Movements

There is an interesting paradox where people tend to display irrational behavior when using probability and reward (i.e, value) information to make decisions, but are able to use value information optimally during sensorimotor tasks. One possible reason for this discrepancy is that probabilities encountered in decision-making tasks often result from external sources of variability (i.e., experimental manipulation), whereas uncertainty faced in sensorimotor tasks is commonly the consequence of internal noise (e.g., motor, perceptual). My postdoctoral work with Ken Nakayama and Shin Shimojo explores if optimal levels of performance can be obtained in a sensorimotor task, even when external probabilities are used and matching strategies are likely to be employed.

Our perceptual system gathers information through several different sources (e.g., vision, audition, haptic - touch). Humans use these sources of information to recreate the scene from which the perceptual data was derived. This is done so effortlessly that it seems trivial; however, the ease with which we carry out this operation disguises its underlying complexity. For example, if we look at a cup of coffee on our desk and wish to grab it, we must turn the 2D visual input from our retina into a 3D representation of the cup and its surroundings. This is called the inverse vision problem, as there are an infinite number of 3D objects that can result from any given 2D image. Therefore, our brain is estimating the type and location of the objects in our environment. These estimates are not perfect - errors are introduced both by the insufficiency of perceptual information and neural processing. This makes the job of the brain to infer the state of nature in the presence of uncertainty, given the data and our prior knowledge. My graduate work with Paul Schrater investigated the efficiency with which the brain estimates various types of uncertainty.

Relevant Publications:

Schlicht, E.J., & Schrater, P.R. (2007). Impact of coordinate transformation uncertainty on human sensorimotor control. Journal of Neurophysiology, 97(6), pp. 4203-14. Schlicht, E.J., & Schrater, P.R. (2007). Effects of visual uncertainty on grasping movements. Experimental Brain Research, 182(1), 47-57.

Relevant Publications:

Schlicht, E.J. (2007). Statistical decision theory for human perception-action cycles. University of Minnesota Doctoral Thesis, Minneapolis, MN.

Schrater, P.R., & Schlicht, E.J. (2006). Internal models for object manipulation: Determining optimal contact locations, Technical Report TR 06-003, University of Minnesota.

Navigating through indoor environments poses an interesting problem since GPS systems lose their signal in most buildings. This is an even bigger dilemma to those who are low-vision or blind. My graduate work with Gordon Legge investigated what information is necessary for remote training of building layouts for low-vision and blind populations. Moreover, we compared normally-sighted people’s performance to that of an ideal navigator, based on principles of a partially observable Marvok decision process (POMDP). Through this effort we were able to assess the contribution of memory, spatial updating and uncertainty in people’s navigation decisions.

Relevant Publications:
Stankiewicz, B.J., Legge, G.E., Mansfield, J.S., & Schlicht, E.J. (2006). Lost in virtual space: Studies in human and ideal spatial navigation. Journal of Experimental Psychology: Human Perception and Performance, 32, 688-704.