Cognitive sequelae of repeated head injury in a population of intravenous drug users

The relationship between closed head injury and performance on neuropsychological (NP) tests was investigated in a group of intravenous drug users (IVDUs). Subjects with repeated head traumas involving loss of consciousness (LOC) performed worse than both a control group without LOC and reference group with only a single episode of LOC. There were no significant differences between the last two groups. Performance on tests of memory, attention, and motor performance was significantly worse in the group with repeated head injury. The average time since the last episode of LOC was more than 11 years. We conclude from these findings that a single episode of LOC does not result in significant cognitive impairment in this population. Two or more episodes, however, are more likely to produce chronic cognitive impairment.     

Decision strategies and visual-field asymmetries in same-different judgments of word meaning

The accuracy with which observers judged whether two words belonged to the same semantic category was determined from a detection-theoretic analysis ofsame-different judgments. In Experiment 1, one word was presented centrally and the other word in either the left visual field (LVF) or the right visual field (RVF); in Experiment 2, both words were presented to either the LVF or the RVF. In order to obtain receiver-operating characteristics (ROCs) of performance, observers were asked to rate their confidence that the two words belonged to the same semantic category. Two models of the decision strategy were fitted to the obtained characteristics: a differencing model, in which the decision variable was the difference between the two observations; and an optimal model, in which each observation was judged in relation to a criterion. In both experiments, the optimal model provided a better fit than the differencing model to the obtained characteristics. Maximum-likelihood estimates of both the criterion-free parameter,d′, and the area under the operating characteristic,p(A), were greater for words presented in the RVF than for those presented in the LVF.     

Measurement and the interpretation of quantum mechanics and relativity theory

The axiomatic approaches of quantum mechanics and relativity theory are compared with approaches in which the theories are thought to describe readings of certain measurement operations. The usual axioms are shown to correspond with classes of ideal measurements. The necessity is discussed of generalizing the formalisms of both quantum mechanics and relativity theory so as to encompass more realistic nonideal measurements. It is argued that this generalization favours an empiricist interpretation of the mathematical formalisms over a realist one.     

Maximal weakly-intuitionistic logics

This article introduces the three-valuedweakly-intuitionistic logicI ¹ as a counterpart of theparaconsistent calculusP ¹ studied in [11].I ¹ is shown to be complete with respect to certainthree-valued matrices. We also show that in the sense that any proper extension ofI ¹ collapses to classical logic.The second part shows thatI ¹ is algebraizable in the sense of Block and Pigozzi (cf. [2]) in a way very similar to the algebraization ofP ¹ given in [8].In the last part of the paper we suggest the definition of certain hierarchies of finite-valued propositional paraconsistent and weakly-intuitionistic calculi, and comment on their intrinsic interest.     

Uncertainty in estimating distances from memory

Magnitude estimations involving spatial characteristics, such as distance, typically show a compressive function when estimates are made from memory. In particular, as the magnitude of a property grows larger and larger, estimates become more and more inaccurate, with increasing underestimates of the actual magnitude. Previous theories have attempted to explain this difference by supposing that magnitude estimation was accomplished through a reperceptual process, in which the errors of perception are magnified, or a transformation process, in which the memory trace undergoes a consistent alteration toward a more schematic form. The present experiments present evidence in support of an uncertainty hypothesis. When subjects are uncertain of the actual value of a distance, they are forced to guess on the basis of the mean distance they encountered, because they are unable to retrieve the information accurately. When they can retrieve the information, they are more certain and their estimates are more accurate. This hypothesis was also extended to integrative conditions in which the subjects were presented with the stimulus display in a piecemeal fashion. In these cases, distance estimates were derived by combining spatial representations. This method of presentation caused distance estimates to become less accurate.     

Accepting the null hypothesis

This article concerns acceptance of the null hypothesis that one variable has no effect on another. Despite frequent opinions to the contrary, this null hypothesis can be correct in some situations. Appropriate criteria for accepting the null hypothesis are (1) that the null hypothesis is possible; (2) that the results are consistent with the null hypothesis; and (3) that the experiment was a good effort to find an effect. These criteria are consistent with the meta-rules for psychology. The good-effort criterion is subjective, which is somewhat undesirable, but the alternative—never accepting the null hypothesis—is neither desirable nor practical.     

A possible genetic basis of accuracy in personality perception

An analysis was conducted to assess whether individuals are more accurate in perceiving those personality characteristics of other' that have a larger genetic component. Adult monozygotic (MZ) twins (63 pairs) and same-sex dizygotic (DZ) twins (35 pairs) completed the Personality Research Form-E (PRF) and the Sibling Evaluation of Personality Characteristics (SEPC) which consists of 20 sets of adjectives corresponding to the 20 trait scales of the PRF. Subjects also evaluated their co-twin with the SEPC. Self-other agreement correlations were then correlated with the heritability estimates of the PRF traits calculated on the same twin sample. The results suggest that accuracy in perceiving the co-twin's personality does increase with the heritability component of the personality dimension.