Your Personality, Your Noise

There are far too many flashy statements about what “science tells us” about introverts and extraverts. This distorts the dialogue and affects school and workplace policy. I take up this subject both because it overlaps with some of my interests and because it bears examination. “Science tells us” statements have popular appeal, a big market, and numerous high-profile outlets. They need pushback or at least vigorous questioning.

When it comes to introversion and extraversion, the findings are far less definite than pundits claim. Any blanket statement about introverts and extraverts needs unblanketing. (I see no need to call anyone an introvert or extravert in the first place, but that’s another matter.)

Here is an example. In an interview with the Harvard Business Review, Susan Cain says,

And just to give you kind of a concrete illustration of [how introverts and extraverts work differently], there’s this fascinating study that was done by the psychologist Russell Geen, where he gave math problem [sic] to introverts and extroverts to solve with varying levels of background noise. And he found that the introverts better [sic] when the noise was lower, and the extroverts did better when the noise was higher.

I can’t find that study anywhere, but the statement alone contains some problems, which I’ll lay out in just a moment. I did find Geen’s 1984 study “Preferred Stimulation Levels in Introverts and Extraverts” (Journal of Personality and Social Psychology, vol. 46, no. 6), and I found it precise and cautious in its wording.

This study consisted of two experiments. Subjects (all male) were selected from the upper and lower 25 percent of the Extraversion scale of the Eysenck Personality Inventory. They were undergraduates enrolled in psychology classes.

For the first experiment (which involved 30 extraverts and 30 introverts), Geen sought to determine whether extraverts and introverts, given the freedom to choose a noise level (other than zero) would differ in their choices, and whether such freedom of choice would equalize their arousal levels. There was a “choice” condition and two control conditions: one where the subject was given the noise level chosen by another (“yoked”) subject with the same personality type, and another where the noise level was selected by the experimenter. The subjects took this test one at a time. After selecting their noise level (or having it selected for them), they had to  wait two minutes. Then the projector was turned on, and they worked to complete a paired-associates learning task. The learning task ended when they completed two successive errorless trials. If, after twelve trials, they had not achieved this, the procedure was terminated.

The second experiment had more subjects (40 extraverts and 40 introverts) and a slightly different approach. This time, in addition to selecting their optimal noise level, introverts indicated the lowest acceptable noise level, and extraverts the highest. This established the four intensity levels used in the study. There was only one control condition: where the experimenter chose the noise level for the subject. (The “yoked” condition was eliminated because, in the first experiment, its results did not differ from those of the choice condition.) Otherwise this experiment followed the same procedures as the first.

I will focus on the results of the second experiment (because I have a bit more to say) and because, in Geen’s words, it provided “a replication and extension of the first.” With respect to pulse rate, something interesting came up: introverts and extraverts did not differ in pulse when they had chosen their noise level. When subjected to moderate noise, introverts were more aroused (i.e., had a higher pulse rate) than extraverts, but at the extreme noise levels (high and low), their rates did not differ from each other. This, right away, casts doubt on the blanket assertion that introverts are more sensitive to stimuli than extraverts. The statement needs careful qualification and questioning.

When it came to the task, introverts and extraverts performed equally well at their chosen noise levels. When subjected to superoptimal noise levels, both introverts and extraverts did significantly worse. When subjected to suboptimal noise levels, extraverts did significantly worse, but introverts did not (or they did worse, but not significantly).

This is interesting (and again, carefully thought out and presented), but I see a few caveats here. (And I haven’t forgotten about the Cain quote; I’ll come back to it in a minute.)

First, there are problems with selecting the top and bottom 25 percent on the extravert scale; your subjects are already at the extremes. How much of this applies to a full population is uncertain. That said, if you didn’t do that, you’d probably end up with so much noise (in the data) that you couldn’t draw any conclusions.

Second, I wonder to what degree the Eysenck Personality Inventory already relates to noise tolerance. That is, are these subjects defined as introverts/extraverts partly on the basis of their reported tolerance of noise? That would make the experiment somewhat redundant.

Third, I wonder to what extent the particular kind of noise influenced the results. (These were one-second bursts of white noise, with a mean of ten seconds between bursts.) I can imagine the high levels being particularly jarring (to anyone), and the low levels annoying (that pesky sound you can’t get rid of).

There are still more open questions; to begin to address them, I would need more statistical  knowledge and access to the raw data. To his credit, Geen does not draw rash conclusions from this study; at the end, he offers possible implications and describes the work that still needs to be done.

So I come back to the Cain quote, in particular: “And he found that the introverts better [sic] when the noise was lower, and the extroverts did better when the noise was higher.”

She could not have been talking about this study, because that was not the finding. There must be another  study that I haven’t located yet. Even so, a person making such a statement should specify the following:

  1. Which study is this? Give identifying information.
  2. How were the introverts and extraverts selected and defined?
  3. What kind of noise was used?
  4. What were the math problems, and what do you mean by “did better”?
  5. Was there any complexity/contradiction to the findings?
  6. Did the author bring up any caveats (and do you see any)?

That’s a lot, I know, and in an interview it might not be realistic. But that’s only scratching the surface; an expert should be able to do things I myself can’t do: for instance, explain the methods used for interpreting the raw data.

What I see instead (and not just from Cain by any means) is a tendency to oversimplify and exaggerate the results of studies, and to do so again and again.

Some of these studies are interesting and valuable. Others are bunk. All of them have limitations, but when taken skeptically and cautiously, they can help us reach greater understanding.

The implications? I see no problem with the idea that different people work well at different noise levels. But reducing the matter to “introverts” and “extraverts” is unnecessary and unfounded. Much depends on the individual, the context, the particular task, and the type of noise. There are situations that call for quiet, situations that call for noise, and a range in between. While a workplace should probably establish basic quiet (so that the noise doesn’t get out of hand), people can learn how to handle both quiet and noise in reasonable degrees.

Note: I made a few minor revisions after posting the piece. Also, Science of Us (New York Magazine) has started challenging some of the pop-psychology assertions about introversion and extraversion. (Here’s another piece on the topic.)

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2 Comments

    • Thank you for this link to the Geen study. (To interested readers: Through this link, you can access the abstract and request the full text.)

      Reply

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