Dale Purves
Encyclopedia
Dale Purves is Director of the Neuroscience and Behavioural Disorders program at Duke-NUS Graduate Medical School
and Executive Director of the Neuroscience Research Partnership at A*STAR, both located in Singapore
. Until 2009 he was Director of the Center for Cognitive Neuroscience and George Barth Geller Professor for Research in Neurobiology at Duke University
. He received a B.A. from Yale University
in 1960 and an M.D. from the Harvard Medical School
in 1964. After several years in clinical medicine as a surgical house officer at the Massachusetts General Hospital
and as a Peace Corps
Physician, he gave up medicine in favor of a career in neuroscience research. He was a postdoctoral fellow in the Department of Neurobiology at Harvard from 1968 to 1971 and in the Department of Biophysics, University College London
, from 1971 to 1973. He then joined the faculty in the Department of Physiology and Biophysics at the Washington University in 1971, where he remained until 1990. During that time he studied the development of the nervous system, and was elected to the National Academy of Sciences
in 1989. He arrived at Duke in 1990 as the founding chair of the Department of Neurobiology, where he became increasingly interested in cognitive neuroscience.
Purves’s work at Duke has focused on visual and auditory perception (including perception of music), exploring the hypothesis that, as a means of contending with the inverse problem
in perception, percepts are generated by a neural strategy that represents the empirical significance of sensory stimuli rather than their physical features (see also empirical theories of perception
).
precludes direct analysis of image features, this strategy must take into account an entire history (on a species and individual level) of associations between sensory impressions and the success or failure of behavior.
For example, the perception of brightness
as it is typically understood is confounded by the fact that an object can send more light to the eye because it’s under a stronger light, because it naturally reflects more light, or for other reasons. Because all the eye receives is the final product, our visual systems cannot logically determine what the relative contributions of each factor are. However, successful behavior depends on the ability to discriminate these different conditions. On the empirical account, perceptions are determined by the frequency with which we encountered both of these various possibilities in in the past, and are not determined by the properties of stimuli as such.
To understand this concept of visual perception, note the discrepancies in brightness between the top and bottom blocks in the picture to the right. While the top block always appears darker than the bottom block, if a finger is held over the junction between the two blocks (enclosed by the four red lines) this apparent brightness difference disappears. In terms of the empirical theory of vision, these perceptual effects arise because in the past, this kind of scene (i.e. the way the shadows are positioned, the luminance difference across the junction) would usually have signified a behaviorally important difference between the two blocks. These kinds of effects can all be explained in terms of experience but are difficult to account for in any other way.
On the wholly empirical account, this strategy determines qualities of perception in all visual domains and sensory modalities. Accumulating evidence suggests that the perception of color, contrast, distance, size, line orientation and angles, and motion, as well as pitch and consonance in music, may be determined by empirically derived associations between the sensory patterns humans have always experienced and the relative success of behavior in response to those patterns.
Duke-NUS Graduate Medical School
The Duke-NUS Graduate Medical School Singapore is a collaboration between the Duke University in North Carolina, United States and the National University of Singapore....
and Executive Director of the Neuroscience Research Partnership at A*STAR, both located in Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
. Until 2009 he was Director of the Center for Cognitive Neuroscience and George Barth Geller Professor for Research in Neurobiology at Duke University
Duke University
Duke University is a private research university located in Durham, North Carolina, United States. Founded by Methodists and Quakers in the present day town of Trinity in 1838, the school moved to Durham in 1892. In 1924, tobacco industrialist James B...
. He received a B.A. from Yale University
Yale University
Yale University is a private, Ivy League university located in New Haven, Connecticut, United States. Founded in 1701 in the Colony of Connecticut, the university is the third-oldest institution of higher education in the United States...
in 1960 and an M.D. from the Harvard Medical School
Harvard Medical School
Harvard Medical School is the graduate medical school of Harvard University. It is located in the Longwood Medical Area of the Mission Hill neighborhood of Boston, Massachusetts....
in 1964. After several years in clinical medicine as a surgical house officer at the Massachusetts General Hospital
Massachusetts General Hospital
Massachusetts General Hospital is a teaching hospital and biomedical research facility in the West End neighborhood of Boston, Massachusetts...
and as a Peace Corps
Peace Corps
The Peace Corps is an American volunteer program run by the United States Government, as well as a government agency of the same name. The mission of the Peace Corps includes three goals: providing technical assistance, helping people outside the United States to understand US culture, and helping...
Physician, he gave up medicine in favor of a career in neuroscience research. He was a postdoctoral fellow in the Department of Neurobiology at Harvard from 1968 to 1971 and in the Department of Biophysics, University College London
University College London
University College London is a public research university located in London, United Kingdom and the oldest and largest constituent college of the federal University of London...
