Some Aspects of the Motor Organization of the Oculomotor System

Oculomotor responses in looking to visual targets were examined for motor coordination parallel to that found in manual pointing. Ocular responses did not show any evidence of speed-accuracy tradeoff when the correlation of latency (reaction time) and accuracy was assessed. The oculomotor system did show a range effect, hidden under a general undershoot of target position and present only when no visual feedback about target position was available to allow correction during the movement. Cues to allow predictive timing of the response seemed very important for oculomotor reaction time. Processing of timing of movement may be handled differently for oculomotor than for manual orienting, and calculation of position in space may be processed in common, leading to both similarities and differences for the two motor systems.     

Oculomotor programming disturbances in the dementia syndrome

Three types of oculomotor programming disturbances are described in patients with the dementia syndrome. This report describes two of these abnormalities, poorly regulated gaze patterns and a programming type of gaze perseveration. All patients showed poorly regulated gaze patterns in contrast to the normal controls, whereas on the whole only the moderately affected patients showed the programming type of gaze perseveration. The third type of oculomotor programming disturbance is efferent perseveration of gaze (a hypokinetic, "staring" type of gaze pattern) and can be seen with severe dementia. The possible significance of these findings is discussed.     

学前儿童性别恒常性的发展

采用改进的访谈方法,考察了3、4、5、6岁儿童的性别恒常性的发展。结果表明：3、4岁儿童已获得性别认同的能力,4、5岁儿童逐步获得性别稳定性的能力,5、6岁是性别一致性发展的快速期,大多数的6岁被试儿童已获得性别恒常性。研究还发现,在提示条件下,各年龄获得性别恒常性的被试人数大大增加;儿童对自己的性别恒常性的认知发展早于对他人,但这一差异仅表现在3岁儿童身上     

Oculomotor atypicalities in Developmental Coordination Disorder

Children with Developmental Coordination Disorder (DCD) fail to acquire adequate motor skill, yet surprisingly little is known about the oculomotor system in DCD. Successful completion of motor tasks is supported by accurate visual feedback. The purpose of this study was to determine whether any oculomotor differences can distinguish between children with and without a motor impairment. Using eye tracking technology, visual fixation, smooth pursuit, and pro‐ and anti‐saccade performance were assessed in 77 children that formed three groups: children with DCD (aged 7–10), chronologically age (CA) matched peers, and a motor‐match (MM) group (aged 4–7). Pursuit gain and response preparation in the pro‐ and anti‐saccade tasks were comparable across groups. Compared to age controls, children with DCD had deficits in maintaining engagement in the fixation and pursuit tasks, and made more anti‐saccade errors. The two typically developing groups performed similarly, except on the fast speed smooth pursuit and antisaccade tasks, where the CA group outperformed the younger MM group. The findings suggest that children with DCD have problems with saccadic inhibition and maintaining attention on a visual target. Developmental patterns were evident in the typically developing groups, suggesting that the pursuit system and cognitive control develop with age. This study adds to the literature by being the first to systematically identify specific oculomotor differences between children with and without a motor impairment. Further examination of oculomotor control may help to identify underlying processes contributing to DCD. A video abstract of this article can be viewed at: https://youtu.be/NinXa2KlB4M . [Correction added on 27 January 2017, after first online publication: The video abstract link was added.]     

Oculomotor Effects in the Size-Distance Paradox and the Moon Illusion

Drawing on 2 concepts—the resting position of the eyes and a binocular geometry for perceived size, the moon illusion is explained as the consequence of different oculomotor adjustments caused by change in the direction of gaze contingent upon the viewing conditions of the moon. Hence, each particular moon will be viewed with a different vergence state which, in turn, yields a different amount of binocular disparity. The vergence state will determine the perceived size of an object whereas disparity will determine its perceived distance. It is further contended that the perceived size of the moon is based on a new binocular information source for size perception enabling the size of an object to be perceived even in the absence of egocentric distance information. Discussion focuses on the paradoxical aspect of the moon illusion and how the size-distance invariance hypothesis may have contributed to its effect.     

Oculomotor adjustments in darkness and the specific distance tendency

Two experiments were performed to investigate the relationship between the oculomotor adjustments assumed in total darkness and perceived distance under reduced visual conditions. Experiment I compared the dark focus of accommodation with the perceived distance of a monocular light point presented in a dark environment. Experiment II compared the convergence angle assumed in darkness (dark convergence) with the perceived distance of the light point. Both accommodation and convergence were found to assume intermediate values in darkness. Perceived distance of the monocular light point was significantly correlated with dark convergence and unrelated to the dark focus of accommodation. It was suggested that ocular vergence is a major determinant of perceived distance under reduced visual conditions, and thus provides a possible mechanism for the specific distance tendency.     

