Influence of stimulus symmetry on visual scanning patterns

Eye movements of four Ss performing a complexity rating task in which the stimuli consisted of random shapes differing in symmetry, number of turns (sides) in the perimeter, and structural angularity were examined. It was found that for both symmetrical and asymmetrical shapes, the number of fixations and fixation time increased directly with structural complexity (number of sides). Distributions of fixations for symmetrical shapes clustered in one-half of the shapes, while the distributions of fixations for asymmetrical shapes did not exhibit this one-sided bias. No differences were found in the distributions of fixation time to either half of asymmetrical or symmetrical shapes. The findings suggest that S utilizes an organizing code in addition to the featural code in characterizing a given shape. The organizing code permits S to generate the feature code for a gwen shape on the basis of partial information.     

Young children's processing of asymmetrical and symmetrical patterns

Dot patterns varying in type of symmetry (double symmetry, vertical symmetry, horizontal symmetry, and asymmetry) were presented tachistoscopically for 200 msec, followed by a patterned mask, to kindergarten, second-grade, and fourthgrade children. All subjects reported symmetrical patterns more accurately than asymmetrical patterns. Double symmetry patterns were reproduced more accurately than vertical symmetry patterns, and vertical symmetry patterns were reproduced more accurately than horizontal symmetry patterns. These results stand in marked contrast to previous research by demonstrating that the ability to process symmetrical relationships evolves early in perceptual development. There was a suggestion that subjects of all ages perceived information about the type of symmetry presented in the display, but there were agerelated differences in subjects' abilities to use this knowledge in constructing their responses. Additionally, analyses revealed no age-related biases toward imposing symmetrical responses on asymmetrical patterns.     

No symmetry advantage when object matching involves accidental viewpoints

The presupposed advantage of symmetrical objects over asymmetrical objects was investigated in an object matching task, using accidental and non-accidental viewpoints. In addition, the accidental views could be symmetric or asymmetric. When two non-accidental views were presented, symmetrical objects were matched faster than asymmetrical objects. When an accidental view was presented first (followed by a non-accidental view), the matching of symmetrical objects was equal to that of asymmetrical objects. When a non-accidental view was presented first (followed by an accidental view), matching was again equal for the symmetrical and asymmetrical objects, although much faster compared with the opposite sequence of presented views. No effects of image symmetry in the accidental viewpoints were found. Apparently, the advantage of symmetrical objects over asymmetrical objects is only present in object matching when 3-D object structures are visible.     

Symmetry and asymmetry in interpersonal relations--with implications for the concept of projection

This paper first reviews evidence for some proposals about interpersonal relations These relations tend to be “symmetrical” or “asymmetrical”—i.e, involve similar or dissimilar characteristics for the two parties—depending on what the characteristics are. Certain characteristics (eg., love-hate) are—and are perceived to be—symmetrical, and others (eg, dominance-submission) asymmetrical The implications are then illustrated for the concept of projection A process of attributing to others characteristics that “explain” one's own would account for symmetrical projection for certain characteristics and asymmetrical projection for others This reformulation can provide a simpler and more unified account for cases that are traditionally treated separately as “supplementary” and “complementary” projection     

Features versus redundancy: comments on Massaro, Venezky, and Taylor's "Orthographic regularity, positional frequency, and visual processing of letter strings"

Massaro, Venezky, and Taylor (1979) found only a modest effect of familiarity on letter search, apparently because they pitted pseudowords (rather than real words) against nonwords and used lowercase rather than uppercase letters. Precuing the target letter seemed to reduce the familiarity effect they found yet further, but this conclusion is clouded by the fact that reaction time data were compared with accuracy data. Because similarity between target and nontarget letters tended to have more of an effect when familiarity had less of an effect. Massaro et al. proposed a successive model, with features being detected in the first stage and orthographic structure being used in a second stage. However, a concurrent model, with a self-terminating race between lower and higher level processes, can account for the data just as well. Data from Massaro et al. and from Krueger decisively demonstrate that there is a familiarity effect based on sequential redundancy over and above any effect based on spatial redundancy (Mason 1975). The Massaro et al. data also indicate that the relative familiarity effect is constant across various age groups (Krueger, Keen & Rublevich, 1974).     

物体相似性对空间表征的影响：来自眼动的证据

以三维场景图片为实验材料,采用眼动追踪技术,通过两个实验考察了对称场景中物体相似性对空间表征的影响。结果表明：（1）无相似物体条件下,场景本身的内在结构对空间表征有重要影响,对称轴方向可以作为空间表征参照方向;（2）存在部分相似物体条件下,物体的相似性会影响空间表征参照方向的选择,并且相似物体方向也是空间表征的参照方向之一。     

Identification of tachistoscopically exposed symmetrical and asymmetrical letter arrays.

