注视方向的知觉对注视追随行为的影响

他人的注视线索可诱导观察者将注意自动地转移到该线索所指示的方向上去(注视追随), 但仍不清楚注视方向的知觉在注视追随中起到何种作用。本研究结合注视适应和注视线索提示范式发现：知觉到的注视线索角度越大, 其线索提示效应越强; 知觉适应后被试判断注视方向的准确性下降, 注视线索引起的注意转移量显著减少。可见, 对注视方向的知觉能直接影响注视追随行为, 而注视方向抽取受到刺激显著性(注视角度)和知觉适应等因素的调节。这提示：在意识状态下, 注视知觉与注视追随存在直接联系, 即可能存在从注视知觉系统到注意转移系统的皮层加工通路; 注视追随并非纯粹的反射式加工, 它受自上而下知觉经验的调节。     

内源性眼跳前的空间注意转移

采用线运动错觉(illusory line motion)测量的单任务范式,以色块为眼跳提示刺激,用三个实验对内源性眼跳前是否存在空间注意转移进行了探讨。实验一要求被试将眼睛跳往提示刺激处,通过对线运动错觉的分析确定该条件下的空间注意转移规律;实验二要求被试在将视线保持在注视点处的条件下判断目标色块是否出现,以探明线运动错觉是否受对目标色块前注意阶段加工的影响;实验三要求被试将眼睛跳往提示刺激的对侧,分析眼跳位置与提示刺激空间方位的一致性对空间注意转移的影响。获得以下主要结果：(1)内源性眼跳前存在注意转移;(2)在视线保持在注视点处的条件下,注意未受对提示刺激前注意加工的引导;(3)眼跳目标位置与提示目标位置的空间一致性对眼跳前空间注意转移无显著影响。     

双眼性的深度运动速度与方向知觉研究

研究双眼性的深度运动知觉,结果表明,双眼视网膜象的速度差信息,在深度运动的速度检测中起重要作用;而速度比信息则有助于判断深度运动的方向,人眼感知的深度运动的速度大小正比于双眼网膜象的速度差,感知的运动方向则取决于速度比。提出人类视觉系统具有从二维网膜信息获得三维运动知党的双限性机制,据此解释了双眼视觉的速度检测特性以及所具有的０．２°的方向分辨率,理论模型与实验结果及日常视知觉符合良好。     

在不同注意定向条件下是否出现返回抑制的知觉优先

返回控制中的知觉优先是指相对于非线索化位置,线索化位置的刺激被优先知觉到的现象。研究采用时序判断方法对不同注意定向下返回抑制的知觉优先现象进行了两个实验。实验１采用连续线索化的安排,发现当注意从线索化位置移开后知觉优先仍然存在;实验２采用同时呈现双线索的安排发现知觉优先也存在。     

停表错觉的机制：注意是否为决定因素

通过两个实验探讨了注意是否影响停表错觉（chronostasis）。实验一要求被试在注视时或眼跳后,估计处于眼跳目标或其附近位置的刺激的持续时间;实验二要求被试在眼跳条件下辨别眼跳目标或其附近位置的刺激,以考查两种位置的注意水平。结果表明,眼跳目标位置的注意水平高于其附近位置,而两种位置均可产生停表错觉,且两者的错觉量近似相等。从而说明注意并不影响停表错觉,停表错觉的机制可能是眼跳目标及其附近刺激的知觉提前。     

抑制控制能力衰退对知觉组织老年化的影响

通过比较注意线索对老年人和年轻人共线性和相似性知觉组织的影响,探讨了知觉组织老年化的原因。研究发现,注意线索对年轻人的助益更大,对老年人的助益较小,符合抑制控制理论的研究假设,同时本文还对加工速度、基本感觉能力等可能引起认知老年化的因素进行了分析。此外,还发现了知觉组织中与阅读习惯一致的方向偏好,无论在有无注意线索的条件下,135°方向上的知觉组织都快于45°方向上的知觉组织。     

