Distortions of depth-order relations and parallelism in structure from motion

Four experiments related human perception of depth-order relations in structure-from-motion dis-plays to current Euclidean and affine theories of depth recovery from motion. Discrimination between parallel and nonparallel lines and relative-depth judgments was observed for orthographic projections of rigidly oscillating random-dot surfaces. We found that (1) depth-order relations were perceived veridically for surfaces with the same slant magnitudes, but were systematically biased for surfaces with different slant magnitudes. (2) Parallel (virtual) lines defined by probe dots on surfaces with different slant magnitudes were judged to be nonparallel. (3) Relative-depth judgments were internally inconsistent for probe dots on surfaces with different slant magnitudes. It is argued that both veridical performance and systematic misperceptions may be accounted for by a heuristic analysis of the first-order optic flow.     

Perceiving surface slant from deformation of optic flow

Perceived surface orientation and angular velocity were investigated for orthographic projections of 3-D rotating random-dot planes. It was found that (a) tilt was accurately perceived and (b) slant and angular velocity were systematically misperceived. It was hypothesized that these misperceptions are the product of a heuristic analysis based on the deformation, one of the differential invariants of the first-order optic flow. According to this heuristic, surface attitude and angular velocity are recovered by determining the magnitudes of these parameters that most likely produce the deformation of the velocity field, under the assumption that all slant and angular velocity magnitudes have the same a priori probability. The results of the present investigation support this hypothesis. Residual orientation anisotropies not accounted for by the proposed heuristic were also found.     

3-D structure perceived from dynamic information: a new theory

Image movement provides one of the most potent two-dimensional cues for depth. From motion cues alone, the brain is capable of deriving a three-dimensional representation of distant objects. For many decades, theoretical and empirical investigations into this ability have interpreted these percepts as faithful copies of the projected 3-D structures. Here we review empirical findings showing that perceived 3-D shape from motion is not veridical and cannot be accounted for by the current models. We present a probabilistic model based on a local analysis of optic flow. Although such a model does not guarantee a correct reconstruction of 3-D shape, it is shown to be consistent with human performance.     

小学儿童英语正字法技能的发展及其在单词阅读中的作用

为系统探讨正字法技能不同成分的发展特点及其在英语单词阅读中的作用,对小学一、三、五年级共110名儿童施测英语正字法规则意识、正字法模式建构技能、正字法编码技能、单词阅读以及一般认知能力和英语语音意识测验。结果表明：（1）汉语儿童的英语正字法技能各成分随年级显著增长,各成分间及其与一般认知技能、语音意识的关系存在年级差异;（2）控制年龄、一般认知能力和语音意识后,正字法技能在三、五年级仍对单词阅读有显著的独立解释作用,且其独立贡献率高于语音意识;（3）进一步控制其他正字法技能成分后,正字法规则意识以正字法模式建构技能为完全中介间接地作用于单词阅读,正字法模式建构技能在三、五年级都仍对单词阅读有显著的独立解释作用,正字法编码技能在五年级中能显著地独立解释单词阅读的部分变异。     

Discriminating constant from variable angular velocities in structure from motion

We investigated accuracy in discriminating between constant and variable angular velocities for orthographic projections of three-dimensional rotating objects. The reported judgments of “constant” or “variable” angular velocity were only slightly influenced by the projected angular velocities, but they were greatly affected by the variations of the deformation, a first-order component of the optic flow. When viewing either a rotating ellipsoidal volume or a planar surface that accelerated and decelerated over the course of rotation, observers’ tendencies to report a variable angular velocity were increased when the temporal phase of the acceleration pattern increased the range of variation of the median deformation; the tendencies were decreased when the same acceleration pattern was used to decrease the range of variation of the median deformation. These results provide evidence contrary to the hypothesis that the visual system performs a mathematically correct analysis of the optic flow.     

Interrelation of the effects of binocular disparity and perspective cues on judgments of depth and height

The effects of binocular disparity (aniseikonia) and perspective cues operating together on judgments of depth and height were studied, both when these stimulus variables operated in the same direction and when they were in conflict. Both depth cues were effective upon the perception of depth and height. The effects of binocular disparity and perspective cues upon perceived depth were found to be additive. The effects of these depth cues upon perceived height showed some interaction in the sense that, operating together, the effect of the perspective cue was stronger than the separate effect of the perspective cue, both when binocular disparity and perspective cues operated in the same direction and when they were in conflict. This interactive effect increased with increasing strength of the perspective cues. The size-distance invariance hypothesis was confirmed under the present experimental conditions. By a causal analysis of inference, this invariant relation could be explained in the following way: both the perceived depth and the perceived height of the sides of the patterns were directly determined by binocular disparity and perspective cues, but the perceived height was also indirectly determined through change of perceived depth. A direct causal relation between perceived depth and perceived height was found.     

