Primary AffiliationMechanisms of Cognitive Control
Status Affiliate Faculty
Home Department of Psychology
Alejandro Lleras received his Ph.D. from the Pennsylvania State University in 2002. He was a postdoctoral fellow at the University of British Columbia until 2004. He is an Assistant Professor in the Department of Psychology and a part-time faculty member in the Beckman Institute Human Perception and Performance group. His main areas of interest are on visual awareness, visual attention, vision for action, and high-level constraints on visual perception.
NSF Researcher Starter Grant (2005); Dean of Arts Travel Award, University of British Columbia (2004); NSF Minority Postdoctoral Research Fellowship (2003); Beckman Institute Postdoctoral Fellowship (2002); William L. and Josephine Berry Weiss Graduate Scholarship (2001-2002); Bruce V. Moore Graduate Fellowship (2001); Eileen Wirtshafter Leibowitz and Herschel W. Leibowitz Scholarship (2000, 2001); College of the Liberal Arts Travel Grant, Pennsylvania State University (2001).
Professor Lleras' larger research program is aimed at addressing a fundamental question in perception: how is it that our mind creates representations of objects in the physical world? In one area of his research, he examines what role various factors play in the creation and "maintenance" of these representations (i.e., when the represented objects change in physical characteristics, such as shape and location). He will also study how those representations ultimately give rise to perceptual awareness of the physical object and/or to overt motor responses. A second line of research focuses on how visual attention influences perception. Whereas most assume that visual attention "helps" perception, there are several important cases where, in fact, attention to an object might hinder the perception of this object (Troxler Fading) or of other salient events in the world (Inattentional Blindness). Furthermore, because visual attention does tend to help perception in many cases, Lleras is also interested in understanding what factors, internal or external to the observer, affect the deployment of attention. Lastly, he is interested in investigating how higher-level factors such as memory, task strategies, and expectancies affect perception.
As part of his Beckman Institute research, Lleras is currently collaborating with other Beckman Faculty (professors Wang, Kramer, Irwin, and Simons) on two projects in the fully immersive CUBE. The first project is aimed at understanding whether Inhibition of Return effects (reluctance to return to a previously searched location) play a role in foraging behavior. They are also examining how the task-determined values (relevance) of locations affect foraging. In a second project, they are examining how memory for objects is affected by the stability of the environment in which they exist. Lastly, Lleras is collaborating with Dan Simons in a series of scene-fading studies, where they have managed to rapidly induce the visual fading of natural scenes. Together, these studies are revealing new and unforeseen properties of the human visual system.
- Panova, T.; Lleras, A., Avoidance or Boredom: Negative Mental Health Outcomes Associated with Use of Information and Communication Technologies Depend on Users’ Motivations. Computers in Human Behavior 2016, 58, 249-258.
- Buetti, S.; Lleras, A.; Moore, C. M., The Flanker Effect Does Not Reflect the Processing of “Task-Irrelevant” Stimuli: Evidence from Inattentional Blindness. Psychonomic Bulletin & Review 2014, 21, (5), 1231-1237, DOI:10.3758/s13423-014-0602-9.
- Lleras, A.; Buetti, S., Not All “Distractor” Tags Are Created Equal: Using a Search Asymmetry to Dissociate the Inter-Trial Effects Caused by Different Forms of Distractors. Frontiers in Psychology 2014, 5, DOI:ARTN 669 DOI:10.3389/Fpsyg.2014.00669.
- Mereu, S.; Zacks, J. M.; Kurby, C. A.; Lleras, A., The Role of Prediction in Perception: Evidence from Interrupted Visual Search. Journal of Experimental Psychology-Human Perception and Performance 2014, 40, (4), 1372-1389, DOI:10.1037/A0036646.
- Michal, A. L.; Lleras2, A.; Beck1, D. M., Relative Contributions of Task-Relevant and Task-Irrelevant Dimensions in Priming of Pop-Out. Journal of Vision 2014, 14, (12), DOI:ARTN 14 DOI:10.1167/14.12.14.
