Tom Cornsweet

Last updated
Tom N. Cornsweet
Born(1929-04-29)April 29, 1929
DiedNovember 11, 2017(2017-11-11) (aged 88)
Resting placedonated his body to science
Alma mater Cornell University, Brown University
Known for Cornsweet illusion
Scientific career
FieldsOphthalmology, psychology
Institutions Yale University (1955–1959), University of California, Berkeley, Stanford Research Institute, Stanford University, Baylor College of Medicine, University of California, Irvine, Brien Holden Vision Diagnostics

Tom Norman Cornsweet [1] (April 29, 1929 – November 11, 2017) was an American experimental psychologist known for his pioneering work in visual perception, especially the effect that bears his name, and in the development of ophthalmic instrumentation. [2] [3]


Academic background and scientific research

Cornsweet is known for documenting the effect that bears his name in the 1960s. [4] Prior to his work on this particular optical illusion, Cornsweet graduated from Cornell University and enrolled in a graduate program at Brown University, operating in the vision research laboratory of Lorrin A. Riggs. [5] [6] During his graduate studies he was co-author of an early paper describing stabilized images. [5] His 1955 Ph.D. dissertation in experimental psychology involved small movements of the eye. Cornsweet was an assistant professor at Yale University from 1955–1959, and then became professor of psychology at the University of California, Berkeley. His interest in psychophysics led him to develop a widely employed improvement in the staircase method. [7] As an outgrowth of the courses he taught, Cornsweet published a frequently-cited textbook. [8]

Inventor and entrepreneur

In the late 1960s and early 1970s, Cornsweet was a key member of the Bioinformation Systems Group at the Stanford Research Institute (SRI). While also teaching in the psychology department at Stanford University, he designed or co-designed several innovative instruments for measuring properties of the eye, including eyetrackers, [9] auto-refractors, [10] and optical fundus scanners. [11] He left SRI to become Chief Scientist at Acuity Systems of Reston Virginia, where he developed the first commercial auto-refractor in 1973. It gave the objective reading of the refractive index of the eye in one second, saving practitioners up to 15 minutes a patient. This saved the Ophthalmologist more than an hour a day on average, immediately adding a huge productivity and income boost. Acuity Systems introduced the worlds first Auto-refractor and sold approximately 3000 world wide between 1975 and 1979 before it was bought by Simmons Instruments Inc. Many copies followed made by Coherent Radiation of California, Nidek of Japan and others. All versions of the Auto-refractor sold are estimated to total $15bn as the instrument is now universally commonplace in the Optometrist and Ophthalmologist workplaces. The Auto-refractor saved sight in many cases. One of many such instances occurred in Sydney Australia when a severely myopic patient, blind because the closest his expert optometrist could come to prescribing spectacles was 5.75 diopter sphere, 3.75 diopter cylinder at an incorrect angle, and the Auto-refractor immediately six times indicated a prescription of 15.75D sphere x 5.75D cylinder at 108 degrees. The patient was seen leaving the practise and heard proclaiming “I can see, I can see!” Multiple thousands of such instances occurred worldwide. A device to measure the refractive index of spectacle lenses, the Auto-lensmeter was also a commercial success in parallel with the Auto-refractor. In the 1980’s Tom Cornsweet developed a number of devices including one which measured the density of cataracts, ESA, the Eye System Analyser, which in a 30 second eye test determined presence of diseases of the nervous or muscular system such as MS 15 years before its noticeable onset, Hopkinson disease two years before onset and many other diseases. An industrial version, FIT 2000, first installations worldwide implemented in the coal mines of Queensland Australia, and later in mines of Chile, resulted in huge safety gains in the workplace, detecting immediately up to 5% of the workforce were participating in sleep deprivation activity, drug taking, prescription medication overuse and alcohol abuse. After a 36 second daily eye test and a ten day baseline was established, it was very easy to determine the presence of drugs, which drugs, alcohol, lack of sleep, and, after medical referral, diseases such as Narcolepsy, Brain diseases and damage. The FIT2000, sold and manufactured by PMI of Rockville, Maryland has also been installed worldwide into Armed forces for such things as fatigue detection in pilots and soldiers required to undertake military activities with severe sleep deprivation over many days. Cornsweet continued to invent devices for measuring various properties of the eye and also to teach, first at the Baylor College of Medicine and later at the University of California, Irvine. [12] He served as Vice President of research and development for Sensory Technologies from 1994 to 1997. In 1999 Cornsweet retired from UC–Irvine and co-founded Visual Pathways, where his team developed an automated retinal imaging system intended for the diagnoses of glaucoma, cataracts, diabetic retinopathy and macular degeneration. Visual Pathways folded into the Brien Holden Vision Institute after several years and successfully installing 24 breakthrough 3D fundus cameras, where from 2013 to 2015, Tom Cornsweet was Chief Scientist at Brien Holden Vision Diagnostics (formerly Quantum Catch), [13] a company developing very low-cost ophthalmic 3D fundus cameras and instruments for detection and monitoring of eye, brain and muscle disease primarily and principally for 3rd world countries which could not afford available instrumentation. Until his death in 2017, Cornsweet was Professor of Cognitive Science, Electrical and Computer Engineering, and Ophthalmology, Emeritus, University of California, Irvine. [14]

