutionary biologist Robin Dunbar on the human brain and social groups.
Example: The size and configuration of armies across the world and throughout history: consist largely of platoons (10-15 soldiers), companies (3-4 platoons), battalions (3-4 companies)..
Reference: Garrett Hardin - described what happens on common land - example of sheep grazing causing a destruction of the land by overuse.
Reference: John Sulston in a report argues humanity to think beyond competition: '"So long as an excess of competition between nations continues," the report concludes, "the future of humanity is in doubt."'
Insight: Hardin's 1968 paper was controversial as it had no technical solution to the problem of resource allocation, only a "fundamental extension of morality".
Insight: Taken together, game theory and The Tragedy of the Commons illustrates the destructiveness of competitive self interest.
Definition: Stress can enhance learning on easy tasks, but will impair learning on more difficult tasks.
Insight: Complex tasks require a lot of energy from the brain including working memory, executive processing, decision-making, and attention. Stress impairs the functioning of the prefrontal cortex - where we do our thinking - and the hippocampus - responsible for complex problem solving.
Insight: We might have the mental capacity but stress can make it challenging to put everything together.
Reference: In 1905 Robert Yerkes and John Dodson studied stress in mice. The put mice into a box wired with electricity. They found that learning in mice increased with the intensity of electric shocks on simple tasks, but declined with intense shocks on more difficult tasks.
