category laboratory

Navigation Menu

Category Laboratory at Vanderbilt

supported by NSF, NEI, and Vanderbilt University

In the CatLab, we study visual cognition, including visual categorization, visual memory, and visual decision making. We study how objects are perceived and represented by the visual system, how visual knowledge is represented and learned, and how visual decisions are made. We approach these questions using a combination of behavioral experiments, cognitive neuroscience techniques, and computational and neural modeling. One line of work, funded by the National Science Foundation, investigates the temporal dynamics of visual object categorization and perceptual expertise for objects and faces. Another line of work, funded by the National Eye Institute, uses computational modeling of visual decision making to predict behavioral dynamics and neural dynamics.


Jin wins Harold Stirling Vanderbilt Fellowship

Posted on Apr 29, 2024

Congratulations to Jin Jeong on winning a Harold Stirling Vanderbilt Fellowship to supplement his support in years four and five as a graduate student the Psychological Sciences PhD program. Jin previously was awarded a University Graduate Fellowship to supplement his support in his first three years. Congratulations Jin!

Read More

Tom Elected Fellow of the Society of Experimental Psychologists (SEP)

Posted on Dec 19, 2023

Tom has been elected as a Fellow of the the Society of Experimental Psychologists (SEP). SEP is the oldest scientific society in the field, started by Titchener over a century ago, and election is a signal honor. Other departmental faculty who are Fellows of SEP are Randolph Blake, Isabel Gauthier, Gordon Logan, and Jon Kaas.

The first meeting of the Society of Experimental Psychologists … was held at Cornell University in 1904. The meetings then, and for many years thereafter, were presided over by Edward Bradford Titchener. Researchers from universities including Cornell, Yale, Clark, Michigan, and Princeton attended these early meetings, with Chicago and Iowa soon joining. Research papers were read and discussed by established researchers and tyros alike. As the number of practicing experimental psychologists grew nationally, along grew discussions concerning the limits that should be placed on membership in the group: Should it be kept small to ensure a manageable series of conferences; or should it be open to all interested, practicing experimental psychologists? The decision was made to keep it small-to follow the so-called Academy model-and eventually Fellows of the society were instrumental in the founding of an alternative organization, called The Psychonomic Society, to serve the needs of broader representation and communication.

The meetings were kept small and brief, just one and half days of sessions, and continued their emphases on communication of ongoing research and the open exchange of ideas among active researchers. In the original bylaws of 1929, the purpose of the Society was stated simply as follows: “To advance Psychology by arranging informal conferences on experimental methodology.” Methodology had been an important focus of the Experimentalists, where visits to laboratories and the demonstration of equipment during meetings were actively encouraged. As the Society’s evolved interest in methodology waned, it was replaced by interest in theory and data.

Read More

Jenn Richler wins Distinguished Alumnus Award

Posted on Dec 12, 2023

Congratulations to Jenn Richler on winning the Psychological Sciences at Vanderbilt Distinguished Alumnus Award! Jenn received her PhD working with Tom Palmeri and Isabel Gauthier where her research focused on face and object perception and recognition, learning, attention, and memory. After a postdoctoral fellowship at Vanderbilt where she also worked as an Associate Editor for Journal of Experimental: Psychology: General and a writer for the American Psychological Association, Jenn chose to move into a scientific publishing career. Jenn joined Nature Climate Change and Nature Energy in 2016 as a Senior Editor handling manuscripts that spanned the behavioral and social sciences. Jenn returned to her psychology roots as the launch Chief Editor of Nature Reviews Psychology in 2021.

To recognize and honor the distinguished alumni of Psychological Sciences at Vanderbilt, we have established the Distinguished Alumnus Lecture. The recipient is a former undergraduate, graduate student, or postdoctoral fellow from the Department of Psychology in the College of Arts and Science or the Department of Psychology and Human Development in Peabody College at Vanderbilt who has made major contributions to the psychological sciences. The recipient will receive a $500 honorarium and will be invited to give the Distinguish Alumnus Lecture.

Read More

Greg Cox wins William K. Estes Early Career Award

Posted on Sep 17, 2023

Former postdoctoral fellow Greg Cox wins the William K. Estes Early Career Award from the Society for Mathematical Psychology. Greg is now an Assistant Professor at the University at Albany. Congratulations Greg!

The Society for Mathematical Psychology presents an annual award for exceptional published research in the field of mathematical psychology by an early career investigator. Previously known as the “New Investigator Award,” it was renamed after William K. Estes in 2009, recognizing his contributions to our Society and the field of mathematical psychology generally.

Read More

Tom to become Department Chair

Posted on Jun 19, 2023

In August 2022, Tom stepped up to become Director of Graduate Studies for the third time for what was supposed to be a three-year term. With Tim McNamara moving from department chair to interim dean of the College of Arts and Science, Tom was asked to step into the role of Chair of the Department of Psychology for a three-year term beginning in July 2023.

