May Shen co-winner of The William F. Hodges Teaching Assistant Award

Posted on Apr 21, 2015

The William F. Hodges Teaching Assistant Award recognizes outstanding achievement as a teaching assistant by a graduate student in the Department of Psychology at Vanderbilt. William Hodges was an undergraduate and a graduate student at Vanderbilt in the 1960s. After his untimely death in 1992, family and friends established the William F. Hodges Teaching Assistant Award at Vanderbilt to honor outstanding teaching assistants in the department.

May is a third year graduate student in the CatLab. She has completed a Certificate in College Teaching from the Center for Teaching and has TAed for a wide array of courses in the department, including PSY208 (Principles of Experimental Design), PSY209 (Quantitative Methods), and PSY225 (Cognitive Psychology); this semester, she is TAing for a statistics course in Psychology and Human Development. Adriane Seiffert, for whom May TAed in PSY208 and PSY209, noted that her work was “exemplary in both courses”, and that students commented that “she was responsive and helpful – gave exact answers to questions”, “conveyed the material in a way she knew would be effective, logical and memorable”. Geoff Woodman, for whom May TAed in PSY225, noted that she “jumped on a week’s worth of lectures when given the opportunity.”

Congratulations, May!

New paper in Journal of Experimental Psychology: General

Posted on Mar 24, 2015

We have a new paper in press:

Mack, M.L., & Palmeri, T.J. (in press). The dynamics of categorization: Unraveling rapid categorization. Journal of Experimental Psychology: General. [PDF]

We explore a puzzle of visual object categorization: Under normal viewing conditions, you spot something as a dog fastest, but at a glance, you spot it faster as an animal. During speeded category verification, a classic basic-level advantage is commonly observed (Rosch, Mervis, Gray, Johnson, & Boyes-Braem, 1976), with categorization as a dog faster than as an animal (superordinate) or Golden Retriever (subordinate). A different story emerges during ultra-rapid categorization with limited exposure duration (<30ms), with superordinate categorization faster than basic or subordinate categorization (Thorpe, Fize, & Marlot, 1996). These two widely cited findings paint contrary theoretical pictures about the time course of object categorization, yet no study has previously investigated them together. Over five experiments, we systematically examined two experimental factors that could explain the qualitative difference in categorization across the two paradigms: exposure duration and category trial context. Mapping out the time course of object categorization by manipulating exposure duration and the timing of a post-stimulus mask revealed that brief exposure durations favor superordinate-level categorization, but with more time a basic-level advantage emerges. But this superordinate advantage was modulated significantly by target category trial context. With randomized target categories, the superordinate advantage was eliminated; and with “blocks” of only four repetitions of superordinate categorization within an otherwise randomized context, the advantage for the basic-level was eliminated. Contrary to some theoretical accounts that dictate a fixed priority for certain levels of abstraction in visual processing and access to semantic knowledge, the dynamics of object categorization are flexible, depending jointly on the level of abstraction, time for perceptual encoding, and category context.

New Papers

Posted on Jan 28, 2015

New papers in press:

Palmeri, T.J., & Mack, M.L. (in press). How experimental trial context affects perceptual categorization. Frontiers in Psychology.

Logan, G.D., Yamaguchi, M., & Schall, G.D., & Palmeri, T.J. (in press). Inhibitory control in mind and brain 2.0: A blocked-input model of saccadic countermanding. Psychological Review.

Richler, J.J., Palmeri, T.J., & Gauthier, I. (in press). Holistic processing does not require configural variability. Psychonomic Bulletin & Review.

NEI Grant Renewed

Posted on Nov 4, 2014

Our NEI Grant Stochastic Models of Visual Decision Making and Visual Search was just renewed for another four years, through end of 2018.

New papers from the CatLab

Posted on Aug 27, 2014

Shen, J., & Palmeri, T.J. (in press). The perception of a face is greater than the sum of its parts. Psychonomic Bulletin & Review.

Folstein, J., Palmeri, T.J., Van Gulick, A.B., & Gauthier, I. (in press). Category learning stretches neural representations in visual cortex. Current Directions in Psychological Science.

Shen, J., Mack, M.L., & Palmeri, T.J. (2014). Studying real-world perceptual expertise. Frontiers in Cognition.

