Alan Gilchrist, Professor Ph.D 

Rutgers University, Psychology Dept.
101 Warren Street, Newark, NJ 07102
Smith Hall Room 342

Phone: (973) 353-5440 x3951
Fax: (973) 353-1171

Staircase Gelb Effect Demo 

Anchoring Theory of Lightness Perception

Research Interests 

I study visual perception, especially the perception of surface color, and especially the black-white dimension. Vision is known to be based on the image projected onto the retina, but the problem of how to assign black, white and gray values to surfaces represented in that image remains unsolved, in human vision as in computer vision. Because of variations in many factors such as the background of a surface and the lighting conditions, the perception of any one specific surface color can be associated with many patterns of local stimulation at the retina. The goal of the work is to describe the software (not the hardware, or wetware) used by the visual system to decode the retinal image. The primary method is psychophysics. Naive observers are exposed to displays specially constructed so that competing theories make opposing predictions of what observers will see. The observer reports, typically involving matches made using a color chart, are then used to evaluate theories. In my lab we have approached this problem in two ways. In earlier work, an inverse-optics approach was taken in which we attempted to determine the computations necessary to recover objective properties like surface color. More recent work has focused on the pattern of errors shown by human observers when judging surface colors. These errors are systematic, not random, and the work is based on the assumption that the pattern of errors is the signature of the software used to decode the retinal image.


Gilchrist, A. L. (2018, May 3).  To compute lightness, illumination is not estimated, it is held constant. Journal of Experimental Psychology: Human Perception and Performance 

Gilchrist, A. (2017). On the Ecological Validity of Computer Displays. Perception, 46, 7, 1-5. 

Gilchrist, A. (2016). The anchoring theory of lightness. In R. Luo (Ed) Encyclopedia of Color Science and Technology. New York: Springer. 

Gilchrist, A. (2016). The Staircase Gelb Illusion. In A. Shapiro & D. Todorovic (Eds.), The Oxford Compendium of Visual Illusions. Oxford, United Kingdom: Oxford University Press 

Gilchrist, A. (2015). Theoretical approaches to lightness and perception. Perception.

Economou, E. Zdravkovic, S., & Gilchrist, A. (2015). Grouping factors and the reverse contrast illusion. Perception, 44, 1383-1399. 

Gilchrist, A. (2015). Perception and the social psychology of “The Dress.” Perception, 44, 1283-1285. 

Gilchrist, A. (2015). A Commentary on: What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception. Frontiers in Human Neuroscience, 9, Article 445, August, 2015. 

Ekroll, V., Gilchrist, A., Koenderink, J., Van Doorn, A., Wagemans, J., (2015). Poggendorff rides again. I-Perception, 6, 1, 15-18. 

Gilchrist, A. (2014). Response to Maniatis critique of anchoring theory. Vision Research, 102, 93-96. 

Gilchrist, A. (2014). Theoretical approaches to lightness and perception. Perception, 44, 339-358. 

Radonjić, A., and Gilchrist, A., (2014). Lightness perception in simple images: Testing the anchoring rules. Journal of Vision, 14(13). 

Gilchrist, A. (2014). Johannes Kepler: the sky as a retinal image. Perception, 43, 1283-1285. 

Gilchrist, A. (2014). A gestalt account of lightness illusions. Perception, 43, 881-895. 

Gilchrist, A. (2014). White in shadow, black in sunlight: Gray level in pigment and perception. In B Salvesen, See The Light, Los Angeles: Los Angeles County Museum of Art, 208-209. 

Gilchrist, A. (2014). Perceptual organization of lightness. In J Wagemans (Ed.), Handbook of Perceptual Organization, 391-412. 

Radonjić, A., and Gilchrist, A., (2013). Depth effect on lightness revisited: The role of articulation, proximity and fields of illumination. iPerception, 4, 437-455. 

Gilchrist, A. (2013). Mapping luminance onto lightness in vision and art: Proc. SPIE 8651, Human Vision and Electronic Imagine SVIII, 865105 (March 14, 2013). 

Gilchrist, A. (2012). Objective and Subjective Sides of Perception. In Visual Experience: Sensation, Cognition, and Constancy (S. Allred and G. Hatfield, Eds). Oxford University Press. 

Allred, S. R., Radonjić, A., Gilchrist, A. L., & Brainard, D. H. (2012). Lightness perception in high dynamic range images: Local and and remote luminance effects. Journal of Vision, 12(2):7.

Zdravković S, Economou E, Gilchrist A.(2012). Grouping illumination frameworks. Journal of Experimental. Psychology: Human Perception and Performance. 38(3): 776-784.

Radonjić, A., Allred, S. R., Gilchrist, A. L., & Brainard, D. H. (2011). The dynamic range of human lightness perception. Current Biology, 21(22), 1931-1936

Radonjić A, Todorović D, Gilchrist A. (2010). Adjacency and surroundedness in the depth effect on lightness. Journal of Vision. 10(9):12.

Gilchrist, A., and Radonjić, A. (2010). Frameworks of illumination revealed by probe disk technique. Journal of Vision. 10(5):6, 1-12. 

Gilchrist, A., and Radonjić, A. (2009). Anchoring of lightness values by relative luminance and relative area. Journal of Vision, 9(9):13, 1-10. 

Economou, E., Zdravković, S., and Gilchrist, A. (2007). Anchoring versus spatial filtering accounts of simultaneous lightness contrast. Journal of Vision, 7(12):2, 1-15. 

Gilchrist, A. (2007). Lightness and Brightness. Current Biology, 17, R267-R269. 

Zdravković, S., Economou, E., and Gilchrist, A. (2006). Lightness of an object under two illumination levels. Perception, 35, 1185-1201. 

