Play-fighting differs from serious fighting in both target of attack and tactics of fighting in the laboratory rat Rattus norvegicus

Play-fighting is often difficult to differentiate from inhibited or immature serious fighting because both may utilize many of the same behavior patterns. In the rat the two behaviors involve different targets of attack. During play-fighting, snout or oral contact is directed at the opponent's nape of the neck, whereas during serious fighting, male residents mostly direct their bites at the intruder's rump. Although similar to those used in serious fighting, the behavior patterns used during play-fighting are modified to achieve the different targets of attack. Even though the tactics of attack and defense appear more adult-like with increasing age, the playful targets persist well into adulthood.     

Lateral display as a combat tactic in richardson's ground squirrel Spermophilus richardsonii

During fighting, adult ground squirrels frequently face each other laterally, arch the back, and piloerect the tail. In a diurnal species, such distinctive visual cues seem consistent with the suggestion that the lateral display serves a communicatory function. However, a detailed analysis of videotaped sequences of free-living Richardson's ground squirrels from two consecutive mating seasons suggested that the lateral maneuver has a functional role in combat. Because most agonistic encounters involve chasing, the rump is the principal body area bitten. When stationary, however, the opponent's rump is bypassed, and bites are targeted at the shoulders. Defensively, a hip thrust is used to block such attacks to the shoulder by pushing the opponent's head away. Offensively, the lateral maneuver is used to push against the opponent, providing a vantage point from which to lunge at the opponent's shoulders. In addition, the defender can launch counterattacks at the side of the head. The lateral orientation provides the attacker with a means of evading such attacks, by swerving laterally away. In some encounters, both the offensive and defensive variations of the lateral maneuver were used by both opponents, often simultaneously. Therefore, irrespective of the signalling function of the lateral display, much of its occurrence during combat can be explained in terms of its role as a combat tactic. © 1996 Wiley-Liss, Inc.     

Supine defense in the intraspecific fighting of male house mice mus domesticus

House mice have been reported rarely to perform the supine behavior pattern as a defensive tactic during intraspecific fighting. However, in this study of intraspecific fighting by male mice, it is shown that mice do indeed rotate to supine. This maneuver is used to evade or extricate themselves from bites to the lower dorsum by the attacking opponent. Once free from the bite the defender does not remain supine, but will immediately turn to prone and flee. Remaining motionless in the supine position may serve a submissive function in other species, but this does not seem to be the case for mice. The present findings illustrate that the supine tactic is a dynamic maneuver for defense of body areas targeted by the opponent. © 1992 Wiley-Liss, Inc.     

Analysis of the targets and tactics of conspecific attack and predatory attack in northern grasshopper mice onychomys leucogaster

Comparisons of tactics of fighting between species are often difficult to make since the body targets attacked may differ. Thus it becomes difficult to assess whether differences in fighting tactics are due to species-specific differences in the tactics themselves or due to the different targets attacked. A solution to this problem is to analyse the tactics of a species that attacks different targets under different circumstances. In this way, differences in tactics can be more readily attributed to differences in targets. In this study, resident male northern grasshopper mice (Onychomys leucogaster) were tested against intruding male conspecifics and against laboratory mice (Mus musculus domesticus). Conspecifics were mainly bitten on the lower dorsum, whereas prey were bitten and killed by bites to the nape of the neck. Therefore, it was possible to analyze the tactics of attack by grasshopper mice when attacking different body targets. For example, in order to defend the lower dorsum and the nape, both intruding conspecifics and prey adopted an upright defensive posture. Resident grasshopper mice used the lateral attack tactic to gain access to the lower flanks but not the nape. This illustrates that the lateral attack tactic is not merely a tactic suitable for overcoming the upright defense tactic, but is used in this context only when the target attacked is on the opponent's posterior dorsum. Such withinpecies comparison enables the identification of the contextual rules which govern the use of fighting tactics. © 1992 Wiley-Liss, Inc.     

Bilateral opercular syndrome and crossed aphemia due to a right insular lesion: A clinicopathological study

A right-handed male patient suddenly noted lower bilateral facial and lingual palsy, and inability to masticate and swallow, but with preserved automatic functions. He was mute, communicating only through writing, but verbal comprehension was normal (aphemia). On anatomopathological examination, an ischemic infarction of the entire right insula, with mild extension to the fronto-temporoparietal operculum was observed. The left hemisphere was normal. The clinical findings suggest a bilateral opercular syndrome due to a right hemisphere lesion and a crossed aphemia.     

Hemispheric specialization for word classes with visual presentations and lexical decision task

In the present paper we study the possible RH capabilities for the processing of adjectives and verbs of high frequency and medium imagery using a lexical decision task and a horizontal display. In the analysis of both RTs and mean errors, a RVF advantage is obtained. The interaction VF x Word Class did not reach significance. Therefore, we did not find evidence of differences in the visual-field effect for any syntactic class. These results support a LH superiority for the processing of both adjectives and verbs. For the nonword conditions (pseudoverbs and pseudoadjectives), no visual field differences were observed in either group. Methodological aspects are also discussed.     

An illusion of eccentricity

The illusion investigated here is that two concentric arcs, drawn in different (though possibly overlapping) circular sectors and having the same angular extent, appear to be eccentric. Three possible explanations of the illusion are tested. The first hypothesis is that concentricity judgments are made by elongating the arcs to see if they intersect, the illusion being due to the tendency, when elongating a curve, to follow the end-tangent. The second hypothesis is that concentricity judgments are based on a test of coincidence of centers, the illusion being due to the overestimation of the radius of short arcs. The third hypothesis is that both of these factors contribute in equal measure. These hypotheses make different predictions about the effect (on the magnitude of the illusion) of the following variables: (1) the angular distance between the arcs; (2) the radial distance between the arcs; (3) the degree of curvature of the arcs; and (4) the angular extent of the arcs. The observed values of the illusion angle (obtained by the method of limits) in relation to these variables did not uniformly support any of the hypotheses. A more complex model that is consistent with the observed results is therefore proposed.     

A search for the physical content of Luders' rule

An interpretation of quantum mechanics that rejects hidden variables has to say something about the way measurement can be understood as a transformation on states of individual systems, and that leads to the core of the interpretive problems posed by Luders' projection rule: What, if any, is its physical content? In this paper I explore one suggestion which is implicit in usual interpretations of the rule and show that this view does not stand on solid ground. In the process, important aspects of the role played by the projection postulate in the conceptual structure of quantum mechanics will be clarified. It will be shown in particular that serious objections can be raised against the (often implicit) view that identifies the physical relation of compatibility preserved by Luders' rule with the relation of simultaneous measurability.