Contrast reduction accounts for phase noise, by Robert A. Morris. Abstract of poster presented at 1995 annual meeting of the Association for Research in Vision and Opthalmology. From the abstract: Purpose: To relate the effect of phase noise to the effect of contrast reduction in human vision.

Towards quantification of the effects of typographic variation on readability, by R. A. Morris, K. Berry and K. A. Hargreaves. 1993 Proceedings of the Society for Information Display, pp. 64-67. From the abstract: Shape distortion [of characters] has more effect [on readability] than spacing distortion.

How typeface variation and typographic scaling affect readability at small sizes, by Robert A. Morris, Karl Berry, Kathryn A. Hargreaves, and Dimitris Liarokapis. 1991 Proceedings of the 1991 International Congress on Advances in Non-Impact Printing Technologies of the Society for Imaging Science and Technology, pp. 344-352. From the summary: Most typographic variation has little or no effect on reading rates for characters at normal reading sizes [and there is no measurable difference between reading rates for fixed-width compared to proportional-width fonts].