Outline Lecture 19 Individual Differences
1. Preamble: person vs. situation?
2. Individual Differences at Diff. Levels of Analysis (Mechanism, Development, Function)
- Differences require an explanation at all levels
3. Why Are There Any Differences? Why Aren’t People Identical?
4. Developmental Causes of Differences
- Malfunctions, pathologies, errors
- Facultative responses
5. Causes of Heritable Differences
– Low selection pressure:
– changing selective pressures:
– byproducts: leftovers of something else that is adaptive & heritable
– Frequency-dependent selection: payoffs for a trait are dependent on their prevalence
within the population
– cliff effect: if there is too much of a given trait in a population it can produce defects?
6. Psychopathy: a frequency-dependent strategy?
– What is a disorder?
– Psychopathy: deceitful, selfish, manipulative, impulsive, aggressive individuals with
little remorse or guilt
– “when a psychopath commits a violent act, they're not doing it because they're
malicious or evil. They're doing it because they don't give a damn.” (Hare, 2005)
– psychopaths account for:
– <1% of general population
– ~23% of correctional population
– perhaps as much as 50% of repeat violent offenders
– parasitic lifestyle, glib superficial charm, pathological lying, manipulation
– The difference between “disorder” and “something we don’t like”
– many people consider psychopathy to be a pathology (disorder)
– think of it as a manipulation of genes (brokeness) during development
– but: we may be equating our dislike of their behaviour with “disorder”.
– There are many things that we dislike that are not disorders, could this be one
– what is a disorder? (not something that we dont like) – wakefield: a disorder is a “harmful dysfunction”
– a failure of a mechanism to perform its evolved function (explanatory
– dysfunction must be socially undesirable (value criteria)
– a dysfunction could be someone who is over the top altruistic, could be
really bad for them but because its not socially undesirable so not a
– psychopathy may not be a dysfunction, but an adaptive life-history
strategy. Maybe there is nothing broken, its just an alternative strategy
– Why might psychopathy be a frequency-dependent strategy?
– Recall prisoners dilemma.
– If everyone is a cooperator, no-one expects the cheaters
– as cheaters become more common, people will be less trusting
– psychopaths have the advantage because they exploit and move on, they reap
benefits because everyone is trusting
– as they become more prevalent in population, people become less trusting and
more willing to punish.
– The more psychopaths, the less the payoffs for psychopaths will be
– frequency-dependent selection for psychopaths: it is advantageous for a single
psychopath to be around, but when there are more psychopaths the payoff for
each becomes less and less. When rare they do better, when common they do
worse than cooperators. Would expect a stable level of psychopaths in population
– psychopaths as discrete class?
– Bimodial distribution of scores on psychopathy checklist (PCL-R): scores best
described as a measure of the “like