Other Sensory Systems
(Vision, Electroperception, Speech perception)
Several faculty members and laboratories associated with the Parmly Hearing Institute
are interested in sensory systems in addition to hearing. As such they provide a broad
perspective on sensory processing, which aids all members of the Institute in better
understanding hearing. In turn, the major interest of the Institute in hearing aids these
other scientists in better understanding these other forms of sensory processing.
Vision
Rich Bowen studying basic visual psychophysics and Ann Sutter studying visual perception
and psychophysics provide a broad base interest in visual function. Their work involves
studies of the spatial and temporal aspects of vision. A visual scene can be reduced to a
sum of very simple visual patterns, called sinwave gratings. By understanding how the
visual system processes these simple sinwave gratings, vision scientists have been able to
describe the neural organization of information from much more complex visual patterns,
like those we experience in everyday life. Rich and Ann's research is concerned with
understanding the basic properties of sinwave gratings and their effect on visual
perception. In addition, our visual world changes from moment to moment and these changes,
especially rapid changes, strongly influence what we see. Dr. Bowen is especially
interested in how temporal changes in simple sinwave gratings influence observers'
performance, and how this performance might provide insights concerning neural
organization of temporally changing visual information.
Electroreception
Electroreception is the ability to detect the very weak electric fields that are produced
in aquatic environments by a variety of biological and physical sources. A number of
different types of vertebrates possess an electrosense, including lampreys, sharks,
sturgeon, lungfish, catfish, salamanders and even several mammals including the
duck-billed platypus. This sensory system is extremely sensitive and is used by the
animals to localize hidden prey and mates, as well as to navigate through the environment.
Several groups of fishes have taken the system a step farther and have evolved weak
electric organs with which they communicate with members of their own species. An analysis
of the evolutionary relationships of animals with an electrosense indicates that it
probably evolved as a specialization of a primitive lateral line mechanoreceptor, and that
it has been lost and subsequently re-evolved several times. Comparative studies of these
electrosensory systems allows us to ask fundamental questions about the evolution and
organization of vertebrate sensory systems. John G. New studies the anatomy and physiology
of electrosensory systems in fishes, and is particularly interested in how patterns of
central nervous system organization reflect both evolutionary history and the
environmental necessities imposed on brains.
Speech
Perception
The speech waveform of humans is very complex and humans develop in early life processes
for understanding and generating speech that out performs our ability to generate and
process other sounds. Understanding speech is an interaction between processing the speech
waveform and our ability to understand language. Language is clearly a learned ability,
while processing sound is probably not. J.D. Trout is interested in the basic ability of
humans to process the speech waveform. In particular, what cues the auditory system uses
to separate the basic elements of speech in running speech discourse. As a philosopher of
science, Dr. Trout sees understanding processing of the basic speech waveform as the
crucial first step in understanding human language and communication.