- Scalf, P. E.; Ahn, J.; Beck1, D. M.; Lleras2, A., Trial History Effects in the Ventral Attentional Network. Journal of Cognitive Neuroscience 2014, 26, (12), 2789-2797, DOI:10.1162/Jocn_a_00678.
- Tseng, Y. C.; Glaser, J. I.; Caddigan, E.; Lleras, A., Modeling the Effect of Selection History on Pop-out Visual Search. Plos One 2014, 9, (3), DOI: 10.1371/journal.pone.0089996.
- Wan, X. A.; Tian, L.; Lleras, A., Age-Related Differences in the Distractor Previewing Effect with Schematic Faces of Emotions. Aging Neuropsychology and Cognition 2014, 21, (4), 386-410, DOI: 10.1080/13825585.2013.824064.
- Lleras, A.; Buetti, S.; Mordkoff, J. T., When Do the Effects of Distractors Provide a Measure of Distractibility?, In Psychology of Learning and Motivation, Vol 59. Ross, B. H., Ed.; Elsevier Academic Press Inc, San Diego, 2013; Vol. 59, 261-315.
- Mereu, S.; Lleras, A., Feelings of Control Restore Distorted Time Perception of Emotionally Charged Events. Consciousness and Cognition 2013, 22, (1), 306-314.
- Tseng, Y. C.; Lleras, A., Rewarding Context Accelerates Implicit Guidance in Visual Search. Attention Perception & Psychophysics 2013, 75, (2), 287-298.
- Wang, R. F., Theories of spatial representations and reference frames:  What can configuration errors tell us?  Psychonomic Bulletin & Review 2012, 19(4), 575-587.
- Ariga, A.; Lleras, A., Brief and Rare Mental "Breaks" Keep You Focused: Deactivation and Reactivation of Task Goals Preempt Vigilance Decrements. Cognition 2011, 118, (3), 439-443.
- Lleras, A.; Porporino, M.; Burack, J. A.; Enns, J. T., Rapid Resumption of Interrupted Search is Independent of Age-Related Improvements in Visual Search. Journal of Experimental Child Psychology 2011, 109, (1), 58-72.
- Mathewson, K. E.; Lleras, A.; Beck, D. M.; Fabiani, M.; Ro, T.; Gratton, G., Pulsed Out of Awareness: EEG Alpha oscillations represent a pulsed inhibition of ongoing cortical processing. Frontiers in Perception Science 2011, 2, (99), 10.3389/fpsyg.2011.00099.
- Wan, X. A.; Voss, M.; Lleras, A., Age-Related Effects in Inter-Trial Inhibition of Attention. Aging Neuropsychology and Cognition 2011, 18, (5), 562-576.
- Mathewson, K. E.; Fabiani, M.; Gratton, G.; Beck, D. M.; Lleras, A., Making waves in the stream of consciousness: Eliciting predictable oscillations in visual awareness with pretarget entrainment at 12 Hz. Visual Cognition 2010, 18, (1), 137-141.
- Caddigan, E.; Lleras, A., Saccadic Repulsion in Pop-Out Search: How A Target's Dodgy History Can Push The Eyes Away From It. Journal of Vision 2010, 10, (14).
- Mathewson, K. E.; Prudhomme, C.; Fabiani, M.; Beck, D. M.; Gratton, G.; Lleras, A., Entraining Neural Oscillations with Rhythmic Visual Stimulation Elicits Simultaneous Fluctuations in Visual Awareness. Psychophysiology 2010, 47, S28-S28.
- Wan, X. A.; Lleras, A., The effect of feature discriminability on the intertrial inhibition of focused attention. Visual Cognition 2010, 18, (6), 920-944.
- Ambinder, M. S.; Lleras, A., Temporal tuning and attentional gating: Two distinct attentional mechanisms on the perception of rapid serial visual events. Attention Perception & Psychophysics 2009, 71, (7), 1495-1506.
- Thomas, L. E.; Lleras, A., Covert shifts of attention function as an implicit aid to insight. Cognition 2009, 111, (2), 168-174.
