Paul Corballis

Phone: +64 9 373 7599 ext 88562
Email: p.corballis@auckland.ac.nz
Room: HSB 532
Office Hours: By Appointment
 

I am a cognitive neuroscientist with research interests in visual perception, attention, and cognition. I completed my BSc and MSc degrees at the University of Auckland before departing for the United States to pursue doctoral studies at Columbia University in New York City. I received my PhD in from Columbia in 1997, and spent the next several years at the Center for Cognitive Neuroscience at Dartmouth College in New Hampshire. In 2002 I joined the School of Psychology at the Georgia Institute of Technology in Atlanta, where I remained until returning to the University of Auckland in June of 2011.

My research incorporates psychophysical, electrophysiological, neuroimaging, and neuropsychological approaches to study human visual perception, attention, and awareness. The hemispheric organization of the visual system has been a major theme in much of my research. I have recently been developing research projects that explore the organization of the visual system at finer scales, and in the relationships between brain activity and variability in human perceptual performance.

The following is a list of some recent and ongoing research activity from my laboratory. It is by no means an exhaustive list. I welcome contacts from potential students and collaborators.

1. Ongoing Brain Activity and Psychophysical Variability.
   One of the most enduring phenomena in experimental psychology is that human performance is variable – even when presented with invariant stimuli. Recent evidence suggests that this variability may be – at least in part – attributable to rhythmic variation in cortical excitability. We are initiating experiments to confirm and extend these findings.
2. Target Selection and Distractor Suppression in Visual Search.
   The visual world is typically crowded with many objects from which we must select those that are relevant to our current behavioral goals. We have recently reported evidence from event-related brain potentials (ERPs) that the selection of task-relevant objects can be dissociated from the active suppression of distractors. This is an ongoing project.
3. Within-Category Competition for Representation in Human Vision.
   When multiple objects from the same perceptual category (e.g., faces, houses, trees, etc.) are presented simultaneously, there is evidence that they “compete” for representation in the visual system. This is manifested by weaker ERP components evoked by objects presented in the context of objects from the same category, compared to other-category contexts. In an ongoing project we are exploring the utility of this phenomenon as a tool to explore the functional organization of the visual cortex.
4. Hemispheric Specialization and Integration in the Split Brain.
   Split-brain patients – who have had the corpus callosum (and sometimes other forebrain commissures) surgically severed to relieve intractable epilepsy – have provided a wealth of information about the specialized functions of the two cerebral hemispheres, as well as the roles of subcortical connections in the integration of information between the hemispheres. I have long-standing research interests in the division of visuospatial abilities between the two hemispheres, and the (sometimes illusory) ability of split-brain patients to integrate visual information in the absence of the corpus callosum.

• Hilimire, M.R., Mounts, J.R.W., Parks, N.A., & Corballis, P.M. (2011). Dynamics of target and distractor processing in visual search: Evidence from event-related brain potentials. Neuroscience Letters, 495, 196-200, doi:10.1016/j.neulet.2011.03.064.
• Parks, N.A., Hilimire, M.R., & Corballis, P.M. (2011). Steady-state signatures of visual perceptual load, neural competition, and neural distractor filtering. Journal of Cognitive Neuroscience, 23, 1113-1124, doi:10.1162/jocn.2010.21460)
• Hilimire, M.R., Mounts, J.R.W., Parks, N.A., & Corballis, P.M. (2010). Event-related potentials dissociate effects of salience and space in biased competition for visual representation. PLoS ONE. 5(9): e12677. doi:10.1371/journal.pone.0012677.
• Hilimire, M.R., Mounts, J.R.W., Parks, N.A., & Corballis, P.M. (2009). Competitive interaction degrades target selection: An ERP study. Psychophysiology, 46, 1080-1089.
• Corballis, P. M. (2003). Visuospatial processing and the right-hemisphere interpreter. Brain and Cognition, 53, 171-176.
• Corballis, P. M., & Gratton, G. (2003). Independent control of processing strategies in the left and right hemifields. Biological Psychology, 64, 191-209.