Memory organization of action events and its relationship to memory performance

Previous research yielded inconsistent results regarding the memory organization of self-performed actions. The authors propose that task performance changes the very basis of memory organization. Enactment during study and test (Experiment 1) yielded stronger enactive clustering (based on motor-movement similarities), whereas verbal encoding yielded stronger conceptual clustering (based on semantic-episodic similarities). Enactment enhanced memory quantity and memory accuracy. Both measures increased with enactive clustering under self-performance instructions but with conceptual clustering under verbal instructions. Enactment only during study (Experiment 2) or only during testing (Experiment 3) also enhanced enactive clustering. It is proposed that different conditions affect the relative salience of different types of memory organization and their relative contribution to recall.     

Affinity propagation: An exemplar-based tool for clustering in psychological research

Affinity propagation is a message-passing-based clustering procedure that has received widespread attention in domains such as biological science, physics, and computer science. However, its implementation in psychology and related areas of social science is comparatively scant. In this paper, we describe the basic principles of affinity propagation, its relationship to other clustering problems, and the types of data for which it can be used for cluster analysis. More importantly, we identify the strengths and weaknesses of affinity propagation as a clustering tool in general and highlight potential opportunities for its use in psychological research. Numerical examples are provided to illustrate the method.     

Depth of processing and memory organization

Summary The study examined the idea that the organization of information in memory varies depending on the depth of processing during input, as well as on the conditions for retrieval. Two types of memory organization are distinguished: Conceptual organization implies a hierarchical structure in which items are grouped according to a principled taxonomic system (e.g., cow — horse). Associative organization, in contrast, is based on direct links among the members of a group (e.g., cow — milk). Two experiments examined the propositions that conceptual relations require more effort to be encoded during learning and more effort to be utilized during remenbering than associative relations. In Experiment 1 a list of 28 words was used, which could be grouped into 14 conceptual categories or, alternatively, into 14 associative categories of two words each. The words were presented under either shallow or deep encoding conditions. Increased depth of encoding resulted in increased conceptual clustering but had little effect on amount of associative clustering. Similar amounts of associative and conceptual clustering were observed during early output positions, but conceptual clustering tended to increase with recall trials, suggesting that it might depend on the establishment of a retrieval schema. In Experiment 2, after memorizing a list of words, subjects recalled the words either with or without the requirement to perform a secondary task while recalling. Relative to the undisturbed recall condition, the secondary task condition indicated stronger associative than conceptual clustering. The results were seen to support the idea that different types of memory organization may become salient under different attentional conditions.     

Genes and family environment in familial clustering of cancer

Familial clustering of a disease is defined as the occurrence of the disease within some families in excess of what would be expected from the occurrence in the population. It has been demonstrated for several cancer types, ranging from rare cancers as the adenomatosis-coli-associated colon cancer or the Li-Fraumeni syndrome to more common cancers as breast cancer and colon cancer. Familial clustering, however, is merely an epidemiological pattern, and it does not tell whether genetic or environmental causes or both in combination are responsible for the familial clustering. Familial clustering may be due to genetic predisposition to the disease, but exposure to environmental factors — shared by members of some families, but not by members of other families — may also cause familial clustering and hence mimic genetic inheritance in the study of nuclear families. Based on assumptions regarding the individual steps in the biological process starting with exposure to carcinogens and ending with death from disseminated cancer we suggest that genetic and environmental factors may both be involved in most of these steps. The present paper focuses on research methodologies necessary to discriminate between the effect of genes and family environment in the development of cancer.     

Free trees and bidirectional trees as representations of psychological distance

Two types of graph-theoretic representations of psychological distances or dissimilarities are proposed: weighted free trees and weighted bidirectional trees. A weighted free tree is a generalization of the sort of graph representation used in hierarchical clustering. A weighted bidirectional tree is a further generalization which allows for asymmetric dissimilarities. The properties of these structures are discussed and numerical methods are presented that can be used to derive a representation for any given set of dissimilarities. The applicability of these structures is illustrated by using them to represent the data from experiments on the similarities among animal terms and on memory for sentences. An analysis based upon free trees is compared and contrasted with analyses using hierarchical clustering and multidimensional scaling.     