Gilchrist, A. (2006). Seeing in Black and White. Scientific American Mind (June/July), 42-49. 

Gilchrist A.L. (2006). Seeing Black & White. Oxford University Press. 

Gilchrist, A.L. (2005). Lightness Perception: Seeing One Color through Another. Current Biology, 15 (9), R330-R332. 

Annan V. and Gilchrist, A. (2004) Lightness Depends on Immediately Prior Experience. Perception & Psychophysics, 66, 943-952. 

Gilchrist, A. (2003). Looking backward: Why we see what we do: an empirical theory of vision. Nature Neuroscience 4, 515-516. 

Gilchrist, A. and E. Economou (2003). Dualistic versus monistic accounts of lightness perception. Levels of Perception. L. Harris and M. Jenkin. New York, Springer: 11-22. 

Gilchrist, A. (2003). The importance of errors in perception. Colour Perception: Mind and the Physical World. R. M. D. Heyer. Oxford, Oxford University Press.: 437-452. 

Gilchrist, A. and Annan, V. (2002). Articulation effects in lightness: Historical background and theoretical implications. Perception, 31, 141-150. 

Li, X. and Gilchrist, A. (1999). Relative area and relative luminance combine to anchor surface lightness values. Perception & Psychophysics, 61(5), 771-785. 

Gilchrist, A. L. (1999). Achromatic color and the anchoring problem. In N. S. F. Purghe, A. Olivero (Ed.), La Percezione Visiva., (pp. 496-517). Torino, Italy: UTET Universita. 

Gilchrist, A., Kossifydis, C., Bonato, F., Agostini, T., Cataliotti, J., Li, X., Spehar, B., Annan, V., and Economou, E. (1999). An anchoring theory of lightness perception. Psychological Review 106(4): 795-834. 

Gilchrist, A. (1999). Lightness Perception. In RA Wilson & FC Keil, (Eds), MIT Enclyclopedia of Cognitive Science, Cambridge: MIT press, pp 471-472. 

Bonato, F. and Gilchrist, A. (1999). Perceived area and the luminosity threshold. Perception & Psychophysics, 61(5), 786-797. 

Gilchrist, A. (1996). The deeper lesson of Alhazen. Perception, 25, 1133-1136. 

Spehar, B., Arend, L., and Gilchrist, A. (1995). Contrast-contrast: interactions between spatial and luminance factors. Review of Psychology, 2, 3-12. 

Spehar, B., Gilchrist, A., and Arend, L. (1995). The critical role of relative luminance relations in White's effect and grating induction. Vision Research, 35, 2603-2614. 

Gilchrist, A. L. and Bonato, F. (1995). Anchoring of lightness values in center/surround displays. Journal of Experimental Psychology: Human Perception and Performance, 21(6), 1427-1440. 

Cataliotti, J. and Gilchrist. A.L. (1995). Local and global processes in surface lightness perception. Perception & Psychophysics, 57(2), 125-135. 

Gilchrist, A. (1994). Absolute Versus Relative Theories of Lightness Perception. Lightness, Brightness, and Transparency. A. Gilchrist. Hillsdale, Erlbaum: 1-33. 

Bonato, F., and Gilchrist, A. L. (1994). The perception of luminosity on different backgrounds and in different illuminations. Perception, 23, 991-1006. 

Gilchrist, A. (1990) Developments in the Gestalt theory of lightness perception. In I. Rock (Ed.). The Legacy of Solomon Asch: Essays in Cognition and Social Psychology. Hillsdale: Lawrence Erlbaum Associates. 

Gilchrist, A. and Jacobsen, A. (1988). Qualitative relationships are decisive. Perception & Psychophysics, Notes and Comment, 45 (1), 92-94. 

Gilchrist, A. (1988). Lightness contrast and failures of lightness constancy: a common explanation. Perception & Psychophysics, 43 (5), 415-424. 

Jacobsen, A., and Gilchrist, A. (1988). Hess and Pretori revisited: Resolution of some old contradictions. Perception & Psychophysics, 43, 7-14. 

Jacobsen, A., and Gilchrist, A. (1988). The ratio principle holds over a million- to-one range of illumination. Perception & Psychophysics, 43, 1-6. 

Gilchrist, A. and Jacobsen, A. (1984). Perception of lightness and illumination in a world of one reflectance. Perception, Vol. 9, No. 6, 936-944. 

Gilchrist, A. L. and Jacobsen, A. (1983). Lightness constancy through a veiling luminance. Journal of Experimental Psychology:Human Perception and Performance, 9, 936-944. 

Gilchrist, A., Delman, S., and Jacobsen, A. (1983). The classification and integration of edges as critical to the perception of reflectance and illumination. Perception & Psychophysics, Vol. 33, No. 5, 425-436. 

Gilchrist, A. L. (1980). When does perceived lightness depend on perceived spatial arrangement? Perception & Psychophysics, 28(6), 527-538. 

Gilchrist, A. (1979). The perception of surface blacks and whites. Scientific American, Vol. 24, no. 3, 88-97. 

Gilchrist, A. (1977). Color constancy. In The International Encyclopedia of Neurology, Psychiatry, Psychoanalysis, and Psychology., Benjamin Wolman (ed.), Van Nostrand. 

Gilchrist, A. L. (1977). Perceived lightness depends on perceived spatial arrangement. Science, 195, 185-187. 

Rock, I. and Gilchrist, A. (1975). The conditions for the perception of the covering and uncovering of a line. American Journal of Psychology, 88, 571-582. 

Rock, I. and Gilchrist, A. (1975). Induced form. American Journal of Psychology, 88, 475-482.