Tagged: Individual Differences

Brains and personality

(Prompted by this.)

The main complaint one hears about the big five is that there’s an absence of theory explaining what’s driving the different dimensions.  It’s all descriptive, or at best “finger in the wind” theorizing.  At least that’s (my perception of) what the critics go on about (usual disclaimers apply).  Oh and the stats can be a bit dodgy (see Borsboom, 2006, for a discussion of misapplications of PCA).

DeYoung and colleagues found a bunch of correlations between personality traits and volume of different brain regions.  That there’s a relationship between personality and brain structure is unsurprising.  That it can be detected is nice, though.  That it can be detected with such a crude measure (bigger is better function – except for one bit of the brain and agreeableness) is perhaps surprising, but has been spotted before in (part of) taxi drivers’ hippocampi in the context of spatial navigation (Maguire et al, 2000).

This work belongs to the genre of trying to work out what cognitive processes are driving personality.  The geography is not particularly interesting in itself.  But with a spot of detective work linking to other studies, the geography gives clues about what might be going on.

Reference

Borsboom, D. (2006). The attack of the psychometricians. Psychometrika, 71, 425-440

DeYoung, C. G., Hirsh, J. B., Shane, M. S., Papademetris, X., Rajeevan, N. & Gray, J. R. (2010).  Testing Predictions From Personality Neuroscience: Brain Structure and the Big Five. Psychological Science, 21, 820-828

Maguire, E. A., Gadian, D. G., Johnsrude, I. S., Good, C. D., Ashburner, J., Frackowiak, R. S. and Frith, C. D. (2000). Navigation-related structural change in the hippocampi of taxi drivers. Proceedings of the National Academy of Sciences of the United States of America, 97, 4398-4403

Your brain predicts your behaviour better than you can!

Falk et al (2010) have an interesting article showing how future behaviour, applying sunscreen, can be predicted by brain activity as people watch persuasive messages.

Activity in the (a priori selected) “region of interest” (ROI), a bit of the frontal cortex (MPFC), explained 24% of variance in the number of days of actual sunscreen use. Self-reported intention to apply sunscreen explained only around 3% of variance in days use. Nice result.

I think some caution is warranted, however, before people testing message persuasiveness, such as health organisations, invest all their money in brain scanning.

Behavioural methods include not only self report. For instance asking people how smart they are (e.g., indirectly, using Need for Cognition) is not as good as testing how smart they are (e.g., using Raven’s Advanced Progressive Matrices). Similarly there might well be behavioural ways to test the effect of persuasion, or to infer who is most likely to be persuaded, which can predict much better than the self-reported intention.

These results clearly demonstrate that the expensive and time consuming method of functional imaging is entirely unnecessary for testing message persuasiveness. Simply show people the message and then ask them later how they actually behaved. Very cheap and easy! Especially nice if you can try out a few different versions and select the one which works best.

There is always the danger that people cannot be trusted to report their actual sunscreen usage, a point acknowledged by the authors (as their data explain variance in a self-report measure): “direct observation of behavior would be preferred in future studies, our measurement of behavior through self-report is unlikely to have artificially enhanced our results.” So here the self-report of actual sunscreen usage is completely trusted.

The imaging might provide some theoretical clues for why people were persuaded. There is little of this theory in the paper. This is it, in fact: “… this region has been associated with selfreferential processing, but our ROI also overlaps with a more ventral portion of MPFC that has been associated with implicit valuation.” Such theoretical depth is sadly common in the function imaging literature.

I am very impressed that they found an ROI that predicts so well and I appreciate that a lot of work must have gone into this study. It will be interesting to see if it replicates and generalises. I also hope some theory is on the way explaining mechanisms of persuasion.

Reference

Falk, E. B., Berkman, E. T., Mann, T., Harrison, B., & Lieberman, M. D. (2010). Predicting persuasion-induced behavior change from the brain. Journal of Neuroscience, 30, 8421-8424.

Mill on patterns of human existence

“… it is important to give the freest scope possible to uncustomary things, in order that it may in time appear which of these are fit to be converted into customs. But independence of action, and disregard of custom are not solely deserving of encouragement for the chance they afford that better modes of action, and customs more worthy of general adoption, may be struck out; nor is it only persons of decided mental superiority who have a just claim to carry on their lives in their own way. There is no reason that all human existences should be constructed on some one, or some small number of patterns. If a person possesses any tolerable amount of common sense and experience, his own mode of laying out his existence is the best, not because it is the best in itself, but because it is his own mode. Human beings are not like sheep; and even sheep are not undistinguishably alike.”
—J. S. Mill, On Liberty

Some troubling and interesting things about investigating reasoning

Competence models are typically created and explored by a small number of experts.  Boole, Gentzen, Kolmogorov, Ramsey, De Finetti, …  The authority can often be shifted to the mathematics.   However, although non-experts can usually understand a statement of the theorem to proved, often they can’t understand the details of the proof.

There are problems with being an expert.  If you stare too long at the formalism, then you lose your intuition, and can’t see why someone would interpret a task “the wrong” way.  Often there are a priori non-obvious interpretations.

