Permanent and transient effects of repeated preweaning stress on social and sexual behaviors of rats

We have reported that exposure of preweaning male and female rats to a model of unpredictable mild physical stressors (Neo-A) can decrease the behavioral and hormonal responses to acute and chronic stress as adults. In this paper we have analyzed the effect of Neo-A on development of social behaviors, including aggressiveness, social dominance, and sexual behavior in adulthood. The subjects were divided into two groups: Neo-A (daily exposed to unpredictable mild stresses- from day 2 up to day 15 of suckling; n = 30 litters) and controls (C) (undisturbed rats, except for testing, during the same period of life; n = 26 litters). When day 6 pups were submitted to a social clustering test the Neo-A group showed a higher rate of litter-mate clustering than C. The 35 days Neo-A males and Neo-A females submitted to a social behavior test after 24 h of social isolation also showed higher scores of time spent in active social interaction than controls, as well as a higher ratio of animals showing aggressive playing. A second social behavior test performed after 48 h of social isolation at days 75-80 of age revealed that only Neo-A females displayed increased social behavior and aggressive behaviors, whereas controls did not. A water competition test performed at 24 and 48 h after water deprivation showed that Neo-A adult males spent more time in possession of the drinking device and drank more frequently than C. When adult proestrous females were exposed to a sexual behavior test, the Neo-A group showed shorter latency and higher scores of lordosis quotient. These results support the view that exposure to this model of repeated mild stress early in life stimulates the development of social behavior, dominance and sexual behavior.     

The Social Phobia and Anxiety Inventory: Reliability and Validity in an Adolescent Spanish Population

The objective of this study is to examine the factor structure and psychometric properties of the SPAI in a sample of adolescent Spaniards. The results obtained support the use of the correlated two-factor SPAI subscales and indicate high coefficient alpha values for the SPAI subscales. The results provide support for the use of the SPAI in an adolescent population in a non-English-speaking country. Both exploratory and confirmatory factor analyses of the Social Phobia subscale showed a four-factor structure, instead of a five-factor dimension, as suggested by previous studies. Effects for gender and age and gender interaction were found. Limitations and suggestions for future research are discussed.     

Retrieving the correlation matrix from a truncated PCA solution: The inverse principal component problem

Whenr Principal Components are available fork variables, the correlation matrix is approximated in the least squares sense by the loading matrix times its transpose. The approximation is generally not perfect unlessr =k. In the present paper it is shown that, whenr is at or above the Ledermann bound,r principal components are enough to perfectly reconstruct the correlation matrix, albeit in a way more involved than taking the loading matrix times its transpose. In certain cases just below the Ledermann bound, recovery of the correlation matrix is still possible when the set of all eigenvalues of the correlation matrix is available as additional information.     

The contribution of working memory resources in the verification of simple mental arithmetic sums

The present study replicated the investigations of Lemaire, Abdi, and Fayol with some modifications: the random time interval generation (RIG) task was used and the stimuli were created in another way. The results provide additional evidence for the crucial role of the central executive in the speed of solving both true and false sums and for the role of the phonological loop in solving false sums. However, the findings concerning the role of this slave system in solving true sums were different. Possible explanations and limitations of these results are discussed. Received: 16 April 1998 / Accepted: 20 July 1998     

An item response model with internal restrictions on item difficulty

An IRT model based on the Rasch model is proposed for composite tasks, that is, tasks that are decomposed into subtasks of different kinds. There is one subtask for each component that is discerned in the composite tasks. A component is a generic kind of subtask of which the subtasks resulting from the decomposition are specific instantiations with respect to the particular composite tasks under study. The proposed model constrains the difficulties of the composite tasks to be linear combinations of the difficulties of the corresponding subtask items, which are estimated together with the weights used in the linear combinations, one weight for each kind of subtask. Although the model does not belong to the exponential family, its parameters can be estimated using conditional maximum likelihood estimation. The approach is demonstrated with an application to spelling tasks. We thank Eric Maris for his helpful comments.     

A case of extreme simplicity of the core matrix in three-mode principal components analysis

In three-mode Principal Components Analysis, theP ×Q ×R core matrixG can be transformed to simple structure before it is interpreted. It is well-known that, whenP=QR,G can be transformed to the identity matrix, which implies that all elements become equal to values specified a priori. In the present paper it is shown that, whenP=QR − 1,G can be transformed to have nearly all elements equal to values spectified a priori. A cllsed-form solution for this transformation is offered. Theoretical and practical implications of this simple structure transformation ofG are discussed. Constructive comments from anonymous reviewers are gratefully acknowledged.     

Symmetry in haptic and in visual shape perception

Four experiments tested the hypothesis that bilateral symmetry is an incidental encoding property in vision, but can also be elicited as an incidental effect in touch, provided that sufficient spatial reference information is available initially for haptic inputs to be organized spatially. Experiment 1 showed that symmetry facilitated processing in vision, even though the task required judgments of stimulus closure rather than the detection of symmetry. The same task and stimuli failed to show symmetry effects in tactual scanning by one finger (Experiment 2). Experiment 3 found facilitating effects for vertically symmetric open stimuli, although not for closed patterns, in two-forefinger exploration when the fore-fingers had previously been aligned to the body midaxis to provide body-centered spatial reference. The one-finger exploration condition again failed to show symmetry effects. Experiment 4 replicated the facilitating effects of symmetry for open symmetric shapes in tactual exploration by the two (previously aligned) forefingers. Closed shapes again showed no effect. Spatial-reference information, finger movements, and stimulus factors in shape perception by touch are discussed.     

Fewer reasons for staying alive when you are thinking of killing yourself: The brief reasons for living inventory

The Linehan Reasons for Living Inventory is a 48-item scale on which respondents rate how important each item would be for living if suicide were contemplated. The inventory possesses good psychometric properties and can distinguish suicidal from nonsuicidal people among shoppers, psychiatric inpatients, college students, and adolescents. As its length limits its utility in many institutional and screening settings, the purpose of this study was (1) to develop a brief form of the Reasons for Living Inventory appropriate for clinical use and (2) to examine the predictive validity of this brief measure, named the Brief Reasons for Living Inventory (BRFL), to distinguish suicidal from nonsuicidal prison inmates. Results indicate that the brief form was as good as either the Beck Depression Inventory or the Beck Hopelessness Scale at predicting suicidality in this population. Further study is needed to validate the BRFL with different institutionalized and other populations as well as to assess its ability to discriminate suicide ideators from those engaging in overt suicidal behavior.Support for this project was provided in part by the New York State Office of Mental Health Bureau of Forensic Services and the New York State Department of Correctional Services.     

Hemispheric dominance in schizophrenics as determined on extrapyramidal side effects of neuroleptics

Phenomena observed during treatment with neuroleptics were clinically measured in an attempt to determine the difference in vulnerability of the two hemispheres and the relation between this difference and schizophrenic diseases. In the group of systematic schizophrenias the increase in tonus was significantly higher in the dominant hemisphere. This finding is considered a verification of the nosological hypothesis of schizophrenias.