Projects
1. Using Sensory-motor Conflicts to Examine the Information Encoded in Spatial Memory.
Although humans rely predominantly on vision to perform a wide variety of behaviors, recent findings in the psychological literature have highlighted a critical role for the information provided by non-visual sources. These body-based sources include information from the vestibular system, which senses linear and angular accelerations of the head, proprioception , which provides information about movement of one’s body parts, and, in the case of active movement, efference copy, which represents the commands to the musculature issued by the central nervous system. Nearly all of the studies that have examined the relative contributions of vision and body-based sensory modalities to spatial cognition have investigated this issue using rudimentary tasks that require only an online transient representation of one’s immediate environment. The HIVE enables researchers to examine the sensory contributions to spatial memory in large-scale, realistic environments and using tasks that require long-term enduring mental representations of space.
2. Using Geometrically Impossible Spaces to Test Theories of Human Spatial Representation.
This line of experiments requires participants to learn “Escher” worlds that appear perfectly coherent to users at a local level, but for which the global structure of the environment does not adhere to Euclidean geometry. According to some theories of spatial representation, such changes to the global geometry of an environment should not affect a person’s mental representation of it. On the other hand, according to enduring representational theories, effortful processes are engaged at encoding that create a coherent, global representation of space. Changes to the global coherence of the environment will thus have predictable effects on one’s representation of it.
3. Self-contained Position Tracking of Human Movement Using Small Inertial/Magnetic Sensor Modules.
Numerous applications require a self-contained personal navigation system that works in indoor and outdoor environments, does not require any infrastructure support, and is not susceptible to noise and interference. Posture tracking with an array of inertial/magnetic sensors attached to individual human limb segments has been successfully demonstrated. The "sourceless" nature of this technique makes possible full body posture tracking in an area of unlimited size with no supporting infrastructure. Such sensor modules contain three orthogonally mounted angular rate sensors, three orthogonal linear accelerometers and three orthogonal magnetometers. This project involves a method for using accelerometer data combined with orientation estimates from the same modules to calculate position during walking and running. The periodic nature of these motions includes short periods of zero foot velocity when the foot is in contact with the ground. This pattern allows for precise drift error correction. Relative position is calculated through double integration of drift corrected accelerometer data. Preliminary experimental results for various types of motion including walking, side stepping, and running have demonstrated the accuracy of distance and position estimates using this method.