空间选择性注意在上下视野间的转移

本实验研究空间选择性注意在上下视野间的转移及其是否受知觉空间的影响。实验采用Posner的位置线索化实验范式和两种深度线索背景,测量分辨任务的反应时(RTs)。实验发现:线索有效时的反应时比线索无效时的反应时短,而且线索对上视野刺激的反应时的影响较大。知觉空间中的深度线索对于注意在上下视野中转移没有显著影响。这些结果表明,空间选择性注意在上下视野转移存在不对称性,并且主要由物理空间决定。     

哭泣表情面孔的注意偏向:眼动的证据

研究采用双选择Oddball范式和线索-靶子范式,并结合眼动技术,以微笑、哭泣和中性表情面孔为刺激材料,综合考察哭泣表情面孔在识别和解离过程中的注意偏向。研究发现:在识别阶段,哭泣表情面孔的识别正确率和反应速度都显著优于微笑表情面孔,进一步的兴趣区注视偏向分析发现,哭泣和微笑表情面孔的注视模式既具有一致的规律,又存在细微的差异;在解离阶段,返回抑制受线索表情类型的影响,在有效线索条件下,哭泣表情线索呈现后个体对目标刺激的平均注视时间和眼跳潜伏期都显著短于其它表情线索。表明哭泣表情面孔在识别和解离过程中具有不同的注意偏向表现,在识别阶段表现为反应输出优势和注视模式上的一致性与差异性;在解离阶段表现为有效线索条件下,对目标刺激定位和视觉加工的促进作用。     

基本特征水平的知觉学习与注意的作用

在基本特征水平的知觉学习的研究中是否存在注意与反馈的作用,是一直存在着争论的问题。该研究通过线索不同的有效性来控制注意的分配,探讨了在基本特征水平的知觉学习中注意与反馈的作用,共进行了两个实验,实验一采用内源和外源性线索影响注意分配,探讨基本特征刺激加工过程中注意的作用;实验二对基本特征刺激的知觉学习过程的特性进行研究。学习和探测任务都是让被试从所呈现的刺激中寻找靶子英文字母L。结果发现：在基本特征水平的知觉学习中存在有注意的作用;其学习过程存在反馈的作用。     

老年抑郁个体注意偏向的发生阶段

本研究以老年抑郁量表、自评抑郁量表和汉密顿抑郁量表为工具筛选出老年抑郁个体和老年正常对照组为研究对象,通过空间线索化范式,以及分离的情绪Stroop范式考察了刺激呈现时间、线索呈现条件对老年抑郁个体注意偏向的影响,并探讨了老年抑郁个体注意偏向的发生阶段。研究结果表明：（1）在空间线索任务中,当刺激呈现时间为250ms或500ms时,老年抑郁组与老年正常组的返回抑制效应在各种情绪刺激下均无显著差异（P>0.05）,即老年抑郁个体没有呈现出对任何情绪刺激类型的注意偏向现象;当刺激呈现时间为750ms或1000ms时,老年抑郁组的返回抑制效应在不同情绪刺激条件下差异显著,F(2, 66)=3.22,P=0.046,而老年正常组则不存在返回抑制效应在情绪刺激类型上的差异（P>0.05）,提示老年抑郁组对不同情绪类型的刺激注意返回抑制能力不同;进一步检验得知：返回抑制效应在悲伤条件下,存在组间差异,分别是F(1, 33)=10.03,P=0.003;F(1, 33)=18.21,P=0.000,即老年抑郁组的返回抑制效应弱于老年正常组。（2）在Stroop实验中,老年抑郁组在单中性、双中性与单悲伤面孔、中性悲伤面孔、双悲伤面孔线索类型下的反应时差异显著;且当线索类型为单悲伤面孔、中性悲伤面孔、双悲伤面孔时,老年抑郁组与老年正常组的反应时差异均显著,即老年抑郁组的反应时明显长于老年正常组,F(1, 41) = 5.37,P=0.026;F(1, 41) = 7.08,P=0.011;F(1, 41) = 7.28,P=0.010;而当线索类型为单中性和双中性面孔时,老年抑郁组与老年正常组的反应时差异不显著（P>0.05）;提示抑郁组可能在自动化注意选择分配期存在注意偏向。研究认为,老年抑郁个体的注意偏向可能发生在注意初始分配阶段和解释阶段,且受加工深度的影响。在刺激呈现时间较长的条件下,注意偏向的效应更明显。     

