Analysis of ultrasonic vocalizations emitted by residents during aggressive encounters among rats (Rattus norvegicus).

Determined the extent to which aggressive resident rats emit 40–70-kHz vocalizations and the effect of these signals on intruders. In Exp I, 16 deafened and intact intruder male Long-Evans rats were given 2 encounters with 8 resident Ss. Deafened intruders engaged in a higher duration of immobile or freezing postures than intact Ss. Exp II indicated that the augmentation of freezing found among deafened intruders was not due to an inability to detect ultrasounds made by residents since intruders encountering devocalized resident males showed no reliable differences in specific motor patterns from intruders paired with intact residents. Results demonstrate that 40–70-kHz vocalizations were produced almost entirely by intruding Ss since there were no significant changes in occurrence of these calls when resident males were devocalized. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of ultrasonic vocalizations emitted by intruders during aggressive encounters among rats (Rattus norvegicus).

Determined the ultrasonic vocalizations produced by intruders during aggressive interactions and investigated the role of these signals in agonistic behavior of rats. In Exp I, 7 experienced resident male Long-Evans rats were paired with both devocalized and intact vocalizing naive intruder males (n?=?14). Devocalization of the intruder males resulted in a drastic decrease in 50-kHz vocalizations and the elimination of all 22-kHz vocalizations. This almost total absence of ultrasonic vocalizations was not accompanied by any change in resident aggressive behavior or intruder defensive and submissive behavior. In Exp II, 16 naive intruders were tested with either deafened or intact resident males (n?=?8). Similarly, preventing residents from hearing intruder ultrasounds had no detectable effect on any aggressive behavior. These experiments are not consistent with the correlative evidence that intruder-produced 22-kHz vocalizations inhibit the aggressive behavior of the resident. Results show that most of the ultrasonic vocalizations emitted during aggressive encounters were probably produced by the intruder. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory cues and movement: Stimuli mediating intraspecific aggression in the wild Norway rat.

Established male sibling pairs of laboratory-bred wild rats (R. norvegicus) in enclosures and in 4 experiments observed their aggressive, amicable, and sexual behavior following the introduction of conspecifics. Intact male Ss behaved amicably toward familiar male conspecifics, both aggressively and sexually towards unfamiliar anestrous and estrous female conspecifics, and aggressively toward unfamiliar male conspecifics. Anosmic males exhibited amicable and sexual behavior toward unfamiliar males, but did not initiate aggression toward them. The storing of a member of a resident pair in a cage with or without wood shavings, urine, and feces from a foreign colony did not affect behavior toward him by his cage mate. The storing of a foreign male in the wood shavings, urine, and feces of a colony did not affect behavior of that colony toward him. Cessation of movement on the part of an intruder of either sex inhibited attack, while immobile anesthetized male intruders elicited aggression. When presented simultaneously with moving and anesthetized intruders, resident Ss attacked only the former. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Electric signals and schooling behavior in a weakly electric fish, Marcusenius cyprinoides L. (Mormyriformes)

Field recordings of electric organ discharges and catches of Marcusenius cyprinoides showed that these electric fish form groups and move about in schools. The role electric organ discharges in group cohesion was investigated by comparing interactions in groups of intact and operated, electrically silent fish. The absence of electric organ dischares reduced locomotor activity and resulted in the disappearance of two behaviors: parallel lineup and single file swimming. Electric signals are considered part of a schooling mechanism that aids the fish in maintaining group cohesion in their turbid enviornment and during migration at night.     

Habituation, sensitization, and redirection of aggression and feeding behavior in the three-spined stickleback (Gasterosteus aculeatus L.).

