Is the Q-on-the-forehead test a valid method of determining extraversion and ability to lie?

Question

Noted skeptic and magician, Richard Wiseman has released a popular Youtube video that claims to test extraversion and ability to lie, with a simple binary test - asking the subject to draw a Q on their own forehead with their finger.

Depending on the outcome of the test:

you are happy being the centre of attention and you are a good liar.

or

you tend to be more of an intravert and not very good at lying.

So if you want to gain a quick and fun insight into someone, ask them to draw a Q on their forehead.

Is there any scientific basis for this?

Answer 1

Quoting from Haas 1984, Experiment 3 which is the one examining individual differences.

Sixty-two undergraduates (15 men and 47 women) participated in Experiment 3.

Power was very low, hence the correlation cannot be reliably estimated.

He also combined this experiment with a manipulation of self-focused attention (showing or hiding a tape recorder during the task).

The effect measured public self-consciousness (using a median-split which wastes information) was not significant:

Chi.square (1, N = 62) = 2.85, p < .10, and the interaction between manipulated 2 self-focus and public self-consciousness, Chi.square (1, N = 62) = 3.09, p < .08, on E direction was not significant either.

The author wrote:

Apparently the presence of the tape recorder in the situation overwhelmed the individual difference variable in the high self-focus condition, so that no difference between high and low public self-conscious subjects could be found. When the self-focus inducing effects of the tape recorder were removed from the situation, however, the relationship between the personality variable and the direction the E was drawn emerged.

He then did post-hoc analyses (known to increase false positives, but it is hard to appropriately correct for this)

Looking at the results in a slightly different way, correlations were computed between each of the Self-Consciousness Scale subscale scores and perspective taking. For all subjects com- bined a significant correlation of .36 (p < .01) was found between public self-consciousness and the likelihood of drawing the E from an external perspective. The correlation between the direction the E was drawn and private self- consciousness was not significant (r = .08). A marginally significant correlation was found between E direction and social anxiety (r = .21, p = .10), but this correlation declined to .12 (ns) when the effect of public self-consciousness was removed using a partial correlation.

The 95% confidence interval of a .31 correlation with 62 subjects is [0.07; 0.52].

All told, if this is all Wiseman is relying on (I didn't watch the video, I trusted @ndwaldner), then there is quite the jump from a just-significant correlation between E direction and public self consciousness to Q direction and being "more of an intravert and not very good at lying".

Obviously, the self consciousness scale relied on self-report. Personality psychologists usually don't worry about that, but when you're making inferences about lying you probably should. Of course it'd easy to change the E/Q direction consciously if you have a hunch of what is being assessed.

PS.: There has been a number of conceptual replications of this paper, which I didn't read.

Answer 2

If you look at the paper (Hass, R.G. 1984), rather than the video, you gain insight into what is actually being suggested. The paper suggests that a person is more likely to be an extrovert or a good liar if they draw a letter so that it could be read from the perspective of another person.

The key point lies in what is meant by "more likely." The paper means that there is a statistically significant increase in scores on the personality-traits in questionnaire the study used. And this is supported by their experimental data.

However, the paper does not support categorically labelling people based on this test. It simply suggests that this test is an indicator of certain personality types.