Influence of background on precision of 3D depth judgment tasks in a real environment

Presently, little is known about the effect of curved backgrounds against which the target stimulus is presented on precision in stereoacuity. The experiment analyzed the influence of stimulus orientation and 3D background configuration on stereoscopic vision. Participants were instructed to perform 3D visual alignment tasks on a modified version of the Howard-Dolman apparatus, whereupon precision in depth perception for different curved backgrounds (flat, black, concave, and convex) was evaluated. In addition, the influence of stimulus orientation (0 degrees, 45 degrees, and 90 degrees) on precision was examined. The findings revealed an underestimation in the perceived depth in all background configurations, indicating highest and lowest precision outcomes for convex and concave backgrounds, respectively. In addition, a significant interaction of background and orientation was found. It was concluded that, in a real environment, background local depth cues are integrated with target stimuli to contribute to depth perception.     

The role of syllabic and orthographic properties of letter cues in solving word fragments

The present research examined the role of phonological and orthographic properties of cues in mediating the retrieval of words from the mental lexicon. The task required subjects to resolve fragmented words when provided with semantically related cues (e.g., spiteful:---DIC----). Phonological properties of the letter cues were manipulated such that the letters either corresponded to the syllables (e.g., DIC in vindictive) or nonsyllables (NDI) in the word. Orthographic properties of the letter cues were manipulated by selecting letter groups that either co-occurred frequently in the language or did not. In two experiments, results revealed little or no effect of the phonological variable (syllables) but a reliable effect of the orthographic variable (letter-cue frequency). Letter cues with a low frequency of co-occurrence in the language led to better completion of the fragmented words. We interpret these findings as support for models of lexical representation that are based on orthographic properties (e.g., Seidenberg & McClelland, 1989) rather than those based on phonological constraints.     

Control-related beliefs and depressive symptoms in clinic-referred children and adolescents: developmental differences and model specificity

The contingency-competence-control (CCC) model links contingency and competence beliefs to perceived control and, in turn, to depression. However, a developmental perspective suggests that noncontingency may be too abstract a concept to be directly tied to depression before adolescence. We tested the CCC model and this developmental notion, using structural equation modeling, with 360 clinic-referred 8- to 17-year-olds. The CCC model fit the data well for the full sample accounting for 46% of the variance in depression. Separate analyses by age group placed perceived contingency in the best-fit model for adolescents (ages 12-17 years) but not for children (8-11 years). This suggests that abstract cause-effect concepts may have more direct affective impact after the cognitive changes of adolescence (e.g., formal operations) than before. Finally, the CCC model accounted for much more variance in depression than conduct problems, suggesting diagnostic specificity.     

Transfer-appropriate processing in the testing effect

The testing effect is the finding that taking a review test enhances performance on a final test relative to restudying the material. The present experiment investigated transfer-appropriate processing in the testing effect using semantic and orthographic cues to evoke conceptual and data-driven processing, respectively. After a study phase, subjects either restudied the material or took a cued-recall test consisting of half semantic and half orthographic cues in which the correct response was given as feedback. A final, cued-recall test consisted of the identical cue, or a new cue that was of the same type or different type of cue (semantic/orthographic or orthographic/semantic) as that used for that target in the review test. Testing enhanced memory in all conditions. When the review cues and final-test cues were identical, final recall was higher for semantic than orthographic cues. Consistent with test-based transfer-appropriate processing, memory performance improved as the review and final cues became more similar. These results suggest that the testing effect could potentially be caused by the episodic retrieval processes in a final memory test overlapping more with the episodic retrieval processes in a review test than with the encoding operations performed during restudy.     

面孔-人格知觉中眼部线索及其效应

人们常常会基于他人面孔特征对其人格做出相应推论。在影响面孔-人格知觉的五官特征中, 眼部特征最具复杂性。总体上, 眼部线索可分为可变和不可变两大类。可变线索包括注视方向、眼睑开放程度与眼部区域的表情等; 不可变线索包括眼睛大小、巩膜着色程度、虹膜颜色以及巩膜暴露指数等。从以上线索效应的潜在作用机制来看, 可以将眼部线索分为三大类, 即受病理因素影响的眼部线索、与特定群体相关的眼部线索和受主观意识或生理因素调控的眼部线索。此外, 也进一步指出了未来研究还需加以考虑的其他眼部特征效应, 以及待拓展深入的研究视角。     

Reading through a noisy channel: why there's nothing special about the perception of orthography

The goal of research on how letter identity and order are perceived during reading is often characterized as one of "cracking the orthographic code." Here, we suggest that there is no orthographic code to crack: Words are perceived and represented as sequences of letters, just as in a dictionary. Indeed, words are perceived and represented in exactly the same way as other visual objects. The phenomena that have been taken as evidence for specialized orthographic representations can be explained by assuming that perception involves recovering information that has passed through a noisy channel: the early stages of visual perception. The noisy channel introduces uncertainty into letter identity, letter order, and even whether letters are present or absent. We develop a computational model based on this simple principle and show that it can accurately simulate lexical decision data from the lexicon projects in English, French, and Dutch, along with masked priming data that have been taken as evidence for specialized orthographic representations.     