Six-letter arrays containing symmetrical, e.g., H, M, T, or asymmetrical letters, e.g., J, K, R, were tachistoscopically exposed bilaterally for 100 msec. to 100 college students. Significantly more asymmetrical than symmetrical letters were identified, and significantly more Ss identified more asymmetrical than symmetrical items. This experiment, which incorporated methodological considerations suggested by Harcum (1964) and Bryden (1968), corroborates their findings. Their ideas and other findings were used to account for the data. Asymmetrical letters have more intrinsic left-to-right directionality than symmetrical elements. The rapidly fading after-stimulation of tachistoscopically presented alphabetical material is usually scanned from left to right. Individual array letters might also be scanned in the same direction. Confluence of directionality of letter and scan, which obtains only with asymmetrical letters, might have typically allowed asymmetrical targets to be scanned more rapidly and, consequently, more efficiently than symmetrical displays.     

Attention switching between global and local elements: Distractor category and the level repetition effect

When selecting information at global and local levels of hierarchical stimuli, there is a robust effect of level repetition in which performance is more efficient when a target is presented at the same level as the previous target. Moreover, the effect is symmetrical; it affects global and local processing equally. Evidence exists to suggest the effect may be automatic; however, we show here that the level repetition effect requires some amount of competition from the ignored level, and that the nature of the irrelevant information can determine whether the level-repetition effect is symmetrical (global and local responses are affected equally) or asymmetrical (global responses are more greatly affected than local responses). In Experiment 1, the level-repetition effect was eliminated when information at the distracting level was invariant across trials; effects of hemisphere bias and level repetition were observed only when suppression or filtering of distractor information was required. Experiment 2 demonstrated that simple featural variance is sufficient to produce the level repetition effect and that the symmetry of the level-repetition effect is sensitive to Garner-type interference that affects global processing to a greater extent than local processing. In Experiment 3, we showed that the absence of a level-repetition effect in the invariant distractor condition persists when the position of relevant stimuli is random within a block, a manipulation which should greatly reduce the contribution of controlled attention. We conclude that simple featural variance at the ignored level is critical to produce the advantage of level repetition, and that the size of the effect can be asymmetrical.     

On the perception of symmetrical and repeated patterns

Four experiments investigated rapid perceptual judgments about tachistoscopically presented patterns that were either symmetrical about or repeated across a vertical axis. The same patterns were presented under two different instructional conditions; some Ss were to judge the two halves of each pattern “same” or “mirror,” others were to judge each pattern as a whole “symmetrical” or “asymmetrical.” With dot patterns, RTs were faster for symmetrical than for repeated patterns when the two halves were close together, but not when they were separated, regardless of instructions. With simpler patterns made up of arrowheads and C-shapes, however, “same” RTs were faster than “mirror,” but “asymmetrical” RTs were marginally slower than “symmetrical,” regardless of spatial separation. The advantage of “same” over “mirror” did not seem to be simply a labeling effect. The results suggest that left-right symmetry is perceptually more salient than left-right repetition when the patterns are perceived holistically. By contrast, distinct patterns can be matched more rapidly when they are the same than when they are left-right mirror images.     

Perception of symmetry in infancy: the salience of vertical symmetry and the perception of pattern wholes

Four experiments were conducted to assess converging aspects of 4-month-old infants' perception of symmetry in visual patterns. Experiments 1 and 2 manipulated the structure and orientation of comparable patterns in order to evaluate the specialty of vertical symmetry. Infants showed no preference among vertically symmetrical, vertically repeated, and obliquely symmetrical patterns, but they processed vertically symmetrical patterns more efficiently than either vertically repeated patterns or obliquely symmetrical patterns. Experiment 3 manipulated the spatial separation of pattern components in order to determine the ability of young infants to integrate and coalesce information in visual patterns that is distributed in space. Infants processed vertically symmetrical patterns whose components were contiguous or nearly contiguous about the vertical axis (0 to 2.5 degrees separations) more efficiently than discontiguous patterns (5 and 10 degrees separations). Thus, extreme spatial separation about the vertical meridian caused infants to lose the advantage for vertical symmetry, and by inference their holistic perception of the visual pattern. Experiment 4 manipulated the organization of individual components of a vertical pattern in order to examine further infants' sensitivity to perceptual organization and synthesis of pattern form. Infants discriminated vertically symmetrical patterns from asymmetrical patterns with a vertical organization, thereby demonstrating sensitivity to the symmetrical organization of the pattern above their perception of components in the pattern. The results of these four experiments together corroborate and extend previous findings that vertical symmetry has a special status in early perceptual development and that infants can perceive pattern wholes.     

Preference for symmetry: only on mars?