颜色恒常理论及模型探索

颜色恒常是指外界环境变化时对客观物体颜色知觉保持不变的心理倾向。本文就Von Kries色系数定律、色域映射理论、谱锐化理论、视网膜皮层理论、双线性模型和神经网络模型等现有代表性的颜色恒常理论作了简单的概括与评价。针对目前该类研究的缺陷,尝试性地提出了发展完备的颜色恒常理论(或模型）的研究思路。     

Age-group Differences in Inhibiting an Oculomotor Response

ABSTRACT

Age-group differences were examined in the delayed oculomotor response task, which requires that observers delay the execution of a saccade (eye movement) toward an abrupt-onset visual cue. This task differs from antisaccade and attentional capture in that inhibition causes saccades to be postponed, not redirected. Older adults executed more premature saccades than young adults, but there were no age-group differences in latency or accuracy of saccades executed at the proper time. The results suggest that older adults are less capable of inhibiting a prepotent saccadic response, but that other aspects of visual working memory related to the task are preserved.     

Oculomotor tonus and visual adaptation

The contribution of oculomotor efference to visual perception and performance can be clarified by considering the functions of tonus. Accommodation and vergence typically ‘relax’ at an intermediate distance, reflecting tonic innervation of the ciliary and extraocular muscles, which varies widely among individuals who have normal vision. In many situations, especially when stimulation is degraded, fixation and focusing responses are biased toward the individual's resting state. Moreover, unusual circumstances, such as alteration of the relation of eye position and distance or prolonged exposure to near work, induce adaptive modification of the resting posture. These normal variations of oculomotor toms affect the accuracy and the effort required to fixate objects, and they may help explain problems of space perception and visual fatigue.     

Oculomotor adjustments and size constancy

The effect on matched size of the oculomotor adjustments was determined by stimulation and relaxation of accommodation and convergence by means of spherical lenses. The normal coupling between accommodation and convergence was maintained by introducing the amount of convergence appropriate to the lens power and each S’s interpupillary distance. Data indicate that the oculomotor adjustments are adequate to account for size constancy up to approximately 1 m, beyond which their effect progressively decreases. The actual accommodation in force was assessed by means of the laser scintillation technique. It was determined that the magnitude of accommodation responds accurately to the spherical lens introduced up to about 1 m observation distance, beyond which underaccommodation was noted. Examination of the matched size as a function of the actual accommodation distance reveals a very close correspondence to the size constancy prediction up to about 1 m.     

Oculomotor effects upon binocular rivalry

Summary Binocular rivalry was generated by projecting dissimilar Julesz-type patterns to each eye. The minimum angular width of the patterns needed to observe rivalry was measured at four retinal eccentricities for two simulated viewing distances: 200 and 20 cm. The angular width needed to just detect rivalry was up to 50% greater for the 20 cm viewing distance as compared with the threshold width measured at 200 cm. This increased tolerance for rivalry for near fixation was inversely proportional to the change in apparent size. The results suggest that the lateral geniculate nucleus is the site of size-scaling or zooming.Supported by the U. S. Air Force under contract No. AFOSR-F44620-67-C0085, with supplementary funding to Prof. H.-L. Teuber, Chairman, from NASA and NIMH under grants NsG 496 and MH 05673.     

Orientation Constancy in Neurons of Monkey Visual Cortex

We studied the effect of body tilt on the orientation selectivity of single neurons in the visual cortex of an alert monkey. The monkey performed a visual fixation task either in the upright position or with its whole body tilted about the naso-occipital (roll) axis by ±25° or ±30°. We determined the preferred stimulus orientation for 51 of 117 neurons in two or, if possible, three body positions (i.e. with the whole body upright, and tilted either left ear or right ear down). In striate cortex, most of the neurons were of a non-compensatory type, showing a change in the preferred orientation according to the body tilt and the estimated counterrolling of the eye. By contrast, about 40% of the neurons in prestriate cortex were of a compensatory type, preferring similar orientations in all body positions. This suggests that mechanisms which produce orientation constancy with respect to the direction of gravity are implemented at an early stage of cortical processing.     

颜色知觉恒常理论的回顾

本文对早期颜色恒常理论、系数理论、计算理论和 Octant模型作了简要回顾 ,并结合已有的研究成果进行评述。对影响颜色恒常性机制的主要因素进行了探讨。强调了知觉经验、记忆、认知决策等高级意识活动对颜色恒常知觉的作用 ,并尝试性地提出了描述颜色恒常知觉过程的一般参照框架。