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James W. Pennebaker, Chairman | SEA 4.212 | The University of Texas at Austin | Austin, TX 78712 | 512-471-1157 |
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Dennis McFadden, Ph.D.
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Email: mcfadden@psy.utexas.edu
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Dr. McFadden received his Ph.D. from Indiana University. His research Interests are sensation and perception, audition, sex differences in the auditory system, prenatal hormonal effects on the auditory system, and the effects of drugs on the auditory system.
Historically, I have been interested in various aspects of auditory performance--sound localization, masking, adaptation-like effects, and the effects of drugs and intense sound on the auditory system. In recent times, I have become interested in certain sex differences in audition and have been using the auditory system as a tool for studying hormonal effects during early development. One measure we have used is otoacoustic emissions (OAEs) which are sounds produced in the inner ear and recorded from the ear canal. OAEs are stronger and more numerous in females than in males, and this sex difference exists in newborns as well as in adults. We have been trying to understand the mechanisms underlying these sex differences. The evidence suggests that prenatal differences in exposure to androgens contribute to the sex difference in OAEs--just as it does for other sex differences in the body and the brain. Some of this evidence comes from work on special populations of humans such as females with male co-twins, homosexual and bisexual females, and children diagnosed with attention-deficit/hyperactivity disorder (ADHD). Also, we have recorded OAEs in spotted hyenas and rhesus monkeys that have been treated with androgenic or anti-androgenic agents during prenatal development and found them generally to be altered in the predicted direction--the greater the exposure to androgens, the weaker the OAEs. We believe that OAEs can act as a marker for the degree of androgen exposure a person receives during early development, and thus, they have the potential to serve as an noninvasive supplemental tool for scientists interested in a wide array of topics other than audition itself. My Macintosh-based lab is equipped to synthesize and generate simple and complex auditory waveforms, and to test up to eight human subjects simultaneously in a wide array of standard psychoacoustical tasks. We also have an advanced system for recording and analyzing otoacoustic emissions. We have the capability to obtain OAE measurements from distant locations over the internet. We use LabVIEW for generating waveforms, controlling experiments, and some data analysis.
Psychology 394U - Psychoacoustics (taught each Spring semester)
Psychology 387N - Fundamentals of Perception (team-taught with W.S. Geisler)
Psychology 323-Perception (undergraduate; team-taught with W.S. Geisler)
Psychology 458 - Experimental Psychology (undergraduate)
McFadden, D. Otoacoustic emissions as a window onto prenatal development and sexual differentiation. Seminars in Hearing, 2001, 22, 347-360.
McFadden, D. Masculinization effects in the auditory system. Archives of Sexual Behavior, 2002, 31, 93-105.
McFadden, D. and Shubel, E. Relative lengths of fingers and toes in human males and females. Hormones and Behavior, 2002, 42, 492-500.
McFadden, D., and Bracht, M.S. The relative lengths and weights of metacarpals and metatarsals in baboons (Papio hamadryas). Hormones and Behavior, 2003, 43, 347-355.
McFadden, D. and Shubel, E. The relationships between otoacoustic emissions and relative lengths of fingers and toes in humans. Hormones and Behavior, 2003, 43, 421-429.
Loehlin, J.C. and McFadden, D. Otoacoustic emissions, auditory evoked potentials, and traits related to sex and sexual orientation. Archives of Sexual Behavior, 2003, 32, 115-127.
Pasanen, E.G., and McFadden, D. Collecting data from afar over the Internet. Echoes, 2004, 14, 8.
McFadden, D. and Bracht, M.S. Sex differences in the relative lengths of metacarpals and metatarsals in gorillas and chimpanzees. Hormones and Behavior, 2005, 47, 99-111.
McFadden, D., Loehlin, J.C., Breedlove, S.M., Lippa, R.A., Manning, J.T. and Rahman, Q. A reanalysis of five studies on sexual orientation and the relative length of the 2nd and 4th fingers (the 2D:4D ratio). Archives of Sexual Behavior, 2005, in press.
McFadden, D., Westhafer, J.G., Pasanen, E.G., Carlson, C.L., and Tucker, D.M. Physiological evidence of hypermasculinization in boys with the inattentive subtype of attention-deficit/hyperactivity disorder (ADHD). Clinical Neuroscience Research, 2005, in press.