Preference for symmetry is a robust bias found throughout the animal kingdom. In humans, the bias for symmetry has been documented in numerous domains, including faces and visual patterns. The function of this potent aesthetic bias still eludes us, but prominent accounts focus on its role in mate selection and perceptual fluency. Previous studies have shown that both males and females find symmetrical faces to be more attractive, but here we show that the preference for symmetry in neutral stimuli (ie everyday and meaningless visual objects) is, on the other hand, unique to male participants. Our findings indicate that symmetry preference cannot be explained exclusively by perceptual or computational efficiency, because such an account is domain-independent yet females did not show any bias for the objects tested here. Further studies are needed to elucidate the utility of the male preference for visual object symmetry.     

道路交通标志中对称结构效应的眼动研究

本研究考察了道路交通标志中路名信息对称结构效应的眼动模式。实验采用眼动跟踪技术和视觉搜索范式,共有16名被试参加。实验结果表明：（1）在对称结构路名信息的视觉搜索中,被试的反应正确率明显优于非对称结构条件下的正确率;（2）对称结构条件下,被试的注视点和回扫次数明显较少,凝视时间明显较短;（3）在以道路交通标志为视觉搜索材料时,搜索区有无路名目标对视觉搜索绩效没有影响。可以认为：在道路交通标志中存在对称结构效应;眼动模式的差异是引起对称结构效应的认知机制。     

Identification of symmetry: Effects of stimulus orientation and head position

It has been argued that the perceptual advantage of symmetry depends upon the essentially symmetrical properties of the visual system. According to this explanation, the ease of identification of symmetries about different axes of orientation should decrease with increasing distance from the vertical: Reaction times to vertical symmetry should be faster than those to diagonal symmetry, which in turn should be faster than those to horizontal symmetry. Previous research demonstrating this pattern of responding employed stimuli with linear axes. In the present study, the subjects viewed tachistoscopically presented symmetrical and asymmetrical dot patterns (which had no explicit axes) in one of three head positions: upright, 45 deg left, and 45 deg right. The subjects’ performance failed to support the structural explanation: Identification of symmetry is equivalently fast for vertical and horizontal; vertical and horizontal show strong advantages over obliques, and this general advantage follows retinal coordinates. Findings are discussed in light of alternative theories of symmetry processing.     

The influence of visual symmetry on the encoding of objects

Two experiments examined how symmetry affects the visual encoding of simple flat objects (lamellae). Experiment 1 showed that subjects encode a lamella's shape as both a facsimile and its enantiomorph. In Experiment 2 the errors made when responding to symmetrical and asymmetrical stimuli showed that there were three factors affecting the reproduction of a symmetrical stimulus. These are, in order of decreasing influence, (i) the orientation of the axis of symmetry, (ii) the presence of overall symmetry (irrespective of orientation), and (iii) identity of the orientation of the elements of the response in relation to those of the stimulus. They also show that symmetry is likely to be reproduced even where the reproduction is not of the same shape as the original stimulus. The relevance of these results to representation of objects is discussed.     

The shapes associated with approach/avoidance words

People prefer curved and symmetrical shapes to their angular and asymmetrical counterparts. While it is known that stimulus valence is central to approach and avoidance motivation, the exact nature of the relationship between curvature/symmetry and approach/avoidance motivation still needs to be clarified. Experiment 1 was designed to investigate whether simple shapes are associated with approach and avoidance words. Participants found it easier to match more symmetrical shapes with approach words. In Experiment 2, symmetry was differentially associated with approach words and was rated significantly higher on the approach dimension than asymmetry. Next, we assessed whether object valence and object curvature (Experiment 3) or symmetry (Experiment 4) would lead to different associations to approach and avoidance words. Only object valence had a significant influence on participants’ ratings, with the positively-valenced objects being more closely associated with approach words than their negatively-valenced counterparts. These results highlight the complex relation between visual properties of objects, their valence, and appetitive and aversive categories.     

Learning to like it: Aesthetic perception of bodies,movements and choreographic structure

Appreciating human movement can be a powerful aesthetic experience. We have used apparent biological motion to investigate the aesthetic effects of three levels of movement representation: body postures, movement transitions and choreographic structure. Symmetrical (ABCDCBA) and asymmetrical (ABCDBCA) sequences of apparent movement were created from static postures, and were presented in an artificial grammar learning paradigm. Additionally, “good” continuation of apparent movements was manipulated by changing the number of movement path reversals within a sequence. In an initial exposure phase, one group of participants saw only symmetrical sequences, while another group saw only asymmetrical sequences. In a subsequent test phase, both groups rated all sequences on an aesthetic evaluation scale. We found that posture, movement, and choreographic structure all influenced aesthetic ratings. Separate ratings for the static body postures presented individually showed that both groups preferred a posture that maximized spatial symmetry. Ratings for the experimental sequences showed that both groups gave higher ratings to symmetrical sequences with “good” continuation and lower ratings to sequences with many path reversals. Further, participants who had been initially familiarized with asymmetrical sequences showed increased liking for asymmetrical sequences, suggesting a structural mere exposure effect. Aesthetic preferences thus depend on body postures, apparent movement continuation and choreographic structure. We propose a hierarchical model of aesthetic perception of human movement with distinct processing levels for body postures, movements and choreographic structure.     

