Gideon P. Caplovitz, Ph.D.


Education :
2008 Ph.D., Cognitive Neuroscience, Dartmouth College
1998 M.S., Mathematics, Courant Institute, New York University
1995 B.A., Computational Mathematics, University of California at Santa Cruz

Research Interests:
Motivated by my personal fascination with how I perceive the world, my research centers around how our brain transforms the light entering our eyes into our visual experiences.
There are two main themes to my research:

1) Examining (and trying to understand) form-motion interactions or how the shape of an object influences the way it is perceived to move and visa versa.

2) Elucidate the neuronal circuitry underlying the perception of emotional valence.
In my research I combine classical psychophysical techniques with modern neuroimaging (fMRI, DTI, EEG/ERP) technology in an attempt to find convergent sources of information about how the brain enables us to "see".


Current Projects:
Neuronal bases of the unconsious processing of emotional valence: This study combines stimulus-design, psychophysics, and functional neuroimaging to dissociate the top-down infleunces of attention and awareness from the bottom-up processing of emotional valence and to further identify the neuronal circuitry through which emotional valence is processed in a bottom-up fashion.

Neural Correlates of Form-Motion Interactions: A combined psychophysics and fMRI project investigating the neural processes underlying how form and motion information is used to generate percepts of rigid-rotational and non-rigid motion. < Manuscripts in Preparation >

Detection and Identification of sudden transient changes in the visual image. How much information about a change is encoded in the change itself? This is a collaboration with Drs. Howard C. Hughes and Robert Fendrich. < Manuscript in Preparation >

The temporal dynamics of change detection using subdural electrode ERP. The recording of evoked potentials prior to, after and at the moment of change detection from electrodes placed on and within the human cortex. This is a collaboration with Drs. Marian E. Berryhill and Terrance Darcey. <Ongoing>

Stimulus Demonstration:
In my research I have developed novel stimuli that illustrate some of the processes underlying visual perception. Click below to see demonstrations.

1. The Bar Cross Ellipse Illusion

2. The Spinning Ellipse Speed Illusion. The skinny ellipse appears to rotate faster than the fat ellipse. If you download and play in 'loop' mode, you can convince yourself that they are in fact rotating at the same speed.

3. The Drifting Edge Illusion. Download to your computer and play in 'loop' mode. Although the grey occluder appeares to drift up and down, it is in fact stationary.

4. The Radial-Motion Rotating Ellipse. The dots in this demonstration are always positioned along an elliptical contour. They move in and out such that the elliptical contour continuously rotates. The local radial motion interferes with the form processing of the contour and instead of perceiving a rotating ellipse, the contour appears to deform as if made out of rubber. If you pause the video, you will see that the dots always form an ellipse.

Selected Publications:
G.P. Caplovitz, N.A. Paymer, P.U. Tse. (2008). The Drifting Edge Illusion: A stationary edge abutting an oriented drifting grating appears to move because of the 'other a perture problem’. Vision Research; 48(22):2403-14.

G.P. Caplovitz, R. Fendrich, H.C. Hughes. (2008). Failures to see: Attentive blank stares revealed by change blindness. Consciousness and Cognition; 17(3):877-86.

G.P. Caplovitz, D.J. Barroso, P-J. Hsieh, P.U. Tse. (2008). fMRI Reveals that non-local processing in ventral retinotopic cortex underlies perceptual grouping by temporal synchrony. Human Brain Mapping; 29(6):651-61.

G.P. Caplovitz , P.U. Tse. (2007). Rotating dotted ellipses: Motion perception driven by grouped figural rather than local dot motion signals. Vision Research; 47(15), 1979-1991.

G.P. Caplovitz, P.U. Tse. (2007). V3A processes contour curvature as a trackable feature for the perception of rotational motion. Cerebral Cortex; 17(5):1179-89.

X.G. Troncoso, P.U., S.L. Macknik, G.P. Caplovitz, P-J. Hsieh, A.A. Schlegel, J. Otero-Millan, S. Martinez-Conde. (2007). BOLD activation varies parametrically with corner angle throughout human retinotopic cortex. Perception; 36(6) 808-820.

G.P. Caplovitz, P.U. Tse. (2006). The Bar-Cross-Ellipse Illusion: alternating percepts of rigid and non-rigid motion based on contour ownership and trackable feature assignment. Perception; 35(7):993-7.

P.U. Tse, G.P. Caplovitz, P-J. Hsieh. (2006). Microsaccade directions do not predict directionality of illusory brightness changes of overlapping transparent surfaces Vision Research; 46(22):3823-30.

G.P. Caplovitz, P-J. Hsieh, P.U. Tse. (2006). Mechanisms underlying the perceived angular velocity of a rigidly rotating object. Vision Research; 46(18):2877-93.

P-J. Hsieh, G.P. Caplovitz, P.U. Tse. (2006). Bistable illusory rebound motion: Event-related Functional magnetic resonance imaging of perceptual states and switches. Neuroimage; 32(2):728-39.

P-J. Hsieh , G.P. Caplovitz, P.U. Tse. (2006). Illusory motion induced by the offset of stationary luminance-defined gradients. Vision Research; 46(6-7):970-8.

P.U. Tse, G.P. Caplovitz. (2006). Chapter 15 Contour discontinuities subserve two types of form analysis that underlie motion processing. Prog Brain Res.; 154:271-92.

P-J. Hsieh, G.P. Caplovitz, P.U. Tse. (2005). Illusory Rebound Motion and the motion continuity heuristic. Vision Research; 45(23):2972-85.

D.L. Jewett, G.P Caplovitz, B. Baird, M. Trumpis, M.P. Olson, L.J. Larson-Prior. (2004). The use of QSD (q-sequence deconvolution) to recover superposed, transient evoked-responses. Clinical Neurophysiology; 115:2754-2775.

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©2003 Neuroscience of Attention & Perception Laboratory
Princeton University