Visual scenes are cluttered and complex, making it necessary to prioritize which objects and regions in an image should be processed. But how does the visual system decide where and what to attend to? We propose that the entire scene, the visual context, guides spatial attention towards objects which are behaviorally relevant to that context, a process that we call contextual cueing. This guidance is driven by implicit memory representations which are acquired incidentally. 

Contextual information is useful because regularities in the visual environment are presented to observers in the form of visual context.  Thus, a core theme of our lab is to characterize how regularities in the visual environment are encoded. As one example, we are exploring the neural substrate of implicit contextual learning. Initial work suggests that contextual learning is subserved by the hippocampus and medial temporal lobe.   

• Chun, M. M., & Jiang, Y. (1998). Contextual cueing: Implicit learning and memory of visual context guides spatial attention. Cognitive Psychology, 36, 28-71.
• Chun, M. M., & Jiang, Y. (1999). Top-down attentional guidance based on implicit learning of visual covariation. Psychological Science, 10, 360-365.
• Chun, M. M., & Phelps, E. A. (1999). Memory deficits for implicit contextual information in amnesic patients with hippocampal damage. Nature Neuroscience, 2, 844-847.
• Chun, M. M., & Nakayama, K. (2000). On the functional role of implicit visual memory for the adaptive deployment of attention across views. Visual Cognition, 7, 65-81.
• Chun, M. M. (2000). Contextual cueing of visual attention. Trends in Cognitive Sciences, 4, 170-178.
• Jiang, Y., & Chun, M. M. (2001). Selective attention modulates implicit learning. Quarterly Journal of Experimental Psychology, 54A, 1105-1124.
• Olson, I. R., Chun, M. M., & Allison, T. (2001). Contextual guidance of attention: Human intracranial event-related potential evidence for feedback modulation in anatomically early, temporally late stages of visual processing. Brain, 124, 1417-1425.
• Olson, I. R., & Chun, M. M. (2001). Temporal contextual cueing of visual attention. Journal of Experimental Psychology: Learning, Memory, & Cognition, 27, 1299-1313.
• Olson, I. R., & Chun, M. M. (2002). Perceptual constraints on implicit learning of spatial context. Visual Cognition, 9, 273-302.
• Chua, K. -P., & Chun, M. M. (2003).  Implicit spatial learning is viewpoint-dependent. Perception & Psychophysics, 65, 72-80.
• Chun, M. M. (2003).  Scene perception and memory.  In D. Irwin and B. Ross (Eds.) Psychology of Learning and Motivation: Advances in Research and Theory: Cognitive Vision, Vol. 42 (pp. 79-108).  Academic Press, San Diego, CA. 
• Chun, M. M., & Jiang, Y. (2003).  Implicit, long-term spatial context memory.  Journal of Experimental Psychology: Learning, Memory, & Cognition, 29, 224-234.
• Jiang, Y., & Chun, M. M. (2003).  Contextual cueing: reciprocal influences between attention and implicit learning.  In L. Jimenez (Eds)., Attention and Implicit Learning (pp 277-296).  John Benjamins Publishing Company.

People are astoundingly blind to unattended information. We employ a rich variety of tasks to examine the costs of inattention and the neural substrates of such attentional deficits.  

• Chun, M. M., & Wolfe, J. M. (2001).  Visual Attention.  In B. Goldstein (Ed.) Blackwell Handbook of Perception (pp. 272-310).  Oxford, UK: Blackwell Publishers Ltd.
• Chun, M. M., & Marois, R. (2002).  The dark side of attention.  Current Opinion in Neurobiology, 12, 184-189.

The Attentional Blink is a deficit for reporting multiple targets presented in rapid successio (Broadbent & Broadbent, 1987; Raymond et al., 1992). It offers insights into understanding why inattention causes functional blindness. Our research on this phenonomenon is guided by a model which proposes that visual events presented at rapid rates are all identified, but that there is a bottleneck in the rate at which they can be consolidated into awareness for immediate report (Chun & Potter, 1995). In collaboration with René Marois, we employ functional MRI to understand the neural substrate of the attentional blink. The neuroimaging work is supported by NSF grant BCS 0094992 (PI: Marois. Co-I: Chun).

• Chun, M. M., & Potter, M. C. (1995). A two-stage model for multiple target detection in rapid serial visual presentation. Journal of Experimental Psychology: Human Perception and Performance, 21, 109-127.
• Chun, M. M. (1997). Types and tokens in visual processing: A double dissociation between the attentional blink and repetition blindness. Journal of Experimental Psychology: Human Perception and Performance, 23, 738-755.
• Potter, M. C., Chun, M. M., Banks, B. S., & Muckenhoupt, M. (1998). Two attentional deficits in serial target search: The visual attentional blink and an amodal task-switch deficit. Journal of Experimental Psychology: Learning, Memory, and Cognition, 24, 979-992.
• Marois, R., Chun, M. M., & Gore, J. (2000). Neural correlates of the attentional blink. Neuron, 28, 299-308.
• Chun, M. M., & Potter, M. C. (2001). The attentional blink and task-switching. In K. Shapiro (Ed) Temporal constraints on human information processing. (pp 20-35).  Oxford: Oxford University Press.
• Olson, I. R., Chun, M. M., & Anderson, A. K. (2001). Effects of phonological length on the attentional blink. Journal of Experimental Psychology: Human Perception & Performance, 27, 1116-1123.
• Marois, R., Yi. D.-J., & Chun, M. M. (2004). The neural fate of consciously perceived and missed events in the attentional blink. Neuron, 41, 465-472.

