Factors influencing the salience of temporal cues in the discrimination of synthetic Japanese monkey (Macaca fuscata) coo calls.

If temporal position of a frequency inflection is the most salient communication cue in Japanese macaque smooth early and smooth late high coos, then macaques should perceive coos differing only along the early–late dimension as belonging to different classes. The perceived similarity of synthetic coos and temporally reversed variants were evaluated, using multidimensional scaling of macaque discrimination latencies. Original calls and calls temporally reversed in the frequency domain could be discriminated if the peak was near a call endpoint but not if the frequency peak in the original call was near the coo midpoint. Perceived similarity of such calls was inversely related to the amount of frequency modulation. Temporal reversals of amplitude contours were also conducted. Although macaques are quite sensitive to amplitude increments, reversal of the relatively flat amplitude contours of these calls did not affect discrimination responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual salience of acoustic features of Japanese monkey coo calls.

Smooth early high (SEH) and smooth late high (SLH) coo calls differ in the temporal location of a frequency inflection and are generally used in different situations. Coo quality is also influenced by additional features, such as relative harmonic level, which may have communicative significance. The authors used multidimensional scaling to analyze the perceptual similarity of SEH and SLH coos. Neither the temporal position of the frequency inflection nor caller identity could explain the coo groupings. Only the temporal relationships of the relative harmonic levels consistently differed between stimulus clusters. Relative level manipulations were conducted on synthetic coo replicas, resulting in substantial stimulus space reorganization. Although temporal position of the frequency inflection may provide the basis for coo classification, the authors suggest that relative harmonic amplitude can also influence response properties. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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;     

Neural lateralization of vocalizations by Japanese macaques: Communicative significance is more important than acoustic structure.

Trained 4 monkeys—2 Japanese macaques (Macaca fuscata) and 2 comparison macaques (M. nemestrina and M. radiata)—in discrimination among monaurally presented exemplars of 2 classes of vocalizations from the Japanese macaque's repertoire to determine whether the neural lateralization of vocal perception in Japanese macaques would depend on acoustic properties or communicative significance. After Ss mastered the discrimination, they performed at equivalent accuracy levels for 150 sessions. However, during this time, Japanese macaques showed a right ear performance advantage, whereas comparison Ss showed no ear advantage. To assess whether comparison and Japanese macaques were attending to the same acoustic cue when performing the discrimination, a generalization test was conducted with 27 novel vocalizations. Individual Ss' generalization gradients were highly similar and revealed that all Ss were listening to the same feature of calls. These findings, coupled with the fact that the calls were of biological significance to Japanese macaques alone, suggest that the laterality effect is related to the communicative valence of the signals rather than to their physical characteristics. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection thresholds for intensity increments in a single harmonic of synthetic Japanese macaque ( Macaca fuscata) monkey coo calls.

There is evidence that Japanese macaques (Macaca fuscata) are extremely sensitive to dynamic changes in the relative amplitudes of coo call harmonics during discrimination tests. To verify this evidence using more controlled stimulus configurations, the authors examined threshold sensitivity of macaque monkeys to amplitude increments added to the standard level of coo call harmonics. Psychophysical threshold determination methods paralleled those used previously to determine macaque sensitivity to amplitude increments added to vowel-like stimuli. Variation was detectable although thresholds were elevated relative to those obtained with vowel-like stimuli in another investigation (C. G. Le Prell, A. J. Niemiec, & D. B. Moody, 2001). This elevation was probably a function of natural amplitude modulation in the standard stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of restricted cortical lesions on absolute thresholds and aphasia-like deficits in Japanese macaques.

The effect of small bilateral cortical lesions on pure-tone audiograms and on the ability to discriminate between two types of Japanese macaque coo vocalizations was determined in 4 Japanese macaques. A lesion that included the middle portion of the superior temporal gyrus of both hemispheres, that is, the primary and secondary auditory areas, resulted in a partial hearing loss as well as an inability to discriminate the vocalizations. Lesions that included the ventral portions of the superior temporal gyrus of both hemispheres but spared auditory cortex on one side also resulted in a partial hearing loss but had either a small effect or no effect on the ability to discriminate the vocalizations. Bilateral ablation of the dorsal superior temporal gyrus and adjacent parietal and occipital areas did not result in a hearing loss and had no effect on the ability to discriminate the vocalizations. Results suggest that a hearing loss may be produced by lesions that involve small portions of the ventral two-thirds of the superior temporal gyrus bilaterally although the resulting loss is not as great as that observed with larger lesions. However, the aphasia-like deficit appears to result from a lesion of primary and/or secondary auditory cortex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential kinship effect on reconciliation in three species of macaques (Macaca fascicularis, M. fuscata, and M. sylvanus).

