Hierarchical structure in perceptual representation

A theoretical framework for perceptual representation is presented which proposes that information is coded in hierarchical networks of nonverbal propositions. The hierarchical structure of the representations implies selective organization: Some subsets of a figure will be encoded as integral, structural units of that figure, while others will not. A context-sensitive metric for the “goodness” of a part within a figure is developed, corresponding to the probability that the subset will be encoded as a structural unit. Converging evidence supporting this position is presented from four different tasks using simple, straight-line figures. The tasks studied are (a) dividing figures into “natural” parts, (b) rating the “goodness” of parts within figures, (c) timed verification of parts within figures, and (d) timed mental synthesis of spatially separated parts into unitary figures. The results are discussed in terms of the proposed theory of representation, the processes that operate on those representations, and the general implications of the data for perceptual theories.     

Ambiguous figures: role of context and critical features

Context and attention to critical features as factors in determining the perceptual organization of ambiguous figures were investigated in the present two studies. In the first study, a fixation point directed attention to a critical or to a neutral feature of an ambiguous figure. Placement of the fixation point on different features of an ambiguous figure did not affect the figure-ground organization of the figure, but it did influence the speed of the identification response. In the second study, presentation of an ambiguous figure was preceded by a biased figure or by features of the figure. Results indicated that the interpretation of the ambiguous figure was overwhelmingly influenced by the advanced presentation of a biased drawing but only slightly influenced by the advanced presentation of a critical feature. These findings support analysis-by-synthesis (Neisser, 1967) as an explanation of the perception of ambiguous figures over other contemporary attention theories.     

Learning geographical information from hypothetical maps

People show biases or distortions in their geographical judgments, such as mistakenly judging Rome to be south of Chicago (the Chicago-Rome illusion). These errors may derive from either perceptual heuristics or categorical organization. However, previous work on geographic knowledge has generally examined people's judgments of real-world locations for which learning history is unknown. This article reports experiments on the learning of hypothetical geographical spaces, in which participants acquired information in a fashion designed to control real-world factors, such as variable travel experiences or stereotypes about other countries, as well as to mimic initial encounters with locations through reading or conventional school-based geography education. Five experiments combine to suggest that biases in judgment based on learning of this kind are different in key regards from those seen with real-world geography and may be based more on the use of perceptual heuristics than on categorical organization.     

Mirror symmetry opposes splitting of chromatically homogeneous surfaces

Chromatically homogeneous surfaces can be seen as single figures but also as two or more overlapping figures. Local factors such as relatability have been proposed in order to explain perception of two or more figures (Kellman and Shipley, 1991 Cognitive Psychology 23 141-221). However, even when these factors are at work, there are conditions favouring the perception of a single figure, which have not been explored so far. Here we propose that one such factor is the mirror symmetry of the surface. Three experiments were designed to test: (a) the main hypothesis, that mirror symmetry enhances perception of a single figure; (b) the role of orientation; (c) the effect of the number of axes of symmetry. The results show that (i) there is a good general correlation between mirror symmetry and perception of a single figure; (ii) vertical and horizontal axes of symmetry are the most effective; and (iii) the more axes of symmetry a surface has, the more likely is the perception of a single figure. These results suggest that mirror symmetry is an important factor in the perception of chromatically homogeneous displays. Some explanations are discussed, particularly one based on the rejection-of-coincidence principle [Rock, 1983 The Logic of Perception (Cambridge, MA: MIT Press)], and a version of the minimum principle in which the strength of the global solution depends on symmetry, whereas the strength of the splitting solution depends on the strength of local factors. In brief, global and local factors compete in determining the perceptual outcome in chromatically homogeneous surfaces.     

Ambiguous figures and representationalism

Macpherson (Nous 40(1):82–117, 2006) argues that the square/regular diamond figure threatens representationalism, construed as the theory which holds that the phenomenal character is explained by the nonconceptual content of experience. Her argument is the claim that representationalism is committed to the thesis that differences in the experience of ambiguous figures, the gestalt switch, should be explained by differences in the NCC of perception of these figures. However, with respect to the square/regular diamond and some other ambiguous figure representationalism fails to offer a unified account of how representational content makes them ambiguous. In this paper, I aim, first, to offer a representationalist account of ambiguous figures and, second, to examine and rebut Macpherson’s arguments. My main point is that in each ambiguous figure Macpherson discusses there are differences in representational content that can explain differences in phenomenal character or content. The representational differences are due to the ways the Cartesian frame of reference in which perceptual content is always cast cuts the figure, underlying different properties of the figure with respect to the axes of the Cartesian frame of reference.     

