Effects of d-amphetamine on self-aggression and posturing in stumptail macaques

The behavioral effects of d-amphetamine sulfate were studied in adult male stumptail macaques living within a large heterogeneous group in an outdoor enclosure. Among five subjects that received a range of doses (.01 to .3 mg/kg), d-amphetamine increased self-aggressive behavior and abnormal posturing in subjects that exhibited these types of behavior prior to drug administration, but it had no effect in subjects not exhibiting those activities in the absence of the drug. For the former subjects, the dose-effect curves for self-aggression were of an inverted U-shape analogous to the effect of d-amphetamine on schedule-controlled behavior. Over the range of doses studied, the curve for abnormal posturing was monotonic. The data indicate that d-amphetamine can have effects on untrained behavior in individual animals in a quasinatural environment that are qualitatively and quantitatively similar to the behavioral effects observed in other laboratory environments, and that d-amphetamine does not evoke or increase a behavioral response in individual subjects that do not exhibit the response in the absence of the drug.     

Intersexual aggression and male sexual activity in captive rhesus macaques

Rape has been posited to be an outgrowth of male reproductive strategies. Forced copulations may have evolved as a consequence of the low parental investment made by males in producing and raising offspring. We designed a laboratory experiment which paired rhesus macaque males with females in order to assess the influence of intersexual aggression on male sexual activity. Younger and older adult males had comparable levels of sexual behavior, but younger males were more aggressive towards females than were older males. In addition, females threatened younger males more than older males. Male attacks on females did not result in sexual intercourse. On the contrary, a negative correlation existed between male aggression towards females and male success at achieving intromissions. Female aggression towards males appeared to be an effective tactic which reduced the chances of sexual intercourse. We conclude that intersexual aggression acts either as a mechanism of dominance assertion or as a means to increase spatial distance between individuals. These data do not support the idea that rape in humans has an evolutionary foundation derived from male reproductive strategies.     

Is the inversion effect in rhesus monkeys face-specific?

This study investigated the face inversion effect in rhesus monkeys (Macaca mulatta). Face stimuli consisted of ten black-and-white examples of unfamiliar rhesus monkey faces, brown capuchin faces, and human faces. Two non-face categories included ten examples of automobiles and abstract shapes. All stimuli were presented in a sequential matching-to-sample format using an automated joystick-testing paradigm. Subjects performed significantly better on upright than on inverted presentations of automobiles, rhesus monkey and capuchin faces, but not human faces or abstract shapes. These results are inconsistent with data from humans and chimpanzees that show the inversion effect only for categories of stimuli for which subjects have developed expertise. The inversion effect in rhesus monkeys does not appear to be face-specific, and should therefore not be used as a marker of specialized face processing in this species. Received: 18 November 1998 / Accepted after revision: 9 May 1999     

Training requirements and retention characteristics of serial list organization by macaque monkeys

This work evaluated the prospect that organizational accounts of the retention of list information by monkeys might be an artifact of familiarity with conditional relationships. Seven sophisticated macaques were trained on four five-item lists. Each acquisition selectively excluded one of the internal conditional pairs of the typical four-problem sequence (AB,BC,CD,DE) that defines a five-item serially ordered list. Then, all possible novel pairings and the trained pairs appeared together in a test. After this, the previously omitted pair was trained and animals were retested. On all tasks, initial tests revealed little organization and much intersubject variability of characteristic choice strategies, but subsequent inclusion of all four conditional pairs always yielded organized serial choice. On both the four-problem tests and in a later retention, errors were directly related to interitem distance between the objects paired on test trials. These results helped to specify the conditions required for demonstration of non-human primate analogs of transitivity, and showed that even sophisticated monkeys organize information in retention only if they know all interitem relationships. Received: 7 October 1998 / Accepted after revision: 10 October 1999     

Response preferences of monkeys (Macaca mulatta) within wavelength and line-tilt dimensions

Four rhesus monkeys were tested for preferences within the wavelength and line-tilt dimensions. In the case of wavelength, the response panel was back-illuminated by light of one of the following wavelengths, presented in a random manner: 470, 525, 580, and 635 nm. Similarly, the line-tilt dimension was studied, by presenting a 5 cm by 0.3 cm black bar tilted at 0, 30, 60, or 90 degrees. No preferences were found within this latter dimension; in contrast, marked wavelength preferences existed, the order of preference being 470 (most preferred), 525, 580, and 635 nm (least preferred). These response preferences were resistant to behavioral manipulation; the number of responses to blue and to red in extinction was about equal when red was used as the training stimulus, but vastly different following training on blue. These results indicate that such response preferences must be taken into account in the design of a wide variety of experiments.     