Macaque societies are typically characterized by despotic dominance styles and strong bonds between related individuals. Interspecies variation in dominance style, however, has been recently documented. This study investigated whether kinship effects on social interactions vary depending on the species dominance style. Reconciliation was chosen as a measure of relationship quality between group members. Groups of Japanese (Macaca fuscata) and long-tailed (M. fascicularis) macaques were selected for their highly despotic style, and Barbary (M. sylvanus) macaques were chosen for their lower level of despotism. The findings confirmed the hypothesis that kinship effects on reconciliation are stronger the more despotic the species is. Barbary macaque nonkin reconciled more often than nonkin of the other 2 species. In addition, the differences in reconciliation frequency between kin and nonkin were less pronounced among the less despotic Barbary macaques. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vocal development in budgerigars (Melopsittacus undulatus): Contact calls.

Budgerigars have a complex vocal repertoire, some of which develops through learning. The authors examined the course of vocal development in budgerigars from hatching to about 4 weeks postfledging (approximately 85 days old). Food-begging calls showed changes in duration, peak frequency, bandwidth, and frequency modulation with age. Within a week of fledging, each bird produced a contact call bearing a strong resemblance to a shortened version of its patterned food-begging call. By 4 weeks postfledging, budgerigar contact call repertoires often contained more than one call type, and there was clear evidence of sharing and imitation among the calls of parents, fledglings, and other social companions. Perceptual testing showed that whereas acoustic variation in the structure of developing calls decreased both within and between nestling birds, the discrimination of these calls was easier for adult birds as young birds matured. These results suggest parallels with certain aspects of language development in humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in mating vocalizations over the ejaculatory series in rats (Rattus norvegicus).

Rats (Rattus norvegicus) produce ultrasonic calls during mating. We examined changes in the structure and pattern of such vocalizations over the ejaculatory series. In Experiment 1, vocalizations were recorded from 11 pairs of rats through 3 ejaculatory series and analyzed spectrographically. We classified 4 categories of call by spectral frequency and duration. Calls of low frequency, long duration, and high intensity occurred more often shortly before the ejaculation and were associated with mounting without intromission, a behavior that often occurs shortly before ejaculation. The high-frequency calls did not vary in number across the series. In Experiment 2, vocalizations were recorded from males paired with devocalized females. Males produced all vocalization patterns produced by pairs in Experiment 1. Results suggest that most pre-ejaculatory calls are produced by males and may potentially affect female sexual behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recognition of heterospecific alarm vocalization by Bonnet Macaques (Macaca radiata).

Recognition of heterospecific alarm vocalizations is an essential component of antipredator behavior in several prey species. The authors examined the role of learning in the discrimination of heterospecific vocalizations by wild bonnet macaques (Macaca radiata) in southern India. The bonnet macaques' flight and scanning responses to playbacks of their own alarm vocalizations were compared with their responses to playbacks of vocalizations of Nilgiri langurs (Trachypithecus johnii), Hanuman langurs (Semnopithecus entellus), and sambar deer (Cervus unicolor). The study was conducted in 3 regions that differed in the frequency with which bonnet macaques encountered these species and included an urban setting. Call recognition was highest in adults and in regions where individuals were frequently exposed to the calling species; calls were not recognized by urban monkeys. Thus, age and experience are important factors in heterospecific call recognition by bonnet macaques. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acoustical and perceptual structures of sexually dimorphic distance calls in Bengalese finches (Lonchura striata domestica).

Characterized the physical structure of distance calls by the Bengalese finch (Lonchura striata domestica) and its relation to perception. Distance calls were recorded from 12 female and 12 male Bengalese finches and analyzed; such acoustic parameters as length, bandwidth, and peak frequency were obtained, and differences between sexes on combinations of these parameters were tested and shown to be significant. To assess perceptual salience of acoustic parameters, discrimination of 4 female and 4 male calls was examined. The reaction time (RT) required to discriminate a pair of distance calls was used as a measure of similarity between the 2 calls and analyzed by a multidimensional scaling procedure to find the perceptual dimensions. The results suggest that the sex difference in Bengalese finch distance calls is easily perceived by Bengalese finches and that the males and females were not different in their perception of the calls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Combined eye-head gaze shifts produced by electrical stimulation of the superior colliculus in rhesus monkeys

