Grouping information for judgments

Models of cue weighting in judgment have typically focused on how decision-makers weight cues individually. Here, the authors propose that people might recognize and weight groups of cues. They examine how judgments change when decision-makers focus on cues individually or as parts of groups. Several experiments demonstrate that people can spontaneously pack information into cue groups. Moreover, group-level weighting depends on how people assess similarity or how they think of categorical hierarchies.     

Perception of illumination

Abstract.— Previous research on the perception of illumination has primarily been occupied with the apparent paradox that "we must know the object colour in order to utilize the reflected light as an index of illumination, while we must know the illumination in order to use the reflected light as an index of object colour". The present study shows this paradox to exist only as a long as the traditional one-dimensional conception of achromatic colours is maintained. Two experiments are reported. In Exp. 1 it is shown that by mere variation of the luminance difference of two adjacent areas, a consistent shift in colourlshadow discrimination is obtained; i.e. within a certain range of luminance differences the observer may find it difficult to decide whether the difference is one of colour (two fields of different greyness in common illumination) or one of illumination (two fields of equal greyness under different illumination), above this range the observer perceives the differences as one of illumination. Taking the bidimensionality of achromatic colours into account in Exp. 2, results are obtained which show the brightness (alternatively termed luminosity) relations of adjacent areas to be the critical factor for the perceptual shift.     

Grouping with and without attention

The effects of perceptual grouping on a line discrimination task were investigated using Moore and Egeth's (1997) paradigm. Observers judged which of two lines, presented one above the other over a matrix of spots, was longer. On some trials, larger spots at both ends of the lines formed arrowheads, thereby making possible the Müller-Lyer illusion. When observers attended only to the lines, they were not aware of the arrowheads. Yet their line judgment performance showed that they had succumbed to the illusion. When the observers' attention was directed to the arrowheads but they nevertheless failed to discern the arrowheads' orientation, their line judgments were still influenced by the illusion.     

Grouping does not require attention

Many theories of visual perception stipulate that Gestalt grouping occurs preattentively. Subjects' failure to report perceiving even salient grouping patterns under conditions of inattention challenges this assumption (see, e.g., Mack, Tang, Tuma, Kahn, & Rock, 1992), but Moore and Egeth (1997) showed that although subjects are indeed unable to identify grouping patterns outside the focus of attention, effects of these patterns on visual perception can be observed when they are assessed using implicit, rather than explicit, measures. However, this finding, which is the only one to date demonstrating grouping effects without attention, is open to an alternative account. In the present study, we eliminated this confound and replicated Moore and Egeth's findings, using the Müller-Lyer illusion (Experiments 1 and 2). Moreover, we found converging evidence for these findings with a variant of the flanker task (Experiment 3), when the amount of available attentional resources was varied (Experiments 4 and 5). The results reinforce the idea that, although grouping outside the focus of attention cannot be the object of overt report, grouping processes can occur without attention.     

Grouping in the shine-through effect

How the elements of a visual scene are grouped into objects is one of the most fundamental but still poorly understood questions in visual neuroscience. Most investigations of perceptual grouping focus on static stimuli, neglecting temporal aspects. Using a masking paradigm, we show that the neural mechanisms underlying grouping seem to be both fast and complex. For example, a vernier target was followed by, first, a briefly presented grating and, then, a long-lasting, extended grating. Under these conditions, the briefly presented grating is hardly visible. Still, vernier discrimination strongly changed with the number of elements of the briefly displayed grating being worst for small gratings. In accordance with a neural network model of masking, we propose that the edges of the briefly presented grating and the vernier interfere in spite of the short presentation time. We suggest that this fast edge processing is a first step for unconscious grouping processes.     

The phantom illumination illusion

A novel brightness illusion in planar patterns is reported. The illusion occurs, for example, when surfaces with a luminance ramp shaded from black to white are positioned on a black homogeneous background, so that each white end of the surfaces faces a single point of the plane of the pattern. The illusion consists of the enhancement of the brightness of the background in a relatively wide area around the white ends of the surfaces. A parametric study was conducted in which participants were asked to rate the difference in brightness between the parts of the background inside and outside a virtual circle formed by disks with different luminance ramps. The results show that mean ratings of brightness depended on the luminance of the background, the luminance range of ramps, and the kind of ramp. Discussion of these results with reference to other brightness illusions (assimilation, neon color spreading, anomalous surfaces, visual phantoms, grating induction, and the glare effect) shows that t hephantom illumination illusion derives from processes producing the perception of ambient illumination.     

