Inhaltspezifische Aktionen

Preisverleihung 2017

Verleihung der Kurt-Koffka-Medaille an die Professoren Jan J. Koenderink und Andrea J. van Doorn

Laudatio Prof. Gegenfurtner:

Dear Andrea, dear Jan, dear students and colleagues,

It is an enormous pleasure for me to tell you about some of the great achievements of our guests of honor today. Andrea van Doorn and Jan Koenderink are giants, as you can all see. J They are truly intellectual giants in their scientific field, and over the last 50 years, they have set the agenda for the study of perception—not only in man but also for machine vision—like only a select handful of other scientists. Objectively, their more than 700 papers have been cited close to 30.000 times. However, these bibliometric measures do not reflect the true genius. Andrea van Doorn and Jan Koenderink were always way ahead of their time. They started new fields of research from scratch, or fundamentally changed existing ones, and typically it took about ten years until their ideas were understood and became accepted knowledge. It is a great and special honor for all of us that you, Andrea and Jan, are prepared to accept the Kurt-Koffka award from our faculty.

It might sound presumptuous to claim that Andrea van Doorn and Jan Koenderink have made a large number of important discoveries, although indeed, they have. Therefore, I will focus on three areas of interest – optic flow, shape, and material perception – where their combination of mathematical insight and thorough experimental investigation has led to real breakthroughs.

Optic flow describes the pattern of visual motion that surrounds us when either objects move or we move. This information is essential for all our interactions with the world, including very basic aspects such as posture, gait and locomotion. For a long time in psychology optic flow was considered a crucial piece of information that was somehow sensed “directly”, where directly meant, “we have no idea how”. In a series of articles in the 1980s, Andrea van Doorn and Jan Koenderink took the mystery out of optic flow by showing that even the most complicated flow patterns could be decomposed mathematically into a few basic elements, very simple forms of motion. This advance finally made it feasible to study these elements in rigorous experiments and indeed led to numerous psychophysical and physiological studies that could finally pinpoint the neuronal basis of optic flow analysis to a particular brain area, the latter work being done by electrophysiologists about 10 years after the initial work by our award winners.

They achieved a similar leap in understanding with respect to shape. At a time when most vision researchers were investigating the detection of simple abstract patterns like “sine wave gratings”, Andrea van Doorn and Jan Koenderink performed groundbreaking theoretical and experimental research on how the visual system could reconstruct the three-dimensional surfaces in the world around us from two-dimensional retinal intensity patterns.  Jan wrote some of the first and most influential mathematical treatments that form the basis for our understanding of the perception of shape from shading, motion, texture and bounding contours. This work is summarized in the 700-page book “Solid Shape”, which is widely acclaimed not just in biological and computer vision, but also in mathematics, and has been cited more than 1000 times.  He has, for example, explained how we can use the outline of a shape to make inferences about its three-dimensional structure.  This was a crucial theoretical advance and relates to how the visual system makes sense of line drawings and other shape depictions used by artists, which involve images that look very different from the typical patterns of retinal stimulation we experience in everyday life.

The true strength of Andrea van Doorn and Jan Koenderink is that they are not only theorists, but also highly successful and creative experimenters. On top of all the work on mathematical theory, they developed probably the single most important experimental technique for measuring human shape perception, the ‘gauge figure task’, which has been used in countless studies of human shape perception. Everybody working on shape perception, be it in man or machines, is standing on the shoulders of Andrea van Doorn and Jan Koenderink.

As a third example of their innovative energy, I would like to mention the field of material perception. Humans have the remarkable ability to judge material properties of objects and surfaces purely from a quick visual inspection. We immediately “see” that a surface is smooth, rough, slippery or shiny, for example. How we arrive at these judgments has been a mystery for a long time, especially since vision science has mainly concentrated on objects and their parts. Only during the past decade has this field gained traction, and as of now it is starting to emerge as a “hot” topic with several major funding initiatives going on. Once again, Andrea van Doorn and Jan Koenderink have tackled the properties of materials and their interactions with illumination, long before anybody else did. For example, as early as 1980, they laid down the theoretical basis for the motion of specular highlights across surfaces as a function of object shape. They proved that when a shiny object moves, the reflections slide slowly across regions of high curvature and rush across regions of low curvature, in a way that is completely different from the behavior of patterns painted onto matte surfaces. Thus, the movement of the highlights can tell us not only about the shape and motion of objects, but also their material properties – whether they are matte or glossy. Only 30 years later scientists –Katja Dörschner and Roland Fleming, who are both in Gießen now– used this work to understand the role of motion information for identifying material properties. It is thus no exaggeration to say that what Andrea and Jan are currently working on will continue to influence our field for decades to come.

I think these three examples point out that Andrea van Doorn and Jan Koenderink are far from being ordinary scientists. They are leaders, and they are leading with ideas. That their ideas are usually far ahead of their time is universally acknowledged in the scientific community. In fact, the European Society for Computer Vision has established a prize named after Jan Koenderink that is given to a paper presented at their annual conference 10 years ago that “has stood the test of time”. There’s no better way to describe the special role that our award winners play in the scientific community!

After having heaped so much praise on the two, I would like to mention one more thins that I find personally quite astonishing. It is about aging. Admittedly, Andrea and Jan are not really young anymore, at least on paper. They are both officially retired for several years now. They were highly productive during their entire life, and Jan headed the “Physics of man” group at Utrecht for more than 30 years. After retirement, they joined the lab of Prof. Johan Wagemans in Leuven as visiting professors, and freedom from administrative duties has increased their productivity. They keep generating journal articles at an ever faster pace, and instead of relying on the traditionally slow publishing process for books, they started their own self-publishing initiative, the Clootcrans Press, and have already produced 15 books! During the past few years, they have been visiting my lab in Giessen several times and I could witness them going at full speed. They still have the excitement of young students, only with the added experience and efficiency of seasoned investigators. It is enormously difficult to keep pace with them! So they only got better and faster with the years, in defiance of all the research on aging we do upstairs on the third floor.

I could not think of anyone being better suited for the Koffka medal than Andrea van Doorn and Jan Koenderink. With a background in physics, but a deep and intuitive calling for psychology, they are capable or proofing mathematically a theorem about the nature of perceptual information, develop new experimental methods to test its consequences, and then stun the field with a result that changes the way we all think about the nature of perception.

This is the 11th time that the Kurt-Koffka medal is awarded. Kurt Koffka was a pioneer of psychology and Gestalt theory. As most of you may know, Koffka is particularly famous for his works on perception and child development – works that partly originate from the time when Koffka was working in Giessen in the years 1911 to 1927. Referring to this famous former Professor of Giessen University, the Kurt-Koffka award is meant to honor scientists who advanced the fields of perceptual or developmental psychology to an extraordinary extent. My colleagues and I are deeply convinced, that you, Andrea and Jan, have advanced and are still advancing the fields of perceptual psychology to an extraordinary extent.


Congratulations to you, Andrea van Doorn and Jan Koenderink!