Alex Petrov's Professional Home Page

Greetings!

Dr. Alexander A. Petrov
Assistant Professor
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

Research Interests

How does the brain adapt to an ever-changing environment? How does it strike a balance between continuity and change? What neural mechanisms underlie this fundamental cognitive ability? These challenging research questions require converging evidence from multiple methodologies and disciplines. The billions of neurons in the brain interact in complex ways to produce behavior, which is itself complex and varied. To make progress in the study of learning, a researcher must master a range of domains and techniques and engage in highly collaborative research with experts in various fields. These are important characteristics of my research.

My specific contribution to the study of learning consists of two interrelated strands. First, behavioral experiments reveal the dynamics of learning in non-stationary environments as a function of context, task difficulty, feedback, and other factors. I use state-of-the art psychophysical methods to track improvements in performance on time scales from seconds to days. This rigorous quantitative probing of behavior integrates seamlessly with the second strand of my research program -- the development, testing, and analysis of various learning models. Such models are indispensable conceptual tools for bridging the gap between brain and behavior. Therefore, in addition to experimental psychology and neuroscience, I have to be proficient in computer simulation and mathematical analysis of complex systems. I develop decentralized and interactive models -- connectionist, symbolic, or mathematical -- that incorporate biologically plausible learning mechanisms and are informed by an integrated cognitive architecture. My expertise in both neural networks and symbolic cognitive architectures makes me particularly qualified for this kind of work.

My research so far has focused on three specific projects:

Perceptual learning via Hebbian reweighting: A connectionist model takes grayscale images as inputs, produces binary responses as outputs, and improves its discrimination accuracy incrementally with practice with no need for external feedback.
ANCHOR: An adaptive memory-based model of category rating and absolute identification. The rating scale unfolds as an adaptive map from a single arbitrarily placed anchor with no need for external feedback. The model accounts for a comprehensive list of scaling phenomena.
AMBR: A hybrid symbolic/connectionist model of analogy making and memory-based reasoning with decentralized representations.

My research projects page describes these projects in some detail and provides access to the associated data sets and software.
A more detailed Research Statement is available in pdf format.

Selected Publications

A complete list of publications (as of March 2007) is available separately, organized by outlet type, topic, or in reverse chronological order.
My curriculum vitae is also available (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)
Petrov, A. & Kokinov, B. (1999): Processing symbols at variable speed in DUAL: Connectionist activation as power supply. In Proceedings of the Sixteenth International Joint Conference on Artificial Intelligence (vol. 2, pp. 846-851).
Abstract Full text 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!

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