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Research in the Corballis lab is focused on the
neural mechanisms underlying visual selective attention and high-level
vision. A number of empirical
techniques are used to investigate attentional and perceptual
phenomena. These include
psychophysical measures, event-related potentials (ERP), functional
magnetic resonance imaging (fMRI), and diffusion tensor imaging (DTI). Here are some of our
ongoing research projects:
Working Memory and Attentional Control – Individual differences
in working memory capacity have been linked to differences in attentional
control. This project has been
using ERP to explore neural correlates of attention and individual
differences in working memory capacity in both visual and auditory
modalities.
Attention and
Depth –
How does visuospatial attention interact with depth? This project incorporates behavioral
and electrophysiological (ERP) measures to examine the configuration of
visuospatial attention when allocated to different depth planes.
Attention and
Emotion Across Lifespan – Visual attention has been shown to be
influenced by the emotional content of stimuli. What remains to be determined is how
age-related changes in visual perception interact with life span changes in
emotional processing to influence how the visual system functions in our
later years. The goal of this
project is to study this interaction by comparing mechanisms of visual
attention in participants of all ages using behavioral and
electrophysiological measures.
Attention
and Eye Movements – Attention and eye movements have long been linked,
and it has been proposed that the same neural circuitry underlying planning
and execution of eye movements is also intimately involved in shifts of
visual attention.
Saccade-locked potentials are being used to investigate the neural
correlates and links between saccade generation and shifts in visuospatial
attention.
Neural Connections
Between Lateral Geniculate Nucleus (LGN) and Extrastriate Visual Areas – This project uses
functional imaging and white matter tractography to investigate the
existence of projections between LGN and extrastriate visual areas. Of particular interest is whether
there exists a direct connection between LGN and putative area hMT. Evidence of such a connection may
provide some insight into the phenomenon of blindsight.
Induced Contrast
Asynchrony
– Induced contrast asynchrony is a temporal visual contrast
illusion. The basic version of the effect consists of two
physically identical patches whose luminance levels are modulated
sinusoidally. One patch is surrounded by a dark surround and the
other by a light surround. The
perceptual experience is such that the two modulating disks are perceived
to be out of phase even though the luminance modulation is completely in
phase. See http://www.shapirolab.net for a
variety of demonstrations. The
steady-state visual evoked potential (SSVEP) is being used to investigate
electrophysiological correlates of contrast and brightness in
visual cortex.
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