Personality Characteristics of Substance Abusers: An MCMI Cluster Typology of Recreational Drug Users Treated in a Therapeutic Community and Its Relationship to Length of Stay and Outcome

The purpose of this investigation was to define homogeneous personality subtypes among substance abusers treated in a long-term, inpatient, drug-free therapeutic community and to determine how the resulting typology was related to length of stay and treatment outcome, A hierarchical agglomerative cluster analysis was performed on the Millon Clinical Multiaxial Inventory (MCMI) scale scores of 235 admissions to a therapeutic community. Five cluster types emerged,, which were similar to typologies found in studies with alcoholic inpatients. A concordant solution evolved when a different clustering algorithm was used with the same sample and when clustering was done with a different group of substance abusers. As hypothesized, clusters of patients with average MCMI elevations that indicated avoidant, schizoid, and antisocial qualities tended to stay in treatment fewer days and relapsed earlier during the 1-year follow-up. The implications, for substance abuse treatment are discussed.     

CLUSTERS PRECEDE SHAPES IN PERCEPTUAL ORGANIZATION

Abstract —Does perceptual grouping require attention? Recent controversy on this question may be caused by a conflation of two aspects of grouping: element clustering (determining which elements belong together) and shape formation (determining cluster boundaries). In Experiment 1, observers enumerated diamonds that were drawn with either lines or dots. These two types of stimuli were subitized (enumerated rapidly and accurately in the range from one to three items) equally well, suggesting that clustering dots into countable entities did not detnand attention. In contrast, when target diamonds were enumerated among distractor squares in Experiment 2. only line-drawn items could be subitized. We propose that clustering and shape formation not only involve different perceptual processes, but play different functional roles in vision.     

Personality characteristics of substance abusers: an MCMI cluster typology of recreational drug users treated in a therapeutic community and its relationship to length of stay and outcome.

The purpose of this investigation was to define homogeneous personality subtypes among substance abusers treated in a long-term, inpatient, drug-free therapeutic community and to determine how the resulting typology was related to length of stay and treatment outcome. A hierarchical agglomerative cluster analysis was performed on the Millon Clinical Multiaxial Inventory (MCMI) scale scores of 235 admissions to a therapeutic community. Five cluster types emerged, which were similar to typologies found in studies with alcoholic inpatients. A concordant solution evolved when a different clustering algorithm was used with the same sample and when clustering was done with a different group of substance abusers. As hypothesized, clusters of patients with average MCMI elevations that indicated avoidant, schizoid, and antisocial qualities tended to stay in treatment fewer days and relapsed earlier during the 1-year follow-up. The implications for substance abuse treatment are discussed.     

Profiling local optima in K-means clustering: developing a diagnostic technique

Using the cluster generation procedure proposed by D. Steinley and R. Henson (2005), the author investigated the performance of K-means clustering under the following scenarios: (a) different probabilities of cluster overlap; (b) different types of cluster overlap; (c) varying samples sizes, clusters, and dimensions; (d) different multivariate distributions of clusters; and (e) various multidimensional data structures. The results are evaluated in terms of the Hubert-Arabie adjusted Rand index, and several observations concerning the performance of K-means clustering are made. Finally, the article concludes with the proposal of a diagnostic technique indicating when the partitioning given by a K-means cluster analysis can be trusted. By combining the information from several observable characteristics of the data (number of clusters, number of variables, sample size, etc.) with the prevalence of unique local optima in several thousand implementations of the K-means algorithm, the author provides a method capable of guiding key data-analysis decisions.     

Dimensions and Categories Underlying Thinking About College Student Types1

Previous work on implicit personality theory and the college student culture suggests that thinking about college student types should include academic involvement and social involvement dimensions. Further, positive and negative social, positive academic, and oppositional clusters of types were predicted based on studies of high school crowds. Using 85 college student type labels as stimuli, a free‐sorting method coupled with multidimensional scaling and hierarchical clustering analyses provided support for these hypotheses. Also, the results suggest convergence in the cognitive structure underlying perception of college student types across major demographic categories.     

