Statistical classification of black-capped (Poecile atricapillus) and mountain chickadee (Poecile gambeli) call notes

Both black-capped (Poecile atricapillus) and mountain chickadees (Poecile gambeli) produce a chick-a-dee call that consists of several distinct note types. In some regions, these 2 species live sympatrically, and it has been shown that 1 species will respond weakly to songs of the other. This suggests that chickadee song, and potentially other of their vocalizations, contains species-specific information. We tested the possibility that call notes were acoustically sufficient for species identification. Black-capped and mountain non-D notes were summarized as a set of 9 features and then analyzed by linear discriminant analysis. Linear discriminant analysis was able to use these notes to identify species with 100% accuracy. We repeated this approach, but with black-capped and mountain D notes that were summarized as a set of 4 features. Linear discriminant analysis was able to use these notes to identify species with 94% accuracy. This demonstrates that any of the note types in these chickadee calls possesses sufficient information for species classification.     

Memory for what, where, and when in the black-capped chickadee (Poecile atricapillus)

Episodic memory is the ability to remember personally experienced past events (Tulving in Organization of memory. Academic Press, San Diego, pp. 381–403, 1972). In non-human animals, the behavioural criterion for episodic-like memory is remembering “what” occurred in conjunction with “when” and “where” (Clayton and Dickinson in Nature 395:272–274, 1998). We conducted tests for “what, where, and when” memory in a food-storing bird, the black-capped chickadee (Poecile atricapillus). In Experiment 1, chickadees found sunflower seeds and mealworms in concealed sites in their home cage. Birds later re-visited these sites after either a short (3 h) or long (123 h) retention interval. Chickadees normally prefer mealworms, but at the long retention interval mealworms were degraded in taste and appearance. Chickadees showed some memory for what kind of food they had encountered and where, but no memory for when food had previously been found. Experiment 2 followed a similar procedure, except that chickadees searched for hidden sunflower seeds and mealworms in trees in an indoor aviary. These more natural conditions increased both the spatial scale of the task and the effort required to find food. In this experiment, birds showed evidence for all three components of what–where–when memory. Unlike some previous studies of episodic-like memory, birds’ behaviour cannot be accounted for by differential memory strength for more recent events. The results show that memory for what, where, and when occurs in food-storing birds outside the corvid family, does not require food caching or retrieval, and that remembering “when” can depend on the nature of the task.     

Call-note discriminations in black-capped chickadees (Poecile atricapillus)

Bioacousticians (M.S. Ficken, S. R. Ficken, & S. R. Witken, 1978) classified black-capped chickadee call notes from the chick-a-dee call complex into 4 note types (A, B, C, and D) identified from sound spectrograms. In Experiment 1, chickadees (Poecile atricapillus) learned operant auditory discriminations both within and between the 4 note types but learned the between note-type discrimination significantly faster. In Experiment 2, when the original, unrewarded between-category exemplars were replaced with novel, rewarded exemplars of these same categories, chickadees showed transfer of inhibitory stimulus control to the novel exemplars. In Experiment 3, when novel exemplars were replaced by the original exemplars, chickadees showed propagation of positive stimulus control back to the original exemplars. This evidence suggests that chickadees and bioacousticians accurately sort conspecific call notes into the same open-ended categories (R. J. Herrnstein, 1990).     

Song sequence discrimination in the black-capped chickadee (Parus atricapillus)

Captive black-capped chickadees (Parus atricapillus) were presented with normal and altered versions of their species-specific "fee bee" song, to determine how note type, number, and sequence affect recognition. The number of perch changes and vocalizations (analyzed separately) given in response to playback did not differ reliably as a function of song type, whereas latency to first vocalization after playback did. In an initial experiment using two-note songs, birds vocalized sooner to songs beginning with fee than with bee and to fee bee than to fee fee. In a second experiment, birds were presented with shortened (single note), normal, and lengthened (three note) songs each consisting of a single-note type (either fee or bee). Habituation slowed responding to altered songs but not to fee bee over three test sessions. Results from the first session suggest that chickadees distinguished single fees and three-note songs from normal song, single fees from single bees, and two-note songs from three-note songs. Results from the third session suggested that chickadees distinguished normal song from any of the altered songs. The internal representation of conspecific song in the chickadee thus distinguishes between fee and bee notes, contains information about note order, and is sensitive to note number. The pattern of responses is consistent with a model of recognition based on note-by-note integration of individual decisions about song structure.     

Black-capped chickadee (Poecile atricapillus) and human (Homo sapiens) chord discrimination

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).     

