Gender differences in IQ among undergraduate psychology students While marking undergraduate coursework relating to gender differences,
it occurred to me that there could well be systematic effects of gender on IQ among the undergraduate populations relied on for so much of psychological research.

My impression is that male psychology students, who are in the minority, are likely to be on average more intelligent than female ones, because (warning, anecdotal evidence, and broad sweeping statements, ahead):


Women tend to study psychology at undergraduate level in the belief that it will involve understanding or helping people, while men tend to be more interested in psychology as a science.
Although women's motivation is probably the more admirable one, men's seems likely to indicate higher general intelligence.
Despite making up a small minority of undergraduate students, men make up about 50% of psychologists at later stages (PhD onwards), with the possible exception of clinical/educational psychologists.
Men's IQ's are more variable - there are more male geniuses, but also more men with extremely low IQ's. Since university students will have above average IQs in general, we would expect more men to have extremely high IQs in this sample (for the same reason as we would expect men who don't finish second-level education to have lower IQs on average than women who don't).


However, all this speculation aside, I haven't been able to find any research putting this apparently simple, and possibly very important, for the interpretation of a lot of research, idea to the test.

Are there any?
I think what happens is that researchers often don't report on - or at least don't highlight - uninteresting results, partly because of the difficulty getting uninteresting results published.  So given that gender differences in IQ in general are eliminated for validity, a lack of gender differences in IQ amongst a seemingly arbitrary sub-population such as undergraduate psychology students doesn't seem to merit attention.  I similarly wouldn't expect to find a study published about the lack of gender differences in IQ amongst say, red-haired truck drivers with carpal tunnel syndrome.  In fact, researchers often highlight the usefulness of psychology students as research subjects for being representative of the general population in many respects, in addition to being convenient to recruit.

On the other hand, as undergraduate psychology students are so often used as subjects in many areas of research, it shouldn't be too difficult to find data that records both IQ and gender, and confirm that it is indeed uninteresting.

Starting in the 1990's, there was a flurry of research based on some interesting results - that there are gender differences in estimates of IQ (presumably due to some stereotypes).  Although these studies don't specifically focus on gender differences in IQ amongst undergraduate psychology students, some of them do measure and report gender and IQ, and in some cases, the subjects are in fact undergraduate psychology students.  Here are some examples:


Furham &amp; Rawles (1995) "Sex differences in the estimation of intelligence":



  ... despite the fact that psychology attaches no significant gender
  differences to general intelligence, psychology students appeared to
  believe in the superiority of males.



Paulhus &amp; Williams (2002) "The Dark Triad of personality: Narcissism,
Machiavellianism, and psychopathy":



  Two hundred and forty-five undergraduate psychology students (65%
  female) participated in the present study for extra course credit. ...
  The only association with cognitive ability was the small positive
  correlation between IQ and narcissism.



Chamorro-Premuzic et al (2005) "The relationship between personality traits, subjectively-assessed and fluid intelligence":



  A total of 182 undergraduate students from British and American
  universities participated in this study. ... 49 males and 132 females
  were included in the statistical analysis ... Students participated in
  this study as part of two lectures on personality and intelligence
  assessment ... Correlations between Raven's test scores (Gf), SAI, ...
  gender and age are presented in Table 1.


(Sex is listed in Table 1 as having a correlation with Gf of -.00.)  There are many other similar examples from all over the world.

In some ways, the premise of the question seems odd: In as much as IQ is correlated with academic achievement (and it is, again for validity), it should correlate as much with acceptance to the program as it does with graduation results.  Thus, other reasons, such as discrimination or life choices might seem like better explanations.  Another possibility to consider is that psychology students are not always enrolled in the psychology program, and might include a disproportionate number of female students early on, who are actually from other programs that list psychology as a requirement, and have a female dominated enrolment throughout (eg, nursing).

However, the question is not entirely baseless.  More recent research has started to use alternative measures of intelligence that are not gender-corrected as standard IQ tests are.  This research does show gender bias in different sub-types of intelligence, and to some degree, overall intelligence.  From a 2011 thesis:


  No uniform agreement exists about male advantage in general
  intelligence (‘g’) (e.g. Colom &amp; Garcia-Lopez, 2002; Deary et al.,
  2003; Halpern et al., 2007; Jackson &amp; Rushton, 2006; Lynn, 1999;
  Spelke, 2005), with historically no sex differences presumed, as
  evidenced by the development of standardised intelligence tests (e.g.
  Ackerman, 2006; Wechsler, 1944). Recent investigations have supplied
  contradicting data, with male advantage reported on various measures
  of Gf and Gc, such as General Knowledge Test (GKT), Raven’s Standard
  and Progressive Matrices (SPM) and Wechsler Adult Intelligence Scale
  (WAIS) (cf. Lynn, Allik, &amp; Irwing, 2004; Lynn, Irwing, &amp; Cammock,
  2001; Lynn, Wilberg, &amp; Margraf-Stiksrud, 2004).


The paper goes on to describe such a study, conducted on 85 undergraduate psychology students, that confirms the gender bias in "g" in that population as well.