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The BBC collaborated with a team of psychologists to create Sex ID, which brings together a series of separate psychological tests related to brain sex differences for the first time.
Most scientists agree that men and women are of equal intelligence, but some believe that they may have differing mental strengths and weaknesses, on average. The reasons for these brain sex differences, if they exist, are not known, though there are a number of theories that offer possible explanations.
Originally the Sex ID website was an online experiment, linked to a database that recorded test takers' answers. The main aims of the experiment were to further investigate theories about brain sex differences and to make new discoveries.
During May 2005 the BBC stopped collecting data because the experiment was finished. Many questions were removed to make the test more fun. People can still test themselves with the challenges used in the experiment, and they will still get the same results profile they would have had if they'd finished the test on the full-sized experiment site.
(Note: The above link to the full-sized version of Sex ID has been provided for people who want to see all the questions asked during the experiment. However, the shortened Sex ID test will be the most enjoyable version for most people.)
The scientists who helped design the test are now studying the data we collected to see if there are recognizable trends, which confirm or contradict current theories about brain sex differences. They will attempt to link test takers' answers to a series of questions with their performance on tasks thought to display sex differences.
The BBC used the scientists' analyses in the BBC One series Secrets of the Sexes.
The scientists are using the data in their research and have published some of their results.
People who took part in the experiment cannot be linked to their results because they are stored anonymously.
The BBC collaborated with the following experimental psychologists and their laboratory staff members to create the Sex ID test:
(The BBC is not responsible for the content of external websites.)
Dr Simon Baron-Cohen
Autism Research Centre, Cambridge, UK
Dr Richard Lippa
California State University, Fullerton, USA
Dr John Manning
University of Central Lancashire, Preston, UK
Prof David Perrett
University of St Andrews, St Andrews, UK
Dr Stian Reimers
University of Warwick, Coventry, UK
Other experts were consulted about licensing agreements for the psychological tests in Sex ID and as part of the research process.
The scientists behind Sex ID asked test takers a series of questions, some of which covered personal or sexual topics. Most of these have been removed from the test because the experiment is finished.
The questions were included to help researchers learn more about brain sex differences. Our experts want to see if there is a link between test takers' responses to the questions and their performance on tasks in the experiment.
For example, they are interested to know how test takers' finger measurements relate to the number of brothers and sisters they have. There is a theory that the amount of testosterone we are exposed to in our mothers' wombs relates to the ratio of the length of our index fingers to the length of our ring fingers – our digit ratios. Furthermore, it's thought that prenatal testosterone may increase or decrease systematically with each male child a woman has. Dr John Manning is particularly interested to learn if there is a link between testosterone and birth order. That's why we asked test takers to measure their fingers and answer questions about their families.
All of the activities in Sex ID are identical to, or similar to, tests used in published, peer-reviewed papers. Some scientists believe that men and women perform differently on these tasks.
Most scientists agree that men and women are of equal intelligence, but some believe that they may have differing mental strengths and weaknesses, on average. The reasons for these differences, if they exist, are not known, though there are a number of theories that offer possible explanations. One of the aims of the Sex ID test was to test some of these theories.