In Exp I, 3-spined stickleback males maintained in individual aquaria built nests and defended the entire aquarium as a territory. Adjacent compartments containing another male, a gravid female, or a nongravid female provided a social context within which to study habituation and sensitization of aggression elicited by a conspecific male intruded into S's territory. Typical sensitization–habituation curves were found for all Ss regardless of kind of neighbor. However, behavior redirected as a result of stimulation of the intruded male differed between conditions. Ss with a male neighbor showed increased aggression toward the neighbor; Ss with a gravid female neighbor showed courtship; and Ss with nongravid female showed neither. A 3rd behavior, nest building, showed no difference between conditions. Exp II elicited the same motor response to the intruded stimulus, but the motivational category was changed by eliciting the behavior by presenting live brine shrimp. Aggression did not change during habituation, but the waning predation was redirected to another food-securing behavior, picking at the substrate. Results provide evidence for the important role that social context plays in understanding the redirection of behaviors, a phenomenon predicted from an extension of the dual-process theory of habituation. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Paired-associate learning and priming effects in amnesia: A neuropsychological study.

Conducted 4 experiments investigating the role of priming effects in paired-associate learning. Ss for all 4 experiments were 5 male and 3 female alcoholics (mean age 53.8 yrs; WAIS—R IQs 85–203) with Korsakoff syndrome. Control Ss were 26 male alcoholics (mean age 47.6 yrs). Exp I illustrated the distinction between the memory impairment of amnesic (Korsakoff) Ss and their intact priming ability. In Exp II, amnesic Ss showed good paired-associate learning for related word pairs but controls performed significantly better. Exp II also showed that the forgetting of related word pairs by amnesic Ss followed the same time course as the decay of word priming. Exp III showed that amnesic Ss were as good as controls at learning related word pairs when word-association tests were used. Exp IV showed that amnesic Ss exhibited normal priming when they were asked to free associate to words that were semantically related to previously presented words. Results indicate that both priming effects and paired-associate learning of related words depended on activation, a process that is preserved in amnesia. Activation is a transient phenomenon presumed to operate on and facilitate access to preexisting representations. (67 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dietary self-selection in intact, ovariectomized, and estradiol-treated female rats.

Six experiments with 84 Long-Evans rats investigated the effects of estrogenic stimulation on diet selection in intact estrous-cycling Ss, ovariectomized (OVX) Ss, and OVX Ss given estradiol benzoate (EB) hormone replacement therapy. In Exp I, OVX was associated with the nearly exclusive choice of the more calorically dense of a pair of diets varying in the concentration of fat, carbohydrate (COH), and protein, an effect that was decreased by EB. In Exp II, dietary self-selection was examined in intact estrous-cycling Ss given access to an isocaloric diet triplet of fat, COH, and protein. Total caloric intake and body weight did not vary across the estrous cycle. However, fat intake increased; COH and, to a lesser extent, protein intake decreased. An opposite diet selection occurred during diestrus. In Exp III, OVX resulted in progressive increases in COH and protein intake, with a concurrent decrease in fat consumption. EB partially reversed this diet selection profile (Exp IV). Results were confirmed by diet pairs with both naturally occurring and experimentally produced estrogenic stimulation (Exps V and VI). Data are consistent with previous findings showing estrogenic reduction in COH intake with standard high-COH commercial diets. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stomach acid secretion in submissive and aggressive rats.

Conducted 4 experiments with 60 female and 162 male Long-Evans rats to determine whether aggressive and submissive behavior are related to either an increase or a decrease in gastric secretion. In Exp I, intruder rats placed in an established male–female colony and attacked by a dominant alpha male secreted less acid than intruders exposed to nonaggressive males and females. In Exp II, intruders exposed to attack and subsequently returned to the encounter site, but protected from physical attack, still demonstrated a gastric hyposecretion. Ss with chronic gastric cannulas in Exp III also revealed an acid inhibition when attacked and later when exposed to, but protected from, attack. Both intruders and attacking males were prepared with gastric cannulas in Exp IV. Both demonstrated secretory inhibition following attack and attack-protected sessions. The inhibitory effect was greater and more persistent for intruders than for aggressive Ss. It is suggested that the inhibition occurring during the attack-protected sessions may have been mediated by some conditioning processes, and other possible associative mechanisms, including a learning model or a direct sensory model, are discussed. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some determinants of a natural food aversion in Norway rats.

