Please mark your calendars for our 2nd Fall term Vision Science Research Seminar Series (VSRSS) lecture, which will take place on November 1st, at 3:30 pm, in OPT 1129. Martin Banks will present a lecture entitled, "Pupil shape is adaptive for many species".
Martin S Banks, PhD
Vision Science Program, School of Optometry, Univ of California, Berkeley; also Departments of Psychology, Neuroscience, and Bioengineering
Abstract
Pupil shape varies considerably across species, though most are circular or elliptical. Elliptical pupils are always elongated vertically or horizontally relative to the head. We examined the usefulness of elongated pupils: specifically, why horizontal elongation is useful to some species and vertical elongation to others. Walls (1942) proposed that such pupils are adaptive for nocturnality, providing more control over retinal illumination. Malmström and Kröger (2006) proposed that they preserve image quality in eyes with multifocal lenses. However, these proposals do not explain why pupil orientation varies across species. We propose a new theory based on the visual requirements of different species in their environments. We examined pupil shape in over 200 animals and related it to activity time, foraging mode, and height. Clear correlations emerged. Round pupils occur in tall or diurnal predators. Vertical elongation occurs in short, nocturnal predators; these animals usually have forward-facing eyes and stereovision. Horizontally elongated pupils occur in prey animals; they tend to have lateral eyes. We argue that vertical pupils are well suited for using stereopsis to estimate distances of vertical contours and using depth-of-field blur for distances of horizontal contours. In an analysis of image formation, we found that the potential usefulness of blur is inversely related to height. This may explain why vertical-slit pupils are more common in short than tall predators. For horizontally elongated pupils, our optical analyses show that the elongation expands field of view horizontally allowing these terrestrial prey animals to see objects near the ground plane both in front of and behind them. Our analyses also show that horizontal elongation allows sharper imaging of horizontal contours on the ground in different directions, particularly directions well off the optic axis. We conclude that elongated pupils evolved to optimize visual information near the ground plane in predators and prey.
Biography of presenter
Martin S. Banks received his Bachelor’s degree at Occidental College in 1970. He majored in Psychology and minored in Physics. After spending a year in Germany teaching in their school system, he entered the graduate program at UC San Diego where he received a Master’s degree in Experimental Psychology in 1973. Banks then moved to the graduate program at the University of Minnesota where he received his Ph.D. in Developmental Psychology in 1976. He was Assistant and Associate Professor of Psychology at the University of Texas at Austin from 1976-1985. He moved to UC Berkeley School of Optometry in 1985 where he has been Associate and Full Professor of Optometry and Vision Science until the present. He was Chairman of the Vision Science Program from 1995-2002, and again in 2012.
Banks has received several awards for his work on basic and applied research on human visual development, on visual space perception, and on the development and evaluation of stereoscopic displays. These include the Young Investigator Award from the National Research Council (1978), Boyd R. McCandless Award from the American Psychological Association (1984), and Kurt Koffka Medal from Giessen University (2007). He has also been appointed Fellow of the Center for Advanced Study of the Behavioral Sciences (1988), Honorary Research Fellow of Cardiff University (2007), Fellow of the American Association for the Advancement of Science (2008), Fellow of the American Psychological Society (2009), Holgate Fellow of Durham University (2011), and WICN Fellow of University of Wales (2011).
