Olfactory discrimination of individual littermates in rats (Rattus norvegicus).

Tested the ability of 4 adult male Sprague-Dawley rats to use odors in discrimination among littermates living as a group. Ss were trained in a Y-maze to discriminate the presence of a littermate from its absence. Results from transfer of training in 3 subsequent testing periods indicated that the animals were capable of distinguishing among individuals when relatedness and familiarity were held constant, that this ability was not due to training, and that performance was based solely on odor cues. Results suggest that laboratory rats exhibit odor sensitivities conmensurate with very complex social processes. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variations in fundamental frequency peak position in Japanese macaque (Macaca fuscata) coo calls.

Japanese macaques (Macaca fuscata) produce coo calls whose use in various contexts is correlated with differences in the relative temporal position of the peak value of a call's fundamental frequency (S. Green, 1975). Studies have produced conflicting results about both the location of the category boundary between smooth early high and smooth late high coo subtypes and macaques' perceptual sensitivity to variations in peak position. In this study, fundamental frequency peak positions were measured in 578 coos produced by 8 captive adult female Japanese macaques in order to test whether calls with peak positions close to either of 2 hypothesized boundaries occurred at low rates. Overall, such calls were found to occur at rates equal to or higher than predicted by chance. Peak position varied more consistently between animals than by behavioral context. The results may indicate that peak position in coos does not form 2 distinct categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acoustic classification of alarm calls by vervet monkeys (Cercopithecus aethiops) and humans (Homo sapiens): I. Natural calls.

A 2-choice, operant-conditioning-based classification procedure was developed in which vervet monkeys (Cercopithecus aethiops) categorized species-typical snake and eagle alarm calls recorded from individually identified free-ranging animals. After preliminary training with a pair of calls from a single animal, 2 vervets were tested with novel exemplars produced by a variety of callers. Experiment 1 combined testing with continued training in routine classification of 14 new calls. In Experiment 2, the Ss were tested with 48 novel calls in rapid succession. Human (Homo sapiens) control Ss participated in the 1st study without extended preliminary training. Monkey and human Ss both showed immediate transfer to classification of unfamiliar alarm calls, despite variations both in voice characteristics and reproduction quality. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acoustic classification of alarm calls by vervet monkeys (Cercopithecus aethiops) and humans (Homo sapiens): II. Synthetic calls.

In 2 experiments classification of synthetic versions of species-typical snake and eagle alarm calls by vervet monkeys (Cercopithecus aethiops) and human (Homo sapiens) control Ss was investigated. In a 2-choice, operant-conditioning-based procedure, this work followed up acoustic analyses that had used various digitally based algorithms (M. J. Owren and R. H. Bernacki; see record 1989-10972-001). All Ss were first tested with alarm-call replicas that were based on analysis data. These models were classified in the same manner as natural stimuli, which verified the appropriateness of the acoustic charcterizations. Synthetic stimuli were then presented to test the importance of specific acoustic cues. Spectral patterning was found to be the most salient cue for classification by the monkeys, whereas results from the human Ss were mixed. Implications for the study of nonhuman primate vocalizations and P. Lieberman's (1984) theory of speech evolution are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Differential sensitivity of Japanese macaques (Macaca fuscata) and humans (Homo sapiens) to peak position along a synthetic coo call continuum.

Difference limens (DLs) for changes in the temporal position of a pitch peak along a synthetic early-high to late-high coo continuum were measured in 2 Japanese macaques and 2 humans in a low-uncertainty, repeating standard discrimination procedure. Lowest DLs (19–32 msec for monkeys;     

Absolute auditory thresholds in three Old World monkey species (Cercopithecus aethiops, C. neglectus, Macaca fuscata) and humans (Homo sapiens).

We investigated the absolute auditory sensitivities of three monkey species (Cercopithecus aethiops, C. neglectus, and Macaca fuscata) and humans (Homo sapiens). Results indicated that species-typical variation exists in these primates. Vervets, which have the smallest interaural distance of the species that we tested, exhibited the greatest high-frequency sensitivity. This result is consistent with Masterton, Heffner, and Ravizza's (1969) observations that head size and high-frequency acuity are inversely correlated in mammals. Vervets were also the most sensitive in the middle frequency range. Furthermore, we found that de Brazza's monkeys, though they produce a specialized, low-pitched boom call, did not show the enhanced low-frequency sensitivity that Brown and Waser (1984) showed for blue monkeys (C. mitis), a species with a similar sound. This discrepancy may be related to differences in the acoustics of the respective habitats of these animals or in the way their boom calls are used. The acuity of Japanese monkeys was found to closely resemble that of rhesus macaques (M. mulatta) that were tested in previous studies. Finally, humans tested in the same apparatus exhibited normative sensitivities. These subjects responded more readily to low frequencies than did the monkeys but rapidly became less sensitive in the high ranges. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classification of domestic cat (Felis catus) vocalizations by naive and experienced human listeners.

To test for possible functional referentiality in a common domestic cat (Felis catus) vocalization, the authors conducted 2 experiments to examine whether human participants could classify meow sounds recorded from 12 different cats in 5 behavioral contexts. In Experiment 1, participants heard single calls, whereas in Experiment 2, bouts of calls were presented. In both cases, classification accuracy was significantly above chance, but modestly so. Accuracy for bouts exceeded that for single calls. Overall, participants performed better in classifying individual calls if they had lived with, interacted with, and had a general affinity for cats. These results provide little evidence of referentiality, suggesting instead that meows are nonspecific, somewhat negatively toned stimuli that attract attention from humans. With experience, human listeners can become more proficient at inferring positive-affect states from cat meows. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Salience of Caller Identity in Rhesus Monkey (Macaca mulatta) Coos and Screams: Perceptual Experiments With Human (Homo sapiens) Listeners.

Recent evidence from acoustic analysis and playback experiments indicates that adult female rhesus monkey (Macaca mulatta) coos are individually distinctive but their screams are not. In this study, the authors compared discrimination of individual identity in these sounds by naive human listeners who judged whether 2 sounds had been produced by the same monkey or 2 monkeys. Each of 3 experiments using this same-different design showed significantly better discrimination of vocalizer identity from coos than from screams. Experiment 1 demonstrated the basic finding. Experiment 2 also tested the effect of non-identity-related scream variation, and Experiment 3 added a comparison with human vowel sounds. Outcomes suggest that acoustic structural differences in coos and screams influence salience of caller-identity cues, with significant implications for understanding the functions of these calls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Auditory frequency discrimination in primates: Species differences (Cercopithecus, Macaca, Homo).

Auditory frequency difference limens (DLs) at 2 kHz were measured in Old World monkeys (Cercopithecus, Macaca) and humans using a go/no-go repeating standard procedure and positive reinforcement operant conditioning techniques. Quantitative and qualitative differences occurred between monkey and human sensitivity. Best DLs for monkeys were 20–60 Hz, and for humans they were 3–4 Hz. Monkey sensitivity decreased as sensation level increased from 30 to 70 dB, whereas human sensitivity increased. Sensitivity differences also occurred in the various monkey species. Cercopithecus monkeys were generally more sensitive to frequency decrements, whereas Japanese macaques were more sensitive to frequency increments, as were humans. Results are related to other comparative psychoacoustic data and primate vocal communication, including human speech. (PsycINFO Database Record (c) 2010 APA, all rights reserved)