Rat Acoustic Startle



The Rat Startle research project is an ongoing doctoral research project at the University of Wisconsin Milwaukee. It is being conducted by graduate student Joseph Richardson and Professor Emeritus Dr. Alan Baron. Richardson is using acoustic startle in his research because of the less invasive nature of the startle sound stimulus. My part is the design and construction of the Rat Startle Operant Chamber, the Electromechanical to Computer Interfaces and creation of the Computer Software that controls the chamber and generates the research data.


The apparatus consists of a suspended acrylic Rat Chamber, dual Retractable Levers, Pellet Dispenser, Accelerometer and associated electronics. A small horn speaker, high power audio amplifier and a computer produces the 95db noise burst that is used as the startle stimulus. The accelerometer then monitors the motion of the cage and produces an electrical signal corresponding to the startle motion of the rat.

The startle apparatus is very electromechanical in nature and uses lots of motors, relays and switches. It is connected to a standard 28 volt rack mount system. The rack system provides the chamber with electrical power and supports the digital interface electronics. I built special rack mounted electronics panels to present stimuli and connect the startle apparatus to a digital computer system.


The entire apparatus is computer controlled. Using Visual Basic I have developed several research programs that control the apparatus and perform the research studies.

Analog to Digital conversion is used to record the startle response signal provided by the accelerometer. Digital Input and Output are used to control the levers, stimuli lights and food dispenser. Computer generated sound is used for the startle stimulus and all other acoustic stimuli.

The programs generate sessions of multiple ratio and interval schedules. For each session a selected schedule and stimuli are presented to the rat and the responses are recorded. All session information is saved and a data file is written to the computer in Excel spreadsheet form.



Richardson & Baron have already presented startle data including “Variations in the acoustic startle response as a function of the schedule of reinforcement” (2004) and “An Index of Emotional Responses toward Ratio Size: The Startle Response on Multiple Fixed-Ratio Schedules” (2006) . Richardson is currently using the startle chamber and software for his Ph.D. Dissertation "Variations in the Startle Response as a Function of Schedules of Positive Reinforcement"



Daniel Shurilla
Electronic Research Technician
Email: dannys@shurilla.com

Joseph Vincent Richardson, M.S.
University of Wisconsin - Milwaukee
Experimental Analysis of Behavior Laboratory
Email: jvr@uwm.edu
WWW: http://www.uwm.edu/~jvr/

Alan Baron, Ph.D.
Professor Emeritus
Department of Psychology
University of Wisconsin-Milwaukee
Email: ab@uwm.edu