The stability and control of conditioned noise aversion in the tilt cage

Twenty-six rats were used to study the development of stable conditioned responding to terminate white noise (100 or 105 db) in a tilt cage apparatus. Preliminary work, with one end of the cage consistently associated with silence, demonstrated stability at a high level of cumulative noise-off time per session. Time spent at the noise-off cage end was unaffected by lay-off and showed adaptation to reversal of the cage end functions. Variability in reversal acquisition, insensitivity to stimulus intensity changes and persistence in remaining at one end of the cage in the absence of noise-termination contingencies indicated the need for more precise behavioral control. A schedule programming several reversals of the no-noise end at variable intervals within each session was developed. Performance on the latter schedule was characterized by stability of high noise-off times and also proved more sensitive than the preliminary method to stimulus intensity changes (55, 70, 100 db) as measured by both cumulated noise-off time and cage crossing rates. The ease of training combined with sensitivity to stimulus change and the lack of highly specific motor response requirements make this technique promising for use with animals potentially debilitated by drugs or surgical after-effects.