Fifteen-year-old girls might not be outperforming boys in traditional science subjects but there is one science subject where girls far outperform boys – psychology.

Statistics from the Joint Council for Qualifications show in 2012 the number of girls obtaining the much coveted A* in A-level psychology was more than double that of the boys, and girls gained significantly more A to C grades than their male classmates. Girls appear to engage more with psychology than any other science and yet this is often overlooked when the topic of girls and science is raised.

Girls not only regularly and significantly outperform boys in psychology, they also make up more than 70% of the 55,000 or so candidates who are entered for A-level psychology exams every year (making psychology the fourth most popular A-level). Unfortunately, 15-year-old girls rarely get the opportunity to study psychology as it is seldom offered in schools (although the number of candidates entered for GCSE psychology has increased by more than 60% the past five years). Psychology is also (by some quirk of fate) classified as a social science at GCSE and a science at A-level. This is despite attempts by the British Psychological Society to have it reclassified in order to smooth the transition from GCSE to A-level and beyond.

The reasons for these stark gender differences within A-level psychology are not clearly understood (they don't appear to exist so sharply in other A-level subjects) but such differences have been identified at undergraduate level as well, where psychology is more readily accepted as science.

So girls are engaging and succeeding in science, it just happens to be a science that is much misunderstood by the public and policymakers. Furthermore, and to the detriment of science, the Russell Group's rejection of A-level psychology as a facilitating subject creates a situation whereby girls are less likely to be accepted into top universities (in fact the Russell Group list is significantly biased against girls with its choice of subjects appealing mainly to boys).

Psychology is actually the only A-level science not represented in the list of facilitating subjects and the only science that attracts a significant number of girls. In 2012, more than 5,500 more girls took psychology than biology (its nearest rival) while chemistry struggled to attract half the number of female psychology candidates and physics rarely attracts more than 7,500 (compared to more than 41,000 girls entered for psychology exams).

It appears that when opportunities arise to encourage girls into science the doors are well and truly slammed in their faces. This appears to be the case both for A-level and for any future changes to GCSE's. Many girls are turned off science well before they choose their GCSE options but by A-level they have been encouraged back into science via psychology. Some of these girls will then go on to university and become the scientists of the future (as some of my past students have done).

The Russell Group list (seen by many as arbitrary and damaging) will no doubt discourage many girls from re-entering science and, consequently, encouraging a greater gender imbalance.

Marc Smith is a chartered psychologist and teacher at a secondary school in North Yorkshire. Marc is a member of the GTN teacher panel and an Associate Fellow of the British Psychological Society. Follow him on twitter @psychologymarc.

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