学业不良学生类型与特点的聚类分析

该研究运用Ｑ聚类分析对上海市区１４８０名初中预备班学生的能力和个性特征进行分类研究。结果发现１４８０名被试中存有心理发展水平不同的六个主要类别,这些类别与学生学业成绩的优劣关系密切。同时,３５３名差生可分为四个主要类型：即,暂时性困难学生、能力型困难学生、动力型困难学生和整体性困难学生,不同类型的差生具有不同的特点。这为针对不同类型学生的特点制定有效的教育措施提供了依据。     

The effects of individual differences in test anxiety and type of orienting task on levels of organization in free recall

In Experiment 1, high and low test-anxious subjects recalled a list composed of words that could be organized either by taxonomic categories or first letters. High-anxiety subjects showed less recall and conceptual clustering. There was no anxiety difference in alphabetic clustering, but low-anxiety subjects used alphabetic clusters to bridge transitions between conceptual categories more often than did high-anxiety subjects. An initial orienting task which required semantic processing reduced the recall deficit for high-anxiety subjects but not the clustering deficit. Low-anxiety subjects seemed minimally affected by a nonsemantic-orienting task. Experiment 2 used a list that could be organized by associates or rhymes. High-anxiety subjects recalled less and exhibited less clustering of both types. The nonsemantic-orienting task depressed performance for both anxiety levels, though the effect was somewhat greater for high-anxiety subjects. Overall, these results provide little evidence to support the hypothesis that high-anxiety subjects process differently only for semantic content, but methodological limitations preclude unequivocally rejecting that view.     

A study of the classification capabilities of neural networks using unsupervised learning: A comparison withK-means clustering

Several neural networks have been proposed in the general literature for pattern recognition and clustering, but little empirical comparison with traditional methods has been done. The results reported here compare neural networks using Kohonen learning with a traditional clustering method (K-means) in an experimental design using simulated data with known cluster solutions. Two types of neural networks were examined, both of which used unsupervised learning to perform the clustering. One used Kohonen learning with a conscience and the other used Kohonen learning without a conscience mechanism. The performance of these nets was examined with respect to changes in the number of attributes, the number of clusters, and the amount of error in the data. Generally, theK-means procedure had fewer points misclassified while the classification accuracy of neural networks worsened as the number of clusters in the data increased from two to five.Acknowledgements: Sara Dickson, Vidya Nair, and Beth Means assisted with the neural network analyses.     

Executive processing in free recall of categorized lists

The present study examines the cognitive processes that operate in free recall of categorized lists by manipulating semantic structure of the lists and using a dual task methodology to restrict the processes that make demands on limited-capacity resources, the central executive resources. Relying on the assumption that, in free recall of categorized lists, the search for category names is a strategic controlled process that demands executive resources, lists with different numbers of categories ranging from 2 to 6 were employed. The results showed an effect of a secondary task on retrieval in the 4- and the 6-category list conditions, but not in the 2-category list condition. In contrast to retrieval, the secondary task interference at encoding produced an effect on recall of all three types of lists. An interesting finding was that an effect on clustering was found only when interference was present at encoding, not when it was at retrieval. This finding was in line with the suggestion (Troyer, Moscovitch, Winocur, Alexander, & Stuss, 1998) that switching (shifting between different category items) rather than clustering is related to executive functioning, and suggested that clustering may be a measure of two different types of processing: (1) executive processing at encoding and (2) automatic processing at retrieval. In addition, a different pattern of results was obtained when low frequency category words were used, indicating that the frequency of category words is an important determinant in free recall of categorized lists. Overall, the present results support the two-process account of retrieval of category words (Rosen & Engle, 1997) and the view that there are fundamental differences between encoding and retrieval processes (Naveh-Benjamin, Craik, Guez, & Dori, 1998; Naveh-Benjamin & Guez, 2000).     

Clustering, seriation, and subset extraction of confusion data

The study of confusion data is a well established practice in psychology. Although many types of analytical approaches for confusion data are available, among the most common methods are the extraction of 1 or more subsets of stimuli, the partitioning of the complete stimulus set into distinct groups, and the ordering of the stimulus set. Although standard commercial software packages can sometimes facilitate these types of analyses, they are not guaranteed to produce optimal solutions. The authors present a MATLAB *.m file for preprocessing confusion matrices, which includes fitting of the similarity-choice model. Two additional MATLAB programs are available for optimally clustering stimuli on the basis of confusion data. The authors also developed programs for optimally ordering stimuli and extracting subsets of stimuli using information from confusion matrices. Together, these programs provide several pragmatic alternatives for the applied researcher when analyzing confusion data. Although the programs are described within the context of confusion data, they are also amenable to other types of proximity data.     

