Orientation perception in Williams Syndrome: Discrimination and integration

Williams Syndrome (WS) is a rare neurodevelopmental disorder, which stems from a genetic deletion on chromosome 7 and causes a profound weakness in visuospatial cognition. Our current study explores how orientation perception may contribute to the visuospatial deficits in WS. In Experiment 1, we found that WS individuals and normal 3–4 year olds had similar orientation discrimination thresholds and had similar prevalence of mirror-reversal errors for diagonal targets (±45 deg). In Experiment 2, we asked whether this immaturity in orientation discrimination would also be reflected in a task requiring integration of oriented elements. We found that sensitivities of WS individuals for detecting orientation-defined contours were higher than sensitivities of normal 3–4 year olds, and were not significantly different from sensitivities of normal adults. Together, these results suggest that orientation discrimination and orientation integration have different maturational trajectories in normal development and different susceptibilities to damage in WS. These may reflect largely separate visuospatial mechanisms.     

Mere presence of distractors: Another determining factor for the attentional blink1

Abstract: When two visual targets are presented in rapid succession, perception of the second target is deteriorated if the temporal lag between the two targets is short (0–300 ms). This ‘attentional blink’ (AB) phenomenon has been believed to occur only when the second target is followed by a backward mask or when there is a task switching between two targets. The present study revealed another determining factor for the occurrence of the AB, the presence or absence of a distractor stream. Five experiments examined the effect of possible confounding factors in the extant literature and suggested that the mere presence of a distractor stream affects the processing of targets even when the observers tried to ignore them, resulting in a processing delay. This effect is discussed in a model of AB deficit in terms of decay of the second target's representation.     

Visual Technologies, Cosmographies, and Our Sense of Place in the Universe

The first part of this paper surveys the visual technologies that have transformed the modern visual environment and argues for the relevance of their study to an understanding of modernity in general and to the field of religion and science in particular. The term cosmography is adopted for the visual and spatial manifestation of a worldview, and the importance of analyzing and advancing modern cosmography is asserted. In the second part, the focus shifts to one particular challenge presented by modern cosmography: how to represent and find visual meaning in the new range of size scales that have been offered up by the modern scientific worldview. Six strategies for representing and finding meaning in this new expanded picture of the universe are explored.     

视觉选择性注意脑机制研究进展

视觉选择性注意一直是认知心理学的研究热点之一。注意的早晚期选择问题和基于空间与基于客体的选择问题是选择性注意研究中长期争论的两大理论问题。脑成像研究不仅为解决这些争论提供了有力的证据 ,而且深化和拓展了这两大问题的研究。该文介绍了脑成像研究在上述两个领域的主要研究成果 ,并展望了今后相关问题的研究重点。     

分配注意与发音抑制对视觉工作记忆的影响

本研究通过两个实验考察了分配注意与发音抑制对视觉工作记忆再认能力的影响.结果表明,保持阶段的分配注意与编码阶段的分配注意相比,对视觉工作记忆成绩影响更大;双任务条件下,被试正确回忆言语刺激时,视觉作业的正确率高,而错误回忆言语刺激时,视觉作业的正确率会降低;发音抑制与视觉工作记忆成绩无关.     

婴儿视觉自我认知的微观发生研究

本研究采用微观发生设计,对大连市15名婴儿在15个月时用摄像追踪观察至23个月,每周观察一次.目的在于探讨婴儿视觉自我认知的具体发生时间和个体差异,以及视觉自我认知各指标的发生顺序.结果表明:(1)婴儿视觉自我认知在15～23个月间发生,随年龄增长而提高;(2)婴儿视觉自我认知一般发生于17.25个月;(3)视觉自我认知并非突然出现,而是从不稳定到稳定的渐进发展过程,在发生过程中存在个体差异;(4)视觉自我认知各指标相继发生,镜像自我认知是视觉自我认知最早出现的标志,随后是客体定向能力、照片自我认知.     

Misconvergence to the stimulus plane causes apparent displacement of the stimulus elements seen monocularly1

Abstract: When one binocularly views a group of vertical lines through a ring, the outermost line segments (one on each side) seen within the ring are seen monocularly while the segments of the same lines outside the ring are seen binocularly. The monocular segments appear to be displaced outward with respect to the center of the ring and with respect to the corresponding binocular segments outside the ring. Three experiments examined the extent and direction of this illusory displacement as a function of viewing distance, fixation disparity created by varying the angles of the two arms of a haploscope, and fixation disparity created by a stereoscope and different Nonius stimuli. The results of the experiments confirmed the hypothesis that the apparent displacement is due to misconvergence in accordance with Wells‐Hering's laws of visual direction.     

New equally readable charts based on anisotropy of peripheral visual acuity1

Abstract: Anstis’ equally readable chart for visual acuity has been widely quoted in textbooks on visual perception. However, this chart does not reflect the anisotropy of peripheral visual acuity that has been reported by previous studies. Here, the authors reexamined peripheral visual acuity by measuring resolution thresholds for Landolt rings and recognition thresholds for hiragana letters as a function of retinal eccentricity across two principal retinal meridians: horizontal and vertical. Observers were required to identify the orientation of a gap in the Landolt ring or recognize a hiragana letter while the stimulus was moved slowly from the periphery toward the fovea across each of four meridians: nasal, temporal, superior, and inferior. The results revealed the horizontal‐vertical anisotropy of visual acuity in accordance with the results of previous studies. The mean thresholds obtained in the vertical meridian were approximately 1.51‐fold (for Landolt rings) and 1.42‐fold (for hiragana letters) higher than those obtained in the horizontal meridian at the same retinal eccentricity. The authors propose new equally readable charts for Landolt rings and hiragana letters.     

Teaching Beginning Braille Reading Using an Alphabet or Uncontracted Braille Approach

This study examined the effects of using a research based print reading program modified to accommodate beginning braille readers using an alphabet or uncontracted braille reading approach with five beginning braille readers. Four of the 5 participants displayed a clear increase in their ability to read high frequency words when they began using the Early Steps reading program modified to an Early Steps Alphabet Braille Reading Program. Study findings indicate that access to reading activities and materials afforded to sighted peers resulted in improved reading outcomes for children with visual impairments. Teachers, participants, and family members all viewed the use of the uncontracted braille reading program and materials favorably. Specialized reading instruction was also perceived as beneficial by teachers of students with visual impairments when the training addressed the specific needs of braille readers.     

奖赏性线索启动和调控视觉搜索额顶网络的神经机制

近期关于奖赏性信息与视觉搜索任务的交互作用研究体现在两个层面, 其一是施加外部奖赏能够影响被试的视觉搜索反应时和正确率, 其二是搜索目标本身具有奖赏特性也能够影响行为反应。但是, 奖赏性信息对负责视觉搜索的额顶注意网络的动态启动和调控作用仍不清楚。本研究结合Posner空间预提示范式和视觉搜索范式, 采用快速事件相关功能磁共振成像技术, 分别操纵线索提示阶段的线索奖赏属性(奖赏性vs.非奖赏性)和线索空间注意属性(有效提示目标位置vs.无效提示目标位置), 并操纵目标搜索阶段的目标属性(奖赏性vs.非奖赏性), 探讨以下两个核心问题：(1)在线索提示阶段, 奖赏性线索产生的自上而下注意准备信号的神经基础, 以及该神经基础与传统的空间注意准备信号的异同; (2)在目标搜索阶段, 奖赏性线索对负责视觉搜索的额顶注意网络产生的启动和调控作用, 重点考察对正确的奖赏性信息的定向过程和对错误的奖赏性信息的重新定向过程。