Adult male Long-Evans rats were permitted to feed on the carcasses of adult male rodents, freshly sacrificed by CO? asphyxiation. In a 2-choice preference test (Exp I), hungry Ss were offered 1 conspecific and 1 house mouse, the pair of carcasses being either intact or skinned. 18 Ss offered intact carcasses fed on the mouse or on neither carcass, but 18 Ss offered skinned carcasses fed indiscriminately, usually on both carcasses. In Exp II, 10 hungry Ss that earlier had observed a cagemate feeding on intact conspecific carcasses fed more readily on a similar carcass during a single-choice test than did 8 controls. In Exp II, 20 food-deprived Ss (96 hrs) fed more readily and consumed more tissue from an intact conspecific carcass than did 20 nondeprived Ss. It is concluded that the aversion to feeding on the intact carcass of a freshly sacrificed adult conspecific is deprivation dependent and is mediated by chemoreceptive stimuli from the skin and/or fur. The aversion is diminished by social facilitation. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Respondent conditioning of self-injurious behavior in early socially deprived rhesus monkeys (Macaca mulatta).

Examined whether certain environmental events could elicit self-injurious behavior (SIB) and whether the resulting SIB could be conditioned to an antecedently presented external stimulus. Exp I showed that SIB could be elicited in 4 socially isolated rhesus monkeys by the application of brief, mild, electric footshock. In Exp II, 3 socially isolated Ss were exposed to a procedure that paired a 10-sec tone with a 1-sec electric footshock. Three control Ss received presentations of the tone alone. Results show that Ss in the experimental group began to show SIB during the tone periods, thereby providing evidence of respondent conditioning. Data expand the scope of the learning model of SIB from primarily operant interpretations to respondent conditioning as well. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of tail autotomy on agonistic behaviour in a territorial salamander

Assessment of potentially asymmetrical characters (such as fighting ability and resident advantage) is often important in determining the outcome of agonistic interactions. Loss of body parts, a predator defence mechanism used by many animals, may lead to a reduction in fighting ability and may be easily assessed by competitors. We investigated the influence of tail loss on the expression of agonistic behaviour in the territorial red-backed salamander, Plethodon cinereus. Residents and intruders were matched for body size, and pairs were tested in all combinations of tailed or tailless residents with tailed or tailless intruders. Neither residents nor intruders altered their behaviour based on their own tail condition, but they did alter their behaviour based on the tail condition of their opponents. Intruders showed more aggression or less submission towards tailless residents than towards tailed residents. When contests were between residents and intruders of the same tail condition (both tailed or tailless), intruders were more aggressive towards residents when both were tailless than when both were tailed, indicating that tail loss does not directly hamper aggressive displays. In contests where the asymmetry between residents and intruders was small (based on tail condition and residency status), intruders showed more aggression and less submission than in contests where the asymmetry was large. Residents did not differ in their behaviour for most comparisons. Thus, for intruders, the tail condition of residents is an important determinant of agonistic behaviour displayed in territorial contests. For residents, factors other than tail condition (such as resource value) may be more likely to influence their behaviour. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.     

Social support as an individual difference variable: Its stability, origins, and relational aspects.

Investigated the stability of social support indices, the relation between these indices and measures of parental bonding, and the relation between the indices and ratings of social behavior. In Exp I, 76 undergraduates responded to a social support questionnaire (SSQ) several times at 5- and 36-mo follow-ups. Exp II partially replicated Exp I with 251 Ss, and it investigated the relation between the SSQ and a parental bonding instrument. In Exp III, 160 Ss rated videotapes of persons with different levels of social support and scored them with regard to indices of personal effectiveness. The studies demonstrate that social support levels are stable over periods up to 3 yrs. They also showed that Ss high in social support reported having received more parental care (affection, interest, empathy) than did those low in social support. High social support Ss were judged by observers to be more competent leaders and problem solvers than were low-support Ss. Female Ss were judged to be more considerate and friendly than male Ss. Results suggest the value of conceptualizing social support as an individual difference variable as well as an environmental provision. (29 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Variations du rythme cardiaque d'enfants soumis à des taches d'observation et de contr?le de stimulations complexes.