Read More

Jason Chow wins 2023 Pat Burns Memorial Graduate Student Research Award

Posted on May 11, 2023

Congratulations to Jason for winning the 2023 Pat Burns Memorial Graduate Student Research Award.

Pat Burns touched generations of doctoral students during her nearly four decades of service to Vanderbilt University. In memory of her tireless efforts to help guide our students through all phases of their graduate education, the Department of Psychology establishes a Graduate Student Research Award to recognize outstanding achievement in research by our most outstanding graduate students. The recipient receives a plaque and a $500 award.

Jason was recognized for his outstanding research. His nomination noted that “Jason is exceptionally creative and talented”. “He has breadth and depth, a great collaborator, writer and teacher, and a very productive graduate student”. “He will certainly make this program proud for years and years to come.”

Congratulations Jason!

Read More

Amir joins the lab

Posted on Dec 1, 2022

Amirsaman Sajad joined the collaboration with Gordon Logan and Jeffrey Schall as a Research Assistant Professor in December 2022. Amir did his PhD in Toronto and did postdoctoral work in primate neurophysiology at Vanderbilt. His recent work has focused on dissecting the neural circuitry serving performance monitoring and adaptive behavior, and on linking this to non-invasive electrophysiological biomarkers. He joined the collaboration to extend his computational expertise and integrate decision-making modeling with models of performance monitoring and cognitive control. His scientific mission is to discover the building blocks of cognition and their biomarkers and translate this knowledge to real-world applications.

Read More

New Psychological Review article: Salience by Competitive and Recurrent Interactions

Posted on Feb 22, 2022

Our major new theoretical paper has been accepted for publication in Psychological Review: Cox, G.E., Palmeri, T.J., Logan, G.D., Smith, P.L., Schall, J.D. (in press). Salience by competitive and recurrent interactions: Bridging neural spiking and computation in visual attention. Psychological Review. PsyArXiv:

Decisions about where to move the eyes depend on neurons in Frontal Eye Field (FEF). Movement neurons in FEF accumulate salience evidence derived from FEF visual neurons to select the location of a saccade target among distractors. How visual neurons achieve this salience representation is unknown. We present a neuro-computational model of target selection called Salience by Competitive and Recurrent Interactions (SCRI), based on the Competitive Interaction model of attentional selection and decision making (Smith & Sewell, 2013). SCRI selects targets by synthesizing localization and identification information to yield a dynamically evolving representation of salience across the visual field. SCRI accounts for neural spiking of individual FEF visual neurons, explaining idiosyncratic differences in neural dynamics with specific parameters. Many visual neurons resolve the competition between search items through feedforward inhibition between signals representing different search items, some also require lateral inhibition, and many act as recurrent gates to modulate the incoming flow of information about stimulus identity. SCRI was tested further by using simulated spiking representations of visual salience as input to the Gated Accumulator Model of FEF movement neurons (Purcell et al., 2010; Purcell, Schall, Logan, & Palmeri, 2012). Predicted saccade response times fit those observed for search arrays of different set size and different target-distractor similarity, and accumulator trajectories replicated movement neuron discharge rates. These findings offer new insights into visual decision making through converging neuro-computational constraints and provide a novel computational account of the diversity of FEF visual neurons.

Read More

New Papers

Posted on Feb 16, 2022

Cox, G.E., Palmeri, T.J., Logan, G.D., Smith, P.L., & Schall, J.D. (in press). Spiking, salience, and saccades: Using cognitive models to bridge the gap between “how” and “why”. In B. Forstmann & B.M. Turner (Eds.), An Introduction to Model-Based Cognitive Neuroscience (2nd Ed.), Springer Neuroscience.

Chow, J.K., Palmeri, T.J., Mack, M.L. (in press). Revealing a competitive dynamic in rapid categorization with object substitution masking. Attention, Perception, & Performance.

Carrigan, A.J., Charlton, A., Wiggins, M.W., Georgiou, A., Palmeri, T.J., & Curby, K.M. (in press). Cue utilisation reduces the impact of response bias in histopathology. Applied Ergonomics.

Chow, J.K., Palmeri, T.J., Gauthier, I. (in press). Haptic object recognition based on shape relates to visual object recognition ability. Psychological Research.

Chow, J.K., Palmeri, T.J., Gauthier, I. (in press). Visual object recognition ability is not related to experience with visual arts. Journal of Vision.

Carrigan, A.J., Charlton, A., Foucar, E., Wiggins, M., Georgiou, A., Palmeri, T.J., & Curby, K. (in press). The role of cue based strategies in skilled diagnosis amongst pathologists. Human Factors.

Read More

Welcome Giwon!

