Wismeijer Dagmar A, Erkelens Casper J
Department Physics of Man, Helmholtz Institute, Utrecht University, Utrecht, The Netherlands.
J Vis. 2009 Dec 9;9(13):12.1-10. doi: 10.1167/9.13.12.
In this study, we investigated the effect of changing size on vergence. Erkelens and Regan (1986) proposed that this cue to motion in depth affects vergence in a similar way as it affects perception. The measured effect on vergence was small and we wondered why the vergence system would use changing size as an additional cue to changing disparity. To elucidate the effect of changing size on vergence, we used an annulus carrying both changing size and changing disparity signals to motion in depth. The cues were either congruent or signaled a different depth. The results showed that vergence was affected by changing size, however in an opposite way than that perception was affected. These results were incongruent with those reported by Erkelens and Regan (1986). We therefore additionally measured the effects on vergence of the individual parameters associated with changing size, i.e., stimulus area, retinal eccentricity, and luminance. Stimulus (retinal) eccentricity was inversely related to vergence gain. Luminance, on the other hand, had a smaller but positive relation to vergence gain. Thus, changing size affected the disparity signal two-fold: it changed the retinal location of the disparity signal and it changed the strength of the disparity signal (luminance change). These effects of changing size on disparity can explain both our results (change in retinal location of the disparity signal) and those of Erkelens and Regan (1986; change in luminance). We thus conclude that changing size did not in itself contribute to vergence, rather its effect on vergence was mediated by disparity.
在本研究中，我们调查了大小变化对聚散度的影响。埃尔凯伦斯和里根（1986年）提出，这种深度运动线索对聚散度的影响方式与其对感知的影响方式相似。测量得到的对聚散度的影响较小，我们不禁要问，为什么聚散度系统会将大小变化用作变化视差的额外线索。为了阐明大小变化对聚散度的影响，我们使用了一个承载大小变化和深度运动视差变化信号的环形物。这些线索要么是一致的，要么指示不同的深度。结果表明，聚散度受到大小变化的影响，然而其影响方式与感知受到影响的方式相反。这些结果与埃尔凯伦斯和里根（1986年）报告的结果不一致。因此，我们还测量了与大小变化相关的各个参数对聚散度的影响，即刺激面积、视网膜离心率和亮度。刺激（视网膜）离心率与聚散度增益呈负相关。另一方面，亮度与聚散度增益的关系较小但为正相关。因此，大小变化对视差信号有双重影响：它改变了视差信号的视网膜位置，并且改变了视差信号的强度（亮度变化）。大小变化对视差的这些影响既可以解释我们的结果（视差信号视网膜位置的变化），也可以解释埃尔凯伦斯和里根（1986年；亮度变化）的结果。因此，我们得出结论，大小变化本身对聚散度没有贡献，相反，其对聚散度的影响是由视差介导的。
