Fisher K, Sanchez N
Ocular Motility Laboratory, New England College of Optometry, Boston, MA 02115, USA.
Ophthalmic Physiol Opt. 1997 Mar;17(2):112-21.
The potential contribution of accommodation to the ability to perceive whether an object is moving in space during lateral movement of the head was examined in 16 visually-normal young adults. The target, which provided a highly effective accommodation stimulus, was viewed monocularly in an otherwise completely darkened room. Self-generated head movements of controlled amplitude and frequency were used to produce lateral target motion of continuously variable amplitude either in-phase or counter-phase to the lateral translation of the head. Tonic accommodation and the target/head displacement ratio needed for apparent target stationarity were measured before and after sustained focus at either the nearpoint or farpoint. Tonic accommodation shifted inward under the nearpoint condition and outward under the farpoint condition. The tonic aftereffects induced under the nearpoint and farpoint conditions were accompanied by increases and decreases, respectively, in the degree of positive (same direction as the head) concomitant motion required for apparent target stationarity. These results suggest that the altered accommodative effort required to compensate for the tonic aftereffects influenced the magnitude of the absolute visual parallax ascribed to self-motion. The accommodative system therefore appears to contribute to position constancy, at least in a relatively impoverished visual environment.
在16名视力正常的年轻人中，研究了在头部横向移动过程中，调节对感知物体是否在空间中移动的能力的潜在贡献。在一个完全黑暗的房间里，单眼观察提供高效调节刺激的目标。通过控制幅度和频率的自主头部运动，使目标产生与头部横向平移同相或反相的连续可变幅度的横向运动。在持续聚焦于近点或远点之前和之后，测量强直性调节以及视目标静止所需的目标/头部位移比。强直性调节在近点条件下向内移动，在远点条件下向外移动。近点和远点条件下诱导的强直性后效应分别伴随着视目标静止所需的正向（与头部同向）伴随运动程度的增加和减少。这些结果表明，为补偿强直性后效应而需要改变的调节力影响了归因于自身运动的绝对视差的大小。因此，调节系统似乎至少在相对贫乏的视觉环境中对位置恒常性有贡献。