- Thomas, L. E.; Lleras, A., Inhibitory tagging in an interrupted visual search. Attention Perception & Psychophysics 2009, 71, (6), 1241-1250.
- Thomas, L. E.; Lleras, A., Swinging into thought: Directed movement guides insight in problem solving. Psychonomic Bulletin & Review 2009, 16, (4), 719-723.
- Lleras, A.; Enns, J. T., Focused spatial attention is independent of rapid resumption of an interrupted search. Attention Perception & Psychophysics 2009, 71, (3), 565-577.
- Lleras, A.; Kawahara, J.; Levinthal, B. R., Past rejections lead to future misses: Selection-related inhibition produces blink-like misses of future (easily detectable) events. Journal of Vision 2009, 9, (3).
- Thomas, L. E.; Lleras, A., Covert shifts of attention function as an implicit aid to insight. Cognition 2009, 111, (2), 168-174.
- Enns, J. T.; Lleras, A., What's next? New evidence for prediction in human vision. Trends in Cognitive Sciences 2008, 12, (9), 327-333.
- Levinthal, B. R.; Lleras, A., Context-free inhibition: Attentional biases transfer strongly across temporal and spatial search tasks. Visual Cognition 2008, 16, (8), 1119-1123.
- Levinthal, B. R.; Lleras, A., Inter-trial inhibition of attention to features is modulated by task relevance. Journal of Vision 2008, 8, (15).
- Lleras, A.; Kawahara, J.; Wan, X. I.; Ariga, A., Inter-trial inhibition of focused attention in pop-out search. Perception & Psychophysics 2008, 70, 114-131.
- Shin, E.; Wan, X. I.; Fabiani, M.; Gratton, G.; Lleras, A., Electrophysiological evidence of feature-based inhibition of focused attention across consecutive trials. Psychophysiology 2008, 45, (5), 804-811.
- Bennett, J. D.; Lleras, A.; Oriet, C.; Enns, J. T., A negative compatibility effect in priming of emotional faces. Psychonomic Bulletin & Review 2007, 14, (5), 908-912.
- Levinthal, B. R.; Lleras, A., The unique contributions of retinal size and perceived size on change detection. Visual Cognition 2007, 15, (1), 101-105.
- Lleras, A.; Rensink, R. A.; Enns, J. T., Consequences of display changes during interrupted visual search: Rapid resumption is target specific. Perception & Psychophysics 2007, 69, (6), 980-993.
- Shin, E.; Wan, X. I.; Fabiani, M.; Gratton, G.; Lleras, A., Electrophysiological evidence of inter-trial inhibition of focused attention. Psychophysiology 2007, 44, S55-S55.
- Thomas, L. E.; Lleras, A., Moving eyes and moving thought: On the spatial compatibility between eye movements and cognition. Psychonomic Bulletin & Review 2007, 14, (4), 663-668.
- van Zoest, W.; Lleras, A.; Kingstone, A.; Enns, J. T., In sight, out of mind: The role of eye movements in the rapid resumption of visual search. Perception & Psychophysics 2007, 69, (7), 1204-1217.
- von Muhlenen, A.; Lleras, A., No-onset looming motion guides spatial attention. Journal of Experimental Psychology-Human Perception and Performance 2007, 33, (6), 1297-1310.
- Lleras, A., Enns, J.T., and Rensink, R., "Rapid Resumption of Interrupted Visual Search: New Insight into the Interactions Between Vision and Memory," Psychological Science, (in press).
- Lleras, A.; Enns, J. T., How much like a target can a mask be? Geometric, spatial, and temporal similarity in priming: A reply to Schlaghecken and Eimer (2006). Journal of Experimental Psychology-General 2006, 135, (3), 495-500.
- Lleras, A.; Moore, C. M., What you see is what you get - Functional equivalence of a perceptually filled-in surface and a physically presented stimulus. Psychological Science 2006, 17, (10), 876-881.
- Moore, C. M.; Lleras, A., On the Role of Object Representations in Substitution Masking. Journal of Experimental Psychology: Human Perception and Performance, (in press).