Heywood M Petry, PhD

Professor Emeritus of Psychological & Brain Sciences

Past Director of the Grawemeyer Award in Psychology

Portrait of Woody Petry

Life Sciences Building Room 316, Dept. of Psychological & Brain Sciences, University of Louisville, Louisville KY 40292 USA



Ph.D. |  Brown University, Providence Rhode Island (Experimental Psychology) 1976-1980

M.A.  |  Connecticut College, New London, Connecticut (Experimental Psychology) 1974-1976

B.A.   |  Bates College, Lewiston, Maine (Psychology) 1970-1974 

Post-Doctoral Research Training

Vanderbilt University | Post-doctoral Fellow, Departments of Anatomy and Psychology, 1980-1982

Brown University | Post-doctoral Research and Teaching Fellow, Department of Psychology, 1982-1984

Academic Faculty Positions (Full-Time Teaching & Research)

University of Louisville | Professor of Psychological & Brain Sciences. College of Arts & Sciences

(Professor Emeritus 2019-present; Full Professor 1997-2018; Associate Professor 1991-1997)

University of Louisville  | Professor of Ophthalmology & Visual Sciences, School of Medicine

(Full Professor 1998- 2001; Associate 1991-1997)

State University of New York at Stony Brook Professor of Psychology, College of Arts & Sciences

            (Adjunct Associate Professor 1992; Assistant Professor 1984-1991)

Academic Faculty Positions (Visiting Research Positions)

 University of Washington | Department of Biological Structure, Visiting Scholar, Fall 2013

Brandeis University  | Department of Biology, Visiting Research Scholar, Spring 2013

Massachusetts Institute of Technology (MIT) Picower Institute for Learning & Memory, Visiting Professor, Fall 2006


Beginnings of my career in Visual Science

My fascination with vision and visual perception began in college when I created the Subjective Necker Cube illusion.  In my last course before graduation at Bates College in Maine, Professor Drake Bradley introduced about a dozen of us to the concept of illusory, or subjective, contours. By cutting 24 pie shapes from blue cardboard and gluing them to an orange poster board, I created the perception of an illusory cube, the "Subjective Necker Cube", that has since become an internationally known visual illusion.  (For a full description my illusion see: Bradley DR & Petry HM (1977) Organizational determinants of subjective contour: the subjective Necker cube.  American Journal of Psychology90, 253-262.)


                 (From Bradley & Petry, 1977)

The gist of the Subjective Necker Cube illusion is that it can be perceived in two different manners. Depending on which perception is seen, different subjective contours are present or absent.  Most obvious is the “cube-in-front” perception where the black pie-shaped areas are perceived as 8 black disks with an illusory cube floating in front.  In this perception, the brain generates illusory bars to connect the corners of the illusory cube.  However, when the black areas are perceived as holes punched in the white surface (like swiss cheese), a bright white cube can be perceived behind the surface (the “cube-in-back” perception). When the cube is seen behind the surface, the subjective contours previously generated by the brain to connect the corners (and make sense) of the cube-in-front perception disappear.  In their place, curved contours that complete the holes may been perceived instead.  Observers often see only one of the two perceptual organizations until cognitively cued to perceive the other. 

Courses often taught


  • PSYC  "Physiological Psychology"
  • PSYC  "Sleep, Dreaming and Biological Rhythms"
  • HON / PSYC "Great Ideas in Psychology: The Grawemeyer Awards"


  • PSYC 635 "Sensory Neuroscience"
  • PSYC 642 "Behavioral Neuroscience"
  • PYYC / VISC "Principles of Visual Science"

Research Interests

I am retired as of December 31st, 2018.  During my career, two common themes of my research were: 1) basic brain mechanisms of vision in humans and animals, and 2) the influence of the post-natal environment on the development and plasticity of these mechanisms. I also developed and applied electrophysiological measures of function in patients with eye disease who had received retinal transplants in hopes of improving vision. 

My overall approach has been to use a wide variety of complementary research methodologies to address specific research questions at neural levels ranging from molecular and cellular to neural systems and behavior. Over recent years my collaborators and have employed optogenetics, in-vivo optical imaging, immunocytochemistry, single-cell electrophysiology, evoked potentials (ERG, VEP), neuroanatomical tract-tracing, molecular biology, microspectrophotometry and visual psychophysics techniques. The variety of research methods in my lab allowed undergraduates, graduate students and post-doctoral fellows to acquire first-hand exposure and technical skills in several areas of basic neuroscience and bio-medical research.

