Search

Metrical phonology is the perceptual "strength" in language of some syllables relative to others. The ability to perceive lexical stress is important, as it can help a listener segment speech and distinguish the meaning of words and sentences. Despite this importance, there has been little comparative work on the perception of lexical stress across species. We used a go/no-go operant paradigm to train human participants and budgerigars (Melopsittacus undulatus) to distinguish trochaic (stress-initial) from iambic (stress-final) two-syllable nonsense words. Once participants learned the task, we presented both novel nonsense words, and familiar nonsense words that had certain cues removed (e.g., pitch, duration, loudness, or vowel quality) to determine which cues were most important in stress perception. Members of both species learned the task and were then able to generalize to novel exemplars, showing categorical learning rather than rote memorization. Tests using reduced stimuli showed that humans could identify stress patterns with amplitude and pitch alone, but not with only duration or vowel quality. Budgerigars required more than one cue to be present and had trouble if vowel quality or amplitude were missing as cues. The results suggest that stress patterns in human speech can be decoded by other species. Further comparative stress-perception research with more species could help to determine what species characteristics predict this ability. In addition, tests with a variety of stimuli could help to determine how much this ability depends on general pattern learning processes versus vocalization-specific cues.

In the introduction to this theme issue, Honing et al. suggest that the origins of musicality--the capacity that makes it possible for us to perceive, appreciate and produce music--can be pursued productively by searching for components of musicality in other species. Recent studies have highlighted that the behavioural relevance of stimuli to animals and the relation of experimental procedures to their natural behaviour can have a large impact on the type of results that can be obtained for a given species. Through reviewing laboratory findings on animal auditory perception and behaviour, as well as relevant findings on natural behaviour, we provide evidence that both traditional laboratory studies and studies relating to natural behaviour are needed to answer the problem of musicality. Traditional laboratory studies use synthetic stimuli that provide more control than more naturalistic studies, and are in many ways suitable to test the perceptual abilities of animals. However, naturalistic studies are essential to inform us as to what might constitute relevant stimuli and parameters to test with laboratory studies, or why we may or may not expect certain stimulus manipulations to be relevant. These two approaches are both vital in the comparative study of musicality.

Cognitive processes are important to animals because they not only influence how animals acquire, store and recall information, but also may underpin behaviours such as deciding where to look for food, build a nest, or with whom to mate. Several recent studies have begun to examine the potential interaction between variation in cognition and variation in personality traits. One hypothesis proposed that there is a speed-accuracy trade-off in cognition ability that aligns with a fast-slow behaviour type. Here, we explicitly examined this hypothesis by testing wild-caught black-capped chickadees in a series of cognitive tasks that assessed both learning speed (the number of trials taken to learn) and accuracy (post-acquisition performance when tested with un-trained exemplars). Chickadees' exploration scores were measured in a novel environment task. We found that slow-exploring chickadees demonstrated higher accuracy during the test phase, but did not learn the initial task in fewer trials compared to fast-exploring chickadees, providing partial support for the proposed link between cognition and personality. We report positive correlations in learning speed between different phases within cognitive tasks, but not between the three cognitive tasks suggesting independence in underlying cognitive processing. We discuss different rule-based strategies that may contribute to differential performance accuracy in cognitive tasks and provide suggestions for future experimentation to examine mechanisms underlying the relationship between cognition and personality.

Timbre is an important attribute of sound both in music and nature. Previously, using an operant conditioning paradigm, we found that black-capped chickadees and humans show similar response patterns in discriminating triadic chords of the same timbre and transferred this discrimination to a novel key center (novel absolute pitch). The current study examined how varying the timbre of the chords influenced discrimination. Using a similar operant conditioning procedure, we trained humans (Experiment 1) and chickadees (Experiments 2 and 3) to discriminate a major chord from 6 other chord types that had semitone deviations from the major chord. The pattern of errors of the 2 species replicated our previous findings. We then tested participants with novel timbres. We found that humans readily transferred their discrimination to novel timbres, suggesting they were attending to triadic pitch relations. The chickadees failed to transfer to novel timbres, suggesting they were using a different strategy to perform the original chord discrimination. We conducted an acoustic analysis examining frequency ranges that are biologically relevant to chickadees. We found that the relative intensity within each chord of the frequencies used in black-capped chickadee song significantly correlated with chickadees' percent response during probe testing. In Experiment 3, we trained a new set of chickadees by including either expanded pitch or timbre training before testing. Although chickadees showed some transfer to novel chords following this expanded training, we found that neither type of expanded training helped the chickadees when probe tested with novel stimuli., ((PsycINFO Database Record (c) 2014 APA, all rights reserved).)