The Grouping Process Across Cultural Change

Based on their extensive experience working with individuals, families, groups and organizations in Greece, the authors describe therapeutic techniques for helping individuals understand and work through the acculturation process. Tasks and procedures employed at various social levels--dyads, triads, small groups of four to six members, and large groups of 18-25--are catalysts for the exploration and clarification of the ways in which old norms and roles are being modified, weakened, or distorted by cultural change, and for the redefinition of values and expectations.     

Comparison, Grouping, and Preference

How does the attractiveness of a particular option depend on comparisons drawn between it and other alternatives? We observe that in many cases, comparisons hurt: When the options being compared have both meaningful advantages and meaningful disadvantages, comparison between options makes each option less attractive. The effects of comparison are crucial in choice problems involving grouped options, because the way in which options are grouped influences which comparisons are likely to be made. In particular, we propose that grouping focuses comparison, making within-group comparisons more likely than between-group comparisons. Consistent with this prediction, experimental results showed that grouping hurts: An option is more likely to be chosen when alone than when part of a group.     

Grouping effects in flash-induced perceptual fading

We show that the flash-induced fading effect can be influenced by grouping based on colour and shape similarity. In flash-induced fading, peripherally presented elements perceptually disappear after a flash has been presented around or next to the element(s) (Kanai and Kamitani, 2003 Journal of Cognitive Neuroscience 15 664-672). In the present study, two elements (which could either be similar or different in both colour and shape) were presented at an eccentricity of 2.6 degrees from a fixation cross. After 2 s, a short flash (40 ms) was presented around one of the elements. The two elements remained on the screen for 2.5 s after the flash. We found a higher percentage of mutual perceptual disappearance when the two elements were similar in colour or in shape. These results converge with other findings showing that perceptual fading phenomena are influenced by effects of perceptual grouping. This indicates that, besides low-level adaptation, more global processes play a part in perceptual fading as well and should thus be taken into account in giving a full explanation of perceptual fading in general.     

Spatial frameworks in imagined navigation

The spatial framework model proposes that people use the extensions of their body axes as a reference frame for encoding spatial layouts in memory, and that the physical and functional properties of our bodies and the world determine the accessibility of egocentric locations from memory representations. The present experiment provides evidence that spatial framework results can be obtained even with perceptual scenes that contain no objects to be held in memory. Using a paradigm in which participants interpreted direction and distance information to follow a mental path within a checkerboard grid, the present study shows that spatial framework results are obtained when reasoning occurs from a perspective that is misaligned with respect to the physical reference frame of the participant. The theoretical implications of these results are discussed.     

汉语词组的先行词联想效应

该研究在两个实验中以眼动控制方法探讨了影响汉语四字词组歧义出现的因素。实验一的结果表明这种观点是错误的:在句子理解过程中偏正词组专科学生中间的两个字符出现了歧义效应,正确的结论是在正常的汉语句子阅读中这种歧义效应不会出现;实验二检验了这种词组出现歧义效应的必要条件即这两个字符作为先行词必须出现在句首,这是一种新近性效应,结果表明这个先行词是汉语四字词组歧义出现的必要条件,这符合单一方向的句法分析假设与先行词联想效应,先行词实际上所发挥的作用就是一种背景效应或者称作先行词联想效应。     

视知觉组织及其神经机制

物理世界通过光信号在我们的视网膜上反映为亮度和颜色的色块集合 ,但是大脑知觉到的却是排列有序的由分离的物体组成的视觉世界 ,其中各种不同的物体占据不同的位置 ,存在相互作用或相对运动。在知觉加工过程中 ,视觉系统必须首先把视觉输入组织成不同的部分以形成视觉加工的基本单元[1,2 ] ,心理学家把这一加工过程称为视知觉组织。视知觉组织是大脑进行图像识别、注意分配及记忆存储等高级加工过程的基础。因此 ,理解视知觉组织的认知和神经机制成为研究大脑认知功能的核心问题之一。本文介绍视知觉组织的基本问题和规律 ,特别是新近关于…     

Grouping by proximity: Selective attention measures

Attention, Perception, & Psychophysics - The role of element proximity in perceptual grouping was examined in tasks requiring speeded discrimination of two-element visual patterns. Grouping of...     