Patents and awards


Cornsweet wrote three books and published more than 100 journal articles. [17]


Seeing.How light tells us about the world.Tom Cornsweet.2017.Publisher University of California presS.

Journal articles

List of publications adapted from Cornsweet's curriculum vitae, published by the University of California, Berkeley. [19]

Related Research Articles

<span class="mw-page-title-main">Eye</span> Organ that detects light and converts it into electro-chemical impulses in neurons

Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons (neurones). In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.

<span class="mw-page-title-main">Color constancy</span> How humans perceive color

Color constancy is an example of subjective constancy and a feature of the human color perception system which ensures that the perceived color of objects remains relatively constant under varying illumination conditions. A green apple for instance looks green to us at midday, when the main illumination is white sunlight, and also at sunset, when the main illumination is red. This helps us identify objects.

<span class="mw-page-title-main">Depth perception</span> Visual ability to perceive the world in 3D

Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth perception happens primarily due to stereopsis and accommodation of the eye.

<span class="mw-page-title-main">Gradient-index optics</span>

Gradient-index (GRIN) optics is the branch of optics covering optical effects produced by a gradient of the refractive index of a material. Such gradual variation can be used to produce lenses with flat surfaces, or lenses that do not have the aberrations typical of traditional spherical lenses. Gradient-index lenses may have a refraction gradient that is spherical, axial, or radial.

<span class="mw-page-title-main">Human eye</span> Mammalian eye

The human eye is a sensory organ, part of the sensory nervous system, that reacts to visible light and allows humans to use visual information for various purposes including seeing things, keeping balance, and maintaining circadian rhythm.

<span class="mw-page-title-main">Eye tracking</span> Measuring the point of gaze or motion of an eye relative to the head

Eye tracking is the process of measuring either the point of gaze or the motion of an eye relative to the head. An eye tracker is a device for measuring eye positions and eye movement. Eye trackers are used in research on the visual system, in psychology, in psycholinguistics, marketing, as an input device for human-computer interaction, and in product design. Eye trackers are also being increasingly used for rehabilitative and assistive applications . There are a number of methods for measuring eye movement. The most popular variant uses video images from which the eye position is extracted. Other methods use search coils or are based on the electrooculogram.

George Sperling is an American cognitive psychologist, researcher, and educator. Sperling documented the existence of iconic memory. Through several experiments, he showed support for his hypothesis that human beings store a perfect image of the visual world for a brief moment, before it is discarded from memory. He was in the forefront in wanting to help the deaf population in terms of speech recognition. He argued that the telephone was created originally for the hearing impaired but it became popularized by the hearing community. He suggested with a sevenfold reduction in the bandwidth for video transmission, it can be useful for the improvement in American Sign Language communication. Sperling used a method of partial report to measure the time course of visual persistence.