Neuronal populations in the songbird nidopallium increase in activity the most to conspecific vocalizations relative to heterospecific songbird vocalizations or artificial stimuli such as tones. Here, we tested whether the difference in neural activity between conspecific and heterospecific vocalizations is due to acoustic differences or to the degree of phylogenetic relatedness of the species producing the vocalizations. To compare differences in neural responses of black-capped chickadees, Poecile atricapillus, to playback conditions we used a known marker for neural activity, ZENK, in the caudal medial nidopallium and caudomedial mesopallium. We used the acoustically complex 'dee' notes from chick-a-dee calls, and vocalizations from other heterospecific species similar in duration and spectral features. We tested the vocalizations from three heterospecific species (chestnut-backed chickadees, tufted titmice, and zebra finches), the vocalizations from conspecific individuals (black-capped chickadees), and reversed versions of the latter. There were no significant differences in the amount of expression between any of the groups except in the control condition, which resulted in significantly less neuronal activation. Our results suggest that, in certain cases, neuronal activity is not higher in response to conspecific than in response to heterospecific vocalizations for songbirds, but rather is sensitive to the acoustic features of the signal. Both acoustic features of the calls and the phylogenetic relationship between of the signaler and the receiver interact in the response of the nidopallium.

We propose that a relatively small number of perceptual skills underlie human perception of music and speech. Humans and songbirds share a number of features in the development of their auditory communication systems. These similarities invite comparisons between species in their auditory perceptual skills. Here, we summarized our experimental comparisons between humans (and other mammals) and songbirds (and other birds) in their use of pitch height and pitch chroma perception and discuss similarities and differences in other auditory perceptual abilities of these species. Specifically, we introduced a functional modular view, using pitch chroma and pitch height perception as examples, as a theoretical framework for the comparative study of auditory perception and perhaps all of the study of comparative cognition. We also contrasted phylogeny and adaptation as causal mechanisms in comparative cognition using examples from auditory perception., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Previous perceptual research with black-capped and mountain chickadees has demonstrated that the D note of the namesake chick-a-dee call controlled species-based discrimination compared to other note types in this call. In the current experiment, we sought to determine whether discrimination performance of the chickadees was controlled by stimulus-specific properties or due to learning through experience. To accomplish this, we tested zebra finches, a songbird species that is distantly related to chickadees, and also unfamiliar with black-capped and mountain chickadee vocalizations, on the same species-based discrimination on which black-capped and mountain chickadees were previously trained. We found that zebra finches learned the discrimination in the fewest number of trials with the D note, compared to other note types (i.e., the A, B, and C notes). In addition, we compared the current results to earlier work and found that zebra finches learned the discrimination in fewer trials compared to black-capped chickadees, and, across all species, males learned the discrimination in fewer trials than females. We discuss the roles that acoustic complexity and learning play in classification of the three species of songbirds tested. More generally, these results point to the benefits derived from testing members of each sex in species that vary in their natural history, vocal output, and phylogenetic relatedness as a means to uncover the mechanisms underlying acoustic communication. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

Octave equivalence occurs when an observer judges notes separated by a doubling in frequency perceptually similar. The octave appears to form the basis of pitch change in all human cultures and thus may be of biological origin. Previously, we developed a nonverbal operant conditioning test of octave generalization and transfer in humans. The results of this testing showed that humans with and without musical training perceive the octave relationship between pitches. Our goal in the current study was to determine whether black-capped chickadees, a North American songbird, perceive octave equivalence. We chose these chickadees because of their reliance on pitch in assessing conspecific vocalizations, our strong background knowledge on their pitch height perception (log-linear perception of frequency), and the phylogenetic disparity between them and humans. Compared to humans, songbirds are highly skilled at using pitch height perception to classify pitches into ranges, independent of the octave. Our results suggest that chickadees used that skill, rather than octave equivalence, to transfer the note-range discrimination from one octave to the next. In contrast, there is evidence that at least some mammals, including humans, do perceive octave equivalence.