Accuracy and awareness in the perception and categorization of male sexual orientation

For clear and unambiguous social categories, person perception occurs quite accurately from minimal cues. This article addresses the perception of an ambiguous social category (male sexual orientation) from minimal cues. Across 5 studies, the authors examined individuals' actual and self-assessed accuracy when judging male sexual orientation from faces and facial features. Although participants were able to make accurate judgments from multiple facial features (i.e., hair, the eyes, and the mouth area), their perceived accuracy was calibrated with their actual accuracy only when making judgments based on hairstyle, a controllable feature. These findings provide evidence that suggests different processes for extracting social category information during perception: explicit judgments based on obvious cues (hairstyle) and intuitive judgments based on nonobvious cues (information from the eyes and mouth area). Differences in the accuracy of judgments based on targets' controllability and perceivers' awareness of cues provides insight into the processes underlying intuitive predictions and intuitive judgments.     

Kinetic depth effect and identification of shape

We introduce an objective shape-identification task for measuring the kinetic depth effect (KDE). A rigidly rotating surface consisting of hills and valleys on an otherwise flat ground was defined by 300 randomly positioned dots. On each trial, 1 of 53 shapes was presented; the observer's task was to identify the shape and its overall direction of rotation. Identification accuracy was an objective measure, with a low guessing base rate of the observer's perceptual ability to extract 3D structure from 2D motion via KDE. (1) Objective accuracy data were consistent with previously obtained subjective rating judgments of depth and coherence. (2) Along with motion cues, rotating real 3D dot-defined shapes inevitably produced a cue of changing dot density. By shortening dot lifetimes to control dot density, we showed that changing density was neither necessary nor sufficient to account for accuracy; motion alone sufficed. (3) Our shape task was solvable with motion cues from the 6 most relevant locations. We extracted the dots from these locations and used them in a simplified 2D direction-labeling motion task with 6 perceptually flat flow fields. Subjects' performance in the 2D and 3D tasks was equivalent, indicating that the information processing capacity of KDE is not unique. (4) Our proposed structure-from-motion algorithm for the shape task first finds relative minima and maxima of local velocity and then assigns 3D depths proportional to velocity.     

Visual inertia of rotating 3-D objects

Five experiments were designed to determine whether a rotating, transparent 3-D cloud of dots (simulated sphere) could influence the perceived direction of rotation of a subsequent sphere. Experiment 1 established conditions under which the direction of rotation of a virtual sphere was perceived unambiguously. When a near-far luminance difference and perspective depth cues were present, observers consistently saw the sphere rotate in the intended direction. In Experiment 2, a near-far luminance difference was used to create an unambiguous rotation sequence that was followed by a directionally ambiguous rotation sequence that lacked both the near-far luminance cue and the perspective cue. Observers consistently saw the second sequence as rotating in the same direction as the first, indicating the presence of 3-D visual inertia. Experiment 3 showed that 3-D visual inertia was sufficiently powerful to bias the perceived direction of a rotation sequence made unambiguous by a near-far luminance cue. Experiment 5 showed that 3-D visual inertia could be obtained using an occlusion depth cue to create an unambiguous inertia-inducing sequence. Finally, Experiments 2, 4, and 5 all revealed a fast-decay phase of inertia that lasted for approximately 800 msec, followed by an asymptotic phase that lasted for periods as long as 1,600 msec. The implications of these findings are examined with respect to motion mechanisms of 3-D visual inertia.     

