Perceptual grouping and attention: Not all groupings are equal

We examined grouping under inattention using Driver, Davis, Russell, Turatto, & Freeman’s (2001) method. On each trial, two successive displays were briefly presented, each comprising a central target square surrounded by elements. The task was to judge whether the two targets were the same or different. The organization of the background elements stayed the same or changed, independently of the targets. In different conditions, background elements grouped into columns/rows by color similarity, a shape (a triangle/arrow, a square/cross, or a vertical/horizontal line) by color similarity, and a shape with no other elements in the background. We measured the influence of the background on the target same-different judgments. The results imply that background elements grouped into columns/rows by color similarity and into a shape when no segregation from other elements was involved and the shape was relatively “good.” In contrast, no background grouping was observed when resolving figure-ground relations for segregated units was required, as in grouping into a shape by color similarity. These results suggest that grouping is a multiplicity of processes that vary in their attentional demands. Regardless of attentional demands, the products of grouping are not available to awareness without attention.     

Great apes’ strategies to map spatial relations

We investigated reasoning about spatial relational similarity in three great ape species: chimpanzees, bonobos, and orangutans. Apes were presented with three spatial mapping tasks in which they were required to find a reward in an array of three cups, after observing a reward being hidden in a different array of three cups. To obtain a food reward, apes needed to choose the cup that was in the same relative position (i.e., on the left) as the baited cup in the other array. The three tasks differed in the constellation of the two arrays. In Experiment 1, the arrays were placed next to each other, forming a line. In Experiment 2, the positioning of the two arrays varied each trial, being placed either one behind the other in two rows, or next to each other, forming a line. Finally, in Experiment 3, the two arrays were always positioned one behind the other in two rows, but misaligned. Results suggested that apes compared the two arrays and recognized that they were similar in some way. However, we believe that instead of mapping the left–left, middle–middle, and right–right cups from each array, they mapped the cups that shared the most similar relations to nearby landmarks (table’s visual boundaries).     

A computer-controlled cardiotachometer

A versatile display system for presenting heart rate information is described. The display has a table with 10 rows and 50 columns. This 10 by 50 matrix contains all integers from 0 to 499, so that it can display the instantaneous R-R intervals of a rat’s EKG to the nearest millisecond. At each beat 1 of 10 vertically and 1 of 50 horizontally arranged indicator lights are turned on to provide the coordinates for reading the table. Either beat-to-beat or averaged heart rate or period is displayed. Small and large changes can be easily and accurately observed on the same scale. The lights are controlled by a PDP-8/e. A listing of the assembler program is presented.     

The effects of temporal synchrony on the perceived organization of elements in spatially symmetric and asymmetric grids

Three experiments were conducted to investigate the influence of fast temporally segmented presentations of alternate rows or columns on the perception of grids of either symmetrically or asymmetrically spaced dot-like stimuli. Experiments 1a and 1b demonstrated that observers were able to discriminate between temporally segmented presentations of rows/columns stimuli, but showed a reduced performance in discrimination between non-temporally segmented stimuli and temporally segmented stimuli that were spatially unstructured. Experiment 2 confirmed the influence of temporally segmented presentations of rows and columns using elements whose mean luminance summed to the same as the display background. Experiment 3 demonstrated that the influence of temporal cues reduced when display elements were asymmetrically spaced. The results are discussed in terms of the influence of external spatio-temporal factors on the neural mechanisms of visual grouping.     

CVC syllables for investigating the phonetic sensitivity of Mandarin and English speakers

Although many individual speech contrasts pairs have been studied within the cross-language literature, no one has created a comprehensive and systematic set of such stimuli. This article justifies and details an extensive set of contrast pairs for Mandarin Chinese and American English. The stimuli consist of 180 pairs of CVC syllables recorded in two tokens each (720 syllables total). Between each CVC pair, two of the segments are identical, whereas the third differs in that a segment drawn from a "native" phonetic category (either Mandarin, English, or both) is partnered with a segment drawn from a "foreign" phonetic category (nonnative to Mandarin, English, or both). Each contrast pair differs by a minimal phonetic amount and constitutes a meaningful contrast among the world's languages (as cataloged in the UCLA Phonological Segment Inventory Database of 451 languages). The entire collection of phonetic differences envelops Mandarin and English phonetic spaces and generates a range of phonetic discriminability. Contrastive segments are balanced through all possible syllable positions, with noncontrastive segments being filled in with other "foreign" segments. Although intended to measure phonetic perceptual sensitivity among adult speakers of the two languages, these stimuli are offered here to all for similar or for altogether unrelated investigations.     