Is optic flow used to guide walking while wearing a displacing prism?

Rushton et al (1998 Current Biology 8 1191 - 1194) recently showed that walkers wearing displacing prisms follow curved trajectories determined by the perceived direction of their target. This suggests that optic flow is not important in guidance, since flow cues are unaffected by the prism and should allow a straight, direct trajectory. We replicated Rushton et al's result but also tried to rule out an important artifact associated with the prism. Prisms restrict the field of view and, particularly, access to the foreground optic flow that is likely to be important in providing guidance cues. We found that performance did not improve when walkers directed their gaze to include the foreground flow, suggesting that Rushton et al's results were not due to this artifact. On the other hand, performance did reliably improve when subjects reduced their viewing height by crawling towards the target. This improvement may be due to coarsening of the visual texture or to increased salience of alignment and motion-parallax cues. Whatever its cause, the improvement demonstrates that guidance is not determined only by perceived target direction and that, under some conditions, flow may be important.     

Effects of motion parallax and perspective cues on perceived size and distance

In three experiments we examined the relative effectiveness of motion parallax and two perspective cues for the perception of size and distance. The experimental stimuli consisted of two ellipses (a standard and a comparison) and a horizontal line that indicated the horizon. The subject's task was to report the apparent size and distance of the comparison stimulus relative to the standard stimulus. Two perspective cues were given by the relative heights of the two stimuli and the absolute height of the standard stimulus below the horizon. Motion parallax was defined by both the ratio and the difference in angular velocities between the two stimuli on the display. In experiment 1 we examined the effects of the two perspective cues and the motion parallax. In experiment 2 we eliminated the horizon line, and examined the role of the horizon in size and distance perception. In experiment 3 we separately evaluated the effects of motion parallax and the relative height cues. The results from the three experiments showed that the effect of motion parallax and the two perspective cues were different in three ways. First, the relative effectiveness of motion parallax and the two perspective cues differed for size and distance estimates. For size estimates, the motion parallax was more effective than the perspective cues (experiments 1 and 3). For distance estimates, the motion parallax was as effective as the two perspective cues (experiments 1 and 3). Second, the role of the horizon differed for size and distance estimates. The size estimates were strongly affected by the horizon, while the distance estimates were not affected much by the horizon (experiment 2). Third, the effective perspective cues differed for the size estimates and the distance estimates: size estimates were affected by the perspective cues as a combination of the horizon and relative height; distance estimates were affected by the perspective cues as an interaction between the absolute and relative heights without the horizon line.     

A Computational Model of the Self‐Teaching Hypothesis Based on the Dual‐Route Cascaded Model of Reading

The self‐teaching hypothesis describes how children progress toward skilled sight‐word reading. It proposes that children do this via phonological recoding with assistance from contextual cues, to identify the target pronunciation for a novel letter string, and in so doing create an opportunity to self‐teach new orthographic knowledge. We present a new computational implementation of self‐teaching within the dual‐route cascaded (DRC) model of reading aloud, and we explore how decoding and contextual cues can work together to enable accurate self‐teaching under a variety of circumstances. The new model (ST‐DRC) uses DRC’s sublexical route and the interactivity between the lexical and sublexical routes to simulate phonological recoding. Known spoken words are activated in response to novel printed words, triggering an opportunity for orthographic learning, which is the basis for skilled sight‐word reading. ST‐DRC also includes new computational mechanisms for simulating how contextual information aids word identification, and it demonstrates how partial decoding and ambiguous context interact to achieve irregular‐word learning. Beyond modeling orthographic learning and self‐teaching, ST‐DRC’s performance suggests new avenues for empirical research on how difficult word classes such as homographs and potentiophones are learned.     