Octave equivalence occurs when notes separated by an octave (a doubling in frequency) are judged as being perceptually similar. Considerable evidence points to the importance of the octave in music and speech. Yet, experimental demonstration of octave equivalence has been problematic. Using go/no-go operant discrimination and generalization, we studied octave equivalence in humans. In Experiment 1, we found that a procedure that failed to show octave equivalence in European starlings also failed in humans. In Experiment 2, we modified the procedure to control for the effects of pitch height perception by training participants in Octave 4 and testing in Octave 5. We found that the pattern of responding developed by discrimination training in Octave 4 generalized to Octave 5. We replicated and extended our findings in Experiment 3 by adding a transfer phase: Participants were trained with either the same or a reversed pattern of rewards in Octave 5. Participants transferred easily to the same pattern of reward in Octave 5 but struggled to learn the reversed pattern. We provided minimal instruction, presented no ordered sequences of notes, and used only sine-wave tones, but participants nonetheless constructed pitch chroma information from randomly ordered sequences of notes. Training in music weakly hindered octave generalization but moderately facilitated both positive and negative transfer.

The fee-bee song of the black-capped chickadee (Poecile atricapillus) is a two-note, tonal song that can be sung at different absolute pitches within an individual. However, these two notes are produced at a consistent relative pitch. Moreover, dominant birds more reliably produce songs with this species-typical interval, compared to subordinate birds. Therefore, we asked whether presenting the species-typical relative pitch interval would aid chickadees in solving pitch interval discriminations. We found that species-typical relative pitch intervals selectively facilitated discrimination performance using synthetic sine-wave stimuli. Using shifted fee-bee song notes from recordings of naturally produced songs, birds learned the discrimination in fewer trials overall compared to synthetic stimuli. These results may reflect greater generalization among stimuli that occur outside species-typical production parameters. In addition, although sex differences in performance are rarely observed in acoustic discriminations in chickadees, female chickadees performed more accurately compared to males.

Human music perception is related both to musical experience and the physical properties of sound. Examining the processing of music by nonhuman animals has been generally neglected. We tested both black-capped chickadees and humans in a chord discrimination task that replicates and extends prior research with pigeons. We found that chickadees and humans, in common with pigeons, showed similar patterns of discrimination across manipulations of the 3rd and 5th notes of the triadic chords. For all species (chickadee and humans here, pigeons previously), chords with half-step alterations in the 5th note were easier to discriminate than half-step manipulations of the 3rd note, which is likely due to the sensory consonance of these chords. There were differences among species in terms of the fine discrimination of the chords within this larger pattern of results. Further, the ability to relearn the chords when transposed to a new root differed across species. Our results provide new comparative data suggesting some similarities in chord perception that span a wide range of species, from pigeons (nonvocal learners) to songbirds and humans (vocal learners).

Abstract concept learning was thought to be uniquely human, but has since been observed in many other species. Discriminating same from different is one abstract relation that has been studied frequently. In the current experiment, using operant conditioning, we tested whether black-capped chickadees (Poecile atricapillus) could discriminate sets of auditory stimuli based on whether all the sounds within a sequence were the same or different from one another. The chickadees were successful at solving this same/different relational task, and transferred their learning to same/different sequences involving novel combinations of training notes and novel notes within the range of pitches experienced during training. The chickadees showed limited transfer to pitches that was not used in training, suggesting that the processing of absolute pitch may constrain their relational performance. Our results indicate, for the first time, that black-capped chickadees readily form relational auditory same and different categories, adding to the list of perceptual, behavioural, and cognitive abilities that make this species an important comparative model for human language and cognition.