The time course of perceptual grouping: the role of segregation and shape formation

The time course of perceptual grouping was examined in two experiments, using a primed matching task. In different conditions, elements were grouped into columns/rows by common lightness, into a shape (triangle/ arrow or square/cross) by common lightness, and into a shape without segregation of elements. The results showed an early and rapid grouping into columns/rows by common lightness and into a shape when no segregation from other elements was involved. Goodness of shape (i.e., triangle/arrow vs. square/cross) had no influence on how early grouping was evident, but the relatively poorer shapes appeared to consolidate with time. In contrast, grouping into a shape that involved segregation and required resolving figure-ground relations between segregated units, as grouping into a shape by common lightness, consumed time, regardless of shape goodness. These results suggest that the time course of grouping varies as a function of the processes involved in it (e.g., segregation and shape formation) and the conditions prevailing for each process.     

Evaluating the conformity of sociometric measurements

The problem of comparing two sociometric matrices, as originally discussed by Katz and Powell in the early 1950's, is reconsidered and generalized using a different inference model. In particular, the proposed indices of conformity are justified by a regression argument similar to the one used by Somers in presenting his well-known measures of asymmetric ordinal association. A permutation distribution and an associated significance test are developed for the specific hypothesis of no conformity reinterpreted as a random matching of the rows and (simultaneously) the columns of one sociometric matrix to the rows and columns of a second. The approximate significance tests that are presented and illustrated with a simple numerical example are based on the first two moments of the permutation distribution, or alternatively, on a random sample from the complete distribution.Partial support for the research of the first author was provided by the National Science Foundation through SOC 75-07860. Equal authorship is implied. The work was done when the first author was at the University of Wisconsin.     

False memories for compound words: Role of working memory

Subjects studied pairs of compound words; pair members were presented simultaneously (one above the other) for 2 sec or sequentially (one immediately following the other) for 1 sec each, and 6-sec interstimulus intervals separated the end of presentation of one pair and the start of that of another. A subsequent recognition test included within-pair and between-pair conjunction foils (recombinations of stimulus parts from the same study pair and from separate pairs, respectively). Previous experiments using faces as stimuli have demonstrated that when faces are presented simultaneously there are many more false alarms to within-pair than to between-pair conjunction items, and when faces are presented sequentially there is an equal number of false alarms in those two conditions. However, Experiment 1 showed that for compound word stimuli there were equally high false alarm rates toboth types of foils in both study conditions relative to completely new test items. Experiment 2 showed that when rehearsal of compound words was prevented, the pattern of conjunction errors was very similar to the one typically obtained for faces. In Experiment 3, subjects falsely recalled conjunctions of within-pair compound words but not conjunctions of between-pair words in the simultaneous-study condition; no conjunctions were recalled in the sequential-study condition. The results support the idea that working memory processing is necessary for binding stimulus parts together in episodic memory.     

Strategic behavior and counterfactuals

The difficulty of defining rational behavior in game situations is that the players' strategies will depend on their expectations about other players' strategies. These expectations are beliefs the players come to the game with. Game theorists assume these beliefs to be rational in the very special sense of beingobjectively correct but no explanation is offered of the mechanism generating this property of the belief system. In many interesting cases, however, such a rationality requirement is not enough to guarantee that an equilibrium will be attained. In particular, I analyze the case of multiple equilibria, since in this case there exists a whole set of rational beliefs, so that no player can ever be certain that the others believe he has certain beliefs. In this case it becomes necessary to explicitly model the process of belief formation. This model attributes to the players a theory of counterfactuals which they use in restricting the set of possible equilibria. If it were possible to attribute to the players the same theory of counterfactuals, then the players' beliefs would eventually converge.I wish to thank Michael Bacharach, In-Koo Cho, William Harper, Aanund Hylland, Isaac Levi, Wolfgang Spohn, Tommy Tan and two anonymous referees for many useful comments and suggestions. Financial support from National Science Foundation grant SES 87-10209 is gratefully acknowledged.     

Computing measures of simplicity of fit for loadings in factor-analytically derived scales

A very simple structure is sought when factor analysis is used to develop measurement scales. The SIMLOAD program computes measures of factorial simplicity for rows and columns of loading matrices (usually the factor pattern) as well as some overall measures. These include Kaiser’s (1974) index of factorial simplicity for variables (rows), the author’s scale fit index for factors (columns), Bentler’s (1977) scale-free matrix measure, and hyperplane counts. Routine use of these measures is recommended for multifactor scale development. The measures may also be useful in more general factor applications and in confirmatory as well as exploratory analyses. SIMLOAD also computes factor scale intercorrelations, scale alpha coefficients (including alpha when an item is removed), and sorted loadings for ease of interpretation.     

