Oculomotor adjustments in darkness and the specific distance tendency

Ocular vergence-induced accommodation and its relation to dark focus

“…Several studies (Fincham, 1962;Ivanoff, 1955;Owens & Leibowitz, 1976) have shown that in the absence of a convergence stimulus and/or in greatly reduced illumination, ocular vergence assumes an intermediate position analogous to OF. The results of the present experiments, however, seem to indicate that it does not require much of a stimulus to produce ocular vergence changes effectively.…”

“…Research, much of it conducted using the laser optometer, has shown that as illumination is decreased, accommodation shifts from a focus that is more or less appropriate to the stimulus distance to an intermediate OF (for reviews, see Miller, 1978aMiller, , 1978b. Accommodation also shifts toward DF when the observer looks through a small artificial pupil, thereby increasing depth of field of the eye and making accommodation unnecessary (Hennessy, Iida, Shiina, & Leibowitz, 1976;Leibowitz, Hennessy, & Owens, 1975;Leibowitz Copyright Owens and Leibowitz (1976) have reported that, -under reduced illumination, ocular vergence assumes an intermediate resting position, analogous to DF (although apparently not identical to it-see Fincham, 1962, andOwens &. The present study presented an opportunity to examine this effect as well.…”

“…These relationships, particularly with regard to OF, have received relatively little attention. Owens and Leibowitz (1976) examined DF and ocular vergence in relation to the specific distance tendency (Gogel, 1972) and found that perceived distance is related to the resting position of convergence. However, they did not examine in much detail the more general relationship of ocular vergence to DF.…”

Perceived size and distance as a perceptual conflict between two processing modes

“…It should be noted that even in the second condition the observer could make use of accommodation and accommodative convergence, despite the restrictive aperture, as well as the information of retinal image size. Recently, Leibowitz and his colleagues (e.g., Owens & Leibowitz, 1976) found in reduced .. cue conditions that both accommodation and convergence assume the resting state and that perceived distance is correlated with the resting state of convergence. (3) The observer viewed the squares binocularly in a fully illuminated alley.…”

“…1 Oculomotor cues such as accommodation and convergence are the most relevant to this processing mode. For example, when convergence is decreased (increased) with no change of the retinal image size, the observer experiences the object as increasing (decreasing) in perceived size (Biersdorf, Ohwaki, & Kozil, 1963;Heinemann, Tulving, & Nachmias, 1959;Hermans, 1954;Holst, 1955aHolst, , 1955bLeibowitz & Moore, 1966;Oyama & Iwawaki, 1972;Wallach & Floor, 197i) and in perceived distance (Lie, 1965;Owens & Leibowitz, 1976;Oyama, 1974;Swenson, 1932). This phenomenon suggests that the perceived size of the object depends on the registered distance or the perceived distance which occurs with changes of convergence.…”