And who decides what constitutes a permissible interpretation?  Some obvious ideas for this are open to debate.  For instance, is it always reasonable for people to keep their interpretation constant across tasks?  Or is it rational to change your mind as you learn more about a problem?  Is it rational to be aware of when you change your mind?

To complicate things further, various measures loading on g predict interpretations.  Does that mean that those who have better cognitive ability can be thought of as having reasoned to the correct interpretation?

Embracing individual differences

This week I finished teaching/facilitating a course entitled Embracing individual differences in thinking and reasoning.  I was asked to give the gist of what this was about.

There’s a bunch of individual differences in how people solve reasoning problems. One way of thinking about this is that some people are very good at reasoning problems and others are not so good, with a continuum in between. But there’s evidence that people are interpreting the tasks in different (and reasonable) ways, and succeeding in reasoning from their interpretation. We examined these sorts of issues on the course.

A simple example is the meaning of “some”, discussed by J S Mill in his 1867, An examination of Sir William Hamilton’s philosophy: And of the principal philosophical questions discussed in his writings. “I saw some of your children today” implicates that I didn’t see all of them (if I had, then I’d have said so), even though the “all” conclusion is compatible with some.

There are many other examples: the degree to which people are affected by how information is presented; whether people can suspend their beliefs and reason from premises which are obviously false; whether people are sensitive to alternative causes of effects, or factors which can disable a relationship between a cause and effect.

The waters are muddied somewhat by complicated relationships with intelligence. So for instance people with higher intelligence (for several of the standard psychological ways to operationalize the concept as IQ) are more likely to go for the normative answer on some (but not all) tasks. But then one can wonder what exactly the IQ tests are measuring.

Things get particularly interesting when people with clinical conditions, such as autism, actually are more likely to give the normative answer for some tasks. There’s a nice example of where their ability to do so was used as an argument for why the normative answer was wrong. One researcher blogged:

Autistics were shown to perform with enhanced logical consistency, avoiding irrational and irrelevant biases that distorted decision-making in their nonautistic controls. However, autistics’ enhanced performance in this study was interpreted by the authors as a litany of autistic failures, imbalances, impairments, deficits, reduced capacities, weaknesses, and impoverishments (several invocations of some of these), none of which were actually found. […] In years to come, we can look forward to interventions designed to overcome this core autistic deficit and to ensure that autistics become as irrational as nonautistics.

There were plenty of issues to debate…

Working on your quirk

Another brief interlude from the stats and cog psych, but related to individual differences in reasoning I think! Interesting aside in a book by Robert Sutton on dealing with assholes (technical term here) in the workplace. He clarifies his defintion of the particular breed of asshole (technical term) in whom he is interested (pp. 16–17):

My focus is squarely on screening, reforming, and getting rid of people who demean and damage others, especially others with relatively little power. […] I am a firm believer in the virtues of conflict, even noisy arguments.

Here’s a special case he describes (pp. 18–19) of people who can occasionally appear to be assholes (technical term), but are not:

I also want to put in a good word for socially awkward people […]. I was struck by how many successful leaders of high-tech companies and creative organizations like advertising agencies, graphic design firms, and Hollywood production companies, had learned to ignore job candidates’ quirks and strange mannerisms, to downplay socially inappropriate remarks, and instead, to focus on what the people could actually do.

Examples he gives include autistic people and those with Tourette’s syndrome.

Reference

Sutton, R  (2007). The No Asshole Rule. NY: Business Plus.

Profiles of intelligence

Johnson, W. & Bouchard, Jr., T. J. Sex Differences in Mental Abilities: g Masks the Dimensions on Which They Lie. Intelligence, 2007, 35, 23-39:

“… we have presented evidence supporting the idealized notion of general intelligence as a general-purpose mechanism that accesses a toolbox made up of components that vary from individual to individual. Though everyone clearly has most if not all of the same tools, individuals appear to differ not only in the skill with which they use their tools, but also in the specific tools they habitually use. For some of the more specific tools, it would appear that using one tool means failing to use another. […] Performance on image rotation tasks is known to predict success in fields such as airplane piloting, engineering, physical sciences, and fine arts better than does general intelligence, and especially verbal ability. What has perhaps not been recognized is that inclusion of verbal ability in assessments used to recruit individuals to those fields may actually act to impair efforts to select those with the talents most relevant to the jobs in question.”

John Raven often quotes Spearman:

“Every normal man, woman and child is a genius at something … the problem is to identify at what … this must be a most difficult task because it occurs in only a minute proportion of circumstances … this cannot be done with any of the procedures in current use …”

(And Raven would still quite like to know how to fix psychometrics.)

"... we have presented evidence supporting the idealized notion of
general intelligence as a general-purpose mechanism that accesses a
toolbox made up of components that vary from individual to individual.
Though everyone clearly has most if not all of the same tools,
individuals appear to differ not only in the skill with which they use
their tools, but also in the specific tools they habitually use. For
some of the more specific tools, it would appear that using one tool
means failing to use another. [...] Performance on image rotation tasks
is known to predict success in fields such as airplane piloting,
engineering, physical sciences, and fine arts better than does general
intelligence, and especially verbal ability. What has perhaps not been
recognized is that inclusion of verbal ability in assessments used to
recruit individuals to those fields may actually act to impair efforts
to select those with the talents most relevant to the jobs in question."