Context influence on the perception of figures as conditional upon perceptual organization strategies

Two experiments tested the effect of context on figure perception. Subjects were shown rapid sequences of three figures: a prime, a whole, and a part. They were asked to decide if the third figure was a part of the second (Experiment 1) or if the second and third figures were the same or different with respect to a particular angle (Experiment 2). The prime served to establish a context for stimuli that followed to be compared. Priming had influence on the part—whole comparison in Experiment 1, but not on the local comparison in Experiment 2. The results of Experiment 1 were interpreted as evidence for a role of prior information in perceptual organization. Experiment 2 showed that the task must require an integrative perceptual organization strategy for the priming effects to occur.     

基于物体的选择性注意理论的证据--对一例视觉忽视病人的研究

对一例视觉忽视病人的研究发现,线段划销任务中其忽视以基于相邻性组织而形成的知觉物体为中心;对视野两侧图形是否一样的判断受连通性组织的影响;报告数字时受基于颜色的相似性组织的影响.结果为基于物体的选择性注意理论提供了神经心理学证据.     

Temporal resolution of figures and grounds

Recent studies have demonstrated that establishing figure–ground organization influences other perceptual processes. Specifically, figures undergo perceptual processing earlier than ground regions (Lester, Hecht, & Vecera, 2009), and they are processed for longer durations relative to ground regions (Hecht & Vecera, 2011). One potential consequence of figures' extended processing is degraded temporal resolution compared to ground regions. To test this hypothesis, observers completed a modified flicker-fusion task while viewing either displays that contained well-defined figures and grounds or displays that were ambiguous. As evidenced by increased sensitivity for flickering targets on the ground regions, the current results support the claim that figures have poorer temporal resolution than ground regions.     

Regularity of symmetry verticality guides perceptual judgments of objects

Previous research indicated that most salient, real-world objects possess natural regularities that observers commonly assume in perceptual judgments of figural orientation and interpretation. Regularities include 3-dimensionality, bilateral symmetry, and the tendency for object tops to possess more salient information than bottoms. Thus, when observers interpret randomly shaped figures, they reliably impose volume, bilateral symmetry, and top and front orientation directions, even when figures are 2-dimensional and asymmetric. We confirmed generalizability for observers to assume these regularities with stimuli that vary in complexity, and we found evidence supporting another regularity, that of symmetry verticality (symmetry about a vertical axis). Findings support use of a family of perceptual heuristics corresponding to natural regularities that constrain stimulus indeterminacy and help guide judgment of object orientation and interpretation.     

Classes and collections: Conceptual organization and numerical abilities

Collections (e.g., forest, army) and classes (e.g., trees, soldiers) are natural concepts that differ in their organizational principles. Collections are organized into part-whole relations (e.g., trees are parts of a forest). Classes are organized according to class inclusion relations (e.g., oaks are kinds of trees). Because of their part-whole organization, collections are assumed to have greater psychological coherence than classes and therefore an advantage on tasks that require thinking about an aggregate as well as the individuals in it. Number requires aggregate analysis since it is a characteristic of sets, not of individuals. Four studies tested the hypothesized collection advantage in numerical reasoning tasks. In each, children viewed identical displays that were labeled with either class or collection terms. With perceptual input constant, the collection labels in contrast to the class labels promoted children's insight into certain numerical principles and facilitated the use of these principles in a variety of numerical tasks. Collection labels appear to induce a cognitive reorganization of importance to the child: the shift from inclusion to part-whole relations.     