My recent research before retirement examined 1) the role of the pulvinar nucleus (the largest subdivision of the thalamus) in neural coding of visual movement and attention, and 2) the impact of a restricted spectral environment during early development on the visual system and adult visual function.  Collaborations have extended to the neural mechanisms of taste in the tree shrew.  The selected publications listed below were chosen to highlight recent projects, as well as to provide a sampling of the breadth of research problems addressed and methodologies used throughout my career. 

Selected Publications


Dittmer AE, Garrett SR, Payne RA, Satterwhite M, Petry HM. (Eds.)  (2008) The Power of Ideas: Volume II. Louisville, KY: Butler Books.

Dittmer AE, Satterwhite M, Petry HM, Ziegler CE, et al.  (Eds.) (2015) The Legacy of the Grawemeyer Awards. Louisville, KY: Butler Books.


Petry, H.M. (2008)  The Grawemeyer Awards in Psychology.  In The Power of Ideas:  Volume II, AE Dittmer, SR Garrett, RA Payne, M Satterwhite and HM Petry.  Louisville KY: Butler Books, pp 210-251.

Petry, HM. (2015)  Introduction: The Grawemeyer Award in Psychology.  In Dittmer AE, Satterwhite M, Petry HM, Ziegler CE, et al. (Eds.), The Legacy of the Grawemeyer Awards.  Louisville, KY: Butler Books, pp. 177-180.


Petry HM (producer); Peak M (director) (2017) Mysteries of Human Memory: A Grawemeyer Awards 30th Anniversary Event. Broadcast on Kentucky Educational Television (KET)  January 2017. 


* Denotes graduate student or post-doc.

