About

Simona Buetti, Ph.D., is a professor associated with the Department of Psychology at the University of Illinois. Her research focuses on visual attention, particularly how real depth influences visual perception and attention mechanisms. She incorporates eye-tracking, behavioral methods, and mathematical modeling in her experiments to study classic visual attention processes with an emphasis on real depth differences. Her work aims to deepen understanding of visual attention dynamics and the role of depth perception in visual cognition.

Research topics

• Psychology
• Developmental psychology
• Computer Science
• Cognitive psychology
• Machine Learning
• Information Retrieval
• Artificial Intelligence
• Cognitive science
• Neuroscience
• Human–computer interaction
• Communication
• Clinical psychology

Selected publications

• Role of Target Feature Predictability for Color and Shape in Attentional Guidance

  OSF Preprints (OSF Preprints) · 2026-04-17

  otherSenior author
  Publisher

• Evaluating the contributions of top-down and bottom-up processing on eye movements during parallel visual search

  Attention Perception & Psychophysics · 2026-02-23

  articleOpen accessSenior author

  In the current study, we used an efficient visual search paradigm in a pseudo-realistic environment, with well-controlled search stimuli that allow a simultaneous evaluation of the impact of top-down and bottom-up factors on eye-movement patterns. Our stimuli varied along the color dimension to manipulate target-distractor similarity and our displays contained a salient stimulus of higher salience than target and other less-salient distractor stimuli. We manipulated task instructions, introducing a free-view instruction condition to serve as a baseline for how bottom-up contrast guided eye movements in one group of participants, and a top-down search instruction in a second group, where subjects were asked to find the red target in the scene. Experiment 1 assessed the impact of set size of less-salient distractors across both instructions. Experiment 2 examined target-distractor similarity effects for the less-salient distractors. We compared the likelihood that the first fixation in a trial would be selective towards the target (top-down) versus the high-salience singleton (bottom-up) and studied how this selectivity varied as a function of initial saccade latency. Interestingly, the results from the free-view conditions showed selectivity for the high-salience item during the first fixation was sustained across saccade latencies, yet the high-salience items capture very few saccades in the search task, suggesting attention might be in limbo early in the trial. Indeed, the results also showed that it takes time for saccades to be correctly directed at the target in a search task.

  PublisherOA PDFDOI

• Toward a better understanding of target distinctiveness in visual search: How color, shape, and texture information combine to guide search.

  Journal of Experimental Psychology General · 2026-01-22

  articleOpen accessSenior author

  People often search for objects distinctive from other objects in the scene along multiple feature dimensions like color and shape. A target distinctive in more than one dimension can lead to an easier search, but it also increases the complexity of modeling search behaviors. Building upon previous research on how people search using information along two feature dimensions, we explored how search unfolds when the target and distractors differ along the dimensions of color, shape, and texture (a tridimensional search). Using a behavioral-computational approach, we found that the target-distractor distinctiveness signal along each dimension combines in a weighted orthogonal way to guide tridimensional searches. Additionally, across two sets of experiments, we demonstrated that the weight assigned to each dimension varied according to its relative usefulness. When the color distinctiveness was most pronounced (Set 1), there was a much stronger prioritization of color information over information carried by shape and texture. When the distinctiveness along individual dimensions was more balanced (Set 2), the weights were distributed more evenly across the three dimensions, but a color prioritization remained. These results have broad implications for cognitive neuroscience, as they place constraints on how visual information from different dimensions is integrated to produce an overall guidance signal, and demonstrate how attention might be flexibly allocated across channels in response to the ecological aspects of the environment. This study should also interest modelers in cognitive science because it demonstrates an approach to understand behavior in complex scenarios based on performance indices estimated under simpler conditions. (PsycInfo Database Record (c) 2026 APA, all rights reserved).

  PublisherDOI

• The effects of chromaticity and perceived color differences on visual search efficiency

  Open MIND · 2026-01-01

  otherOpen accessSenior author

  The goal of the present study is to see how much of the impact of color constancy on visual search is driven by low-level visual information versus a higher-level percept of the colors present. We aim to determine whether the target-distractor color similarity that drives visual search processes is computed at the level of chromaticity or perceived colors.

  PublisherOA PDFDOI

• Exploring the Impact of Target-Distractor Featural Contrast on Feature Prioritization in Efficient Visual Search.