Open-ended categorization of chick-a-dee calls by black-capped chickadees (Poecile atricapilla)

The authors trained black-capped chickadees (Poecile atricapilla) in an operant discrimination with exemplars of black-capped and Carolina chick-a-dee calls, with the goal of determining whether the birds memorized the calls of conspecifics and heterospecifics or classified the calls by species. Black-capped calls served as both rewarded (S+) and unrewarded (S-) stimuli (the within-category discrimination), whereas Carolina chick-a-dee calls served as S-s (the between-category discrimination) in the black-capped chick-a-dee call S+ group. The Carolina call S+ group had Carolina calls as S+s and S-s (within-category) and black-capped calls as S-s (between-category). Both groups discriminated between call categories faster than within a call category. In 2 subsequent experiments, both S+ groups showed transfer to novel calls and propagation back to between-category calls. The results favor the hypothesis that the acoustically similar social calls of the 2 species constitute separate open-ended categories.     

Comparing black-capped (Poecile atricapillus) and mountain chickadees (Poecile gambeli): use of geometric and featural information in a spatial orientation task

Since Cheng (Cognition 23:149–178, 1986) first proposed the “geometric module” in rats, a great deal of research has focused on how other species use geometric information and how geometric encoding may differ across species. Here, hand-reared and wild-caught black-capped chickadees and wild-caught mountain chickadees searched for food hidden in one corner in a rectangular environment. Previous research has shown that mountain chickadees do not spontaneously encode geometric information when a salient feature is present near the goal location. Using a slightly different training and testing procedure, we found that both hand-reared and wild-caught black-capped chickadees encoded geometric information, even in the presence of a salient landmark. Some, but not all, mountain chickadees also encoded geometric information. Overall, our results suggest that use of geometric information may be a less preferred strategy for mountain chickadees than for either wild-caught or hand-reared black-capped chickadees. To our knowledge, this is the first direct interspecies comparison of use of geometric information in a spatial orientation task.     

Frequency-range discriminations and absolute pitch in black-capped chickadees (Poecile atricapillus), mountain chickadees (Poecile gambeli), and zebra finches (Taeniopygia guttata)

The acoustic frequency ranges in birdsongs provide important absolute pitch cues for the recognition of conspecifics. Black-capped chickadees (Poecile atricapillus), mountain chickadees (Poecile gambeli), and zebra finches (Taeniopygia guttata) were trained to sort tones contiguous in frequency into 8 ranges on the basis of associations between response to the tones in each range and reward. All 3 species acquired accurate frequency-range discriminations, but zebra finches acquired the discrimination in fewer trials and to a higher standard than black-capped or mountain chickadees, which did not differ appreciably in the discrimination. Chickadees' relatively poorer accuracy was traced to poorer discrimination of tones in the higher frequency ranges. During transfer tests, the discrimination generalized to novel tones when the training tones were included, but not when they were omitted.     

Discrimination of individual vocalizations by black-capped chickadees (Poecile atricapilla)

The auditory perceptual abilities of male black-capped chickadees (Poecile atricapilla) were examined using an operant go/no-go discrimination among 16 individual vocalizations recorded at 5 m. The birds learned to discriminate about equally well among eight male chickadee fee-bee songs and eight female zebra finch (Taeniopygia guttata) distance calls. These results do not indicate that chickadees have a species-specific advantage in individual recognition for conspecific over heterospecific vocalizations. We then transferred the chickadees to a discrimination of the same songs and calls rerecorded at a moderate distance. These results showed accurate transfer of discrimination from 16 vocalizations recorded at 5 m to novel versions of the same 16 songs and calls rerecorded at 25 m. That is, chickadees recognized individual songs and calls despite degradation produced by rerecording at 25 m. Identifying individual vocalizations despite their transformation by distance cues is here described as a biologically important example of perceptual constancy.     

Operant discrimination of relative frequency ratios in black-capped chickadee song

The two-note fee bee song of the black-capped chickadee (Poecile atricapillus) is sung at many different absolute frequencies, but the relative frequencies, or “pitch ratios”, between the start and end of the fee note (glissando) and the fee and the bee notes (inter-note interval) are preserved with each pitch-shift. Ability to perceive these ratios and their relative salience varies with sex of the bird and setting: while both sexes appear to perceive changes in the inter-note interval, males appear to attend to the glissando in the field, and females appear to attend to both ratios. In this study, we compared directly whether male and female chickadees could discriminate between normal fee bee songs and songs that had one or both of the pitch ratios altered, and whether birds attended to one type of alteration over another. Both sexes learned to discriminate normal from altered songs; songs lacking an inter-note interval were more easily discriminated than songs with only the glissando removed. Females performed slightly better than males, including in the most difficult task with the stimuli lacking the glissando. Our study illustrates the value of using perceptual tasks to directly compare performance between the sexes and to demonstrate the difference between perception of and attention to acoustic features of vocal communication.     

