Classes are on Tuesdays and Thursdays, 3-4:50 pm.
  See detailed schedule for Fall 2019.
  PHYS 110 / 331
  Prof. Hong Z. Tan (ECE)
  Office: MSEE272
  Email: hongtan at
Office Hour:
  Thursdays, 1:45-2:45 pm

Human Research Protection Program at Purdue

Online Experiments

History of EE595T/PSY594I Psychophysics

Prof. Tan (ECE) and Prof. Pizlo (PSY) had independently come up with the idea of a course on Psychophysics. When the two of us realized that we both had an interest in developing such a course, we decided to join force.

While many people view Psychophysics as nothing more than a collection of methods for performing experiments (limits, adjustment, constant stimuli etc.), we developed our course with a broader view. Our syllabus covers the methodology of studying the relation between geometrical and physical properties of objects and the percept. By studying it is meant not only collecting data, but also formulating mathematical and computational models of the underlying mental mechanisms. Traditionally, psychophysics is included as an introductory part of courses on perception. This is usually limited to a brief review of classical methods described by Fechner, and selected methods that were developed in the 20th century (signal detection with the receiver operating characteristic, speed-accuracy tradeoff, attention operating characteristic, information transfer, adaptive methods). Such an introduction is usually limited to 2 or 3 weeks, so that there is enough time for discussing results and theories of perception. We realized that a comprehensive review of all important experimental methods, as well as review of mathematical and computational tools used in modeling perceptual mechanisms (not to mention demos illustrating the use of the experimental methods and data analysis) calls for a full semester course.

Both of us have educational and research experience in both engineering and psychophysics. Prof. Tan was trained in Electrical Engineering and Computer Science, but has conducted extensive psychophysical experiments on haptic perception. Prof. Pizlo has doctoral degrees in Electronics as well as in Psychology. We feel strongly that psychophysics has been, and continues to be, a multidisciplinary endeavor. In the 19th century, people such as Fechner, Weber, Helmholtz, Hering, Maxwell, and Wundt were active in using and perfecting psychophysics (both experimental methods and mathematical models). In the 20th century, the development in a number of engineering areas such as machine vision and image analysis started attracting engineers to the field of psychophysics. It follows that this course has been designed to meet the needs of a wide range of groups (psychologists, biologists, physicists, engineers), and to facilitate the interaction among those groups.

Prof. Pizlo had previously used web-based demonstrations in his course on Perception (PSY628). It was thought that similar demonstrations of psychophysical paradigms would greatly facilitate student's learning. Towards that goal, this website was setup during the Spring of 2000. Initial demos were closely based on those used in PSY628. As time went on, other demos (such as those for detection theory) were added to this site.

The first offering of this course, called "Psychophsyics for Interface Engineering," occurred during the Fall of 2000. Profs. Tan and Pizlo taught the course together. A total of thirteen Purdue graduate students from Engineering and Psychology majors took the course. Lectures were held in a state-of-the-art classroom (MSEE184) where each student had access to an HP workstation. During the lectures, students would spent 10-15 minutes to run demo experiments on themselves. Their results were then collected and discussed immediately afterwards. Many students commented that the on-line demos gave them hands-on experience with experimental methods that greatly facilitated grasping the underlying theoretical and practical aspects of psychophysics.

On August 7, 2001, Profs. Tan and Pizlo jointly presented a one-day tutorial on Psychophysics at The 9th International Conference on Human Computer Interaction (HCII 2001). We presented it again as a half-day tutorial on June 23, 2003 at HCI International 2003, and as a one-day tutorial on July 24, 2005 at HCI International 2005. Prof. Tan taught a half-day tutorial to Mechatronics students at Gwangju Institute of Science and Technology in South Korea on July 21, 2009. Most recently, Prof. Tan co-presented a half-day tutorial with Dr. Lynette Jones (MIT) at the World Haptics Conference 2011 on June 21, 2011.

The course was offered in Fall 2001 and Fall 2002 under the new name Psychophysics. Since Fall 2005, it has been permanently cross-listed in the School of Electrical and Computer Engineering and the Department of Psychological Sciences as ECE511/PSY511 Psychophysics.


Many individuals have contributed to this website. Seungmoon Choi set up this website in Spring 2000 and developed many demos used during the first offering of this course. He received much help from Prof. Greg Francis (PSY) and Mike Scheessele. Pamela Wilson made improvements to the existing JAVA-codes in Fall 2000. Filip Pizlo, Brian House, and Matthew Pearson are continuing to polish up exiting demos and creating new ones for this website.

This website has been partly supported by a National Science Foundation Faculty Early Career Development (CAREER) Award under Grant No. 9984991-IIS.


It is the intention of Profs. Tan and Pizlo to use the demos available on this website for teaching Psychophysics. These demos are not meant to be "perfect" examples of how a particular experiment should be conducted. Instead, they are used to familiarize students with the procedures of many experimental paradigms, and to expose students to issues and problems related to the design of psychophysical experiments. The instructors and students have enjoyed and learned much from discussions on how these online demos can be improved.