Influence of timing of post-weaning isolation on play fighting and serious aggression in the male golden hamster (Mesocricetus auratus)

Effects of timing of social isolation on play fighting and serious fighting were studied at different ages in male golden hamsters. Litters were isolated at 21, 35, and 65 days of age, and tested in a resident-intruder paradigm. Behaviors were compared within grous and with a fourth group of socially reared conspecifics. The earlier the pups were isolated, the more they engaged in play activities. Later, in adulthood, the aggression level of the same animals was retested using the same paradigm. The three isolated groups showed a high level of aggression, with significant differences among them. When compared with socially reared subjects, a reliable difference in the level of aggression was also found. These results support the view that early social experience is important, suggesting that isolation during early critical periods of socialization has a significant impact on play fighting, whereas short periods of isolation may be enough to trigger adult agonistic behavior. © 1994 Wiley-Liss, Inc.     

Intra- and lnterspecific aggression in two species of field crickets,Gryllus integer and G. alogus

Adult, laboratory-reared, and singly caged field crickets, Gryllus integer, of known ages and representing F1 to F4 generations, were exposed to 15–20-minute bouts of social interaction with introduced adult intruder males on alternate days from approximately 1 week after adult molt to time of death. A total of 3,523 paired-male bouts for 116 male G. integer were recorded over a 2.5-year study period. Adult males used as intruders were wild-caught or laboratory reared G. integer, but for nine of the 116 experimental males, wild-caught intruders of a closely related sympathetic species, G. alogus, were used for all or many of the bouts. Bouts between male G. integer and conspecific intruders were characterized by significantly elevated levels of aggression (t=6.04, P<0.001) compared with males exposed to heterospecific G. alogus intruders in interspecific interactions. Significant differences (p<0.005, chi-squared test of independence) existed at four out of five levels in a hierarchy of agonistic behaviors. Most G. integer males exposed to both G. integer and G. alogus intruders showed significantly reduced aggression levels during the interspecific interactions (p<0.001, Mann-Whitney U test). Conspecific G. integer dyads in the intraspecific interactions showed significantly stable dominant-subordinate relationships over time. Confusion surrounding the use of the term aggression is described with reference to Arthropods in general and Orthopteran insects in particular, and some likely proximate and ultimate bases for reduced interspecific aggression in field crickets are discussed.     

Alterations in shock-induced fighting and locomotor activity following intracerebroventricular injection of hydrocortisone in the rat

Three experiments were conducted in an attempt to clarify the facilitatory influence of hydrocortisone on shock-induced fighting in rats. Results of the first experiment indicated a biphasic, dose-dependent action of intraventricularly-administered hydrocortisone. Low (25 μg) and intermediate (50 μg) doses both facilitated fighting whilst the high (100 μg) dose exerted a potent suppressant effect. Two control tests were performed to determine whether alterations in pain reactivity or locomotor activity could have accounted for the observed changes in fighting behaviour. None of the treatments altered shock thresholds (Experiment 2) but whilst neither low nor intermediate doses affected activity measures, the high dose preferentially reduced vertical activity (Experiment 3).     

Development of rules and strategies: balancing the old and the new

The experiments described in the lead articles replicate findings from previous studies of development of knowledge about balance scales, add several new findings, and raise four key questions: (a) How can rule use best be assessed? (b) How can we reconcile systematic use of rules with variable use of strategies? (c) When do children begin to use rules? and (d) How do children generate new rules? In this Reflection, we summarize current understanding of development of knowledge about balance scales and consider each of the four questions.     

The nature of regularity and irregularity: evidence from Hebrew nominal inflection

Most evidence for the role of regular inflection as a default operation comes from languages that confound the morphological properties of regular and irregular forms with their phonological characteristics. For instance, regular plurals tend to faithfully preserve the base's phonology (e.g., rat-rats), whereas irregular nouns tend to alter it (e.g., mouse-mice). The distinction between regular and irregular inflection may thus be an epiphenomenon of phonological faithfulness. In Hebrew noun inflection, however, morphological regularity and phonological faithfulness can be distinguished: Nouns whose stems change in the plural may take either a regular or an irregular suffix, and nouns whose stems are preserved in the plural may take either a regular or an irregular suffix. We use this dissociation to examine two hallmarks of default inflection: its lack of dependence on analogies from similar regular nouns, and its application to nonroots such as names. We show that these hallmarks of regularity may be found whether or not the plural form preserves the stem faithfully: People apply the regular suffix to novel nouns that do not resemble existing nouns and to names that sound like irregular nouns, regardless of whether the stem is ordinarily preserved in the plural of that family of nouns. Moreover, when they pluralize names (e.g., the Barak-Barakim), they do not apply the stem changes that are found in their homophonous nouns (e.g., barak-brakim lightning), replicating an effect found in English and German. These findings show that the distinction between regular and irregular phenomena cannot be reduced to differences in the kinds of phonological changes associated with those phenomena in English. Instead, regularity and irregularity must be distinguished in terms of the kinds of mental computations that effect them: symbolic operations versus memorized idiosyncrasies. A corollary is that complex words are not generally dichotomizable as regular or irregular different aspects of a word may be regular or irregular depending on whether they violate the rule for that aspect and hence must be stored in memory.     

中国幼儿数数过程信息加工活动研究

探讨中国幼儿数数发展特点。实验1探讨3－5岁幼儿数数的终结点分布状况,结果表明,最大的密集终结点是“19”。实验2进一步考察幼儿在其数数范围内与范围外的起点进行数数的成绩,结果表明,数数范围为11－19的幼儿就开始有部分人可以在其数数范围外的起点进行数数,此表明他们开始应用了数列规则。据此可以认为,中国幼儿的数数活动同样包括联结学习与数列规则学习两种信息加工活动,但中国幼儿数列规则的学习活动在“11－19”数数过程开始。     

Admissibility of Cut in <Emphasis Type="Italic">LC</Emphasis> with Fixed Point Combinator

The fixed point combinator (Y) is an important non-proper combinator, which is defhable from a combinatorially complete base. This combinator guarantees that recursive equations have a solution. Structurally free logics (LC) turn combinators into formulas and replace structural rules by combinatory ones. This paper introduces the fixed point and the dual fixed point combinator into structurally free logics. The admissibility of (multiple) cut in the resulting calculus is not provable by a simple adaptation of the similar proof for LC with proper combinators. The novelty of our proof—beyond proving the cut for a newly extended calculus–is that we add a fourth induction to the by-and-large Gentzen-style proof. Presented by Robert Goldblatt     

What Is Legal Philosophy?

This article delineates some of the main issues that are debated by philosophers of law. It explores the connections between legal philosophy and other areas of philosophy, while also seeking to specify the distinctiveness of many of the concerns that have preoccupied philosophers of law. It illustrates its abstract points with examples focused on the separability of law and morality, the nature of the rule of law, the nature of rights, justifications for the imposition of punishment, and the identification of basic legal entitlements.