Posted on Jan 20, 2022

Giwon Bahg joined the lab, working as part of the collaboration with Palmeri, Logan, and Schall on their NEI-funded grant. Giwon received his Ph.D. from The Ohio State University in 2021 under the supervision of Dr. Brandon Turner, where he studied how category learning interacts with attention, information search, and other higher-order cognitive processes. His particular interest lies in understanding how such processes evolve over time in a closed-loop, interactive environment. His research also involves joint modeling of multimodal data using computational cognitive modeling, Bayesian methods, and machine learning approaches. His current research project involves linking our computational models of visual selection, attention, and decision making (SCRI+GAM) with behavioral, EEG, and neural spiking data.

Read More

Welcome Jin!

Posted on Sep 22, 2021

We welcomed Jinhyeok Jeong to the lab this Fall 2021. Jin received his bachelor’s degree in Psychology and master’s degree in Cognitive Science at Yonsei University. Under the supervision of Professor Sang Chul Chong, he studied ensemble perception, especially the variability perception of multiple visual items. As a graduate student at Vanderbilt, he is interested in the computational mechanisms of ensemble perception and how it relates to object categorization. Jinhyeok also has great interests in cognitive models of perception, memory, and decision-making processes, and how deep neural networks can be combined with these models. His current first year research project involves developing and testing computational models of ensemble processing and looking at relations with models of categorization, memory, and decision making.

Read More

Congratulations Claire!

Posted on Jun 12, 2021

Congratulations to Claire Hanson on graduating with Highest Honors in Neuroscience in May 2021.

Claire began working in the CatLab after being awarded a DSI-SRP fellowship for the summer of 2020. Her project, How the brain makes decisions: Modeling the dynamics of neurons that drive choice, became her senior honors thesis.

Claire’s DSI-SRP and honors project aimed to understand how the brain makes decisions. Historically, the canonical model of firing rates of decision-making neurons has been the accumulation of evidence model; accumulation of evidence is also the canonical model used to explain human and non-human primate decision-making behavior. This model assumes that neural activity gradually ramps up until a threshold is reached and then a decision is made. A relatively recent publication challenged this notion, introducing evidence for the possibility that an immediate transition in firing rates – a step rather than a ramp – is a better model to describe the dynamics of decision-making neurons when those dynamics are measured on a trial-to-trial basis rather than averaged across trials. The question of whether the firing rates of decision-making neurons are better characterized by ramping vs. stepping dynamics is foundational for our theoretical understanding how the brain makes decisions. Claire’s project involved conducting Monte Carlo simulations of model neurons with known dynamics and using a Bayesian statistical analysis program testing for ramping vs. stepping dynamics (an adaptation of same analysis program used by the authors who proposed stepping dynamics as the preferred model). These simulated model neurons included those with simple steps or with simple ramps, as well as the diffusion model of decision making and the leaky competing accumulator (LCA) model of decision making (both of which are members of the class of accumulator models); each of these models produced simulated spike trains across multiple trials that could be analyzed in the same way that real neural data is analyzed. Claire’s simulations have shown that while simple steps are classified as simple steps by the analysis program and that simple ramps are characterized as simple ramps by the analysis program, the more complex dynamics of the diffusion and LCA are actually characterized as steps by the analysis program. Even though models like the diffusion model and LCA are clearly accumulating evidence over time, the analysis program characterizes them as steps. While real neurons might look “step-like” on a trial-by-trial basis, the computations being performed by these neurons may still be best characterized as an accumulation of evidence over time.

Claire joined the NIH baccalaureate program in the summer of 2021 in the Section on Developmental Neurogenomics, where she will use computational techniques to better understand childhood-onset neuropsychiatric disorders. Claire then plans to go on to an MD-PhD program.

Read More

Welcome Simon!

Posted on Feb 13, 2021

We welcome Simon Lilburn to the CatLab, Vanderbilt, Nashville, and the United States as a new postdoctoral fellow. Simon comes from the land of sunny beaches, large marsupials, and disgustingly salty spreads which Australians pretend to like to fool foreigners. He received his Ph.D degree from the University of Melbourne investigating the dynamics of visual short-term memory in the Vision and Attention Lab under the supervision of Prof. Philip Smith and Dr David Sewell. His work has used a blend of traditional psychophysical experimentation with computational models of memory and decision-making to understand some of the fundamental limits on perception. His research centers on coupling intensive and individualized experiments with formal theories of basic cognitive processes with a particular emphasis on the link between perception (what we see, hear, feel) and action (what we do).

Read More

Vanderbilt University announces launch of new undergraduate data science minor

Posted on Jan 29, 2021

Vanderbilt University has announced the addition of an undergraduate minor in data science beginning with the fall 2021 term.

Driven by the growing interest on the part of the data science community at Vanderbilt for an undergraduate program in data science, the Data Science Minor Working Group was established in March 2020 by Provost and Vice Chancellor for Academic Affairs Susan R. Wente and the deans of the College of Arts and Science, Blair School of Music, Peabody College and School of Engineering to develop and propose a trans-institutional undergraduate minor in data science. Palmeri chaired the working group that developed and proposed the minor and will serve as Director of the minor.

Click below for a MyVU story:

Click below for a Vanderbilt Hustler story:

Read More