Anticipating who will say what: The influence of speaker-specific memory associations on reference resolution

Some accounts of common ground assume that successful communication requires detailed consideration of others’ knowledge. In two studies, we provide evidence for an alternative account that views common ground as being mediated in part through domain-general memory mechanisms. On each trial, participants heard prerecorded instructions from one of two speakers indicating which of two displayed pictures to select. During an initial association phase, each speaker repeatedly referred to different sets of pictures. In Experiment 1, we contrasted a “between-speaker mapping” condition, in which each speaker referred to only one picture from critical item pairs (e.g., the cat drinking milk vs. the cat sitting up), and a “within-speaker mapping” condition, in which each speaker referred to both pictures within each pair, although item categories differed across speakers. On subsequent test trials, we recorded participants' eye fixations to critical displays that included both items from a category pair. Prior to the linguistic point of disambiguation, participants in the between-speaker mapping condition were more likely to fixate on the picture previously described by the current speaker, suggesting that knowledge associated with the speaker was prompting expectations for which picture would be the intended target. In Experiment 2, we used two prerecorded speakers of the same gender to strengthen the claim that the relevant implicit memory associations are speaker-specific. These results demonstrate how domain-general memory associations can be an important constraint upon language use.     

Note on matrices of random numbers

The statistical and structural characteristics of 13 matrices of random numbers in which both the cells and the entries were randomly chosen are discussed. Each matrix was explored considering row means, standard deviations, and correlations as well as column means, standard deviations, and correlations. A study concerning the sequential arrangement of digits was performed by finding out in tables of random numbers how many times the values 0 to 9 are followed by any other digit. Analyses indicate clear factor structures when factor analyzing correlations of rows and of columns and when examining sequential arrangements, concluding that for a given set of digits it is possible to assert both randomness and nonrandomness depending on how the data are examined.     

The interaction of objective and subjective organizations in a localization search task

We investigated how both objective and subjective organizations affect perceptual organization and how this perceptual organization, in turn, influences observers’ performance in a localization search task. Two groups of observers viewing exactly the same stimuli (objective organization) performed in significantly different ways, depending on how they were induced to parse the display (subjective organization). In Experiments 1 and 2, the observers were asked to describe the location of a tilted target among a varying number of vertical or horizontal distractors. Subjective organization was induced by instructing observers to parse the display into either three horizontal regions (rows) or three vertical regions (columns). The position of the target was critical: location performance, as assessed by reaction time and errors, was consistently impaired at the locations adjacent to the boundaries defining the regions, producing what we refer to as thesubjective boundary effect. Furthermore, the extent of this effect depended on whether the stimulus-driven and conceptually driven information concurred or conflicted. This made location information more or less accessible. In Experiment 1, the strength of objective grouping was a function of the proximity of the items (near or far conditions) and their orientation in a 6×6 matrix. In Experiment 2, the strength of objective grouping was a function of similarity of color (items were color coded by rows or by columns) and the orientation of the items in a 9×9 matrix. The subjective boundary effect was more pronounced when the display promoted grouping in the direction orthogonal to that of the task (e.g., when observers parsed by rows but vertical distractors were closer together [Experiment 1] or color coded [Experiment 2] to induce global columns). In contrast, this effect decreased when the direction of both objective and subjective organizations was parallel (e.g., when observers parsed by rows and horizontal distractors were closer together [Experiment 1] or were color coded [Experiment 2] to induce global rows). A localization search task proved to be an ideal forum in which objective and subjective organizations interacted. We discuss how these results indicated that observers’ performance in a localization task was determined by the interaction of objective and subjective organizations, and that the resulting perceptual organization constrained coarse location information.     

Matrices with a given number of violations of Regular Minimality

A row (or column) of an n×n matrix complies with Regular Minimality (RM) if it has a unique minimum entry which is also a unique minimum entry in its column (respectively, row). The number of violations of RM in a matrix is defined as the number of rows (equivalently, columns) that do not comply with RM. We derive a formula for the proportion of n×n matrices with a given number of violations of RM among all n×n matrices with no tied entries. The proportion of matrices with no more than a given number of violations can be treated as the p-value of a permutation test whose null hypothesis states that all permutations of the entries of a matrix without ties are equiprobable, and the alternative hypothesis states that RM violations occur with lower probability than predicted by the null hypothesis. A matrix with ties is treated as being represented by all matrices without ties that have the same set of strict inequalities among their entries.     

Influence of Response Similarity on Interference in Perceptual Motor Learning

Motor interference was measured in terms of average response time in sorting 15 pairs of cards, each pair containing words which were either unrelated or identical but printed in different colors. The two words of each pair were used in labeling two cubicles in such a way that they were apart by 0, 1, 2, or 3 intervening cubicles in quasirandomly chosen directions. Interference was inversely related to response similarity, but this relationship may not appear in the absence of sufficient stimulus similarity. The findings are interpreted in the light of a hypothesis which views motor interference as a tendency for responses to deflect from their own courses and be pulled towards those of other responses with which they are at conflict.     