More broadly, the attentional blink paradigm can be used to examine the attentional requirements of other visual processes such as orientation pop-out detection, illusory conjunctions, or distractor interference.

• Joseph, J. S., Chun, M. M., & Nakayama, K. (1997). Attentional requirements in a "preattentive" feature search task. Nature, 387, 805-808.
• Chun, M. M. (1997). Temporal binding errors are redistributed by the attentional blink. Perception & Psychophysics, 59, 1191-1199.
• Jiang, Y., & Chun, M. M. (2001). The influence of temporal selection on spatial selection and distractor interference: An attentional blink study. Journal of Experimental Psychology: Human Perception & Performance, 27, 664-679.

The change blindness paradigm allows us to explore these issues of inattention using real scene stimuli (Rensink et al., 1997; Simons & Levin, 1997).  One project examined how scene context guides detection of targets in real scenes.

• Kelley, T.A., Chun, M.M., Chua, K.-P. (2003).  Effects of scene inversion on change detection of targets matched for visual salience.  Journal of Vision, 3, 1-5.

Finally, many members of our lab employ object substitution masking to study how consciousness of visual events can be erased by masking stimuli (Di Lollo et al., 2000).  This form of masking is due to attentional limitations rather than low-level visual interference.

• Jiang, Y., & Chun, M. M. (2001).  Asymmetric object substitution masking.  Journal of Experimental Psychology: Human Perception & Performance, 27, 895-918.
• Jiang, Y., & Chun, M. M. (2001). The spatial gradient of visual masking by object substitution.  Vision Research, 41, 3121-3131.

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The ability to recognize an object can be understood as the process of matching a perceptual image to a representation in memory.  We employ both fMRI and psychophysics to identify how the brain develops representations for the many objects that we can see and recognize.       

• Kanwisher, N., Chun, M. M., McDermott, J., & Ledden, P. (1996). Functional imaging of human visual recognition. Cognitive Brain Research, 5, 55-67.
• Kanwisher, N. G., McDermott, J., & Chun, M. M. (1997).The fusiform face area: A module in human extrastriate cortex specialized for face perception. Journal of Neuroscience, 17, 4302-4311.
• Aslin, C., Blake, R., & Chun, M. M. (2002).  Perceptual learning of temporal structure. Vision Research, 42, 3019-3030.

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Many perceptual processes require the observer to retain information briefly in working memory. How is such information organized and represented? In a project headed by Yuhong Jiang, we propose that the organization of visual short-term memory is based on spatial configurations. In a project initiated by Daeyeol Lee, we tested the units of visual working memory. René Marois is leading a neuroimaging project that studies the neural substrates of visual short-term memory capacity.

• Jiang, Y., Olson, I. R., Chun, M. M. (2000). Organization of visual short-term memory. Journal of Experimental Psychology: Learning, Memory, and Cognition, 26, 683-702.
• Lee, D., & Chun, M. M. (2001). What are the units of visual short-term memory: Objects or spatial locations? Perception & Psychophysics, 63, 253-257.
• Jiang, Y., Chun, M. M., Olson, I. R. (in press).  Perceptual grouping in change detection. Perception & Psychophysics.

We perceive a continuous, coherent visual world despite the fact that the visual input is severely fragmented over space and time. Episodic visual representations, known as object files (Kahneman & Treisman, 1984), may subserve this crucial ability. Depending on the task, object files may allow us to perceive motion from discrete frames (apparent motion) or trigger impairments on detecting repeated events (repetition blindness).

• Chun, M. M., & Cavanagh, P. (1997). Seeing two as one: Linking apparent motion and repetition blindness. Psychological Science, 8, 74-79.

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Our lab members pursue a broad range of topics in visual attention research.

• Chun, M. M., & Wolfe, J. M. (1996).  Just say no : How are visual search trials terminated when there is no target present?.  Cognitive Psychology, 30, 39-78.
• Jiang, Y., Chun, M. M., & Marks, L. E. (2002). Visual marking: Dissociating effects of new and old set size. Journal of Experimental Psychology: Learning, Memory, & Cognition, 28, 293-302.
• Jiang, Y., Chun, M. M., & Marks, L. E. (2002). Visual marking: Selective attention to asynchronous temporal groups. Journal of Experimental Psychology: Human Perception & Performance, 28, 717-730.
• Yi, D.-J., Kim, M.-S., & Chun, M. M. (2003).  Inhibition of return to occluded objects. Perception & Psychophysics, 65, 1222-1230.

The lab is grateful for support from NIH EY014193 and Yale University.