Personality and cognitive abilities are closely and inextricably linked. If you are high in introversion you may focus a good deal of your energy on your own inner world. Extraverts, in contrast, tend to be highly aware of what’s going on around them as part of their overall outgoing personality orientation. It would follow, then, that their differing attentional styles may lead introverts and extraverts to process the information they need to understand and react to the physical world around them.
Surprisingly very few studies actually peer into the cognitive processes of introverts and extraverts. One theory dating back to the mid-1980’s is the “Unified Model of Extraversion” proposed by Australian psychologist John Brebner. According to this view, the events going on around you require that you either excite or inhibit your mental state depending on which type of analysis you’re required to perform. Some situations demand that you analyze incoming information, such as deciding whether your phone is actually ringing while you’re in the middle of doing something else. According to Brebner’s model, the brains of introverts generate more excitation in this phase of stimulus analysis. Extraverts, in contrast, need to inhibit everything else going on in their minds in order to make this decision. This is part one of the stimulus-response cycle. In part two, when you actually have to prepare a response, introverts are more likely to inhibit an action, causing them to take longer than extraverts, who can move quickly. The introvert may hesitate longer before picking up the phone, but the extravert will answer it right away.
Researchers using electroencephalograms (EEG’s) have powerful tools available now to analyze how quickly our brains respond to incoming stimuli and what they do when they have to initiate a response. You’ve probably seen those images of laboratory subjects wearing what look like bathing caps with hundreds of small tubes sticking out of them all around their scalps. These are the sophisticated EEG recorders that allow researchers to see how much electrical activation the brain is initiating (called “Event Related Potentials,” or ERP’s). By tracking that activation over time (the “latency”) they can also determine which of your thought processes are clicking the strongest (see figure).
Peaks of activity right after a stimulus appears (1/10th of a second) suggest that you’re just becoming alerted to the stimulus. As the milli-seconds tick (or zoom) by, other cognitive processes kick in, such as analyzing the incoming information and then eventually prepping your reaction.
Swiss researchers Corinne Stauffer (2012) and her associates decided to test the Unified Model of Extraversion in an innovative study comparing the ERP’s of college undergraduates (all of them female) who scored either very high or very low on a standard extraversion questionnaire. In their elegant and well-conceived study, they asked their participants to examine computer screens that presented sets of little colored squares containing from 2 to 4 to 6 different colors. All the squares were different colors on each trial.
The study's procedure was as follows. First, the participants had to look at a cross in the middle of the screen for half a second. Then they saw a sample display (the 2, 4, or 6 squares) followed nearly 1 second later with a set of test stimuli (again 2, 4, or 6). In this test set, one of the color squares either changed or it did not. On half of the tests the squares didn't change and on the other half they did, meaning that you had to pay particular attention to the all of the squares on each trial. There were a total of 96 trials in all. You might imagine that this test placed a great deal of mental load on the participants, even though they all were average undergraduate age and supposedly in peak mental shape. However, by the time they were judging up to sets of six squares for this tiny fraction of time, their cognitive abilities were certainly taxed, well worth the $40 (in U.S. equivalent) they were all paid.
As they had predicted, Stauffer and her team found that the introverts showed larger N1 peaks than their extraverted counterparts. This was a finding that other researchers had also demonstrated, but Stauffer was giving them a harder task then other investigators had used. So far, then, it appeared that introverts reacted strongly to the sensory stimuli coming their way, more so than did the extraverts. The researchers believed that this finding showed introverts to be more sensitive to incoming information, and also to expend more mental effort by analyzing those stimuli more deeply and carefully.
Despite their more engaged processing of incoming stimuli, there were no behavioral differences in performance. In other words, the introverts didn’t have better or worse memory performance than the extraverts. However, the behavioral data didn’t tell the complete picture. Once again, turning to those ERP’s, Stauffer and her team found that extraverts were more sensitive to the changes in colors within those sets of small squares. In the condition when the study and test set were exactly the same, all participants reacted the same way in terms of their ERP’s. However, when those little squares changed colors, it was the brain waves of the extraverts that showed a larger reactivity.
Everyone maintains mental representations of their environments that are updated as soon as the environment changes. Stauffer believes that, on the basis of her findings, extraverts show greater sensitivity than their introverted counterparts to such changes in their surroundings.
The introvert reacts strongly and quickly when something new appears on the horizon. Extraverts, in contrast, almost have to turn down their brain’s readiness to trigger reactions to new stimuli. However, extraverts are better able to monitor the events going on around them and seem particularly programmed to register changes. Introverts react to change more slowly and less intensely.
If we can extrapolate from studies on the thought processes of introverts and extraverts under these highly controlled lab conditions with female undergraduates, the results provide a window into how introverts and extroverts react to their worlds. Both introverts and extroverts have cognitive strengths, though those strengths are quite different. When new stimuli come their way, introverts react quickly and strongly. Extraverts, in contrast, seem better attuned to detecting small differences from one situation to the next.
The changes studied in this lab study involved, of course, very short time intervals. Eventually, extraverts notice new stimuli and introverts detect slight changes. However, for those fleeting seconds that mark how our brains initially understand the world, our personalities seem to play important roles. Stauffer's research shows us that there's no such thing as "pure" cognition. We bring our personalities into all of our interactions in the world, even those that involve our brain's respose to stimuli.
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Copyright Susan Krauss Whitbourne, Ph.D. 2013
Stauffer, C. C., Indermühle, R., Troche, S. J., & Rammsayer, T. H. (2012). Extraversion and short-term memory for chromatic stimuli: An event-related potential analysis. International Journal of Psychophysiology, 86, 66-73. doi: 10.1016/j.ijpsycho.2012.07.184