Why Barbie feels heavier than Ken: the influence of size-based expectancies and social cues on the illusory perception of weight

In order to examine the relative influence of size-based expectancies and social cues on the perceived weight of objects, two studies were performed, using equally weighing dolls differing in sex-related and age-related vulnerability or physical strength cues. To increase variation in perceived size, stimulus objects were viewed through optical lenses of varying reducing power. Different groups of participants were required to provide magnitude estimates of perceived size, physical strength, or weight, or of expected weight. A size-weight illusion (SWI) was demonstrated, such that smaller objects felt heavier than larger ones, that was entirely accounted for by the mediating role of expected weight. Yet, perceived physical strength exerted an additional and more reactive influence on perceived weight independently of measured expectancies. Results are used to clarify the nature of "embodied", internal sensory-motor representations of physical and social properties.     

The perception of surface curvature from optical motion

Observers viewed the optical flow field of a rotating quadric surface patch and were required to match its perceived structure by adjusting the shape of a stereoscopically presented surface. In Experiment 1, the flow fields included rigid object rotations and constant flow fields with patterns of image acceleration that had no possible rigid interpretation. In performing their matches, observers had independent control of two parameters that determined the surface shape. One of these, called the shape characteristic, is defined as the ratio of the two principle curvatures and is independent of object size. The other, called curvedness, is defined as the sum of the squared principle curvatures and depends on the size of the object. Adjustments of shape characteristic were almost perfectly accurate for both motion conditions. Adjustments of curvedness, on the other hand, were systematically overestimated and were not highly correlated with the simulated curvedness of the depicted surface patch. In Experiment 2, the same flow fields were masked with a global pattern of curl, divergence, or shear, which disrupted the first-order spatial derivatives of the image velocity field, while leaving the second-order spatial derivatives invariant. The addition of these masks had only negligible effects on observers’ performance. These findings suggest that observers’ judgments of three-dimensional surface shape from motion are primarily determined by the second-order spatial derivatives of the instantaneous field of image displacements.     

Why do lie-catchers fail? A lens model meta-analysis of human lie judgments

Decades of research has shown that people are poor at detecting lies. Two explanations for this finding have been proposed. First, it has been suggested that lie detection is inaccurate because people rely on invalid cues when judging deception. Second, it has been suggested that lack of valid cues to deception limits accuracy. A series of 4 meta-analyses tested these hypotheses with the framework of Brunswik's (1952) lens model. Meta-Analysis 1 investigated perceived cues to deception by correlating 66 behavioral cues in 153 samples with deception judgments. People strongly associate deception with impressions of incompetence (r = .59) and ambivalence (r = .49). Contrary to self-reports, eye contact is only weakly correlated with deception judgments (r = -.15). Cues to perceived deception were then compared with cues to actual deception. The results show a substantial covariation between the 2 sets of cues (r = .59 in Meta-Analysis 2, r = .72 in Meta-Analysis 3). Finally, in Meta-Analysis 4, a lens model analysis revealed a very strong matching between behaviorally based predictions of deception and behaviorally based predictions of perceived deception. In conclusion, contrary to previous assumptions, people rarely rely on the wrong cues. Instead, limitations in lie detection accuracy are mainly attributable to weaknesses in behavioral cues to deception. The results suggest that intuitive notions about deception are more accurate than explicit knowledge and that lie detection is more readily improved by increasing behavioral differences between liars and truth tellers than by informing lie-catchers of valid cues to deception.     

Shifts of spatial attention in perceived 3-D space.

Previous studies have shown that spatial attention can shift in three-dimensional (3-D) space determined by binocular disparity. Using Posner's precueing paradigm, the current work examined whether attentional selection occurs in perceived 3-D space defined by occlusion. Experiment 1 showed that shifts of spatial attention induced by central cues between two surfaces in the left and right visual fields did not differ between the conditions when the two surfaces were located at the same or different perceptual depth. In contrast, Experiment 2 found that peripheral cues generated a stronger cue validity effect when the two surfaces were perceived at a different rather than at the same perceptual depth. The results suggest that exogenous but not endogenous attention operates in perceived 3-D space.     

Sentence reading: do we make use of orthographic cues in homophones?

Starting from the finding that currently phonological models of visual word processing predominate, we examined what happened when important morphological information is disclosed in the orthography but not in the phonology. To do so, we made use of a peculiarity in Dutch. In this language, some forms of the present and the past tense of verbs are homophones or homographs. This allowed us to look at the power of orthographic and phonological cues to derive the tense of the verb. Two experiments showed that orthographic cues alone suffice to recover the tense of the verb, and that this recovery does not take more time than tense recovery on the basis of a combination of orthographic and phonological cues. On the basis of these results, we conclude that orthographic cues in homophones are very efficient during silent reading. Our findings, however, do not allow us to conclude whether this is due to a direct route from orthography to meaning, or to a specialised, morpho-syntactic back-up strategy elicited by certain sequences of letters.