[visionlist] Mourning the loss of Dana H. Ballard

[Chen Yu]

It is with great sadness that we inform the scientific community of the
death of an international giant. Dana Ballard passed away on Nov 3rd, 2022,
at the age of 76.

It is hard to single out Dana’s “signature” work among many of his
achievements. In the past few decades, his unabated scientific curiosity
has driven him deeply into multiple interrelated fields in computer vision
and artificial intelligence, vision science, cognitive science, and
neuroscience. The interdisciplinary nature of his research created
synergistic insights that were always ahead of his time. His work led to
paradigm-shifting contributions not just in one but multiple research
fields. Perhaps one way to share Dana’s research journey is to go through
the pathways Dana has created that connect those scientific fields.

*From computer vision to human vision*. Most of Dana’s early work was on
computer vision. In 1982, with Chris Brown, Dana co-authored a highly
influential first textbook on computer vision. Around the same time, he
invented two powerful algorithms -- Color Indexing and Generalized Hough
Transform – both of which have been widely used. In 1985, Dana led a team
that designed and built a high-speed binocular camera control system
capable of simulating human eye movements. This system has led to an
increased understanding of the role of action in simplifying visual tasks.

*From behavior to the brain*. In 1995, Dana and his longtime collaborator
Mary Hayhoe developed an experimental setup to capture time-locked
multimodal data from mobile eye trackers and motion tracking devices with
precise measurements of a freely moving participant in a natural situation.
With this technological breakthrough, they have conducted a series of
studies to examine how behavioral programs control the selection of visual
information, in particular, the pervasive role of the task in guiding where
and when to deploy gaze. To further examine the top-down effects on vision
and attention, Dana and his Ph.D. student Rajesh Rao in 1999, published a
predictive coding model of the visual cortex, which could explain a vast
amount of data from visual cortex.

*From computational models to cognitive theories. *By combining
computational and experimental approaches, these seminal works led
collectively to three major theoretical contributions: 1) *Predictive
coding*. Dana’s research suggested that the brain uses its prior knowledge
of the world to generate hypotheses about the causes of incoming sensory
information based on an internal model. Due to his work, now probably the
majority of neuroscientists see the brain as a “prediction machine.” *2)
Active vision. *Through Dana’s work, the field discovered that biologically
motivated active vision could be much more efficient than static image
analysis. Sensorimotor tasks are easier when sensors are closely integrated
with effectors. 3) *Embodied cognition*. A seminal paper proposed that the
physical world serves as our memory and that deictic behavior serves to
link the brain and the external world. This idea has stirred much interest
not only in vision science but also in philosophy.

Dana was a fabulous mentor and a great colleague. For his previous
trainees, he will be remembered for his wit, his humor, and his kindness.
Dana found ways to create a unique bed to nurture many different flowers to
blossom. I am sure that there are many fun memories of Dana that would
bring a smile to his previous colleagues and friends at the University of
Rochester and the University of Texas at Austin. He was one of the kindest
people I have had the pleasure of knowing and working with. I, for one,
will forever be grateful for his contributions to science and his kindness
and support in my life.

Dana Ballard was a true giant in the field. His research has always been
“ahead of the curve.” He was an influential thinker and an innovative
experimenter. Dana will be long remembered for his outstanding
accomplishments, his compassion, his strength, his style, and his
commitment to science.



Prof. Chen Yu

Department of Psychology, Center for Perceptual Systems

The University of Texas at Austin

108 E Dean Keeton St

Austin, Texas, 78712 U.S.A.

Lab website: https://www.la.utexas.edu/users/dil/

E-mail: chen.yu at austin.utexas.edu
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