  • Maher* EE, Prillaman* ME, Keskinoz* EN, Petry HM, Erisir A (2021) Immunocytochemical and Ultrastructural Organization of the Taste Thalamus of the Tree Shrew (Tupaia belangeri).  Journal of Comparative Neurology, Epub ahead of print 2021 Jan 28  doi: 10.1002/cne25109.
  • Schilder* BM, Petry HM, Hof PR (2020) Evolutionary shifts dramatically reorganized the human hippocampal complex.  Journal of Comparative Neurology, 528(17): 3143-3170.  doi: 10.1002/cne.24822. [Epub ahead of print 2019 Dec 2]
  • Petry HM, Bickford ME (2019) The second visual system of the tree shrew.  Journal of Comparative Neurology, 527(3):679-693. doi: 10.1002/cne.24413. PMID: 29446088.  (Epub ahead of printing 2018 Mar 9)
  • Day-Brown JD*, Slusarczyk AS, Zhou N*, Quiggans* R, Petry HM, Bickford ME. (2017) Synaptic organization of striate cortex projections in the tree shrew: A comparison of the claustrum and dorsal thalamus.  Journal of Comparative Neurology, 525:1403-1420. doi: 10.1002/cne.23998. PMID: 26971364. [Epub 2016 Mar 29]
  • Familtsev* D, Quiggins* R, P Masterson* S, Dang* W, Slusarczyk* AS, Petry HM, Bickford ME. (2016) Ultrastructure of geniculocortical synaptic connections in the tree shrew striate cortex.  Journal of Comparative Neurology, 524(6), 1292-1306. doi: 10.1002/cne.23907. PMID: 26399201 [Epub ahead of printing 2015 Oct 13]
  • Vanni* M, Thomas* S, Petry HM, Bickford ME, Casanova C. (2015) Spatiotemporal profile of voltage-sensitive dye responses in the visual cortex of tree shrews evoked by electrical microstimulation of the dorsal lateral geniculate and pulvinar nuclei. Journal of Neuroscience, 35(34), 11891-11896. doi: 10.1523/JNEUROSCI.0717-15.2015.
  • Balaram* P, Isaamullah* M, Petry HM, Bickford ME, Kaas J. (2015) Distributions of vesicular glutamate transporters 1 and 2 in the visual system of tree shrews (Tupaia belangeri).  Journal of Comparative Neurology, 523:1792-1808. doi: 10.1002/cne.23727. [Epub ahead of printing 2015 Jun 3]
  • Baldwin* MKL, Wei* H, Reed* JL, Bickford ME, Petry HM, Kaas JH. (2012) Cortical projections to the superior colliculus in tree shrews (Tupaia belangeri). Journal of Comparative Neurology, 521(7):1614-32. doi: 10.1002/cne.23249
  • Wei* H, Bonjean* M, Petry HM, Sejnowski T, Bickford ME (2011) Thalamic burst firing propensity: a comparison of the dorsal lateral geniculate and pulvinar nuclei in the tree shrew. Journal of Neuroscience, 31(47), 17287-17299. doi:10.1523/JNEUROSCI.6431-10.2011
  • Wei* H, Masterson* SP, Petry HM, Bickford ME (2011) Diffuse and specific tectopulvinar terminals in the tree shrew: synapses, synapsins, and synaptic potentials. PLoS ONE, 6(8): e23781. doi:10.1371/journal.pone.0023781 [Epub 2011 Jun 15]
  • Day-Brown* JD, Wei* H, Chomsung* RD, Petry HM, Bickford ME (2010) Pulvinar projections to the straitum and amygdala in the tree shrew. Frontiers in Neuroanatomy, 4, article 143. (published November 15, 2010, doi: 10.3389/fnana.2010.00143)  Reprinted in Frontiers in Neuroanatomy Research Topics e-book: Basal Ganglia Circuits (hosted by JL Lanciego), 2012, 136-146. 
  • Chomsung* RD, Wei* H, Day-Brown* JD, Petry HM, Bickford ME. (2009) Synaptic organization of connections between the temporal cortex and pulvinar nucleus of the tree shrew. Cerebral Cortex, 20(4), 997-1011.  Epub ahead of print 2009 Aug 14, doi:10.1093/cerecor/bhp162.
  • Chomsung* RD, Petry HM and Bickford ME. (2008) Ultrastructural examination of diffuse and specific tectopulvinar projections in the tree shrew. Journal of Comparative Neurology, 510(24), 24-46.
  • Radtke ND, Aramant RB, Petry HM, Greene PT, Pidwell DJ, Seiler M. (2008) Vision improvement in retinal degeneration patients by implantation of retina together with retinal pigment epithelium. American Journal of Ophthalmology, 146(2), 172-182. Epub 2008 Jun 10.
  • Lu*, H. and Petry, H.M. (2003) Temporal modulation sensitivity of tree shrew retinal ganglion cells. Visual Neuroscience, 20(4), 363-372.
  • Callahan*, T.L. and Petry, H.M. (2000) Psychophysical measurement of temporal modulation sensitivity in the tree shrew. Vision Research, 40, 455-458.
  • Ball*, S.L. and Petry, H.M. (2000) Non-invasive measurement of retinal function in rats using multifocal electroretinography. Investigative Ophthalmology & Visual Science, 41, 610-617.
  • Cao*, Q.-L., Murphy*, H.A. and Petry, H.M. (1999) Localization of nitric oxide synthase in the tree shrew retina. Visual Neuroscience, 16, 399-409.
  • Petry, H.M. and Murphy*, H.A. (1995) Differentiation of short-wavelength-sensitive cones by NADPH-diaphorase histochemistry. Proceedings of the National Academy of Sciences (USA), 92, 5121-5123.
  • Petry, H.M. (1993) Long-term changes in visual mechanisms following differential stimulation of color and luminance channels during development. Progress in Brain Research, 95, 235-250.
  • Petry, H.M. (1993) Magno and parvo visual channels and the subjective Necker cube. Vision Research, 33, 845-847.
  • Agarwala*, S., Günlük*, A.E., May, J.G., and Petry, H.M. (1992) Immunohistochemical organization of the ventral lateral geniculate nucleus in the tree shrew. Journal of Comparative Neurology, 318, 267-276.
  • Petry, H.M. and Kelly*, J.P. (1991) Psychophysical measurement of spectral sensitivity and color vision in red-light-reared tree shrews (Tupaia belangeri). Vision Research, 31, 1749-1757.
  • Petry, H.M. and Hárosi, F.I. (1990) The visual pigments of tree shrew (Tupaia belangeri) and galago (Galago crassicaudatus): a microspectrophotometric investigation. Vision Research, 30, 839-851.
  • Norton, T.T., Irvin*, G.E., Casagrande, V.A., Sesma*, M.A., and Petry, H.M. (1988) Contrast sensitivity functions of W-, X- and Y-like relay cells in the lateral geniculate nucleus of the bush baby (Galago crassicaudatus). Journal of Neurophysiology, 59, 1639-1656.
  • Petry, H.M., Donovan, W.J., Moore*, R.K., Dixon*, W.B., and Riggs, L.A. (1982) Changes in the human visually evoked potential in response to chromatic modulation of a sinusoidal grating. Vision Research, 22, 745-755.
  • White*, K.D., Petry, H.M., Riggs, L.A., and Miller, J. (1978) Binocular interactions during establishment of McCollough effects. Vision Research, 18,1201-1215.
  • Bradley, D.R., and Petry, H.M. (1977) Organizational determinants of subjective contour: the subjective Necker cube. American Journal of Psychology, 90, 253-262.
  • Bradley, DR, Dumais SM, Petry HM (1976) Ambiguous cognitive contours: a reply to Cavonius.  Nature, 261, 78.