Human figure drawings of gender-problem and school-problem boys

In this study 19 boys aged 4 through 13 years referred for gender problems were compared with 35 similar-aged boys referred for school problems on variables derived from sets of human figure drawings. The results indicated that gender-problem boys, relative to school-problem boys, were more likely to draw female figures in response to a Draw-a-Person (DAP) instruction, were more likely to draw figures with good rather than average body proportion, tended to draw more articles of clothing on their figures, and tended to draw their female figures larger than their male figures. There were no differences between the groups in the frequency of emotional disturbance indicators, frequency of age-expected or age-exceptional figure details, and total number of body features. These results are discussed in terms of their implications for the validation of the DAP procedure, their contribution to an understanding of boyhood effeminacy, and their implications for the role of the DAP test as a clinical assessment procedure only in conjunction with other sources of information.     

A further investigation of apparent size and retinal size as determinants of the figural after-effect

A figure which is more distant from the eye than another but subtends the same visual angle is usually seen as the larger. This phenomenon is called perceptual size constancy. Experiments have been reported which show that sometimes the apparent and sometimes the retinal sizes of the stimulus figures determine the direction of the figural after-effect. These experiments are reviewed and two further experiments are reported. In the first experiment two types of stimulus figure (discs and annuli) which subtended a visual angle of 1° 36' resulted in figural after-effects, the direction of which would have been predicted by the retinal sizes of the figures. In the second experiment larger figures were used which subtended a visual angle of about 4° and which were the same as those used by Sutherland (1954). In this experiment the after-effects were generally in a direction which would have been expected if apparent size determined the direction of the after-effect. In the interpretation of the results attention is drawn to the “Central Tendency Effect” which has been observed in size judgements of stimulus figures of varying size. Two hypotheses are suggested; one is that the true figural aftereffect has been obscured by the “Central Tendency Effect” in successive judgements, and the other is that time error in successive judgements of size is essentially a figural aftereffect. Some supportive evidence for the latter hypothesis is reported. It is concluded that apparent size is not a critical determinant of the figural after-effect.     

Illusion decrement and transfer of illusion decrement in real- and subjective-contour Poggendorff figures

The reduction in illusion magnitude with visual inspection and the transfer of such illusion decrement to a noninspected figure were examined in real- and subjective-contour Poggendorff figures. For both types of figures, illusion magnitude decreased significantly, and in a similar manner, during a 5-min inspection period. Postinspection tests showed that inspecting either a real- or subjective-contour figure resulted in a reduction in illusion magnitude for the other, noninspected figure. These findings suggest that real- and subjective-contour Poggendorff figures share a similar global organization and are thus probably processed in a similar manner. These characteristics make subjective-contour figures a useful tool for separating illusion-producing mechanisms into structural and strategy components.     

The effects of figure/ground, perceived area, and target saliency on the luminosity threshold

Observers adjusted the luminance of a target region until it began to appear self-luminous, or glowing. In Experiment 1, the target was either a face-shaped region (figure) or a non-face-shaped region (ground) of identical area that appeared to be the face's background. In Experiment 2, the target was a square or a trapezoid of identical area that appeared as a tilted rectangle. In Experiment 3, the target was a square surrounded by square, circular, or diamond-shaped elements. Targets that (1) were perceived as figures, (2) were phenomenally small in area, or (3) did not group well with other elements in the array because of shape appeared self-luminous at significantly lower luminance levels. These results indicate that like lightness perception, the luminosity threshold is influenced by perceptual organization and is not based on low-level retinal processes alone.     

Psychological relations and psychophysical scales: On the status of “direct” psychophysical measurement

Arguments, originally developed some fifteen years ago, concerning the sort of “direct” psychophysical measurement advocated by S. S. Stevens are reproduced here in order to facilitate access by a wider audience. Considerations of measurement theory, biological adaptation, perceptual invariance, and neurophysiological noise, as well as various empirical results, suggest (a) that it is primarily the relations—particularly the ratios—between stimulus magnitudes and not the individual magnitudes themselves that are represented within the organism and, accordingly, (b) that “direct” psychophysical measurement, by itself, uniquely determines neither a psychological magnitude of any one stimulus nor a psychophysical law relating such psychological magnitudes to corresponding physical magnitudes. What such measurement can uniquely determine, evidently, is a psychological parameter characterizing each sensory continuum.     

