Comparison of pilots and naive subjects regarding spatial orientation during centrifugation

Fighter pilots (pil) and naïve subjects (sub) were compared regarding their perception of the horizontal during gondola centrifugation. Methods: Eight sub and nine pil adjusted a narrow lumnious line so that it was perceived as horizontal (subjective visual horizontal; SVH) at 1g and during centrifugation (2G for 5 min) heading forwards (F) and backwards (B). Deflections from the horizontal plane with respect to the gravitoinertial vector were registered. Results: At 1 g the SVH tilt was minute both for pil and sub. Following acceleration to 2G facing F the mean SVH was 29.1 degrees for pil and 20.9 degrees for sub. After 5 min centrifugation the SVH tilt had declined to 1.8 degrees for sub but showed little change for pil (24.9 degrees). Also in the B position the SVH response differed between pil and sub with initial SVH tilts of - 17.8 and -6.9, respectively. After 5 min of B centrifugation SVH was -25.5 for pil and 0.3 for sub. Conclusions: Perception of horizontal during centrifugation differs markedly between pil and sub. In particular, pil but not sub maintain a perception of change in the roll position for at least 5 minutes following such change. The significance of this acquired capacity for spatial orientation during flying remains to be established