Neural correlates of age-related reduction in visual motion priming

Previously we reported that priming of visual motion perception is reduced in older adults compared to younger adults (Jiang, Greenwood, & Parasuraman, 1999, Psychology and Aging, 14(4), 619; Jiang, Luo, & Parasuraman, 2002b, Neuropsychology, 16(2), 140). To examine the neural mechanisms underlying this age-related effect, event-related brain potentials (ERPs) were recorded during perceptual judgments of motion directions by younger and older adults in two experiments. When judging single-step motion, both younger and older adults evoked significantly larger ERP late positive component (LPC) responses to unambiguous motion compared to LPC responses elicited by ambiguous motion. In contrast, compared to the younger adults, the older adults evoked comparable but delayed ERP responses to single motion steps. In the second experiment the younger and older groups judged the directions of two successive motion-steps (either motion priming or motion reversals). Under short (200-400 ms) stimulus onset asynchrony (SOA), the difference between the ERP responses to priming and reversal conditions was significantly larger for the younger than for the older adults. This study provides the first electrophysiological evidence that brain aging leads to delayed processing of single motion direction and visual motion priming as early as 100 ms in the early visual cortex. Age-related changes in strength and temporal characteristics of neural responses in temporal-parietal regions were particularly pronounced in older adults when successive motion signals are placed closely in time, within 400 ms.     

Priming by motion too rapid to be consciously seen

When a rapidly rotating ring of dots was briefly flashed, observers saw only a solid ring with no discriminable rotation. However, when this stimulus served as a prime that was followed by a target that consisted of a clearly rotating ring of dots, response times (RTs) to report the target's rotation were shorter when the prime and target directions were congruent than when they were incongruent. In accord with shape priming data, this priming effect increased monotonically with the prime-target stimulus-onset asynchrony (SOA). The prime also biased the perceived direction of an ambiguous apparent motion target, but only at an intermediate SOA. At the same SOA, we also found that target presentations enabled above-chance discrimination of prime's rotation direction. These outcomes demonstrate the processing of motion direction information that is not phenomenally represented. They suggest a common mechanism may mediate the priming of RTs by shape and motion, whereas a different mechanism mediates perceptual measures of motion priming.     

Resolving ambiguous behavioral intentions by means of involuntary prioritization of gaze processing

Anticipation of others' actions is of paramount importance in social interactions. Cues such as gaze direction and facial expressions can be informative, but can also produce ambiguity with respect to others' intentions. We investigated the combined effect of an actor's gaze and expression on judgments made by observers about the end-point of the actor's head rotation toward the observer. Expressions of approach gave rise to an unambiguous intention to move toward the observer, while expressions of avoidance gave rise to an ambiguous behavioral intention (as the expression and motion cues were in conflict). In the ambiguous condition, observers overestimated how far the actor's head had rotated when the actor's gaze was directed ahead of head rotation (compared to congruent or lagging behind). In the unambiguous condition the estimations were not influenced by the gaze manipulation. These results show that social cue integration does not follow simple additive rules, and suggests that the involuntary allocation of attention to another's gaze depends on the perceived ambiguity of the agent's behavioral intentions.     

The interplay between stereopsis and structure from motion

In a series of psychophysical experiments, an adaptation paradigm was employed to study the influence of stereopsis on perception of rotation in an ambiguous kinetic depth (KD) display. Without prior adaptation or stereopsis, a rotating globe undergoes spontaneous reversals in perceived direction of rotation, with successive durations of perceived rotation being random variables. Following 90 sec of viewing a stereoscopic globe undergoing unambiguous rotation, the KD globe appeared to rotate in a direction opposite that experienced during the stereoscopic adaptation period. This adaptation aftereffect was short-lived, and it occurred only when the adaptation and test figures stimulated the same retinal areas, and only when the adaptation and test figures rotated about the same axis. The aftereffect was just as strong when the test and adaptation figures had different shapes, as long as the adaptation figure contained multiple directions of motion imaged at different retinal disparities. Nonstereoscopic adaptation figures had no effect on the perceived direction of rotation of the ambiguous KD figure. These results imply that stereopsis and motion strongly interact in the specification of structure from motion, a result that complements earlier work on this problem.     