<span class="mw-page-title-main">Blue field entoptic phenomenon</span> Optical phenomenon

The blue field entoptic phenomenon is an entoptic phenomenon characterized by the appearance of tiny bright dots moving quickly along squiggly lines in the visual field, especially when looking into bright blue light such as the sky. The dots are short-lived, visible for a second or less, and traveling short distances along seemingly random, curvy paths. Some of them follow the same path as predecessors. The dots may be elongated along the path like tiny worms. The speed of the dots varies in sync with the pulse; they briefly accelerate at each heartbeat. The dots appear in the central field of view, within 15 degrees from the fixation point. The left and right eye see different dots; someone looking with both eyes sees a mixture.

<span class="mw-page-title-main">Eye movement</span> Movement of the eyes

Eye movement includes the voluntary or involuntary movement of the eyes. Eye movements are used by a number of organisms to fixate, inspect and track visual objects of interests. A special type of eye movement, rapid eye movement, occurs during REM sleep.

The Stiles–Crawford effect is a property of the human eye that refers to the directional sensitivity of the cone photoreceptors.

<span class="mw-page-title-main">Shack–Hartmann wavefront sensor</span>

A Shack–Hartmannwavefront sensor (SHWFS) is an optical instrument used for characterizing an imaging system. It is a wavefront sensor commonly used in adaptive optics systems. It consists of an array of lenses of the same focal length. Each is focused onto a photon sensor. If the sensor is placed at the geometric focal plane of the lenslet, and is uniformly illuminated, then, the integrated gradient of the wavefront across the lenslet is proportional to the displacement of the centroid. Consequently, any phase aberration can be approximated by a set of discrete tilts. By sampling the wavefront with an array of lenslets, all of these local tilts can be measured and the whole wavefront reconstructed. Since only tilts are measured the Shack–Hartmann cannot detect discontinuous steps in the wavefront.

Parallax scanning depth enhancing imaging methods rely on discrete parallax differences between depth planes in a scene. The differences are caused by a parallax scan. When properly balanced (tuned) and displayed, the discrete parallax differences are perceived by the brain as depth.

<span class="mw-page-title-main">F. J. Duarte</span>

Francisco Javier "Frank" Duarte is a laser physicist and author/editor of several books on tunable lasers.

Stabilized Images are images that remain immobile on the retina. Under natural viewing conditions, the eyes are always in motion. Small eye movements continually occur even when attempting to maintain steady gaze on a single point. Experiments in the early 1950s established that stabilized images result in the fading and disappearance of the visual percept, possibly due to retinal adaptation to a stationary field. In 2007, studies indicated that stabilizing vision between saccades selectively impairs vision of fine spatial detail.

R. Clark Jones was an American physicist working in the field of optics. He studied at Harvard University and received his PhD in 1941. Until 1944 he worked at Bell Labs, later until 1982 with the Polaroid Corporation. In a sequence of publications between 1941 and 1956 he demonstrated a mathematical model to describe the polarization of coherent light, the Jones calculus.

Single-shot multi-contrast x-ray imaging is an efficient and a robust x-ray imaging technique which is used to obtain three different and complementary types of information, i.e. absorption, scattering, and phase contrast from a single exposure of x-rays on a detector subsequently utilizing Fourier analysis/technique. Absorption is mainly due to the attenuation and Compton scattering from the object, while phase contrast corresponds to phase shift of x-rays.

Memory color is the canonical hue of a type of object that allistic human observers acquire through their experiences with instances of that type. For example, most allistic human observers know that an apple typically has a reddish hue; this knowledge about the canonical color which is represented in memory constitutes a memory color.

Optical coherence tomography angiography (OCTA) is a non-invasive imaging technique based on optical coherence tomography (OCT) developed to visualize vascular networks in the human retina, choroid, skin and various animal models. OCTA may make use of speckle variance optical coherence tomography.