Grouping by achromatic color and surface segregation

The study explored the achromatic-color determinants of grouping of uniform surfaces. The stimuli were a set of separate uniform achromatic disks on either a uniform or a bipartite achromatic background. The participants rated the salience of grouping of these disks for different combinations of stimulus luminances. The results show that achromatic color similarity alone could not sufficiently explain the pattern of obtained factorial curves but this factor coupled with the factor of surface segregation could. Luminance contrast similarity per se was found to be unimportant for grouping.     

Lightness constancy and illumination discounting

Contrary to the implication of the term "lightness constancy", asymmetric lightness matching has never been found to be perfect unless the scene is highly articulated (i.e., contains a number of different reflectances). Also, lightness constancy has been found to vary for different observers, and an effect of instruction (lightness vs. brightness) has been reported. The elusiveness of lightness constancy presents a great challenge to visual science; we revisit these issues in the following experiment, which involved 44 observers in total. The stimuli consisted of a large sheet of black paper with a rectangular spotlight projected onto the lower half and 40 squares of various shades of grey printed on the upper half. The luminance ratio at the edge of the spotlight was 25, while that of the squares varied from 2 to 16. Three different instructions were given to observers: They were asked to find a square in the upper half that (i) looked as if it was made of the same paper as that on which the spotlight fell (lightness match), (ii) had the same luminance contrast as the spotlight edge (contrast match), or (iii) had the same brightness as the spotlight (brightness match). Observers made 10 matches of each of the three types. Great interindividual variability was found for all three types of matches. In particular, the individual Brunswik ratios were found to vary over a broad range (from .47 to .85). That is, lightness matches were found to be far from veridical. Contrast matches were also found to be inaccurate, being on average, underestimated by a factor of 3.4. Articulation was found to essentially affect not only lightness, but contrast and brightness matches as well. No difference was found between the lightness and luminance contrast matches. While the brightness matches significantly differed from the other matches, the difference was small. Furthermore, the brightness matches were found to be subject to the same interindividual variability and the same effect of articulation. This leads to the conclusion that inexperienced observers are unable to estimate both the brightness and the luminance contrast of the light reflected from real objects lit by real lights. None of our observers perceived illumination edges purely as illumination edges: A partial Gelb effect ("partial illumination discounting") always took place. The lightness inconstancy in our experiment resulted from this partial illumination discounting. We propose an account of our results based on the two-dimensionality of achromatic colour. We argue that large interindividual variations and the effect of articulation are caused by the large ambiguity of luminance ratios in the stimulus displays used in laboratory conditions.     

Grouping and binding in visual short-term memory

Findings of 2 experiments are reported that challenge the current understanding of visual short-term memory (VSTM). In both experiments, a single study display, containing 6 colored shapes, was presented briefly and then probed with a single colored shape. At stake is how VSTM retains a record of different objects that share common features: In the 1st experiment, 2 study items sometimes shared a common feature (either a shape or a color). The data revealed a color sharing effect, in which memory was much better for items that shared a common color than for items that did not. The 2nd experiment showed that the size of the color sharing effect depended on whether a single pair of items shared a common color or whether 2 pairs of items were so defined-memory for all items improved when 2 color groups were presented. In explaining performance, an account is advanced in which items compete for a fixed number of slots, but then memory recall for any given stored item is prone to error. A critical assumption is that items that share a common color are stored together in a slot as a chunk. The evidence provides further support for the idea that principles of perceptual organization may determine the manner in which items are stored in VSTM. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Australian Aborigine: Transition in Family Grouping

In the brief period of fifty years, under the tutelage of the missionaries, there has been a marked transition of family structure in one group of Australian Aborigines from polygynous to monogamous. Those who are now middle-aged have lived as man and wife in Western-style nuclear families. Presently, however, there is a tendency for the youth not to marry but for the young women to incorporate their offspring into the household of their monogamous parents. A matrilocal pattern is developing that has the potential for matriarchal dominance. Some of the forces contributing to these changes are discussed. Several parallels with transitions in American minority family groupings are presented.