, from 1971 to 1973. He then joined the faculty in the Department of Physiology and Biophysics at the Washington University in 1971, where he remained until 1990. During that time he studied the development of the nervous system, and was elected to the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
in 1989. He arrived at Duke in 1990 as the founding chair of the Department of Neurobiology, where he became increasingly interested in cognitive neuroscience.
Purves’s work at Duke has focused on visual and auditory perception (including perception of music), exploring the hypothesis that, as a means of contending with the inverse problem
Inverse problem
An inverse problem is a general framework that is used to convert observed measurements into information about a physical object or system that we are interested in...
in perception, percepts are generated by a neural strategy that represents the empirical significance of sensory stimuli rather than their physical features (see also empirical theories of perception
Empirical theories of perception
An empirical theory of perception is a kind of explanation for how percepts arise. These theories hold that sensory systems incorporate information about the statistical properties of the natural world into their design and relate incoming stimuli to this information, rather than analyzing sensory...
).
Wholly empirical theory of perception
According to the wholly empirical theory of perception developed by Dale Purves, R. Beau Lotto and others, perception must be understood as the outcome of a neural strategy to generate appropriate behavior from sensory stimulation. Since the inverse problem in opticsInverse problem in optics
The inverse problem in optics refers to the fundamentally ambiguous mapping between sources of retinal stimulation and the retinal images that are caused by those sources....
precludes direct analysis of image features, this strategy must take into account an entire history (on a species and individual level) of associations between sensory impressions and the success or failure of behavior.
For example, the perception of brightness
Brightness
Brightness is an attribute of visual perception in which a source appears to be radiating or reflecting light. In other words, brightness is the perception elicited by the luminance of a visual target...
as it is typically understood is confounded by the fact that an object can send more light to the eye because it’s under a stronger light, because it naturally reflects more light, or for other reasons. Because all the eye receives is the final product, our visual systems cannot logically determine what the relative contributions of each factor are. However, successful behavior depends on the ability to discriminate these different conditions. On the empirical account, perceptions are determined by the frequency with which we encountered both of these various possibilities in in the past, and are not determined by the properties of stimuli as such.
To understand this concept of visual perception, note the discrepancies in brightness between the top and bottom blocks in the picture to the right. While the top block always appears darker than the bottom block, if a finger is held over the junction between the two blocks (enclosed by the four red lines) this apparent brightness difference disappears. In terms of the empirical theory of vision, these perceptual effects arise because in the past, this kind of scene (i.e. the way the shadows are positioned, the luminance difference across the junction) would usually have signified a behaviorally important difference between the two blocks. These kinds of effects can all be explained in terms of experience but are difficult to account for in any other way.
On the wholly empirical account, this strategy determines qualities of perception in all visual domains and sensory modalities. Accumulating evidence suggests that the perception of color, contrast, distance, size, line orientation and angles, and motion, as well as pitch and consonance in music, may be determined by empirically derived associations between the sensory patterns humans have always experienced and the relative success of behavior in response to those patterns.
Selected recent publications
- Yang Z, Purves D (2003) Image/Source statistics in natural scenes. Network: Computation in Neural Systems 14: 371–390http://www.iop.org/EJ/abstract/0954-898X/14/3/301.
- Yang Z, Purves D (2003) A statistical explanation of visual space. Nature Neuroscience 6: 632–640http://www.nature.com/neuro/journal/v6/n6/full/nn1059.html.
- Schwartz D, Howe CQ, Purves D (2003) The statistical structure of human speech sounds predicts musical universals. J Neurosci 23:7160–7168http://www.jneurosci.org/cgi/content/full/23/18/7160.
- Purves D, Lotto RB (2003) Why we see what we do: An empirical theory of vision. Sunderland, MA: Sinauer Associateshttp://www.sinauer.com/detail.php?id=7528.
- Howe Q, Purves D (2003) Size contrast explained by the statistics of scene geometry. J Cog Neurosci 16:90–102http://jocn.mitpress.org/cgi/content/abstract/16/1/90.
- Long F, Purves D (2003) Natural scene statistics as a universal basis for color context effects. Proc Natl Acad Sci 100 (25): 15190–15193.http://www.pnas.org/cgi/content/full/100/25/15190?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=purves&searchid=1086895810292_6541&stored_search=&FIRSTINDEX=10
- Purves D, Williams MS, Nundy S, Lotto RB (2004) Perceiving the intensity of light. Psychological Rev 111(1): 142–158.
- Yang Z, Purves D (2004) The statistical structure of natural light patterns determines perceived light intensity. Proc Natl Acad Sci 101: 8745–8750http://www.pnas.org/cgi/content/full/101/23/8745?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=purves&searchid=1086895544544_6520&stored_search=&FIRSTINDEX=0.
- Schwartz D, Purves D (2004) Pitch is determined by naturally occurring periodic sounds. Hearing Research 194: 31–46http://www.elsevier.com/wps/find/journaldescription.cws_home/506060/description#description.