  Journal of Vision · 2025-07-15

  articleOpen accessSenior author

  The visual attention system is thought to be highly adaptive to the ecology of the environment. Here, we attempted to quantify how the visual system prioritizes various visual features as a function of target-distractor featural contrast. Specifically, we quantified the contributions of color and shape to attentional guidance in conditions where shape and color dimensions varied in terms of their relative contrast. We first measured featural contrasts, indexed by logarithmic search efficiency, between targets and a wide range of homogeneous distractors in unidimensional searches. In Experiment 1, participants searched for a target differing from distractors only in shape (10 shapes). In Experiment 2, they searched for a target differing from distractors only in color (8 colors). In Experiments 3-4, the target differed from distractors along both color and shape and we selected shape and color features so that one dimension had larger contrasts than the other. In Experiment 3 (color contrasts > shape contrasts), the color logarithmic search slopes were 60, 68, 93, whereas the shape slopes were 276, 175 and 150. In Experiment 4 (color contrasts < shape contrasts), the color search slopes were 249, 144 and 140, whereas the shape slopes were 87, 75, 52. Contrary to our predictions, the results of Experiment 3 showed that participants relied more on the shape dimension, even though relying more on color dimension would have led to better performance. In Experiment 4, participants relied to equal extents on both dimensions, even though relying more on shape would have led to better performance. Overall, the results suggests that participants might not always rely on the most efficient feature to search. A follow-up study using more efficient search conditions for the larger contrast dimension was run to investigate at which point participants choose to preferentially attend to the most useful feature.

  PublisherDOI

• Investigating the contribution of unpredictable target features to attentional guidance

  Journal of Vision · 2025-07-15

  articleOpen accessSenior author

  Visual search targets are not always predictable - sometimes observers know one feature of the target (color of a scarf) but might not be able to anticipate other features (the scarf shape). Here, participants searched for a target that differed from distractors along both color and shape, with one feature dimension being known and one varying randomly across trials. Using a model comparison approach, we quantified the contribution of each feature dimension to attentional guidance. Participants were asked to search using the known dimension. In Experiment 1 (color known), the target was red and had one of four possible shapes. Distractors were orange (color-similar) or pink (color-dissimilar) and had one of two possible shapes. In Experiment 2 (shape known), the target was a house in one of four possible colors. Distractors were triangles (shape-similar) or circles (shape-dissimilar) in one of two possible colors. In both experiments, response times for all target-distractor pairs (e.g., red house target among pink diamonds) were predicted by the weighted combination of the search slopes evaluated in simple color (red among pink) and shape searches (house among diamonds). These weights indicate the extent to which each feature dimension was prioritized in attentional guidance. In Experiment 1, the results showed that the priority given to the unpredictable shape dimension depended on the usefulness of color: the shape weight was 0.85 (color weight=1.15) in the color-dissimilar condition, while the shape weight was 1.6 (color weight=0.4) in the color-similar condition. In Experiment 2, the weight for the unpredictable color dimension was 0.47 (shape weight=1.53) in the shape-dissimilar condition, and the color weight was 1.59 (shape weight=0.41) in the shape-similar condition. These results demonstrate that when the target and distractors are too similar along the known dimension, the visual system increases its reliance on the unpredictable dimension.

  PublisherDOI

• Quantifying the relationship between search efficiency and perceptual similarity in color space across different efficient search tasks.

  Journal of Experimental Psychology Human Perception & Performance · 2025-05-15

  articleOpen accessSenior author

  When looking for a specific object in the environment, the visual system guides attention toward objects in the scene that contain features that are similar to those of the object in mind, also known as the target template. However, the precise relation between search performance and perceptual similarity (between objects in the scene and the target template) has not been properly characterized. Recently, target-contrast signal theory proposed an explicit relationship linking search performance to the concept of top-down "target-distractor contrast," with contrast being a measure of the amount of perceptual evidence that allows peripheral processing to differentiate target from distractors. We used a well-characterized color space to investigate the relationship between target-distractor similarity and search efficiency. We compared three different models relating color distance to search performance: the universal law of generalization, and two implementations of target-contrast signal theory. In the first, target-distractor distance indexes the target-distractor contrast, while the second uses the signal-to-noise ratio (SNR) between the neuronal responses to the attended color and the distractor color to index target-distractor contrast. When the target color is known but the distractor color cannot be anticipated, perceptual distance best predicts performance (Experiments 1, 2A, and 2B). When target and distractor colors repeat from trial to trial, the SNR measure best captures performance (Experiments 3A and 3B). Finally, when neither the target nor the distractor color is known to observers, performance deteriorates significantly and is no longer indexed by either of these two measures of target-distractor contrast (Experiment 4). (PsycInfo Database Record (c) 2025 APA, all rights reserved).

