Conspecific Recognition in the Chimpanzee (Pan troglodytes): Cardiac Responses to Significant Others

The ability of a chimpanzee (Pan troglodytes) to recognize photographs of conspecifics was evaluated with heart-rate measures. Heart rate was recorded before, during, and after viewing photographs of an aggressive chimpanzee, a friendly companion animal, and an unfamiliar chimpanzee. The subject displayed a differential pattern of heart-rate response to the stimulus animals, without prior experience with the photographs. Responses to the aggressive animal were acceleratory, which suggests a defensive response. Respiratory sinus arrhythmia suggested that this response was associated with sympathetic activation. In contrast, responses to the familiar animal were minimal, whereas cardiac deceleration was observed in response to the strange chimp, which likely reflects an orienting response. Results suggest the chimpanzee is able to recognize photographs of individual conspecifics and that heart-rate change can reflect the nature of established social relationships between chimpanzees

Numerical Competence in a Chimpanzee (Pan troglodytes)

A chimpanzee (Pan troglodytes), trained to count foods and objects by using Arabic numbers, demonstrated the ability to sum arrays of 0-4 food items placed in 2 of 3 possible sites. To address representational use of numbers, we next baited sites with Arabic numbers as stimuli. In both cases performance was significantly above chance from the first sessions, which suggests that without explicit training in combining arrays, the animal was able to select the correct arithmetic sum for arrays of foods or Arabic numbers under novel test conditions. These findings demonstrate that counting strategies and the representational use of numbers lie within the cognitive domain of the chimpanzee and compare favorably with the spontaneous use of addition algorithms demonstrated in preschool children

Specificity of the Cardiac Response to Conspecific Vocalizations in Chimpanzees

Heart rate measures were used to examine the functional response of young chimpanzees and orangutans to acoustic stimuli, including white noise and chimpanzee vocalizations (threat, stress, and alarm). The initial response of the animals to all stimuli was characterized by a prominent cardiac deceleration and an increase in heart period variability. The deceleratory responses persisted with repeated presentations of the noise, stress, and alarm stimuli. In contrast, the response of chimpanzees to the conspecific threat stimulus reverted over trials to a notable cardiac acceleration. This acceleratory response was not attributable to potential patterns of evoked somatic responses. The features of the cardiac response, together with the results of frequency-domain analyses of heart period variability, suggest that this acceleratory response was consistent with the evocation of an aversive or a defensive reaction characterized by sympathetic activation. This pattern of cardiac response appeared early in ontogeny (within 48 hr postnatally) and was not manifest in orangutans. Taken together, the results suggest the existence of specialized perceptual processing mechanisms for vocal stimuli in the chimpanzee. Further examination of these mechanisms may contribute to our understanding of central perceptual processes and the evolution of vocal communication

Multigenerational challenges and the future of graduate medical education

Background: Demographics are changing on a global scale. In the United States, an aging population continues to work, either by preference or because of insufficient resources to retire. Of even greater importance, a younger generation, referred to as the Millennial Generation, will soon predominate in the workforce and even now accounts for nearly 100% of resident physicians. By the year 2020, there will be 5 generations in the workplace. Methods: This paper defines and details the characteristics of the 5 generations and examines how the vision, attitudes, values, and expectations of the most recent generations will reshape the workforce and graduate medical education. Results: The need for change is imminent to educate the next generation of physicians. Among the changes necessary to adapt to the multigenerational challenges ahead are adopting mobile devices as preferred communication tools; using social networking sites to recruit residents; adding games, simulations, and interactive videos to the curriculum to engage students; breaking down departmental silos and forming learning teams that come from different specialties; developing benchmarks and milestones to measure progress; extending the social learning ecosystem beyond the resident years; embracing diversity as the norm for both practice and learning; and providing both coaching and mentoring. Conclusion: For decades, resident physicians have shown commitment, tenacity, and selflessness while shouldering the dual responsibility of patient care and the pursuit of their own education and skills development. Resident engagement has been shown to drive change in undergraduate medical education and in the learning and performance of their teachers. The latter is evidence of reverse mentoring that will be a major factor for improvement in this digital age. We have only to embrace this opportunity to the benefit of our patients, our learners, and ourselves

Scale space consistency of piecewise constant least squares estimators -- another look at the regressogram