Three experiments were conducted to determine the cardiac responses of 30 preschool children requested to be attentive to stimulations and/or to try to control their occurrences by a simple or more complex motor behavior. In Exp I, Ss were instructed to pay attention to the movements, lights, and sounds originating from a harlequin puppet (observation condition). In Exp II, Ss were told that they could initiate the harlequin stimulations with a simple motor response (easy control condition). In Exp III, Ss had to perform a more complex response to initiate the stimulation (difficult control condition). In the observation condition, the first stimulations elicited a decelerative heart rate response. In the easy control condition, both groups displayed an equivalent number of keypresses. Ss in the difficult control condition, while making as many keypress responses, obtained fewer stimulations than Ss of the easy contingent group. Their tonic and phasic cardiac responses during the demonstration–observation phase were similar. During the control trials, the first and last stimulations within trials were followed by phasic decelerative responses in this group. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social memory of the male laboratory rat.

Used duration of social-investigatory behavior by 36 mature male Long-Evans rats as a measure of individual recognition in 5 experiments to assess social memory. In Exp I, the duration of social investigation during a 2nd exposure to the same juvenile (n?=?12) was directly related to the length of the interexposure interval. In Exp II, Ss were exposed to the same or different juvenile 10 min after an initial 5-min exposure to a novel juvenile; reexposure to the same juvenile elicited significantly less social investigation than an exposure to a different juvenile. Exps III and IV demonstrated that following a 5-min introductory exposure, social memory of the juvenile was relatively brief in comparison with that of mature Ss. Exp V revealed a retroactive interference effect on recently acquired memory for an individual: 12 mature Ss exposed to interpolated social experience engaged in significantly longer investigation of a juvenile than those with no interpolated social experience. The combined results suggest that (1) the rat normally engages in spontaneous learning of individual identity and (2) social memory may be a significant aspect of complex social interactions. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social position and competition in laboratory rats.

Conducted 2 experiments with male albino rats which controlled for social position (i.e., relative dominance-submission) in an appetitive social learning-performance setting. The 10 most dominant and 10 most submissive of 30 Ss were used in Exp I, and the 20 most dominant of 30 Ss were paired in Exp II. Results indicate that Ss which performed effectively when alone exhibited significantly reduced levels of responding when placed into a social environment. The severity of the response decrement was partly a function of the relative social position of the Ss involved. A dominant male made few responses when paired with another dominant male. Yet, a dominant S made even fewer responses when paired with a submissive S, which barpressed at approximately half the individual level. Findings suggest that social position, with its accompanying characteristic form of aggression, is an important determinant of performance in a social learning environment. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sham feeding in rats after ventromedial hypothalamic lesions and vagotomy.

Two studies examined sham feeding in female Sprague-Dawley rats with ventromedial hypothalamic (VMH) lesions with or without abdominal vagotomy. In Exp I, intact Ss consumed more than twice as much sweet milk during 1-hr tests of sham feeding as they did when feeding normally. Ss with VMH lesions showed exaggerated sham feeding, which was elevated almost four-fold over their already high normal feeding baseline. In Exp II, vagotomy substantially reduced sham feeding in Ss with VMH lesions. After vagotomy, VMH Ss sham fed half as much as nonvagotomized VMH Ss. Vagotomy did not, however, reduce sham feeding to control levels. Results are consistent with the hypothesis that VMH hyperphagia arise from exaggeration of orosensory responsiveness, which is, in part, a consequence of perturbed vagal function. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Predation, aggression, and activation levels in food-deprived sunfish (Lepomis macrochirus and L. gibbosus): Motivational interactions.

