It seems possible that there are biological differences in the way men and women think; certainly, there are currently differences in men's and women's thinking styles. There is no way to tell now how great the biological differences are. While they may imply that women will never reach parity with men in computer science and in engineering, there are two major reasons to believe that women's roles can increase greatly from today's: First, as shown throughout this report, females face immense cultural barriers. Second, as alluded to in this appendix, many technical fields play to men's strong areas. Computer science is built, in large part, on mathematics, which relies on spatial ability. Computer programming, however, does not in itself require spatial ability, and some areas of computer science, such as user interface design, require more knowledge of human psychology than mathematics. Additionally, sex-based differences are a tendency, and their degree of effect in an individual cannot be known.