Restricted multidimensional scaling models for asymmetric proximities

Restricted multidimensional scaling models [Bentler & Weeks, 1978] allowing constraints on parameters, are extended to the case of asymmetric data. Separate functions are used to model the symmetric and antisymmetric parts of the data. The approach is also extended to the case in which data are presumed to be linearly related to squared distances. Examples of several models are provided, using journal citation data. Possible extensions of the models are considered. This research was supported in part by USPHS Grant 0A01070, P. M. Bentler, principal investigator, and NIMH Grant MH-24819, E. J. Anthony and J. Worland, principal investigators. The authors wish to thank E. W. Holman and several anonymous reviewers for their valuable suggestions concerning this research.     

Hippocampal deafferentation: transplantderived reinnervation and functional recovery

A brief review is provided of the capacity of neural tissue transplants to reinnervate the deafferented hippocampus and repair functional deficits induced by the lesion. The techniques for transplantation of solid pieces of embryonic septum, locus coeruleus or raphe nuclei, or tissue suspensions of embryonic septum, to the adult rat hippocampus are described. Such grafts manifest good long-term survival, provide a good reinnervation of the hippocampus that is histochemically and biochemically appropriate and specific, can establish ultrastructural synaptic contacts with the host, and are electrophysiologically active. Rats with septal grafts manifest recovery of the capacity to learn certain aspects of radial 8-arm maze, T-maze alternation and Morris water-maze tasks. Rats with locus coeruleus grafts manifest an amelioration of lesion-induced hyperactivity. It is concluded that neural tissue transplantation provides a powerful new tool in the study of the functional organization of the hippocampus and its various neurotransmitter-specific afferent systems.     

A note on the investigation of local and global identifiability

In general, nonlinear models such as those commonly employed for the analysis of covariance structures, are not globally identifiable. Any investigation of local identifiability must either yield a mapping of identifiability onto the entire parameter space, which will rarely be feasible in any applications of interest, or confine itself to the neighbourhood of such points of special interest as the maximum likelihood point.The author would like to thank J. Jack McArdle and Colin Fraser for their comments on this paper.     

On Chomskyan mentalism: A reply to Peter Slezak

Conclusion Introducing his paper, Slezak (p. 428) proposes to examine Botha's criticisms in detail with a view to demonstrating that they are without foundation and are based on the most fundamental misunderstandings. Concluding his paper, Slezak (p. 439) expresses the hope that he has shown that the conceptions on which these criticisms rest are so seriously flawed as to make it unprofitable to attempt to unravel the rest of his analysis. These formulations, by all standards, represent rather strong rhetoric. But, as the preceding paragraphs have shown, Slezak's discussion sadly lacks the relevant and accurate analyses needed to give substance to his rhetoric.I would like to thank Marina Savini and Thereza Botha for suggestions which led to improvements in the formulation of this paper.     

Factors affecting entrapment in escalating conflicts: The importance of timing

Entrapping conflicts are those in which individuals continue to invest their resources—even in seemingly losing propositions-in large part to justify previous unfilled expenditures. It has been demonstrated that individuals define their motivation for investing very differently at the various stages of an entrapping conflict. One implication of this motivational dynamic is that various factors may differentially affect degree of entrapment (i.e., amount invested), depending upon the point in time at which they are introduced. The present studies were designed to test this notion. All subjects were given an initial monetary stake and had the opportunity to win more by taking part in an entrapping investment situation. In Experiment 1, half the subjects were provided with a payoff chart that made salient the costs associated with investing (Highcost salience condition) whereas half were not (Low-cost salience condition). Moreover, for half of the subjects the payoff chart was introduced before they were asked to invest (Early condition) whereas for the other half it was introduced after they had invested a considerable portion of their resources (Late condition). Entrapment was lower in the High salience-Early than in the Low salience-Early condition. However, there was no difference between groups in the Late condition. In Experiment 2, the perceived presence of an audience interacted with personality variables related to face-saving to effect entrapment. When the audience was described as “experts in decision making,” subjects high in public self-consciousness (or social anxiety) became less entrapped than those low on these dimensions. When the audience consisted of individuals who “wished simply to observe the experimental procedure,” however, high public self-consciousness (or social anxiety) individuals were significantly more entrapped than lows. Moreover, these interaction effects occurred when the audience was introduced late, but not early, into the entrapment situation. Taken together, these (and other) findings suggest that economic factors are more influential determinants of behavior in the earlier stages of an entrapping conflict, whereas face-saving variables are more potent in the later phases. Alternative explanations are discussed.     

Mentally retarded individuals outperform college graduates in judging the nonconservation of space and perimeter

Most adults of average and superior intelligence incorrectly assume that in a two dimensional figure two attributes, area, and perimeter, are locked in a fixed relationship such that if one remains unchanged so does the other. Consequently, when they correctly conserve one attribute during shape transformation, they incorrectly conserve the other. Mentally retarded individuals assume no such fixed relationship but depend exclusively on perceptual information. Although this dependence adversely effects their judgment of conservation, it allows them to correctly judge the changed state of the nonconserved attribute.     

The personality of women who wish to adopt alternative delivery positions

The personalities of 51 women who wished to avoid obstetric intervention and to adopt alternative delivery positions were assessed. The EPQ was completed by the women and their consorts. The women were slightly higher on tough-mindedness (Psychoticism), more extra-verted and had lower dissimulation (Lie scores), than the average woman. Their Neuroticism scores were within the normal range for their age group. The personality scores for their consorts did not differ from the normal population.     

Choice between finger movements of different and identical form: The effect of relative signal frequency

Summary Binary choice reaction time depends on the relationship between the alternative responses. In particular, it is longer when choice is between finger movements of either hand, which have different forms, than when choice is between movements of identical form. This effect can be interpreted in terms of conjunctive preparation. If everything common to both responses is prepared in advance of the response signal, the form of the movement can only be prepared if it is the same for both responses. An alternative interpretation is in terms of single preparation. Under this hypothesis either one or the other response is prepared completely, but in case the not prepared response is demanded by the signal the time needed to shift should be longer if the movements are of different form. Thus, an effect of the form-relation will be seen only in unprepared responses, while under the hypothesis of conjunctive preparation it should be present in prepared responses as well. To decide between both hypotheses relative signal frequency and thus the proportion of expected (and prepared) responses was varied in three experiments. It turned out that the effect of the form-relation is larger with low relative signal frequency than with high frequency. This indicates the existence of single preparation. However, single preparation appears to be incomplete. When the obtained data are extrapolated to a relative signal frequency of 1.0 an effect of the form-relation still remains.This research was supported by Deutsche Forschungsgemeinschaft (grants No. He 1187/1 and 1187/2-1)