My Apologies

By jtm | December 12th, 2009

To those of you waiting for new posts, I’m sorry to say the site is on indefinite hiatus due to my return to formal education.  With any luck I will be writing about psychology in peer-reviewed publications soon, so you may hear from me again, if only indirectly.  I will leave my first three posts up for posterity for anyone, particularly students, who may be interested in the topics.

Regards,

- JTM

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Controversy #3: How Are Inherited Traits Influenced by the Environment?

By jtm | June 29th, 2009

According to search engine trackers, the phrase “are inherited traits influenced by the environment?” is one of the most asked science questions online, with hundreds of hits on Google per day.  On the surface though, it appears a needless question; of course traits that have a genetic component are also influenced by the environment.  No behavioral genetic study has ever come up with a perfect heritability of 1.00 for a trait that varies within a population, least of all because measurement error limits reliable interpretation above approximately the 0.90 level (heritability runs on a scale of 0.00-1.00 like the correlation coefficient, where the variance accounted for is the coefficient squared).  Most commonly, about half the variation of a given behavioral trait is due to environmental influences and half to genes.  What the question really should be asking is not whether inherited traits are influenced by the environment, but how they are, because that’s where the answer becomes interesting, and it depends on who you ask.
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Posted in Behavioral Genetics, Developmental Psychology | Leave a comment

Controversy #2: Causes of the Person-Situation Debate

By jtm | June 17th, 2009

The person-situation debate was an extended disagreement, originally between social psychologists and personality psychologists, on whether the “situation” or personality traits are more predictive of people’s behavior. As the story goes, the debate was initiated by the publication of Walter Mischel’s 1968 book Personality and Assessment, which made two empirical claims about the trait approach to personality. Mischel argued that (1) a review of the literature shows that personality traits only have a correlation of about 0.30 with how people behave in any given situation, and (2) the cross-situational consistency of behavior is also only around 0.20 to 0.30. Thus, he concluded that personality traits are not good predictors of behavior, and that situations are much more important in how people behave. Furthermore, he maintained, personality traits do not really exist: the personality descriptors used by lay people are illusory because behavior is not really consistent from one situation to the next.1 Read More »

Posted in Personality, Social Psychology | 3 Comments

Controversy #1: Neural Plasticity, Miracle or Banality?

By jtm | June 11th, 2009

Brain plasticity is often touted as a ground-breaking finding in neuroscience, one with important implications for human learning potential, and the malleability of human nature, as seen in psychology.  Norman Doidge, author of The Brain That Changes Itself, called it: “one of the most extraordinary discoveries of the twentieth century.”1

Intuitively though, neuroscientists have always known that something must be changing in the adult brain when learning occurs: unfortunately, they just couldn’t find any physical evidence of it for the first half of the twentieth century. The complexity of the human brain, as well as the simpler ones of research animals, eluded them. It was an important affirmation of their premises and hard work then, when starting in the 1960s and 70s, neuroscientists like Eric Kandel found actual changes in neuronal responding due to classical conditioning. The research project to find new forms of functional and structural plasticity of the brain was later greatly accelerated through the 1990s through brain scanning technology, such as magnetic resonance imaging (MRI). Many of the results were fascinating and important milestones for neuroscience.

To get to the controversy, the main problem critics identify with a lot of the recent talk about brain plasticity in psychology is that it glosses over the built-in structure and constraints placed upon the brain by evolution. Read More »

Posted in Neuropsychology | 2 Comments