An important first step in characterizing a vocalization is to classify, describe, and measure the elements of that vocalization. Here, this methodology is employed to study the chick-a-dee call of the boreal chickadee (Poecile hudsonicus). The note types (A, B, C, D, and D(h)) in a sample of boreal chickadee calls are identified and described, spectral and temporal features of each note type are analyzed, and production phenomena in each note type are identified and quantified. Acoustic variability is compared across note types and individuals to determine potential features used for note-type and individual discrimination. Frequency measures appear to be the most useful features for identifying note types and individuals, though total duration may also be useful. Call syntax reveals that boreal chick-a-dee calls follow a general rule of note-type order, namely A-B-C-D(h)-D, and that any note type in this sequence may be repeated or omitted. This work provides a thorough description of the boreal chickadee chick-a-dee call and will serve as a foundation for future studies aimed at elucidating this call's functional significance within this species, as well as for studies comparing chick-a-dee calls across Poecile species.

Animal personality, defined as consistent individual differences across context and time, has attracted much recent research interest in the study of animal behaviour. More recently, this field has begun to examine how such variation arose and is maintained within populations. The habitat-dependent selection hypothesis, which posits that animals with differing personality types may fare better (i.e. have a fitness advantage) in different habitats, suggests one possible mechanism. In the current experiment, we tested whether slow- and fast-exploring black-capped chickadees (Poecile atricapillus), determined by performance in a novel environment exploration task, perform differentially when the demands of an acoustic operant discrimination (cognitive) task were altered following successful task acquisition. We found that slow-exploring birds learn to reverse previously learned natural category rules more quickly than faster exploring conspecifics. In accordance with the habitat-dependent selection hypothesis, and previous work with great tits (Parus major), a close relative of the black-capped chickadee, our results suggest that fast-exploring birds may perform better in stable, predictable environments where forming a routine is advantageous, while slow-exploring birds are favoured in unstable, unpredictable environments, where task demands often change. Our results also support a hypothesis derived from previous work with great tits; slow-exploring birds may be generally more flexible (i.e. able to modify their behaviour in accordance with changes in environmental stimuli) in some learning tasks.

Songbird auditory areas (i.e., CMM and NCM) are preferentially activated to playback of conspecific vocalizations relative to heterospecific and arbitrary noise. Here, we asked if the neural response to auditory stimulation is not simply preferential for conspecific vocalizations but also for the information conveyed by the vocalization. Black-capped chickadees use their chick-a-dee mobbing call to recruit conspecifics and other avian species to mob perched predators. Mobbing calls produced in response to smaller, higher-threat predators contain more "D" notes compared to those produced in response to larger, lower-threat predators and thus convey the degree of threat of predators. We specifically asked whether the neural response varies with the degree of threat conveyed by the mobbing calls of chickadees and whether the neural response is the same for actual predator calls that correspond to the degree of threat of the chickadee mobbing calls. Our results demonstrate that, as degree of threat increases in conspecific chickadee mobbing calls, there is a corresponding increase in immediate early gene (IEG) expression in telencephalic auditory areas. We also demonstrate that as the degree of threat increases for the heterospecific predator, there is a corresponding increase in IEG expression in the auditory areas. Furthermore, there was no significant difference in the amount IEG expression between conspecific mobbing calls or heterospecific predator calls that were the same degree of threat. In a second experiment, using hand-reared chickadees without predator experience, we found more IEG expression in response to mobbing calls than corresponding predator calls, indicating that degree of threat is learned. Our results demonstrate that degree of threat corresponds to neural activity in the auditory areas and that threat can be conveyed by different species signals and that these signals must be learned.

Previous perceptual research with black-capped and mountain chickadees has demonstrated that these species treat each other's namesake chick-a-dee calls as belonging to separate, open-ended categories. Further, the terminal dee portion of the call has been implicated as the most prominent species marker. However, statistical classification using acoustic summary features suggests that all note-types contained within the chick-a-dee call should be sufficient for species classification. The current study seeks to better understand the note-type based mechanisms underlying species-based classification of the chick-a-dee call by black-capped and mountain chickadees. In two, complementary, operant discrimination experiments, both species were trained to discriminate the species of the signaler using either entire chick-a-dee calls, or individual note-types from chick-a-dee calls. In agreement with previous perceptual work we find that the D note had significant stimulus control over species-based discrimination. However, in line with statistical classifications, we find that all note-types carry species information. We discuss reasons why the most easily discriminated note-types are likely candidates to carry species-based cues.