1. We electrically stimulated the intermediate and deep layers of the superior colliculus (SC) in two rhesus macaques free to move their heads both vertically and horizontally (head unrestrained). Stimulation of the primate SC can elicit high-velocity, combined, eye-head gaze shifts that are similar to visually guided gaze shifts of comparable amplitude and direction. The amplitude of gaze shifts produced by collicular stimulation depends on the site of stimulation and on the parameters of stimulation (frequency, current, and duration of the stimulation train). 2. The maximal amplitude gaze shifts, produced by electrical stimulation at 56 sites in the SC of two rhesus monkeys, ranged in amplitude from approximately 7 to approximately 80 deg. Because the head was unrestrained, stimulation-induced gaze shifts often included movements of the head. Head movements produced at the 56 stimulation sites ranged in amplitude from 0 to approximately 70 deg. 3. The relationships between peak velocity and amplitude and between duration and amplitude of stimulation-induced head movements and gaze shifts were comparable with the relationships observed during visually guided gaze shifts. The relative contributions of the eyes and head to visually guided and stimulation-induced gaze shifts were also similar. 4. As was true for visually guided gaze shifts, the head contribution to stimulation-induced gaze shifts depended on the position of the eyes relative to the head at the onset of stimulation. When the eyes were deviated in the direction of the ensuing gaze shift, the head contribution increased and the latency to head movement onset was decreased. 5. We systematically altered the duration of stimulation trains (10-400 ms) while stimulation frequency and current remained constant. Increases in stimulation duration systematically increased the amplitude of the evoked gaze shift until a site specific maximal amplitude was reached. Further increases in stimulation duration did not increase gaze amplitude. There was a high correlation between the end of the stimulation train and the end of the evoked gaze shift for movements smaller than the site-specific maximal amplitude. 6. Unlike the effects of stimulation duration on gaze amplitude, the amplitude and duration of evoked head movements did not saturate for the range of durations tested (10-400 ms), but continued to increase linearly with increases in stimulation duration. 7. The frequency of stimulation was systematically varied (range: 63-1,000 Hz) while other stimulation parameters remained constant. The velocity of evoked gaze shifts was related to the frequency of stimulation; higher stimulation frequencies resulted in higher peak velocities. The maximal, site-specific amplitude was independent of stimulation frequency. 8. When stimulating a single collicular site using identical stimulation parameters, the amplitude and direction of stimulation-induced gaze shifts, initiated from different initial positions, were relatively constant. In contrast, the amplitude and direction of the eye component of these fixed vector gaze shifts depended upon the initial position of the eyes in the orbits; the endpoints of the eye movements converged on an orbital region, or "goal," that depended on the site of collicular stimulation. 9. When identical stimulation parameters were used and when the eyes were centered initially in the orbits, the gaze shifts produced by caudal collicular stimulation when the head was restrained were typically smaller than those evoked from the same site when the head was unrestrained. This attenuation occurred because stimulation drove the eyes to approximately the same orbital position when the head was restrained or unrestrained. Thus movements produced when the head was restrained were reduced in amplitude by approximately the amount that the head would have contributed if free to move. 10. When the head was restrained, only the eye component of the intended gaze shift     

Fiber type composition of abdominal muscles in Japanese macaques (Macaca fuscata)

The muscle fiber composition and cross-sectional area of muscle fiber types were investigated histochemically in the abdominal muscles (rectus abdominis muscle, obliquus externus abdominis muscle, obliquus internus abdominis muscle and transversus abdominis muscle) of three Japanese macaques (Macaca fuscata). Muscle fibers were classified into three fiber types (Type I, II A and II B) by myosin ATPase activity and succinate dehydrogenase activity. Each abdominal muscle in Japanese macaques contained high proportion of Type II B fibers and there were no large differences in the fiber type composition between the abdominal muscles. The range of mean fiber type percent was 26-32% Type I, 21-22% Type II A, and 46-52% Type II B fibers. Thus, based on the histochemical fiber type composition, the separate abdominal muscles appear to have a similar functional capacity. The cross-sectional area was larger for Type II than for Type I fibers, and the areas were similar in Type II A and Type II B fibers in each muscle. The rectus abdominis showed larger fibers of each type compared to the lateral abdominal muscles. The high proportion of Type II B fibers and large fiber size for Type II B fibers suggest that the abdominal muscles of Japanese macaques have properties similar to the propulsive and locomotory muscles in the limbs.     

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)     

Perceptual organization of acoustic stimuli by budgerigars (Melopsittacus undulatus): III. Contact calls.

