Mechanisms of blocking by contextual stimuli

The influence of contextual stimuli on the conditioning and performance of responding to a discrete stimulus was examined in the US preexposure paradigm using both context shift manipulations and a measure of context conditioning. Four groups of rats received both repeated exposure to an electric shock US in one context (Context 1), and repeated nonshocked exposure to a second context (Context 2). Two additional groups of rats received exposure to these contexts, but never received shock presentations. Rats exposed to shock learned to escape from the stimuli of Context 1, but did not escape from the stimuli provided by Context 2. Rats not exposed to shock failed to escape from either context. All rats then received a single CER conditioning session in which four pairings of a 3-min noise CS and shock US were presented. Half the rats received those CS-US pairings in the excitatory Context 1, while the remaining rats received those pairings in the neutral Context 2. Finally, half the rats in each of the CER conditioning treatments received extinction test trials of the noise CS in Context 1, while the remaining rats received those test trials in Context 2. Thus, this design factorially manipulated the presence of excitatory or neutral contextual stimuli during both conditioning and testing of a discrete CS. In comparison with the two groups of rats never preexposed to shock alone, attenuation in acquisition of conditioned suppression observed during test trials occurred only when CER conditioning had been administered in the excitatory Context 1, and this effect was manifested when testing occurred in either the excitatory Context 1 or the neutral Context 2. These results support the model of R. A. Rescorla and A. R. Wagner (1972) (in A. H. Black & W. F. Prokasy (Eds.) Classical Conditioning II, pp. 64–99, New York: Appleton-Century-Crofts) which asserts that contextual stimuli and sicrete CSs compete for limited associative strength supportable by a given US.     

REPEATED MEMORY OF ORAL PROSE IN GHANA AND NEW YORK1

On a lu en anglais un court passage de prose à difféients groupes d'étudiants ghanéens et new yorkais. Ensuite, et par trois fois, on leur demande de dire ce qu'ils ont retenu. Le premier rappel a lieu après 30–45 minutes, le second et le troisiàme après plusieurs semaines. On a utilisé trois histoires différentes, mais chaque groupe de sujets n'en entendait qu'une seule. Les résultats montrent que, conformément à L'idée que la tradition orale est plus forte en Afrique Occidentale qu'à New York, les étudiants ghanéens retenaient mieux que les américains. Pour deux des histoires, on a enregistré peu de perte de rétention des thèmes entre le 1^er et le 3^e rappel; pour la troisiéme, entre le 2^e et le 3^e rappel. Mais la capacité à reteñir les thèmes de L'histoire ne s'explique pas uniquement par puré routine de mémoire. On peut penser que L'ordonnancement de L'histoire, loin de constituer un obstacle comme c'est souvent le cas quand on doit retenir dans L'ordre des faits sans liaison entre eux, favorisait ici la rétention des thèmes.     

Characteristics of Schizogenic Families During a Joint Story-Telling Task

For a joint family story-telling task, families with a schizophrenic offspring were compared to normal families on the completeness and clarity of the final composite stories and on their interactional behavior. The composite stories from schizogenic families were more “vague and confused”, fragmented, and less complete as to the five components required to satisfy the task instructions. Schizogenic families displayed more conflict, failure, and confusion during the interactional task than control families, and, fathers and mothers of schizophrenic offspring displayed more “anxiety and tension”, “depressive mood”, “evasiveness” and “lack of interest” than fathers and mothers of normal families. Mothers of schizophrenic offspring were also described as more “hostile” than control mothers. Comparing schizogenic families from which the patient was absent during the task with schizogenic families with the patient present, and with control families, indicated that the central findings were not attributable to the immediate presence and participation of the schizophrenic member.     

Rules in relevant logic — II: Formula representation

This paper surveys the various forms of Deduction Theorem for a broad range of relevant logics. The logics range from the basic system B of Routley-Meyer through to the system R of relevant implication, and the forms of Deduction Theorem are characterized by the various formula representations of rules that are either unrestricted or restricted in certain ways. The formula representations cover the iterated form,A ₁ .A ₂ . ... .A _n B, the conjunctive form,A ₁&A ₂ & ...A _n B, the combined conjunctive and iterated form, enthymematic version of these three forms, and the classical implicational form,A ₁&A ₂& ...A _n B. The concept of general enthymeme is introduced and the Deduction Theorem is shown to apply for rules essentially derived using Modus Ponens and Adjunction only, with logics containing either (A B)&(B C) .A C orA B .B C .A C.I acknowledge help from anonymous referees for guidance in preparing Part II, and especially for the suggestion that Theorem 9 could be expanded to fully contraction-less logics.     

The predictive validity of teacher nominations: A five-year followup of at-risk youth

The purpose of this study was to examine the predictive validity of a teacher nomination procedure for identifying at- risk children. Two hundred and twenty-five children were nominated by their teachers as well- adjusted (n= 75), socially withdrawn (n=76), or socially aggressive (n=74) during the fourth grade. Five years later, 198 of these children (88%) were located and their adjustment evaluated. Significant differences among the nominated children were found on a variety of measures, including academic grades, sociometric status, and social behavior. In addition, differences in school dropout and delinquent offenses were noted. Results are discussed in terms of the validity of teacher nomination procedures and their utility in identifying at- risk youth.