Where the Sum of Our Expectation Fails Us: The Exchange Paradox

In the exchange paradox, two players receive envelopes containing different amounts of money. The assignment of the amounts ensures each player has the same probability of receiving each possible amount. Nonetheless, for each specific amount a player may find in his envelope, there is a positive expectation of gain if the player swaps envelopes with the other player, in apparent contradiction with the symmetry of the game. I consider a variant form of the paradox that avoids problems with improper probabilities and I argue that in it these expectations give no grounds for a decision to swap since that decision must be based on a summation of all the expectations. But this sum yields a non-convergent series that has no meaningful value. The conflicting recommendations – that it is to one or the other player's advantage to swap – arise from different ways of grouping terms in the sum that yield an illusion of convergence. I describe a generalized exchange paradox, explore some of its properties and display another example.     

Complementarity cannot resolve the emergence–reduction debate: Reply to Harré

Rom Harré thinks that the Emergence–Reduction debate, conceived as a vertical problem, is partly ill posed. Even if he doesn’t wholly reject the traditional definition of an emergent property as a property of a collection but not of its components, his point is that this definition doesn’t exhaust all the dimensions of emergence. According to Harré there is another kind (or dimension) of emergence, which we may call—somewhat paradoxically—“horizontal emergence”: two properties of a substance are horizontally emergent relative to each other if they cannot be displayed in the same conditions. Contrary to vertical emergence, horizontal emergence is a symmetrical relation. Harré endorses horizontal emergentism. I argue that this position faces a principled difficulty: it makes it impossible to bind different horizontally emergent discourses in an interesting way. Physics and biology for example become “island” discourses, each speaking of a distinct kind of entities. The only way to ensure that two different discourses can relate to the same entity is to reintroduce verticality into the picture.     

Perceptual grouping between successively presented stimuli and its relation to visual simultaneity and masking

Summary A 4×4 matrix of dots was presented by a tachistoscope. The first and the third columns of the stimulus pattern were presented first for 20 ms and then the second and the fourth columns were presented for 20 ms with SOAs of 0 to 170 ms. Luminous dots on a dark background, black dots on a white background, and black dots and small outline circles on a white background were used in Experiments I, II, and III, respectively. In each experiment, 5 Ss were asked to report whether the stimulus dots were seen as 4 horizontal rows or 4 vertical columns, and whether they were seen simultaneously or successively. The experimental results showed that the time range of successive grouping was nearly the same as that of perceptual simultaneity in Experiments I and II, but was much greater than the latter in Experiment III where the similarity factor favored successive grouping. Successive grouping generally occurred in the same time range with visual masking of dot patterns by random dots, temporal organization of patterns from successive stimulus elements. But the time range was generally wider than those of contrast reduction caused by temporal luminance summation, metacontrast, and apparent movement.A part of this study was conducted during the junior author's stay at Chiba University and presented by him at the 20th International Congress of Psychology at Tokyo, August 13–19, 1972 (Yamada and Oyama, 1972)     

藏-汉-英双语者字词识别中的语码切换及其代价

以母语为藏语、汉语熟练、英语不熟练的藏-汉-英双语者为被试,采用词汇判断的研究范式,在无切换、预期切换和无预期切换三种条件下,考察了藏-汉-英三种语言之间的语码切换及其代价。结果表明：⑴在三种条件下,被试对汉语词和藏语词的反应时和错误率的差异不显著,藏语词和汉语词的切换代价差异不显著。⑵在无切换条件下,对藏语词和英语词的反应时和错误率的差异不显著;在切换条件下,对英语词反应时长,错误率也高;英语词的切换代价显著大于藏语词的切换代价。⑶在无切换条件下,对汉语词和英语词的反应时和错误率的差异不显著;在切换条件下,对英语词反应时长,错误率也高;英语词的切换代价显著大于藏语词的切换代价。整个研究表明,藏-汉-英双语者在字词识别中的语码切换代价主要受语言的熟练程度影响     

Some factors that influence the acquisition of complex, stereotyped, response sequences in pigeons

Two pigeons were required to peck six to nine illuminated response keys. A response on any one of the keys darkened that key. When each key had been darkened, a reinforcer was delivered. No specific sequence of key pecking was ever required. The keys were presented in various matrices: three by two, three by three, horizontal rows, and vertical columns. The keys either presented the same stimulus, white light; or each key presented a different stimulus, a color or form. The results indicated that although there were 720 to 362,880 different sequences that would produce reinforcement, each bird developed a particular, stereotyped sequence that dominated its behavior. Variability among the birds across phases yielded less than 60 sequences, .0001 to 6 percent of the possible sequences. The data suggest that a reinforcement contingency that includes “free choice” of response sequence will produce stereotypical response sequences that function as complex “units” of behavior.