Welch R B, Cohen M M, DeRoshia C W
NASA-Ames Research Center, Moffett Field, CA 94035-1000, USA.
Percept Psychophys. 1996 Jan;58(1):22-30. doi: 10.3758/bf03205471.
Ten subjects served as their own controls in two conditions of continuous, centrifugally produced hypergravity (+2 Gz) and a 1-G control condition. Before and after exposure, open-loop measures were obtained of (1) motor control, (2) visual localization, and (3) hand-eye coordination. During exposure in the visual feedback/hypergravity condition, subjects received terminal visual error-corrective feedback from their target pointing, and in the no-visual feedback/hypergravity condition they pointed open loop. As expected, the motor control measures for both experimental conditions revealed very short lived underreaching (the muscle-loading effect) at the outset of hypergravity and an equally transient negative aftereffect on returning to 1 G. The substantial (approximately 17 degrees) initial elevator illusion experienced in both hypergravity conditions declined over the course of the exposure period, whether or not visual feedback was provided. This effect was tentatively attributed to habituation of the otoliths. Visual feedback produced a smaller additional decrement and a postexposure negative after-effect, possible evidence for visual recalibration. Surprisingly, the target-pointing error made during hypergravity in the no-visual-feedback condition was substantially less than that predicted by subjects' elevator illusion. This finding calls into question the neural outflow model as a complete explanation of this illusion.
十名受试者在持续的离心产生的超重（+2 Gz）的两种条件和1-G对照条件下作为自身对照。在暴露前后，获取了以下开环测量值：（1）运动控制，（2）视觉定位，以及（3）手眼协调。在视觉反馈/超重条件下暴露期间，受试者从其目标指向中获得终端视觉误差校正反馈，而在无视觉反馈/超重条件下他们进行开环指向。正如预期的那样，两种实验条件下的运动控制测量均显示，在超重开始时出现了非常短暂的伸手不足（肌肉加载效应），并且在恢复到1 G时出现了同样短暂的负面后效应。在两种超重条件下最初经历的显著（约17度）的电梯错觉在暴露期间逐渐减弱，无论是否提供视觉反馈。这种效应初步归因于耳石的习惯化。视觉反馈产生了较小的额外减少和暴露后的负面后效应，这可能是视觉重新校准的证据。令人惊讶的是，在无视觉反馈条件下超重期间的目标指向误差明显小于受试者电梯错觉所预测的误差。这一发现使神经流出模型作为这种错觉的完整解释受到质疑。
