Faculty
Karen Dobkins
Professor
Our primary research goal is to understand visual perception in terms of underlying neural mechanisms, with an emphasis on development and plasticity of visual perception. As a means of exploring the link between neural function and visual perception, we focus particularly on visual motion and color perception.
- Development of Visual Perception.
This line of study involves conducting visual psychophysical experiments in both infants and adults, in order to understand how the developing perceptual system changes with time and experience, and how underlying neural mechanisms can account for the changes. In particular, we focus on the development of motion and color processing, which we investigate using behavioral techniques specially designed for infants (e.g., “Forced-Choice Preferential Looking” and “Directional Eye Movement Assessment”). These projects are supported by a 5-year NIH grant awarded to K. Dobkins.
Dobkins KR, Anderson CM & Lia B (1999). Infant temporal contrast sensitivity functions (tCSFs) mature earlier for luminance than for chromatic stimuli: Evidence for precocious magnocellular development? Vision Research, 39(19), 3223-3239.
Dobkins KR & Anderson CM (2002). Color-based motion processing is stronger in infants than in adults. Psychological Science, 13, 75 – 79.
- Visual Plasticity from Altered Early Sensory Experience: Deaf Studies.
These psychophysical studies are aimed at understanding the ways in which visual perception is altered through specific sensory experience. In particular, we study visual processing in deaf individuals, who experience altered sensory input (i.e., auditory deprivation) and have acquired a visual language (i.e., American Sign Language). More recently, we have investigated the neural basis of these perceptual differences between hearing and deaf subjects using functional magnetic resonance imaging (fMRI). The goal of this research is to determine what aspects of visual processing may be enhanced in the deaf, and to understand these perceptual changes within an ecological context. These projects are supported by a 3-year NSF grant awarded to K. Dobkins.
Bosworth RG & Dobkins KR (1999). Left hemisphere dominance for motion processing in deaf signers. Psychological Science, 10 (3): 256-262.
Finney, E., Fine, I & Dobkins, KR (2001). Visual stimuli activate auditory cortex in the deaf. Nature Neuroscience, 4(12), 1171 - 1173.
Bosworth RG Wright CE, Bartlett MS, Corina DP, & Dobkins KR (2002). Characterization of the visual properties of spatial frequency and speed in ASL signs. TISLR Proceedings, Signum Press (in press).
- Visual Neurophysiology in Monkeys.
Another ongoing line of research includes neurophysiological experiments in awake behaving monkeys, conducted at the Salk Institute in collaboration with Dr. Thomas Albright. These studies involve recording responses of single neurons in a region of monkey visual cortex, area MT, known to be a key component of the neural substrate for motion perception. Specifically, these experiments are aimed at understanding how motion-sensitive cortical neurons utilize information about object features to signal direction of motion. These projects are supported by a Howard Hughes grant awarded to T. Albright.
Thiele A, Dobkins KR & Albright TD (2001). Neural correlates of chromatic motion processing. Neuron, 32, 1-20.
Dobkins, KR (2000). Moving Colors in the Lime Light. Neuron, 25, 15-18.
- Adult Psychophysics: Color, Motion and Attention.
Some of our other studies investigate basic color and motion processing in adult subjects. Most recently, we have been investigating the effects of visual attention on color and motion processing.
Thiele A, Rezec A and Dobkins KR (2002). Chromatic input to motion processing in the absence of attention. Vision Research, 42, 11, 1395- 1401.
Gunther KL & Dobkins KR (2002). Individual differences in chromatic (red/green) contrast sensitivity are constrained by the relative number of L- and M- cones in the eye. Vision Research, 42, 11, 1367- 1378.
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