Department of Psychological Sciences
School of Electrical and Computer Engineering (by courtesy)
West Lafayette, IN 47907-2081
>> city map
email: pizlo at psych dot purdue dot edu
Tel. (765) 494 6930
Fax: (765) 496 1264
Room #: PRCE 194
What is the nature of perception?
Perception is an inference that provides the observer with a veridical representation of the external world. Illusions almost never happen in everyday life.
Perception is based on algorithms, not on look-up tables. These algorithms are automatically applied to the incoming sensory stimulation. This automaticity gives
us the impression that perception is easy and effortless. Computationally, it is not. Perception algorithms are innate – we are born with them. It is possible,
perhaps even likely that some parameters of these algorithms are estimated or tuned after birth. This makes sense because the genes that convey the information
about these algorithms are communication channels with finite information capacity. The parameters may have to be tuned to varying input as the child grows up
and ages. It is very unlikely, however, that the algorithms, themselves, are either learned or modified through learning during life. This permanence and innateness
allows all human beings to perceive the external world the same way from their first to last day. This is critical for successful interaction among humans and with
objects in the world “out there”. The key to understanding how perception algorithms work is to recognize the critical role a priori simplicity constraints play in
perception. The sensory data, which comes in is always ambiguous, and it is subjected to the simplest possible interpretation. It so happens that the simplest
interpretation is almost always the correct interpretation. This predilection for choosing the simplest interpretation implies that the human mind is solving an
“optimization problem”. Unlike the numerical methods most scientists use for solving optimization problems with conventional computers, the human mind uses
physiological mechanisms that probably implement what is called the “least action” principle of physics (Lanczos, 1970). The concept called “optimization”,
which is widely used in explaining physical and biological systems, as well as in designing engineering systems, is becoming popular in explaining cognitive
systems where it is likely to shed light on the relationship between the mind and the brain. It may also demystify the perennial question about whether machines can see and think.
To see how our robot solves figure-ground organization problem
and performs simple navigations tasks go to Yunfeng's web site and
to the VSS demo site.
3D Shape: its unique place in visual perception, MIT Press.
Read more >>