Document Type

Dissertation

Degree

Doctor of Philosophy

Major

Physiological Optics

Date of Defense

10-26-2009

Graduate Advisor

Carol K. Peck, Ph.D.

Committee

Carol K. Peck, PhD

Carl J. Bassi, PhD

William G. Bachman, OD, MS

George Taylor, PhD

Abstract

PURPOSE: The chromatic contribution to brightness perception was compared in males and females. METHODS: Direct brightness matching (DBM) and heterochromatic flicker photometry (HFP) were used to measure relative luminous efficiency, and DBM/HFP ratios were predicted to be higher for females than males on repeated measures and for each "primary" color. No gender differences were predicted in DBM or HFP measures. Within-females effects of estradiol (E2) and progesterone (PG) levels, contraceptive use, and menstrual cycle phase were also investigated. It was expected that E2 would directly predict DBM/HFP ratios and that PG would antagonize that relationship. Based on that prediction, DBM/HFP ratios would be at a maximum during the ovulatory phase, intermediate during the menstrual phase and minimum during the luteal phase. No effects were predicted for DBM or HFP measures. RESULTS: DBM/HFP ratios were significantly higher for female subjects than male subjects. Contraceptive use had no effect on overall DBM/HFP ratios. There were limited effects of hormone levels, menstrual cycle phase and contraceptive use on DBM/HFP ratios and on DBM and HFP measures analyzed separately. However, hormone effects on DBM/HFP ratios and DBM measures at 650 nm agree with previous findings involving long-wavelength sensitive (L-) cone mechanisms. CONCLUSIONS: The present findings supporting a female advantage in chromatic contribution to brightness are robust. The significant results are discussed in the context of previous findings suggesting organizational and short-term effects of ovarian steroid hormones.

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Optometry Commons

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