Multidimensional letter similarity derived from recognition errors

In order to provide a reliable measure of the similarity of uppercase English letters, a confusion matrix based on 1,200 presentations of each letter was established. To facilitate an analysis of the perceived structural characteristics, the confusion matrix was decomposed according to Luce’s choice model into a symmetrical similarity matrix and a response bias vector. The underlying structure of the similarity matrix was assessed with both a hierarchical clustering and a multidimensional scaling procedure. This data is offered to investigators of visual information processing as a valuable tool for controlling not only the overall similarity of the letters in a study, but also their similarity on individual feature dimensions.     

Alphabetic letter identification: effects of perceivability, similarity, and bias

The legibility of the letters in the Latin alphabet has been measured numerous times since the beginning of experimental psychology. To identify the theoretical mechanisms attributed to letter identification, we report a comprehensive review of literature, spanning more than a century. This review revealed that identification accuracy has frequently been attributed to a subset of three common sources: perceivability, bias, and similarity. However, simultaneous estimates of these values have rarely (if ever) been performed. We present the results of two new experiments which allow for the simultaneous estimation of these factors, and examine how the shape of a visual mask impacts each of them, as inferred through a new statistical model. Results showed that the shape and identity of the mask impacted the inferred perceivability, bias, and similarity space of a letter set, but that there were aspects of similarity that were robust to the choice of mask. The results illustrate how the psychological concepts of perceivability, bias, and similarity can be estimated simultaneously, and how each make powerful contributions to visual letter identification.     

The Goldmeier effect in adults and children: environmental, retinal, and phenomenal influences on judgments of visual symmetry

Adults judge that patterns symmetrical about the vertical axis are more similar to standard patterns symmetrical about both major orthogonal axes than are patterns which are symmetrical only about the horizontal axis (the Goldmeier effect). Thus, symmetry about the vertical axis is more salient for adults than symmetry about the horizontal axis. Two experiments are reported in which subjects from three age groups (preschool, 8 years old, and adult) were given Goldmeier problems under different conditions. In experiment 1 three head-tilt conditions were used (0 degrees, 45 degrees, 90 degrees); in experiment 2 there were four conditions defined by head orientation (0 degrees, 90 degrees) and phenomenal instructions (top of figure at 0 degrees or at 90 degrees). In both experiments, increasing head tilt from 0 degrees decreased the consistency with which the environmentally vertical pattern was chosen. Noncorrespondence between the three spatial frameworks (environmental, retinal, and phenomenal) failed to produce biases in favor of either retinal-egocentric or phenomenal systems. For rotated adult subjects in experiment 2, 0 degrees phenomenal instructions strengthened an environmental bias, and 90 degrees phenomenal instructions shifted responses toward a retinal bias. These findings provide strong refutation of explanations for symmetry perception that are based solely upon the anatomical symmetry of the visual system. The data also fail to support arguments for environmental or phenomenal frameworks as singular influences. The results are best explained in terms of failure of constancy mechanisms to coordinate environmental and retinal information as a function of degree of head rotation and stimulus complexity.     

Biased information and the exchange paradox

This paper presents a new solution to the well-known exchange paradox, or what is sometimes referred to as the two-envelope paradox. Many recent commentators have analyzed the paradox in terms of the agent’s biased concern for the contents of his own arbitrarily chosen envelope, claiming that such bias violates the manifest symmetry of the situation. Such analyses, however, fail to make clear exactly how the symmetry of the situation is violated by the agent’s hypothetical conclusion that he ought to switch envelopes on the assumption that his own envelope contains some specific amount of money. In this paper, I offer an explanation of this fact based on the idea that the agent’s deliberations are not only constrained by the epistemic symmetry reflected in the agent’s uniform ignorance as to the contents of the two envelopes, but also by a deeper methodological symmetry that manifests itself in the intuition that the two envelopes constitute equally legitimate sources of potential information. I interpret this intuition as implying that the agent’s final decision should reflect a point of rational equilibrium arrived at through an iterated process of counterfactual self-reflection, whereby the agent takes account of what he would have thought had he instead chosen the other envelope. I provide a formal model of this method of counterfactual self-reflection and show, in particular, that it cannot issue in the paradoxical conclusion that the agent ought to switch regardless of how much money is in his envelope. In this way, by correcting for the bias in the agent’s reasoning, the paradox is resolved.