Abstract # 2036 Poster # 94:

Scheduled for Thursday, August 17, 2006 07:00 PM-09:00 PM: Session 8 (Regency West 1/3 ) Poster Presentation

A Behavioral Method for Measuring Visual Acuity in Non-human Primates

C. C. Veilleux1, K. Klymus2 and E. C. Kirk1
1The University of Texas at Austin, Department of Anthropology, 1 University Station C3200, Austin, TX 78712-0303, USA, 2University of Missouri at Columbia
     Hypotheses regarding primate evolution, ecology, and sociality often involve discussions of primate visual acuity. Visual acuity is the ability to resolve fine spatial details. Few studies, however, have compared visual acuity in extant primate taxa, in part because of the difficulty of measuring visual acuity in non-human subjects. Anatomical measurements require sacrificing the animal, which is often unacceptable for primate subjects. Furthermore, non-invasive behavioral tests traditionally have required complex and expensive equipment. We present a behavioral methodology for measuring visual acuity which does not require access to complex or expensive apparatuses. This methodology, adapted from one used on marsupials (Arrese et al. 1999. Brain Behav. Evolut. 53:111-126), was tested on blue-eyed black lemurs (Eulemur macaco flavifrons). Using a modified Mitchell jumping platform to create a 2-interval forced-choice paradigm, subjects were required to discriminate between horizontal and vertical high-contrast square wave gratings of equal spatial frequency. The research design utilized positive reinforcement with a food reward and allowed subjects to choose whether or not to participate in test trials. Preliminary data collected for one subject using this methodology suggest that Eulemur visual acuity is between 4 and 6.54 cycles per degree, which is within the range of expected acuity in a cathemeral prosimian. This material is based upon work supported under a National Science Foundation Graduate Research Fellowship.