We study the asymptotic behavior of piecewise constant least squares regression estimates, when the number of partitions of the estimate is penalized. We show that the estimator is consistent in the relevant metric if the signal is in $L^2([0,1])$, the space of c\`{a}dl\`{a}g functions equipped with the Skorokhod metric or $C([0,1])$ equipped with the supremum metric. Moreover, we consider the family of estimates under a varying smoothing parameter, also called scale space. We prove convergence of the empirical scale space towards its deterministic target.Comment: Published at http://dx.doi.org/10.1214/074921707000000274 in the IMS Lecture Notes Monograph Series (http://www.imstat.org/publications/lecnotes.htm) by the Institute of Mathematical Statistics (http://www.imstat.org

Zooplankton biomass in the ice-covered Weddell Sea, Antarctica

Zooplankton was sampled by a Rectangular Midwater Trawl (RMT 1 + 8) in Weddell Sea surface waters (0 to 300 m) between 66 and 78°S during austral summer (February – March 1983). Sixty-nine taxa including different developmental stages were considered and divided into 16 size classes between 39.5 mm length. Biomass was determined by taxon and size class for three different meso- and macroplankton communities in the oceanic region, on the northeastern shelf and on the southern shelf of the Weddell Sea. The highest biomass of 11.2 mg DW m−3 (3.4 g DW m−2) was found in the northeastern shelf community (70 to 74°S), where juvenile and adultEuphausia crystallorophias accounted for 3.7 mg DW m−3 (1.1 g DW m−2). Although not quantitatively sampled, early copepodite stages (CI to CIII) ofCalanoides acutus andCalanus propinquus ranked second with 2.7 mg DW m−3 (0.8 g DW m−2). Biomass in the northeastern shelf community was concentrated in the size ranges 1 to 4 mm and 19.5 to 39.5 mm. The oceanic community of the central Weddell Sea was dominated by copepods smaller than 5 mm, which made up half of the total oceanic biomass. The tunicateSalpa thompsoni (7.0 to 8.5 mm) was the dominant single species with 1.6 mg DW m−3 (0.5 g DW m−2). Euphausiids, mainly juvenile and adult krillEuphausia superba, comprised 1.2 mg DW m−3 (0.4 g DW m−2). Total standing stock in the oceanic community was 9.4 mg DWm−3 (2.8 g DW m−2). Lowest biomass values were found in the southern shelf community (south of 75°S) with 4.0 mg DW m−3 (1.2 g DW m−2), concentrated in the 1 to 4 mm and 14.5 to 34.5 mm size classes. Abundant species were the pteropodLimacina helicina (1 to 2 mm; 0.7 mg DW m−3; 0.2 g DW m−2) andE. crystallorophias (24.5 to 39.5 mm; 0.9 mg DW m−3; 0.3 g DW m−2). The data reveal that it is essential to distinguish among subsystems in the Southern Ocean. This leads to a better understanding of the structure and function of those pelagic food webs which represent alternatives to the paradigmatic krill-centered system

Size Matters: Impact of Item Size and Quantity on Array Choice by Chimpanzees (Pan troglodytes)

The authors previously reported that chimpanzees (Pan troglodytes) showed a striking bias to select the larger of 2 candy arrays, despite a reversed reward contingency in which the animals received the smaller, nonselected array as a reward, except when Arabic numerals were used as stimuli. A perceptual or incentive-based interference occurred that was overcome by symbolic stimuli. The authors of the present study examined the impact of element size in choice arrays, using 1 to 5 large and small candies. Five test-sophisticated chimpanzees selected an array from the 2 presented during each trial. Their responses were not optimal, as animals generally selected arrays with larger total mass; thus, they received the smaller remaining array as a reward. When choice stimuli differed in size and quantity, element size was more heavily weighted, although choices reflected total candy mass. These results replicate previous findings showing chimpanzees\u27 difficulties with quantity judgments under reverse reward contingencies and also show that individual item size exerts a more powerful interference effect

Vocal Perception: Brain Event-Related Potentials in a Chimpanzee

We describe the first brain event-related potential (ERP) study of cognitive processes in the chimpanzee. In an extension of our studies on the ontogeny of vocal perception, ERP measures were obtained during the presentation of simple nonsignal stimuli as well as conspecific and human vocalizations. We initially confirmed findings from humans and monkeys of the appearance of a long-latency positivity in the ERP waveform to a rare stimulus in an oddball paradigm. This ERP component is reminiscent of the P3a reported in humans under similar (passive) experimental conditions. We further demonstrated that both conspecific and human vocal stimuli having affective significance also enhanced late positive components of the ERP. These late positive components displayed a predominant fronto-central distribution, with a maxima at Cz. Additionally, responses to adaptively significant vocal stimuli showed a right hemisphere laterality, whereas no significant laterality was observed with the rare stimulus in the oddball paradigm. Results document the feasibility of ERP measures in chimpanzees and their potential utility in the study of the ontogeny and phylogeny of vocal perception