Three experiments investigated the effects of food deprivation on several behavioral categories in a total of 56 bluegill and pumpkinseed sunfish ( Lepomis macrochirus and L. gibbosus, respectively). In Exp I, predatory behavior and general activity were observed under 5 levels of deprivation. For both species, predation measures increased in a similar negatively accelerating manner with increasing deprivation, while activity changed in a more complex fashion. Exp II examined the effects of deprivation on activity in a novel environment and showed that the deprivation effects of Exp I were masked by the response to the new setting. In Exp III, measures of aggression toward intruders of each species were recorded from resident fish of both species under 3 levels of food deprivation. Both species were more aggressive toward conspecifics, and bluegills were more aggressive overall. Aggression was significantly affected by food deprivation, with the effects dependent on the species making up the pair. Theories of motivational summation, generalized drive, and activity-mediated aggression are seen as inadequate to explain the differential effects of hunger on the 3 behavioral categories observed. A dynamic boundary-state model of behavior was, however, found to predict the motivational interactions observed between distinct behavioral control systems. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Isolation-induced aggression in newly hatched ducklings.

Describes 3 experiments with a total of 40 Khaki Campbell ducklings. In Exp I newly hatched Ss were initially housed in pairs and subsequently transferred to isolated housing conditions. Ss living with another bird displayed filial behavior and little aggression upon encountering another duckling in a test arena. In contrast, Ss housed in isolation exhibited aggressive pecking in addition to filial behavior when another duckling was subsequently encountered. In Exp II, Ss were housed with an imprinting object (i.e., an object that elicits attachment behavior) but were otherwise isolated from other birds. These Ss displayed little aggression when they were subsequently reunited with a conspecific, indicating that the aggression-precluding effects of social housing are not limited to the particular social stimulus with which the ducklings are housed. In Exp III, Ss were again housed with an imprinting object, but this time the object was behind glass, thereby precluding tactile contact with it. Since these Ss also exhibited little aggression when reunited with a conspecific, it is apparent that visual stimulation from an imprinting object is sufficient in itself to preclude subsequent aggression. Findings suggest that stimulation that elicits attachment behavior is the critical factor mediating isolation-induced aggression. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic differences in avoidance learning by Rattus norvegicus: Escape/avoidance responding, sensitivity to electric shock, discrimination learning, and open-field behavior.

Studied the behaviors of Long-Evans rats selectively bred for either good (SHA line) or poor (SLA line) shuttle box avoidance learning. The results of Exp I indicated that the phenotypic difference in avoidance learning was not associated with differences in speed of escape or avoidance responding. Differences between the lines in frequency of intertrial responses (ITRs), which appeared during training but not during pretest, suggest that ITRs in Ss of the low-avoidance SLA line were more suppressed by electric shock than in Ss of the high-avoidance SHA line. This result suggests that SLA Ss may be more emotionally responsive than SHA Ss. Exp II demonstrated that the Ss of the 2 lines did not differ in absolute sensitivity to electric shock, and Exp III showed that the poor performance of the SLA line was not due to an inability to learn. Ss also provided evidence that the poor avoidance learning by SLA Ss was due to their emotional reactivity. Observations of open-field behavior in Exp IV were consistent with this hypothesis. It is concluded that the major consistent correlate of the phenotypic difference in avoidance learning was greater emotionality or emotional reactivity in SLA than in SHA Ss. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of social isolation and social separation in domestic chicks.

Conducted 2 experiments with 60 white Leghorn chicks, with subsamples of 24 and 36 animals tested in 2 independent replications, to assess the impact of early social isolation and social separation on the behavior of domestic chicks. In Exp I, a 3-wk longitudinal study, the day-to-day behavior of isolated chicks was compared to the behavior of birds housed in pairs. Ss in a 3rd group were reared in pairs for 2 wks, and then were permanently separated. The daily observations of all Ss recorded disturbance reactions, exploratory activities, consummatory behavior, grooming, and inactivity. In Exp II, 36 Ss from the 3 experimental conditions were tested in the 4th posthatch week for general social responsiveness in the presence of unfamiliar conspecifics. Results show that (a) both isolation and separation produced behavioral anomalies; (b) separated Ss' reactions indicated patterns analogous to post-separation patterns seen in other species; and (c) the effects of isolation and separation were not qualitatively equivalent--exposure to conspecifics revealed antisocial behavior in the isolates, relative to the responses of their socially reared and separated counterparts. Results are discussed in terms of a model for differences in the essence and consequences of early social isolation and social separation. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)