Successive negative contrast in one-way avoidance learning in rats

In three experiments, successive negative contrast was examined in one-way avoidance learning. Reward magnitude in first (pre-shift) and second (post-shift) phases was manipulated by time spent in the safe compartment. Experiment 1 demonstrated that when time in the danger compartment was held constant, a group shifted from a large reward--30 sec spent in the safe compartment--to a small reward--1 sec--showed poor performance and longer response latency than a group conditioned with the small reward in both phases. Experiment 2 replicated this effect with a less intense shock and also demonstrated that a group shifted from large to small reward performed more poorly than a group exposed to large reward--30 sec--in both phases. Finally, Experiment 3 showed that changes in intertrial interval, defined as total time spent in the safe compartment and the danger compartment before the onset of the warning signal, were not responsible for this contrast effect. These results suggest that time spent in a safe place can act as appetitive incentive during one-way avoidance learning.     

The probability of war in then-crises problem: Modeling new alternatives to Wright's solution

In hisStudy of War, Q. Wright considered a model for the probability of warP during a period ofn crises, and proposed the equationP=1–(1–p) ⁿ , wherep is the probability of war escalating at each individual crisis. This probability measure was formally derived recently by Cioffi-Revilla (1987), using the general theory of political reliability and an interpretation of the n-crises problem as a branching process. Two new, alternate solutions are presented here, one using D. Bernoulli's St. Petersburg Paradox as an analogue, the other based on the logic of conditional probabilities. Analysis shows that, while Wright's solution is robust with regard to the general overall behavior ofp andn, some significant qualitative and quantitative differences emerge from the alternative solutions. In particular,P converges to 1 only in a special case (Wright's) and not generally.C.C.-R. acknowledges support provided by the Merriam Laboratory for Analytic Political Research, the Research Board of the University of Illinois, and grant SES-84-00877 from the U.S. National Science Foundation.     

Strong Boethius’ Thesis and Consequential Implication

The paper studies the relation between systems of modal logic and systems of consequential implication, a non-material form of implication satisfying Aristotle's Thesis (p does not imply not p ) and Weak Boethius' Thesis (if p implies q, then p does not imply not q ). Definitions are given of consequential implication in terms of modal operators and of modal operators in terms of consequential implication. The modal equivalent of Strong Boethius' Thesis (that p implies q implies that p does not imply not q) is identified.     

The role of Canadian school psychologists: Perceptions of a sample from the general public

A sample of 77 subjects responded to a questionnaire designed to collect information about their perceptions of the role of school psychologists. The results indicate that overall the respondents had a fairly accurate sense of what a school psychologist does, although they overestimated the importance of psychotherapy as one of the school psychologist's functions. It is recommended that school psychologists more clearly specify their function when dealing with members of the general public.     

Family therapy in Mexico—1978

The status of family therapy in Mexico is described. The Instituto de la Familia was formed in 1974 as a facility to train family therapists by Macias, Estrada, Dersbez, Chagoya and Barragan. In 1975 Barragan formed the Instituto Mexicano de la Familia. Various centers utilizing family therapy are noted.     

Individual differences in the study of human aggression

Excessive concern for simplicity has often led us to underestimate the complexity of aggression. Over the years, several scales related to aggression have been identified and validated both on adults and on children. Ultimately, two main higher order dimensions, emotional responsivity and proneness to aggression, repeatedly emerged in a series of second-order factor analysis. These dimensions are rather similar to two of the big five factors of personality: neuroticism/emotinal stability and hostility/agreeableness, respectively. Several studies corroborate the plausibility of a higher level bidimensional conceptualization of aggression that, while preserving the heuristic validity of looking for more specific constructs of aggression, can link the field of aggression to the field of personality. © 1994 Wiley-Liss, Inc.     

Mental representation of prepositional compounds: evidence from Italian agrammatic patients

The processing of Prepositional compounds (typical Neo-latin noun--noun modifications where a head noun is modified by a prepositional phrase, e.g., mulino a vento, windmill) was preliminarily studied with a group of six agrammatic aphasic patients, and, in more detail, with a further agrammatic patient (MB). Omission was the most frequent error type in naming, whereas in the other tasks (repetition, reading, writing, and completion) errors were mostly substitutions of the target preposition. This happened even with fully lexicalized compound forms, i.e., those forms where the linking preposition is syntactically and semantically opaque. These findings are interpreted in terms of a dual-route theory of lexical access to morphologically complex words.     

Retrieval improvement is induced by water shortage through angiotensin II

Angiotensin II (ANGII) has an evolutionary preserved role in determining adaptative responses to water-shortages. In addition, it has been shown to modulate diverse phases of memory. Still, it is not clear whether ANGII improves or spoils memory. We demonstrated that endogenous angiotensins enhance consolidation of a long-term associative memory in the crab Chasmagnathus and that water shortage improves memory consolidation through brain ANGII actions. Here, we show that weakly trained crabs, when water-deprived, exhibit enhanced retrieval. Subsequently, memory retention is indistinguishable from that of strongly trained crabs. ANGII, but not angiotensin IV, is a necessary and sufficient condition for such enhancing effect. We conclude that ANGII released due to water shortage leads to enhanced memory retrieval. Thus, it seems that ANGII has an evolutionary preserved role as a multifunction coordinator that enables an adaptative response to water-shortage. The facilitation of memory consolidation and retrieval would be among those coordinated functions.