Jan P. Allebach is an American engineer, educator and researcher known for contributions to imaging science including halftoning, digital image processing, color management, visual perception, and image quality. He is Hewlett-Packard Distinguished Professor of Electrical and Computer Engineering at Purdue University.

Data visualization achieves its significance today due to information technology: big data processed in computers with capable visualization software, combined with statistical techniques and color coding on electronic displays. This article is about color coding in data visualization.


  1. Osborne, Roy (2016-12-29). Books on Colour 1495-2015: History and Bibliography. ISBN   9781326459710.
  2. Purves, Dale (January 8, 2010). Brains: How They Seem to Work. FT Press. pp. 139–142. ISBN   9780137060283 . Retrieved December 23, 2013.
  3. American Men of Science: Physical and Biological Sciences. Providence, N.J.: Bowker RR. 1967.
  4. Plait, Phil (December 7, 2013). "Viral Illusion Will—and Should—Have You Doubting Your Eyes". Slate . Retrieved December 23, 2013.
  5. 1 2 Riggs, Lorrin A.; Ratliff F.; Cornsweet J.; Cornsweet T. (1953). "The Disappearance of Steadily Fixated Visual Test Objects". Journal of the Optical Society of America. 43 (6): 495–500. Bibcode:1953JOSA...43..495R. doi:10.1364/josa.43.000495. PMID   13070111 . Retrieved March 20, 2011.
  6. D.H. Kelly, ed. (March 30, 1994). Visual Science and Engineering: Models and Applications. CRC Press. p. 91. ISBN   9780824791858 . Retrieved December 23, 2013.
  7. Cornsweet, TN (September 1962). "The Staircase-method in Psychophysics". Am. J. Psychiatry. 75 (3): 485–491. doi:10.2307/1419876. JSTOR   1419876.
  8. Cornsweet, Tom N. (1970). Visual Perception . New York, NY: Academic Press. p.  475. ISBN   978-0-12-189750-5.
  9. Cornsweet, TN; Crane HD (1973). "Accurate two-dimensional eye tracker using first and fourth Purkinje images". Journal of the Optical Society of America. 63 (8): 921–928. Bibcode:1973JOSA...63..921C. doi:10.1364/JOSA.63.000921. PMID   4722578 . Retrieved March 20, 2011.
  10. Cornsweet, TN (August 1973). "Computer-assisted automated refractions". The Australian Journal of Optometry. 56 (8): 310–313. doi:10.1111/j.1444-0938.1973.tb00727.x.
  11. Kelly, DH; Crane; Hill; Cornsweet (1969). "Non-contact method of measuring small eye- movements and stabilizing the retinal image". J. Opt. Soc. Am. 59: 509.
  12. "Conferences, Workshops, Seminars" (PDF). The Linguistic Reporter. Center for Applied Linguistics. December 1982 – January 1983. p. 9. Retrieved December 23, 2013. Note: Part of The Linguistic Reporter (1959–1982), Volume 25, published in 1982.
  13. "Leap in Detection and Diagnoses of Eye and Other Disorders". Medical Design Technology. Advantage Business Media. August 3, 2012. Retrieved December 23, 2013.
  14. "Obituary: Tom N. Cornsweet". Retrieved 23 November 2017.
  15. "UC Berkeley teaching award".
  16. "Charles F. Prentice award" . Retrieved March 21, 2011.
  17. "TN Cornsweet Google Scholar publications" . Retrieved March 21, 2011.
  18. Cornsweet, Tom. "Why is Everything!: Doing Science by Tom Cornsweet" . Retrieved December 17, 2013.
  19. "Curriculum Vitae: Tom N. Cornsweet: Professor of Cognitive Science, Electrical and Computer Engineering, and Ophthalmology, Emeritus: University of California, Irvine" (PDF). University of California, Berkeley. Retrieved December 17, 2013.