On the Cross‐Cultural Replicability of the Resilient,Undercontrolled, and Overcontrolled Personality Types

Personality types reflect typical configurations of personality attributes within individuals. Over the last 20 years, researchers have identified a set of three replicable personality types: resilient (R), undercontrolled (U), and overcontrolled (O) types. In this study, we examined the cross‐cultural replicability of the RUO types in Italy, Poland, Spain, and the United States. Personality types were identified using cluster analyses of Big Five profiles in large samples of college students from Italy (n = 322), the United States (n = 499), Spain (n = 420), and Poland (n = 235). Prior to clustering the profiles, the measurement invariance of the Big Five measure across samples was tested. We found evidence for the RUO types in all four samples. The three‐cluster solution showed a better fit over alternative solutions and had a relatively high degree of cross‐cultural generalizability. The RUO types are evident in samples from four countries with distinct linguistic and cultural traditions. Results were discussed in light of the importance of considering how traits are organized within individuals for advancing contemporary personality psychology.     

Parolee Concentration,Risk of Recidivism,and the Consequences for Neighborhood Crime

ABSTRACT

We examine whether the clustering of certain types of higher-likelihood-of-recidivating parolees in neighborhoods differentially influences violent and property crime. We also test whether the relationship between the concentration of certain types of parolees and crime is moderated by disadvantage. We examine parolees released between 2000 and 2009 in Cleveland, Ohio, and neighborhood crime data. Results suggest that increases in certain types of parolees contribute to a corresponding increase in crime. This suggests that risk factors associated with reoffending might explain larger crime trends in neighborhoods. Furthermore, the broader neighborhood context compounds these risk factors, resulting in higher rates of crime.     

Recall of Subject-Performed Tasks,Verbal Tasks,and Cognitive Activities Across the Adult Life Span: Parallel Age-Related Deficits

Motor activity during encoding of verbal information has been suggested to reduce age differences in episodic memory. Here we examined memory for sentences encoded with enactment (SPTs, subject-performed tasks) or without enactment (VTs, verbal tasks) in a population-based sample consisting of 10 groups ranging in age from 35 to 80 years (N = 1000). Memory performance was assessed by immediate free- and category-cued recall. Degree of clustering was measured by the adjusted ratio of clustering score. Recall of cognitive activities served as a complementary measure of memory for performed tasks. Sentence recall showed a gradual decline across age, of about the same magnitude for SPTs and VTs, in both free and cued recall. Clustering in free recall was higher for SPTs than for VTs, but there were no age differences in clustering. A pattern of gradual decline from age 35 was observed also in activity recall, regardless of whether the activities involved motor activity or not. Across the memory measures, differences in education accounted for all of the age-related variance in performance among the younger (35-55 years) but not the older groups (60-80 years), suggesting that genuine aging effects in these measures are more prominent in old age. Together, the results indicate that age differences in episodic memory, in line with most, if not all, types of encoding support, generalize across the performed/non-performed distinction.     

Typological analysis of MMPI personality patterns of drug dependent men

This study replicated Types I and II of Berzins, Ross, English and Haley's (1974) initial typological research with a drug dependent sample. In this research, Minnesota Multiphasic Personality Inventory (MMPI) profiles of 447 drug dependent men were submitted to Johnson's (1967) hierarchical clustering procedure. The hierarchical clustering procedure yielded nine small but clinically meaningful personality subtypes. These types were compared to Berzin's (Berzins et al.) profiles and categorized into three diagnostic classes: character disorder, 42% of the sample; neurotic characters, 35% of the sample; and borderline disorder, 23% of the sample. The profiles were discussed with respect to the scale similarity and differences within the diagnostic class. The results were discussed, with implications for treatment and further research efforts with the drug dependent population.