NSF REU Supplement awarded

Posted on Jul 15, 2014

The CatLab has just been awarded a $19,500 supplementary grant from the National Science Foundation for a Research Experience for Undergraduates. Academic year REU students will receive a $3000 stipend per semester. Summer REU students will receive a $5000 stipend, a $1500 housing and meal allowance, and

$250 travel allowance. Interested undergraduates should contact Professor Palmeri at thomas.j.palmeri@vanderbilt.edu for information on how to apply.

Braden Purcell wins Jum Nunnally Dissertation Award

Posted on Apr 22, 2014

Congratulations to Braden Purcell for winning the 2014 Jum Nunnally Dissertation Award! This makes the third CatLab PhD student to win this prestigious award, along with Mike Mack in 2011 and Jenn Richler in 2010.

The Jum Nunnally Dissertation Award recognizes a recent outstanding doctoral dissertation in the Department of Psychology. The recipient receives a certificate and a $500 award. Jum Nunnally came to Vanderbilt in 1960. In 1961, he became the second chair of the department. He served as chair from 1961-1964 and again from 1967-1970. Under Jum’s leadership, the department grew substantially in stature, including significant increases in both the number and quality of the faculty. A memorial fund to support student awards was established in 1982 by his friends and family. Proceeds from this fund were used to establish the Jum Nunnally Dissertation Award in 2010.

Two new postdocs join the CatLab

Posted on Apr 1, 2014

Brent Miller joins to lab as a postdoctoral fellow this month with a background in computer engineering and psychology. He comes from the University of California, Irvine, where he received his PhD in 2014 with Mark Steyvers. Brent is broadly interested in how the mechanisms of information storage, retrieval, and encoding affect judgment and decision making. Previously, he used computational modeling to show how certain decision behavior necessarily arises from probabilistic information representation in the brain. As a postdoctoral fellow at Vanderbilt, he will work on developing and testing computational models of behavior and neurophysiology in our collaboration with Jeff Schall and Gordon Logan.

Jeff Annis will receive his PhD from the University of South Florida this summer, where he has been studying the relationship between memory and perception via sequential dependencies with Ken Malmberg. Jeff is interested in the mechanisms and representations involved in memory and categorization. He will join the lab as postdoctoral fellow this summer to use computational models and empirical investigations to understand the dynamics of perceptual expertise.

Recent PNAS paper highlighted by Vanderbilt News

Posted on Feb 13, 2014

Research News@Vanderbilt recently did a story about our PNAS paper, “Response times from ensembles of accumulators”: http://news.vanderbilt.edu/2014/02/number-of-neurons/

Paper to appear in PNAS

Posted on Jan 8, 2014

Zandbelt, B.B., Purcell, B.A., Palmeri, T.J., Logan, G.D., Schall, J.D. (2014). Response times from ensembles of accumulators. Proceedings of the National Academy of Sciences. [PDF]

Decision making is explained by psychologists through stochastic accumulator models and by neurophysiologists through the activity of neurons believed to instantiate these models. This paper investigated an overlooked scaling problem: How does a response time (RT) that can be explained by a single model accumulator arise from numerous, redundant accumulator neurons, each of which individually appears to explain the variability of RT? 

Three new contributions to edited volumes

Posted on Jan 8, 2014

Three new papers. Two in the Oxford Handbook of Computational and Mathematical Psychology and one in An Introduction to Model-Based Cognitive Neuroscience.

Palmeri, T.J., Schall, J.D. & Logan, G.D. (in press). Neurocognitive modeling of perceptual decision making. To appear in J.R. Busemeyer, J. Townsend, Z.J. Wang, & A. Eidels (Eds.), Oxford Handbook of Computational and Mathematical Psychology, Oxford University Press. [PDF]

Nosofsky, R.M., & Palmeri, T.J. (in press). Exemplar-based random walk model. To appear in J.R. Busemeyer, J. Townsend, Z.J. Wang, & A. Eidels (Eds.), Oxford Handbook of Computational and Mathematical Psychology, Oxford University Press. [PDF]

Logan, G.D., Schall, J.D., & Palmeri, T.J. (in press). Inhibitory control in mind and brain: The mathematics and neurophysiology of the underlying computation. To appear in B. Forstmann & E.J. Wagenmakers (Eds.), An Introduction to Model-Based Cognitive Neuroscience, Springer Neuroscience. [PDF]