The spectral frequency ranges of song notes are important for recognition in avian species tested in the field. Frequency-range discriminations in both the field and laboratory require absolute pitch (AP). AP is the ability to perceive pitches without an external referent. The authors provided a network model designed to account for differences in AP among avian species and evaluated it against discriminative performance in eight-frequency-range laboratory tests of AP for five species of songbirds and two species of nonsongbirds. The model's sensory component describes the neural substrate of avian auditory perception, and its associative component handles learning of the discrimination. Using only two free parameters to describe the selectivity and the sensitivity of each species' auditory sensory filters, the model provided highly accurate predictions of frequency-range discrimination in songbirds and in a parrot species, but performance and its prediction were less accurate in pigeons: the only species tested that does not learn its vocalizations. Here for the first time, the authors present a model that predicted individual species' performance in frequency-range discriminations and predicted differences in discrimination among avian species with high accuracy., (Copyright (c) 2009 Elsevier B.V. All rights reserved.)

We report on operant conditioning and artificial neural network (ANN) simulations aimed at further elucidating mechanisms of black-capped chickadee chick-a-dee call note category perception. Specifically, we tested for differences in the speed of acquisition among different discrimination tasks and, in two selected discrimination groups, searched for evidence of peak shift. Earlier, unreported ANN data were instrumental in providing the motivation for the current set of studies with chickadees and are provided here. The ANNs revealed differences in the speed of learning among note-type discrimination groups that is related to the degree of perceptual similarity among the three note types tested (i.e., A, B, and C notes). In many respects, bird and network results were in agreement (i.e., in the observation of peak shift in the same group), but they also differed in important ways (i.e., all discrimination groups showed differences in speed of learning in simulations but not in chickadees). We suggest that the start, peak and end frequency of the chick-a portion of chick-a-dee call notes, which form a graded but overlapping continuum, may drive the peak shift observed.

A first step to understanding how a species communicates acoustically is to identify, categorize, and quantify the acoustic parameters of the elements that make up their vocalizations. The "chick-a-dee" call notes of the chestnut-backed chickadee (Poecile rufescens) were sorted into four call note categories, A, C, D, and Dh notes, based on their acoustic structure as observed in sound spectrograms, and evaluated based on the syntactical ordering of the note types within calls. The notes were then analyzed using quantitative measures and it was determined which features have the potential to convey information to discriminate note type, individual, and the geographic origin of the producer. The findings were comparable to previous research of congeners in that chestnut-backed chickadee calls were produced with a relatively fixed syntax and contained similarly structured note types across all geographic regions. Overall this information will form a base for future research on chestnut-backed chickadee vocalizations and will strengthen the foundation for future comparative evolutionary studies.

A previous study has shown that the stress responsive neurohormone arginine vasopressin (AVP) is activated in the amygdala during early withdrawal from cocaine. The present studies were undertaken to determine whether (1) AVP mRNA levels in the amygdala or hypothalamus, as well as hypothalamic-pituitary-adrenal (HPA) activity, would be altered during chronic intermittent escalating heroin administration (10 days; 7.5-60 mg/kg/day) or during early (12 h) and late (10 days) spontaneous withdrawal; (2) foot shock stress would alter AVP mRNA levels in the amygdala or hypothalamus in rats withdrawn from heroin self-administration (7 days, 3 h/day, 0.05 mg/kg/infusion); and (3) the selective V1b receptor antagonist SSR149415 (1 and 30 mg/kg, intraperitoneal) would alter heroin seeking during tests of reinstatement induced by foot shock stress and by heroin primes (0.25 mg/kg), as well as HPA hormonal responses to foot shock. We found that AVP mRNA levels were increased during early spontaneous withdrawal in the amygdala only. This amygdalar AVP mRNA increase was no longer observed at the later stage of heroin withdrawal. Foot shock stress increased AVP mRNA levels in the amygdala of rats withdrawn from heroin self-administration, but not in heroin naïve rats. Behaviorally, SSR149415 dose-dependently attenuated foot shock-induced reinstatement and blocked heroin-induced reinstatement. Finally, SSR149415 blunted the HPA activation by foot shock. Together, these data in rats suggest that stress responsive AVP/V1b receptor systems (including the amygdala) may be critical components of the neural circuitry underlying the aversive emotional consequences of drug withdrawal, as well as the effect of negative emotional states on drug-seeking behavior.