  PublisherDOI

• Color-color feature guidance in visual search

  Attention Perception & Psychophysics · 2025-04-28

  article
  PublisherDOI

• Evaluating the contribution of parallel processing of color and shape in a conjunction search task

  Scientific Reports · 2025-03-05 · 1 citations

  articleOpen access

  Traditionally, researchers interpret the difficulty in conjunction search as difficulty in binding features. In the present study, we used a behavioral-computational approach to assess if parameters from feature search could predict performance in a color-shape conjunction search task. We also investigated whether pooling-mediated processing in peripheral regions was a key-limiting factor in performance in conjunction search by manipulating display arrangements across different experiments. The results indicated that parameters in homogeneous search displays can indeed be used to successfully predict performance in conjunction search displays. This finding is noteworthy because it indicates that the visual system must be extracting the same information from the display in feature and conjunction search tasks (i.e., the target-distractor similarity) using color and shape. Furthermore, there was no compelling evidence that pooling-mediated processing was the primary constraint on performance in this conjunction search task. A model-comparison approach compared the accuracy of different distractor rejection architectures in predicting performance in conjunction search tasks. The winning model showed participants engaging hierarchically with the display, selecting and rejecting distractor subsets based on a single defining feature. Taken in the context of previous research on heterogeneous search performance, the current results imply that the inherent demands of search for a conjunction of color and shape compel participants to adopt this targeted search strategy.

  PublisherOA PDFDOI

• Parallel Sequential Rejection in Conjunction Search: Insights from Eye-Tracking on Distractor Processing Dynamics

  Journal of Vision · 2025-07-15 · 1 citations

  articleOpen access

  This study builds upon the findings of Cui et al. (2022) and Cui et al. (in revision), which proposed that the difficulty in conjunction search arises from a distractor rejection mechanism operating in a parallel-sequential manner, whereby participants first reject distractors based on one feature dimension, then reject distractors based on the second feature dimension. Here, we employed eye-tracking to investigate how participants process and reject color-differentiated and shape-differentiated distractors in conjunction search tasks. We recorded eye movements as participants searched for a target (a red triangle) among two types of distractors: orange triangles (color-differentiated) and red circles (shape-differentiated). Stimuli were arranged in quadrants, each containing only one distractor type to maintain local feature homogeneity. We analyzed fixation counts, durations, and sequences to investigate attentional allocation to different distractor types. Our results revealed a strong bias toward fixating on shape-differentiated distractors as early as the second fixation, suggesting that color-differentiated distractors were efficiently rejected via peripheral vision. Participants made significantly more fixations and had longer total fixation durations within shape-differentiated regions, indicating higher attentional costs associated with rejecting these distractors. Temporal dynamics showed that while initial fixations were unbiased, participants quickly adjusted their strategy to focus on the more challenging shape-differentiated distractors. These findings support the parallel-sequential mechanism, demonstrating that participants employ a strategic allocation of attention during conjunction search—prioritizing the rejection of easily distinguishable distractors via peripheral vision before focusing on more difficult ones. Our study underscores the importance of eye movement analysis in understanding visual search mechanisms and suggests that attentional strategies are dynamically adjusted based on distractor characteristics. In two follow-up experiments, we varied the discriminability along each feature dimension to evaluate the extent to which the parallel sequential rejection mechanism is sensitive to the relative processing ease of one feature discrimination over the other.

  PublisherDOI

Recent grants

• CompCog: Template Contrast and Saliency (TCAS) Toolbox: a tool to visualize parallel attentive evaluation of scenes

  NSF · $657k · 2019–2023

Frequent coauthors

• Alejandro Lleras

  University of Illinois Urbana-Champaign

  88 shared

• Zoe Xu

  University of Illinois Urbana-Champaign

  21 shared

• Gavin Ng

  University of Illinois Urbana-Champaign

  18 shared

• Dirk Kerzel

  University of Geneva

  16 shared

• Anna Madison

  12 shared

• Deborah Cronin

  Drake University

  7 shared

• Florin Dolcos

  University of Illinois Urbana-Champaign

  6 shared

• John E. Hummel

  University of Illinois Urbana-Champaign

  5 shared

Labs

• Vision LabPI

  Not provided

Awards & honors

• 2019 research grant from the National Science Foundation (Be…
• 2016 research grant from the BRIDGE Birmingham-Illinois part…
• 2014 NARSAD Young Investigator Grant, Brain & Behavior resea…