We trained budgerigars by operant conditioning to discriminate among a set of contact calls in a same–different task and analyzed response latencies from this task by using multidimensional-scaling (MDS) and cluster-analysis procedures. Humans listened to the same calls and indicated the similarity between pairs of calls by a direct rating procedure. An MDS program ({sindscal}) was used to arrange these complex acoustic stimuli in multidimensional space reflecting perceptual organization. Multiple regression techniques were used to identify the acoustic characteristics of contact calls that were correlated with the peceptual dimensions obtained from MDS. A number of spectral characteristics (e.g., peak frequency, rate of frequency modulation, and concentration of spectral energy) emerged as important for both budgerigars and humans, but the relative salience of these cues differed for the two species. Additional tests with two groups of budgerigars—cagemates and noncagemates—showed that experience with calls can change the salience of various acoustic characteristics used for perceptual organization and individual recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Communication among hamsters by high-frequency acoustic signals: I. Physical characteristics of hamster calls.

In Exp I, 2 random-bred (Lak:LVG) female hamsters emitted high-frequency sounds at average intensities of 53 db (SPL). These calls tended to be 80–200 msec long and to emphasize frequencies of 34–42 kHz. However, female "ultrasounds" typically included rapid fluctuations in frequency and amplitude. In Exp II, male hamsters also emitted high-frequency vocalizations, with dominant frequencies of 32–38 kHz and average durations of 70–250 msec. Although male cells generally included fewer rapid changes in amplitude and frequency than did female calls, male call structures depended on contextual factors. Calls produced by males in the presence of estrous females tended to have lower minimum frequencies, higher maximum frequencies, longer durations, and fewer rapid frequency changes than calls by solitary males. These results show that both sex differences and situational factors influence the structures of hamster ultrasounds. The frequency and amplitude changes typical of calls by females and solitary males should facilitate the localization of a calling individual over moderate distances. Calls by males in the presence of females should be more difficult to localize and might operate over shorter distances to serve a different social function. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral and Emotional Response of Japanese Macaque (Macaca fuscata) Mothers After Their Offspring Receive an Aggression.

The authors of this study investigated the behavioral and emotional response of female Japanese macaques (Macaca fuscata) to an aggression received by their offspring to evaluate the existence of cognitive empathic responses in a naturalistic setting. After their offspring received an aggression, mothers did not direct increased affiliative contacts to them. The factors likely to affect the degree of distress in the offspring or the perceived risk for the mother failed to appropriately modulate maternal behavior. Finally, mothers did not increase their frequency of scratching (a behavioral indicator of anxiety) after their offspring had received an aggression. The results suggest Japanese macaque mothers may be unable to understand their offspring's need for distress alleviation after the receipt of aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of maternal proximity on behavioral and physiological responses to separation in infant rhesus monkeys (Macaca mulatta).

The effects of maternal proximity on the behavioral and physiological responses of infant rhesus macaques during 4 days of total or adjacent separations from the mother were studied. The 6 infants tested showed behavioral responses that differentiated the two separation conditions. Major differences were found in the quantity and quality of vocalizations, the occurrence of cage-biting and cage-shaking behavior, object exploration, and hunched and freezing postures. In particular, the structure of coo vocalizations clearly discriminated between the presence or the absence of the mother during separation. Cerebrospinal fluid (CSF) concentrations of dopamine and serotonin metabolites did not discriminate between the two separation conditions but showed a transient elevation at 24 hr after separation and were not different from baseline by 96 hr after separation. In contrast, both the plasma cortisol and the CSF norepinephrine metabolite responses tended to be greater and to persist for a longer period of time when infants were totally isolated. The results are discussed within the context of attachment and coping theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gaze following and joint attention in rhesus monkeys (Macaca mulatta).

Gaze and attention direction provide important sources of social information for primates. Behavioral studies show that chimpanzees spontaneously follow human gaze direction. By contrast, non-ape species such as macaques fail to follow gaze cues. The authors investigated the reactions of rhesus macaques (Macaca mulatta) to attention cues of conspecifics. Two subjects were presented with videotaped images of a stimulus monkey with its attention directed to 1 of 2 identical objects. Analysis of eye movements revealed that both subjects inspected the target (object or position attended by the stimulus monkey) more often than the distractor (nonattended object or position). These results provide evidence that rhesus monkeys follow gaze and use the attention cues of other monkeys to orient their own attention to objects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dove coos and flashed lights: Interruptibility of "song" in a nonsongbird.

The vocal control mechanism of the collared dove (Streptopelia decaocto) was examined by analyzing the effect of a light flash on the interruptibility of the perch coo. Flashes sometimes resulted in an immediate startle response, which often coincided with a distortion of the ongoing vocalizations. Some flashes led to an interruption of cooing, usually some time after the flash and startle response. Stops occurred between coos, but also between or during the elements within a coo. Flashes during pauses between elements resulted in more stops that flashes during elements. The findings suggest that the element the unit of vocal production. Some features of the vocal control mechanism in songbirds may be more general than assumed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)