Alex Petrov's Professional Home Page

Dr. Alexander A. Petrov
Assistant Professor
Laboratory for Cognitive Modeling and Computational Cognitive Neuroscience
Department of Psychology
Ohio State University

200B Lazenby Hall
1827 Neil Avenue
Columbus, OH 43210
Email: apetrov [at] alexpetrov.com
WWW: http://alexpetrov.com/
Tel: (614) 247-2734
Skype: apetrov1969
Facebook: http://www.facebook.com/alexander.petrov1969

Research Interests

My research focuses on the interface between visual perception and decision-making, with a special emphasis on learning. For example, consider a medical student learning to diagnose breast cancer on mammograms. At first, each mammogram appears as an undifferentiated blob similar to any other mammogram. With practice, however, the student learns to identify cancerous formations with high reliability. The question is, what has changed in the brain of the expert relative to that of a novice? How do these changes occur? In addition to their practical importance, questions such as these are of great theoretical interest.

Even the simplest perceptual task involves significant decision-making components. In the above example, if one type of cancer is 10 times more prevalent than another, an experienced radiologist takes these base rates into account while inspecting an image. Even in the controlled conditions of the psychophysical laboratory, factors such as response biases (e.g., Petrov & Anderson, 2005), decision strategies (e.g., Petrov, 2009), and speed-accuracy tradeoffs (e.g., Petrov, Van Horn, & Ratcliff, 2011) affect the threshold and accuracy measurements. Therefore, the decision-making components must be considered even when one is primarily interested in the perceptual aspects. Conversely, the data on decision-making and categorization depend critically on the low-level properties of the stimuli, and factors such as signal-to-noise ratios (e.g., Petrov, Dosher, & Lu, 2005) and Weber fractions (e.g., Petrov, 2008a) must be considered even when one is primarily interested in the cognitive aspects. All too often, vision scientists design their experiments to minimize the cognitive aspects, whereas cognitive psychologists design their experiments to minimize the perceptual aspects. This is a valid strategy that has produced a wealth of knowledge in each discipline. The time has come, however, to integrate the two and explore the relationships between them.

This integrative thrust is a guiding principle of my research program. I have solid expertise in both disciplines and attend regularly the conferences of the Vision Sciences Society (VSS), on one hand, and of the Psychonomic, Mathematical Psychology, and Cognitive Science societies, on the other. In my laboratory, we measure how accuracy, response times, and eye-movement patterns change with extended practice on various visual tasks. We develop models that implement specific hypotheses about the underlying mechanisms, and test the quantitative predictions of these models against the behavioral data. Such models are valuable conceptual tools for bridging the gap between brain and behavior.

My research projects page describes some (old) research projects in some detail and provides access to the associated data sets and software.

Selected Publications

A complete list of publications (as of October 2011) is available separately, organized by outlet type, topic, or in reverse chronological order.
My curriculum vitae is also available (pdf).

Hayes, T., Petrov, A. & Sederberg, P. (2011)

A novel method for analyzing sequential eye movements reveals strategic influence on Raven's Advanced Progressive Matrices. Journal of Vision, 11 (10:10), 1-11, http://www.journalofvision.org/11/10/10/.
Abstract Reprint (pdf) Matlab report (html)

Petrov, A. & Hayes, T. R. (2010)

Asymmetric transfer of perceptual learning of luminance- and contrast-modulated motion. Journal of Vision, 10 (14:11), 1-22, http://www.journalofvision.org/10/14/11/.
Abstract Reprint (pdf) Matlab reports (html)

Petrov, A. (2009)

Symmetry-based methodology for decision-rule identification in same-different experiments. Psychonomic Bulletin & Review, 16(6), 1011-1025.
Abstract Reprint (pdf)

Petrov, A., Dosher, B., & Lu, Z.-L. (2005)

The Dynamics of Perceptual Learning: An Incremental Reweighting Model. Psychological Review, 112(4), 715-743.
Abstract Reprint (pdf) Data sets Software

Petrov, A. & Anderson, J. R. (2005)

The Dynamics of Scaling: A Memory-Based Anchor Model of Category Rating and Absolute Identification. Psychological Review, 112(2), 383-416.
Abstract Reprint (pdf) Software

Kokinov, B. & Petrov, A. (2001)

Integrating memory and reasoning in analogy-making: The AMBR model. In D. Gentner, K. Holyoak, & B. Kokinov (Eds.), The analogical mind: Perspectives from cognitive science (pp. 59-124). Cambridge, MA: MIT Press.
Abstract Excerpts Preprint (pdf)

Branching Out

My teaching home page provides access to course syllabi, reading assignments, presentation slides, and various student resources.

My personal home page presents photos of my dear wife Petya, my adorable daughter Vicky, my native country Bulgaria, and other personal stuff.

A sizable portion of this site is devoted to assorted ideas of general interest: philosophy, humanism, politics, science, astronomy, aikido, ... Life is so interesting and deep, check it out!

Last but not least, help support Max and other kids with short gut/short bowel syndrome and TPN-associated Liver Disease . If you know anyone with these conditions, spread the word about Omegaven. It saves lives!