A Flawed Study?

I was just reading an article about a study in Japan on brain function of transsexuals and I noticed something about the research (besides using “gender identity disorder” instead of “gender dysphoria”).  What I noticed was this,

In the behavioral studies, 41 transsexual participants watched silent clips of films, some erotic in nature, others neutral, then rated the degree to which they identified with the male or female character. In both contexts, transsexual subjects gave significantly higher scores to the person of their desired gender than did 38 members of the reference group. Even during neutral films, the strength of this gender preference (desired versus non-desired) was much greater for transsexuals. The results pinpoint the pervasiveness of transsexuals' identification with their desired sex--in erotic situations, but also in neutral circumstances of daily life. This is considered a psychological trait that is a marker for gender identity disorder, said Prof. Jen-Chen Hsieh of National Yang-Ming University's Institute of Brian Science.

Practically about this “In the behavioral studies, 41 transsexual participants watched silent clips of films, some erotic in nature, others neutral, then rated the degree to which they identified with the male or female character.” What jumped out at me was the fact that they based their data on responses to erotic films. What the article does not say was if they considered lesbians.

If a trans-woman was attracted to women did the researches discount that attraction because it wasn’t “typical” women behavior?