home cv courses          research         contact

---

Projects:

risk and visuomotor behavior

interaction between the senses

visual perception and illusions

risk and visuomotor behavior

Movements have consequences with different levels of cost or reward. How is a movement to a visual target modified in the presence of obstacles associated with a high cost or risk?  To give a real life example: how will I adjust my motor plan if I have to reach for an object past a fragile crystal vase vs. past a cardboard box? 

By recording subjects' movements as they reach for targets in the presence of obstacles with various costs we are trying to derive a computational model of how cost is represented in the visuomotor system.  This research might have important applications to the rehabilitation of neurological patients who have often been conditioned to move abnormally because initially following their injury some normal movements resulted in a high cost such as clumsiness or pain.  By changing the cost/ reinforcement structure of their movement environment one might recondition these patients to again utilize their normal movement range and repertoire. 

This project is funded by an NIH (NINDS) grant and will involve a collaboration with my post-doc advisor Larry Maloney at NYU and my former mentor at the University of Montreal, Daniel Bourbonnais, who works at a rehabilitation center for patients with motor impairments.  (click here for a news release about this research, and here for a more detailed explanation on Larry Maloney's webpage)

return to top

interaction between the senses

Traditionally, the five basic senses are thought of as separate.  However there are now many examples of interactions between them.  Such cross-modal interaction makes sense from a functional standpoint:  why, for example, would you use only vision to locate a mosquito that also makes a sound and that you might feel close to your skin?

Fascinating illusions result from conditions in which the senses give conflicting information.  In one study, subjects had their own arm hidden from view but saw a rubber arm being touched while simultaneously having their own hidden arm touched in the same way.  They experienced the illusion that the rubber arm was their own and that their own arm was in the position of the rubber arm instead of its real position (Botvinick & Cohen, 1998), see

http://cogsci.ucsd.edu/~desa/hand.pdf

To see another effect resulting from a conflict of vision and audition, see:

http://www.media.uio.no/personer/arntm/McGurk_english.html

We recently completed a study (Wolfe et al., 2003; Wolfe et al., in press) that revealed a visually induced somatosensory illusion which demonstrates a fundamental interaction between the senses of vision, touch and proprioception.  It is induced by dark-adapting only one eye and then exposing both eyes to a dim environment.  The illusion consists in a strong feeling of "sagging" or "heaviness" in the eyelid of the eye that is not dark-adapted (and that can therefore not see in the dark). This effect decreases when covering the eye with the hand or a patch thus introducing tactile information congruent with the unequal visual inputs from the two eyes.  Our experimental results are consistent with the hypothesis that the illusion is caused by the brain's attempt to create a unified perceptual interpretation that is consistent across the senses of vision, proprioception and touch.  Simply put, it appears that the brain creates the illusion that one eye is closed in order to explain the difference in input from the two eyes. Our findings imply the neural integration of inputs from different sensory modalities, and it is consistent with the relatively recent findings of multisensory neurons and of interactions of different sensory cortices in human subjects.

In a current project we investigate how the perception of visual motion is influenced by audition.  For an example of how the perception of a movement can change depending on sound see:

http://www.michaelbach.de/ot/mot_bounce/index.html

return to top

visual perception and illusions

Optical illusions are not only fascinating gimmicks, but they also provide vision scientists with a window into the normal functioning of the sense of sight.  By uncovering what aspect of an illusion fools the visual system researchers can infer the processes and biases involved in visual perception. For example, in the picture below (developed by Roger Shepard) the difference between the size of the two monsters is illusory and induced by the strong percept of difference in distance.  In our previous research we investigated which biases in the visual system could explain such illusions (see Wolfe, Maloney & Tam, 2005).   We also test whether these illusion would not only influence one’s visual perception but also one’s movements.

return to top