Psychophysical Studies of Biosonar
HOME | PROJECTS
Psychophysical experiments
The bat produces sonar vocalizations and processes information in returning echoes to detect, track and intercept insect prey that may be only a few millimeters in diameter. To accomplish this task, the bat must sort out its own sonar vocalizations from returning echoes. In addition, it may encounter echoes from multiple targets (several insects in a cluster, branches, walls, etc.), as well as signals produced by other bats in close proximity. To successfully intercept the insect and avoid obstacles, the bat must organize acoustic information collected from multiple sonar targets arriving from different directions and at different arrival times. Moreover, changes in the auditory scene, produced by movement of sonar targets and by the bat's own flight path, are sampled at a low duty cycle by species that use frequency modulated (FM) echolocation cries, resulting in brief acoustic snapshots of the world. The bat's auditory system must assemble information over time to build a representation of the dynamic auditory scene (Moss and Surlykke, 2001).
We hypothesize that active perceptual processes and active vocal control over echo information obtained from the environment operate in concert, permitting an elaborate representation of a dynamic auditory scene. We are presently conducting experiments that are designed to determine if the bat hears out streams of echoes from an echo-cluttered background that would allow it to segregate and track moving targets against background.
In addition, we are conducting experiments that test Doppler-delay trading and range discrimination performance as a function of target distance. In all of these experiments, we record and analyze the signals produced by the bat for each trial. This allows us to measure the signal characteristics that contribute to behavioral performance in a variety of perceptual tasks.
Bat performing in psychophysical task
Vocalizing
Waiting for food reward
Waiting for food reward