Differences in top-down influences on the reversal rate of different categories of reversible figures

Understanding the mechanisms underlying the multistability of reversible figures may provide valuable insights into the normal functioning of our visual system. The proposed factors that control the perceptual alternations of reversible figures can be classified into bottom-up and top-down processes. In the present study, we report differences in top-down effects on the reversal rate depending on whether a structural perspective (Necker cube, Schr?der staircase) or a meaningful content (duck/rabbit figure, chef/dog figure) is subject to the reversal phenomenon. In order to activate top-down mechanisms explicitly the subjects had the instruction to bring the reversal rate under voluntary control. The results indicated that both slowing down and speeding up the rate of alternations was more effective for the content-reversal figures (duck/rabbit, chef/dog) than for the rather abstract perspective-reversal figures (Necker cube, Schr?der staircase). In order to investigate the effect of meaningfulness in figure/ground reversals, the effect of the same instructional variable was also determined for Rubin's vase/faces and the Maltese cross. The results showed a similar tendency as in the case of the comparison between perspective reversals and content reversals. Possible cognitive processes that may play a role in top-down influences on figure reversal and theoretical implications of these findings for the interaction of bottom-up and top-down processes are discussed.     

Figure-ground organization in real and subjective contours: a new ambiguous figure, some novel measures of ambiguity, and apparent distance across regions of figure and ground

This study was designed to assess the effects of organization, luminance contrast, sector angle, and orientation on a new, highly ambiguous Cs-keyhole figure. Organization and contrast were the most important factors, and sector angle also influenced figure-ground relationships. There was no significant effect of orientation, nor was there any significant interaction between any of the factors. Several new measures of figure-ground organization were developed, such as ambiguity ratios based on reaction times and on ratings of the strength of perceived organizations, providing new quantitative measures of figure-ground relationships. Distances measured across figural regions appeared smaller than equal distances across the ground in the new reversible figure, and also in Rubin's classic vase-face figure presented in real and subjective contours. Inducing a perceptual set to see a particular organization in a reversible figure influenced the apparent distance across that organization. Several possible explanations of the observed effects are considered: (1) an instance of Emmert's law, based on the difference in apparent depth of figure and ground; (2) an aspect of the Müller-Lyer illusion; (3) a feature-detector model of contour attraction; (4) a natural set or predisposition to see a figure as smaller; and (5) framing effects. The first two explanations appear the most promising.     

More evidence on size modification in spatial axes systems of varying complexity

Pictorial space can be conceptualized as aggregate space (where figures compete for limited available space) or as axial space (where space is infinite and exists independently of figures). That these two kinds of space concepts follow a developmental sequence was tested by investigating size regulation mechanisms in 7- to 12-year-old children's figure drawings. An earlier longitudinal study had shown that the more figures were drawn and the more complex the spatial axes system, the smaller the figures. Two studies confirmed that object-driven size reduction was the size regulation mechanism in younger children, whereas axes-driven size reduction was the only factor regulating figure size in 12-year-old children. Size reduction occurred in a gradual fashion in younger children, whereas size reduction was more pronounced in crossed axes systems in older children. In addition, 7-year-old children showed a dynamic and fluid interaction between internal and external task demands for size regulation.     

Relative spatial expansion and contraction within the Müller-Lyer and Judd illusions

The shaft portions of Müller-Lyer (M-L) figures, one-ended M-L figures, Judd figures, and their respective control (tails-up) figures were divided by subjects into eight equal-appearing intervals by means of successive bisections. For most of the control stimuli the length of the left half of the shaft tended to be overestimated relative to the length of the right side. For the tails-out version of the M-L figure, there was relative overestimation of segments of the shaft adjacent to the tails, while for the tails-in version there was relative underestimation of these segments. These results indicate that the distortion of perceived length in the M-L illusion is not distributed evenly along the shaft. For the one-ended M-L figures the apparent overestimations and underestimations extended further along the shaft than for the standard figures. For the Judd figure perceived length varied systematically along the length of the shaft from underestimation near the tails-in end of the figure to overestimation near the tails-out end. These results are contradictory to the hypothesis that the M-L illusion results from inappropriate size scaling produced through the operation of size-constancy mechanisms, since this conjecture would predict uniform expansion or contraction. The results are compared with findings that localization responses are accurate for M-L figures but biased for one-ended M-L figures and Judd figures.