- Howe CQ, Purves D (2005) Natural scene geometry predicts the perception of angles and line orientation. Proc Natl Acad Sci 102: 1228–1233http://www.pnas.org/cgi/content/abstract/102/4/1228?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=purves&searchid=1108137675033_3161&stored_search=&FIRSTINDEX=0&journalcode=pnas.
- Howe CQ, Purves D (2005) The Müller-Lyer illusion explained by the statistics of image-source relationships. Proc Natl Acad Sci 102: 1234–1239http://www.pnas.org/cgi/content/abstract/102/4/1234?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=purves&searchid=1108137675033_3161&stored_search=&FIRSTINDEX=0&journalcode=pnas.
- Howe CQ, Yang Z, Purves D (2005) The Poggendorff illusion explained by natural scene statistics of image-source relationships. Proc Natl Acad Sci 102:7707–7712 http://www.pnas.org/cgi/content/abstract/102/21/7707?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=purves&searchid=1126275575934_5551&stored_search=&FIRSTINDEX=0&journalcode=pnas.
- Long F, Yang Z, Purves D (2006) Spectral statistics in natural scene predict hue, saturation, and brightness. Proc Natl Acad Sci 103: 6013–6018http://www.trends.com/tics/default.htm.
- Howe CQ, Lotto RB, Purves D (2006) Comparison of bayesian and empirical ranking approaches to visual perception. J Theor Biol 241: 866–875http://linkinghub.elsevier.com/retrieve/pii/S0022-5193(06)00030-0.
- Boots B, Nundy S, Purves D (2007) Evolution of visually-guided behavior in artificial agents. Network: Computation in Neural Systems 18 (1): 1–24http://www.informaworld.com/smpp/content~content=a776416767~db=all~order=page.
- Ross D, Choi J, Purves D (2007) Musical intervals in speech. Proc Natl Acad Sci 104(23): 9852–9857http://www.pnas.org/cgi/content/full/104/23/9852.
- Purves et al. (2007) Principles of Cognitive Neuroscience. Sunderland,MA: Sinauer Associates, 2007http://www.sinauer.com/detail.php?id=6946
- Purves D, Augustine GA, Fitzpatrick D, Hall W, LaMantia A-S, McNamara JO, Williams SM (2008) Neuroscience, 4th edition. Sinauer Associates: Sunderland, MAhttp://www.sinauer.com/detail.php?id=6977..
- Wojtach W.T., Sung K, Truong S, Purves D (2008) An empirical explanation of the flash-lag effect. Proc Natl Acad Sci 105(42): 16338–16343http://www.pnas.org/content/105/42/16338.full.pdf+html.
- Sung K, Wojtach W.T., Purves D (2009) An empirical explanation of aperture effects. Proc Natl Acad Sci 106: 298–303http://www.pnas.org/content/106/1/298.
- Wojtach W. T., Sung K, Purves D (2009) An empirical explanation of the speed-distance effect. PLoS ONE 4(8): e6771http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0006771.
- Gill KZ and Purves D (2009) A biological rationale for musical scales. PLoS ONE 4: e8144http://www.purveslab.net/publications/gill_purves_2009.pdf.
- Bowling DL, Gill KZ, Choi JD, Prinz J, and Purves D (2009) Major and minor music compared to excited and subdued speech. J Acoust Soc Am 127(1): 491–503.http://www.purveslab.net/publications/bowling_purves_2009.pdf.
- Purves, Dale. Brains: How they Seem to Work. Financial Times Press Science, New Jersey, 2010.
External links
- Laboratory of Dale Purves, M.D.
- Duke University
- Center for Cognitive Neuroscience, Duke University
- Neuroscience 4th Edition
- Kruglinski, Susan (2008) Musical Scales Mimic Sound of Language. Discover Magazine – 100 Top Science Stories of 2007: January
- Jackson, Joab (2007) "Virtual Robots" Befuddled by Optical Illusions. National Geographic News : October 11
- Music Rooted in Speech (2007); video featuring Dale Purves and Jonathan Choi.YouTube
- Tenenbaum, David (2007) Music: The Universal Scale. The Why Files: June 7
- Music Tones in Speech (2007) Scenta
- Essential Tones of Music Rooted in Human Speech (2007)Science Daily May 25
- Meredith, D (2005) New book explains age-old mystery of geometrical illusions. Duke News Releases: September 30.
- Kenneally, C (2003) Songs of ourselves. Boston Globe: November 9.
- Black, R (2003) Science finds key to music. BBC News: August 6.
- Farley, P (2003) Musical roots may lie in human voice. Newscientist.com: August 3.
- Billock, VA (2003) A framework for vision's bag of tricks. Science May 2; 300: 742–743.
- How We See (2002) Transcript from News Hour with Jim Lehrer that aired December 25.