Studying Primate Color: Towards Visual System-dependent Methods
Primates exhibit a striking diversity of colors and patterns in their pelage and skin markings, used in functions as diverse as camouflage to sexual signaling. In studying primate colors, it is important to adopt approaches not based on human assessment wherever possible, and that preferably take account of the visual system of the appropriate receiver(s). Here, we outline some of the main techniques for recording the colors exhibited and encountered by primates, including the use of digital photography and reflectance spectrometry. We go on to discuss the main approaches for analyzing the data obtained, including those not linked to a particular visual system, such as direct analyses of reflectance spectra. We argue that researchers should strive for analyses based on the visual system of the relevant receiver, and outline some of the main modeling approaches that can be used, such as color space and discrimination threshold modeling. By analyzing color measures with respect to specific visual systems, field studies can link behavioral ecology to the visual and cognitive sciences, and move toward descriptions of signal information content that incorporate elements of receiver psychology. This in turn should lead to a greater understanding of the detection and interpretation of signals by receivers, and hence their likely use in decision making.
Keywordscoloration color measurement photography primates reflectance
We thank Daniel Osorio, Lauren Brent, Brenda Bradley, and two anonymous referees for helpful comments on the manuscript, and attendees at the primate coloration symposium at the 2008 International Primatological Symposium for discussion. M. Stevens thanks Innes Cuthill, Tom Troscianko, Julian Partridge, Alejandro Párraga, and many others for a range of advice and discussion. M. Stevens’ attendance at IPS 2008 was funded by the British Ecological Society and Girton College. M. Stevens was supported by a Research Fellowship from Girton College, Cambridge. M. Caswell Stoddard was supported by the Marshall Aid Commemoration Commission and Gonville and Caius College, Cambridge. J. Higham thanks Melissa Gerald and Ann MacLarnon for discussions on the measurement, analysis, and interpretation of color. J. Higham’s attendance at IPS 2008 was funded by Roehampton University.
A range of self-written MATLAB files for undertaking modeling of quantal catch data and camera calibration are available on request from the corresponding author (email@example.com).
- Abràmoff, M. D., Magalhäes, P. J., & Ram, S. J. (2004). Image processing with Image J. Biophotonics International, 7, 36–43.Google Scholar
- Andersson, S., & Prager, M. (2006). Quantifying colors. In G. E. Hill & K. J. McGraw (Eds.), Bird coloration, vol. I: Mechanisms & measurements (pp. 41–89). Cambridge, MA: Harvard University Press.Google Scholar
- Bergman, T. J., & Beehner, J. C. (2008). A simple method for measuring colour in wild animals: Validation and use of chest patch colour in geladas (Theropithecus gelada). Biological Journal of the Linnean Society. Linnean Society of London, 94, 231–240. doi: 10.1111/j.1095-8312.2008.00981.x.CrossRefGoogle Scholar
- Cuthill, I. C. (2006). Color perception. In G. E. Hill & K. J. McGraw (Eds.), Bird coloration, vol. I: Mechanisms & measurements (pp. 3–40). Cambridge, MA: Harvard University Press.Google Scholar
- Darst, C. R., Cummings, M. E., & Cannatella, D. C. (2006). A mechanism for diversity in warning signals: Conspicuousness versus toxicity in poison frogs. Proceedings of the National Academy of Sciences of the United States of America, 103, 5852–5857. doi: 10.1073/pnas.0600625103.CrossRefPubMedGoogle Scholar
- Efford, N. (2000). Digital image processing: A practical introduction using Java. Harlow, Essex: Pearson Education.Google Scholar
- Endler, J. A., Westcott, D. A., Madden, J. R., & Robson, T. (2005). Animal visual systems and the evolution of color patterns; sensory processing illuminates signal evolution. Evolution; International Journal of Organic Evolution, 50, 1795–1818.Google Scholar
- Gerald, M. S., Bernstein, J., Hinkson, R., & Fosbury, R. A. E. (2001). Formal method for objective assessment of primate color. American Journal of Primatology, 53, 79–85. doi: 10.1002/1098-2345(200102) 53:2<79::AID-AJP3>3.0.CO;2-N.CrossRefPubMedGoogle Scholar
- Gerald, M. S., Weiss, A., & Ayala, J. E. (2006a). Artificial colour treatment mediates aggression among unfamiliar vervet monkeys (Cercopithecus aethiops): A model for introducing primates with colourful sexual skin. Animal Welfare (South Mimms, England), 15, 363–369.Google Scholar
- Gonzalez, R. C., Woods, R. E., & Eddins, S. L. (2004). Digital image processing using MATLAB. London: Pearson Education.Google Scholar
- Gregory, R. L. (1998). Eye and brain: The psychology of seeing. Oxford: Oxford University Press.Google Scholar
- Higham, J. P. (2006). The reproductive ecology of female olive baboons (Papio hamadryas anubis) at Gashaka-Gumti National Park, Nigeria. PhD thesis. Roehampton University: London.Google Scholar
- Jordan, G., & Mollon, J. D. (1992). Do tetrachromatic women exist? Investigative Ophthalmology & Visual Science, 33, 754.Google Scholar
- Lovell, P. G., Tolhurst, D. J., Párraga, C. A., Baddeley, R., Leonards, U., Troscianko, J., et al. (2005). Stability of the color-opponent signals under changes of illuminant in natural scenes. Journal of the Optical Society of America, 22, 2060–2071. doi: 10.1364/JOSAA.22.002060.CrossRefPubMedGoogle Scholar
- Montgomerie, R. (2006). Analyzing colors. In G. E. Hill & K. J. McGraw (Eds.), Bird coloration, Vol. I: mechanisms & measurements (pp. 90–147). Cambridge, MA: Harvard University Press.Google Scholar
- Rasband, W. S. (1997–2009). Image J. Bethesda, MD: National Institutes of Health. Retrieved from http:/rsb.info.nih.gov/ij/.
- Rolls, E. T., & Deco, G. (2002). Computational neuroscience of vision. Oxford: Oxford University Press.Google Scholar
- Santos, S. I. C. O., De Neve, L., Lumeij, J. T., & Förschler, M. I. (2007). Strong effects of various incidence and observation angles on spectrometric assessment of plumage colouration in birds. Behavioral Ecology and Sociobiology, 61, 1499–1506. doi: 10.1007/s00265-007-0373-7.CrossRefGoogle Scholar
- Wyszecki, G., & Stiles, W. S. (1982). Color science: Concepts and methods, quantitative data and formulae. New York: John Wiley & Sons.Google Scholar