Marr integrated results from psychology, artificial intelligence, and neurophysiology into new models of visual processing.
His doctoral dissertation, supervised by Giles Brindley, was submitted in 1969 and described his model of the function of the cerebellum based mainly on anatomical and physiological data garnered from a book by J.C. Eccles.
His findings are collected in the book Vision: A computational investigation into the human representation and processing of visual information, which was finished mainly in the summer of 1979, was published in 1982 after his death and re-issued in 2010 by The MIT Press.
The theory of neocortex[5] was primarily motivated by the discoveries of David Hubel and Torsten Wiesel, who found several types of "feature detectors" in the primary visual area of the cortex.
Marr proposed, generalising on that observation, that cells in the neocortex are flexible categorizers—that is, they learn the statistical structure of their input patterns and become sensitive to combinations that are frequently repeated.
The theory of hippocampus[6] (which Marr called "archicortex") was motivated by the discovery by William Scoville and Brenda Milner that destruction of the hippocampus produced amnesia for memories of new or recent events but left intact memories of events that had occurred years earlier.
He put forth (in concert with Tomaso Poggio) the idea that one must understand information processing systems at three distinct, complementary levels of analysis.
[12] Marr described vision as proceeding from a two-dimensional visual array (on the retina) to a three-dimensional description of the world as output.
A more recent, alternative, framework proposed that vision is composed instead of the following three stages: encoding, selection, and decoding.