Long-tailed macaques avoid conflicts during short-term crowding

Crowding has been viewed as a factor eliciting increased levels of aggression and tension in gregarious animals. The present study tested predictions derived from two models, the “density/aggression” model and the “active coping” model, which have been proposed to explain the responses of primates to crowding. In particular, we investigated the responses of a well-established group of long-tailed macaques (Macaca fascicularis) to short-term crowding. The group was periodically crowded for 2-3 hr into a familiar area. Control observations were carried out when the monkeys were in a six times larger enclosure. Data from 42 individuals belonging to different age-sex classes showed that only mild forms of aggression increased under the crowded condition. Crowding also resulted in a decrease in counteraggression, allogrooming, playing, and exploring the environment, while it produced an increase in huddling with companions. The frequency of reconciliation and redirection was not affected by crowding. These findings do not support either of the models but suggest that macaques adopt a “conflict-avoidance strategy” during short-term crowding. They reduce the risk of severe aggression in an environment where interindividual distances are small by simply decreasing the level of activity. Interestingly, however, when aggression occurs during crowding, tension reduction mechanisms such as reconciliation and redirection are used as often as in control conditions. © 1995 Wiley-Liss, Inc.     

Rhesus monkeys (<Emphasis Type="Italic">Macaca mulatta</Emphasis>) succeed on a computerized test designed to assess conservation of discrete quantity

Conservation of quantity occurs through recognition that changes in the physical arrangement of a set of items do not change the quantity of items in that set. Rhesus monkeys (Macaca mulatta) were presented with a computerized quantity judgment task. Monkeys were rewarded for selecting the greater quantity of items in one of two horizontal arrays of items on the screen. On some trials, after a correct selection, no reward was given but one of the arrays was manipulated. In some cases, this manipulation involved moving items closer together or farther apart to change the physical arrangement of the array without changing the quantity of items in the array. In other cases, additional items were added to the initially smaller array so that it became quantitatively larger. Monkeys then made another selection from the two rows of items. Monkeys were sensitive to these manipulations, changing their selections when the number of items in the rows changed but not when the arrangement only was changed. Therefore, monkeys responded on the basis of the quantity of items, and they were not distracted by non-quantitative manipulations of the sets.Electronic Supplementary Material Supplementary material is available for this article at     

Intertroop agonistic behavior of a feral Rhesus Macaque troop ranging in town and forest areas in India

The intertroop agonistic behavior of a troop of Macaca mulatta villosa was studied in both forested and urban areas. Intertroop contacts lasted longer and were more likely to involve aggression in the town than in the forest. In particular, adult males and adult females when in urban areas showed a significantly higher rate of the most extreme forms of agonism, such as attacks, chases, and fights, than when in the forest. Data are explained in relation to feeding patterns and environmental differences and show the great flexibility of social behavior in these primates. Genetic selection for a high level of aggression in an urban population of macaques is not considered likely.     

熟悉嗓声识别中猴脑的事件相关电位

在四只三岁龄雄性猕猴(Macaca mulatta)中,研究了识别熟悉人与陌生人、熟悉猴与陌生猴嗓声中的脑事件相关电位(ERPs)。结果表明,对熟悉猴和陌生猴的噪声“er”所诱发的ERPs在左颞区和左、右两顶区存在着显著差异。熟悉猴嗓声在左颞区诱发的P200波潜伏期长,左顶区N100波幅值大,在左、右顶区P300波潜伏期短。熟悉人与陌生人嗓声“pa”诱发的ERPs在左、右顶区P200波潜伏期有显著性差异,熟悉“Pa”诱发反应潜伏期短。熟悉人与陌生人噪声“ba”诱发的ERPs没有差异。熟悉猴嗓声与熟悉人嗓声加“pa”诱发的ERPs相比,在右颞区的P300波幅值显著变大,两顶区N100波幅值也增大,在右顶区P200和P300波的潜伏期也明显变短。顶问区N100波潜伏期短、幅值高。陌生人与陌生猴“pa”嗓声诱发的ERPs间没有差异。熟悉猴嗓声和陌生猴嗓声出现的概率不同,并不引起ERPs的明显差异。