Carnegie Mellon University
August 21, 2015

Alumni Q&A with Patrick Cavanagh

By Shilo Rea

Alumni Q&A with Patrick Cavanagh

Patrick Cavanagh (DC’72) started out as a computer and electrical engineer, but an interest in artificial intelligence led him to Carnegie Mellon University, where he could study “the really big computer.” Since receiving his Ph.D. in cognitive psychology from CMU, Cavanagh worked on aspects of memory and now focuses on how the visual perception system constructs our three-dimensional world. He is currently on the faculty at Harvard University and Université Paris Descartes.

Cavanagh calls vision research “an adventure of discovery, full of surprises and challenges, with the ever-pleasant company of hardy, ingenious colleagues and students.” He recently answered questions for the Department of Psychology’s newsletter, #CMUPsych, on his career, the future of brain research and his time at CMU.

In a 2005 Nature paper, you compared how the visual brain works to how an artist’s work reflects how we see, saying that they “act as research neuroscientists.” Could you elaborate?

Artists discovered how to make us “see” things that of course aren’t really there: objects in paintings and drawings, light, shadow, space. All of this is usually accomplished on flat surfaces with variation in pigment and line. Some of this magic occurs simply because the pattern of pigments on the painting mimics the pattern of light we would see if we looked at the actual object.

However, many aspects of art deviate from this simple copying and still work. That’s where artists become neuroscientists, discovering how to foil the visual brain, for their own purposes, thought. They are only inadvertent neuroscientists. For example, line drawings, one of the first styles of art from cave walls, can capture the sense of a scene and the interposition of objects. But there is no way for this meaning of taking lines as boundaries to evolve in nature: There are no lines around objects in the real world.

This style works because the edge detectors of the visual system are designed to pick up light/dark edges that mark the normal boundaries of objects. By chance, they also respond to lines and so give meaning to drawings that could never occur naturally. Artists discovered that their line sketches could capture the sense of object shape and in doing so revealed to us, much later on, an important property of visual neuroscience.

Similarly, painters will often bend the rules of physics in paintings by including impossible shadows, shapes, or reflections, all to make the composition more effective. Importantly, many of these deviations go unnoticed by viewers – these undetected errors are the ones that tell us which rules of physics actually count for visual perception and which are ignored by the brain. After all, the brain cannot check all rules of physics, all possible clues about where the light is coming from or what should actually be in a reflection. There isn’t time. As artists find the rules they can break without penalty, they act as research neuroscientists, and we have only to look at their paintings to uncover the short cuts used by our brains in responding rapidly to the scenes around us.

With both the U.S. and Europe declaring brain research as a priority, what do you think are the most needed and realistically possible outcomes?

The US BRAIN Initiative at $4.5B over 12 years and the now controversial European Human Brain Project at $1.6B over 10 years are encouraging steps but are not yet a signal that neuroscience is a priority among other sciences. These new initiatives are much deserved for a rapidly advancing field that is overcoming pathologies, improving quality of life, and extending neuroscience into new areas of applications.

But in fact, this amount will not get us far. Let’s put it into perspective. Last year all of US neuroscience received only $5.5B, about 15% of the NIH budget, divided among 16,000 projects (so about $0.3M each). These new brain-oriented programs will not add much to that (maybe 10% increase).

Let’s look at the individual science projects that get real money: the Large Hadron Collider, $9B, the ITER fusion reactor, $7B, the Cassini-Huygens satellite $3.3B, and development for just one drug, Lipitor, $4B. And these are dwarfed by the $100B it took to land on the moon.

For the moment, there is nowhere near this level of funding to, how should we say it, land science on the brain. So these new initiatives are encouraging, but neuroscience is still, inexplicably, a small player in science funding. It deserves real priority with top-level funding.

What is the most exciting thing about your job as a faculty member and researcher?

The most exciting thing is opening student’s eyes to the wonders of the brain. Showing them that these wonders can be accessed and some even understood. I am always thrilled to work with colleagues, students, and faculty on new ideas where off-the-wall suggestions are followed up and tracked down. Seeing students develop their own passion for science is an enormous reward and of course the only real downside is that they then move on to work elsewhere. I watch them as they form their own groups and scientific goals and hope their journey is as adventurous and fulfilling as mine.

Did you have a favorite professor, mentor or class at CMU that helped shape your career?

Well, first, I would have to thank Dean Swank, dean of student affairs at the time, for guiding a lot of us through troubled but exciting times. His patience in dealing with our high crimes and misdemeanors was epic.

But that just allowed me to have a career, it was my advisor Bill Chase who really changed my understanding of science and gave me a sense of pure joy in using experiments to answer questions. Bill unfortunately died only a few years after I left, and while he was still very young. He is remembered in many ways around the CMU campus but I will always remember him for his gruff laugh and endless bravado in the face of any experimental problem. The real outcome was always in reach, every obstacle was merely a sign that we were getting closer, and the final result when we got it was cause for big smiles and celebration. I have never been more inspired.