Adams C W, Johnson C A
Department of Ophthalmology, School of Medicine, University of California, Davis 95616.
Vision Res. 1991;31(4):751-60. doi: 10.1016/0042-6989(91)90013-u.
The Mandelbaum effect refers to an inadvertent accommodation response to an intervening surface (e.g. a window screen) while attempting to focus a distant object of interest. Previous research has attributed the Mandelbaum effect to a tendency for the accommodation mechanism to preferentially focus the stimulus nearest the dark (resting) focus position. The present study extends this work by examining dynamic accommodation response properties for different distances and stimulus separations. Accommodation measurements of nine young, emmetropic subjects were obtained with an infrared optometer while they viewed superimposed horizontal and vertical square-wave gratings at various dioptric separations. Three subjects demonstrated a strong focussing preference for the target located nearest their dark focus position for all stimulus conditions, while two other subjects showed a similar, but weaker, preference. Conversely, two subjects primarily focussed the nearer of the two targets, and two subjects tended to focus the vertical target (regardless of whether it was near or far, or was closet to the dark focus). For all subjects, accommodation rarely fluctuated from one target to the other, and was seldom focussed midway between the two targets. Our findings indicate that the influence of the dark focus on the Mandelbaum effect varies among individuals, and plays little or no role in some individuals. Thus, accommodation responses to competing stimuli are more complex than previous findings would suggest.
曼德尔鲍姆效应是指在试图聚焦远处感兴趣的物体时，对中间表面（如纱窗）产生的一种无意的调节反应。先前的研究将曼德尔鲍姆效应归因于调节机制倾向于优先聚焦最接近暗（静止）焦点位置的刺激。本研究通过检查不同距离和刺激间隔下的动态调节反应特性，扩展了这项工作。九名年轻正视眼受试者在通过红外验光仪观察不同屈光度间隔的水平和垂直方波光栅叠加时，进行了调节测量。三名受试者在所有刺激条件下都表现出对最接近其暗焦点位置的目标有强烈的聚焦偏好，而另外两名受试者表现出类似但较弱的偏好。相反，两名受试者主要聚焦两个目标中较近的一个，两名受试者倾向于聚焦垂直目标（无论其是近还是远，或者是否最接近暗焦点）。对于所有受试者，调节很少在两个目标之间波动，也很少聚焦在两个目标之间的中间位置。我们的研究结果表明，暗焦点对曼德尔鲍姆效应的影响因人而异，在某些个体中作用很小或没有作用。因此，对竞争性刺激的调节反应比先前的研究结果所表明的更为复杂。