Sensory memory of illusory depth in structure-from-motion

When multistable displays (stimuli consistent with two or more equally plausible perceptual interpretations) are presented intermittently, their perceptions are stabilized by sensory memory. Independent memory traces are generated not only for different types of multistable displays (Maier, Wilke, Logothetis, & Leopold, Current Biology 13:1076–1085, 2003), but also for different ambiguous features of binocular rivalry (Pearson & Clifford, Journal of Vision 4:196–202, 2004). In the present study, we examined whether a similar independence of sensory memories is observed in structure-from-motion (SFM), a multistable display with two ambiguous properties. In SFM, a 2-D planar motion creates a vivid impression of a rotating 3-D volume. Both the illusory rotation and illusory depth (i.e., how close parts of an object appear to the observer) of an SFM object are ambiguous. We dissociated the sensory memories of these two ambiguous properties by using an intermittent presentation in combination with a forced-ambiguous-switch paradigm (Pastukhov, Vonau, & Braun, PLoS ONE 7:e37734, 2012). We demonstrated that the illusory depth of SFM generates a sensory memory trace that is independent from that of illusory rotation. Despite this independence, the specificities levels of the sensory memories were identical for illusory depth and illusory rotation. The history effect was weakened by a change in the volumetric property of a shape (whether it was a hollow band or a filled drum volume), but not by changes in color or size. We discuss how these new results constrain models of sensory memory and SFM processing.     

Sensory memory of structure-from-motion is shape-specific

Perceptual priming can stabilize the phenomenal appearance of multistable visual displays (Leopold, Wilke, Maier, & Logothetis, Nature Neuroscience, 5, 605–609, 2002). Prior exposure to such displays induces a sensory memory of their appearance, which persists over long intervals and intervening stimulation, and which facilitates renewed perception of the same appearance. Here, we investigated perceptual priming for the apparent rotation in depth of ambiguous structure-from-motion (SFM) displays. Specifically, we generated SFM objects with different three-dimensional shapes and presented them in random order and with intervening blank periods. To assess perceptual priming, we established the probability that a perceived direction of rotation would persist between successive objects. In general, persistence was greatest between identical objects, intermediate between similar objects, and negligible between dissimilar objects. These results demonstrate unequivocally that sensory memory for apparent rotation is specific to three-dimensional shape, contrary to previous reports (e.g., Maier, Wilke, Logothetis, & Leopold, Current Biology, 13, 1076–1085, 2003). Because persistence did not depend on presentation order for any pair of objects, it provides a commutative measure for the similarity of object shapes. However, it is not clear exactly which features or aspects of object shape determine similarity. At least, we did not find simple, low-level features (such as volume overlap, heterogeneity, or rotational symmetry) that could have accounted for all observations. Accordingly, it seems that sensory memory of SFM (which underlies priming of ambiguous rotation) engages higher-level representations of object surface and shape.     

On the Role of Vertical Texture Cues in Height Perception

When people judge height from the top looking down they tend to overestimate vertical distance. Initial findings suggest that this perceptual bias may be in part due to the experienced fear of falling. However, previous studies did not control for potentially relevant optical invariants, especially vertical texture gradient cues, that may inform such perceptual judgments. In this study, we examined to what degree texture gradient cues may account for the perceptual bias in height perception. To this end, in 2 different conditions in which vertical texture gradient cues were either present or absent, participants provided distance and size judgments from an elevated position (5.68 m) and from the ground. Results revealed a systematic overestimation of vertical extent and object size when judged from a height. Yet, the absence or presence of texture gradient cues did not differentially influence these judgments. Finally, although fear levels were reported to be larger at the elevated position than on the ground, fear levels did not correlate with the perceptual bias, thereby demanding further research into the mechanisms underlying the perceptual bias in height perception.