Information theoretical approaches to chick-a-dee calls of Carolina chickadees (Poecile carolinensis)

One aim of this study was to apply information theoretical analyses to understanding the structural complexity of chick-a-dee calls of Carolina chickadees, Poecile carolinensis. A second aim of this study was to compare this structural complexity to that of the calls of black-capped chickadees, P. atricapillus, described in an earlier published report (Hailman, Ficken, & Ficken, 1985). Chick-a-dee calls were recorded from Carolina chickadees in a naturalistic observation study in eastern Tennessee. Calls were analyzed using approaches from information theory, including transition probability matrices, Zipf's rules, entropies, and information coding capacities of calls and notes of calls. As described for black-capped chickadees, calls of Carolina chickadees exhibited considerable structural complexity. Most results suggested that the call of Carolina chickadees is more structurally complex than that of black-capped chickadees. These findings add support to the growing literature on the complexity of this call system in Paridae species. Furthermore, these results point to the feasibility of detailed cross-species comparative analyses that may allow strong testing of hypotheses regarding signal evolution.     

Divided attention,memory, and spatial discrimination in food-storing and nonstoring birds,black-capped chickadees (Poecile atricapilla) and dark-eyed juncos (Junco hyemalis)

Food-storing birds, black-capped chickadees (Poecile atricapilla), and nonstoring birds, dark-eyed juncos (Junco hyemalis), matched color or location on a touch screen. Both species showed a divided attention effect for color but not for location (Experiment 1). Chickadees performed better on location than on color with retention intervals up to 40 s, but juncos did not (Experiment 2). Increasing sample-distractor distance improved performance similarly in both species. Multidimensional scaling revealed that both use a Euclidean metric of spatial similarity (Experiment 3). When choosing between the location and color of a remembered item, food storers choose location more than do nonstorers. These results explain this effect by differences in memory for location relative to color, not division of attention or spatial discrimination ability.     

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 subjects was investigated. In a 2-choice, operant-conditioning-based procedure, this work followed up acoustic analyses that had used various digitally based algorithms (Owren & Bernacki, 1988). All subjects 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 characterizations. 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 subjects were mixed. Implications for the study of nonhuman primate vocalizations and Lieberman's (1984) theory of speech evolution are discussed.     

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 subjects were tested with 48 novel calls in rapid succession. Human (Homo sapiens) control subjects participated in the first study without extended preliminary training. Monkey and human subjects both showed immediate transfer to classification of unfamiliar alarm calls, despite variations both in voice characteristics and reproduction quality.     

Discrimination of acoustically similar conspecific and heterospecific vocalizations by black-capped chickadees (<Emphasis Type="Italic">Poecile atricapillus</Emphasis>)

Chickadees produce a multi-note chick-a-dee call in multiple socially relevant contexts. One component of this call is the D note, which is a low-frequency and acoustically complex note with a harmonic-like structure. In the current study, we tested black-capped chickadees on a between-category operant discrimination task using vocalizations with acoustic structures similar to black-capped chickadee D notes, but produced by various songbird species, in order to examine the role that phylogenetic distance plays in acoustic perception of vocal signals. We assessed the extent to which discrimination performance was influenced by the phylogenetic relatedness among the species producing the vocalizations and by the phylogenetic relatedness between the subjects’ species (black-capped chickadees) and the vocalizers’ species. We also conducted a bioacoustic analysis and discriminant function analysis in order to examine the acoustic similarities among the discrimination stimuli. A previous study has shown that neural activation in black-capped chickadee auditory and perceptual brain regions is similar following the presentation of these vocalization categories. However, we found that chickadees had difficulty discriminating between forward and reversed black-capped chickadee D notes, a result that directly corresponded to the bioacoustic analysis indicating that these stimulus categories were acoustically similar. In addition, our results suggest that the discrimination between vocalizations produced by two parid species (chestnut-backed chickadees and tufted titmice) is perceptually difficult for black-capped chickadees, a finding that is likely in part because these vocalizations contain acoustic similarities. Overall, our results provide evidence that black-capped chickadees’ perceptual abilities are influenced by both phylogenetic relatedness and acoustic structure.     

Selective mechanisms in visual perception

The notion of perceptual tuning is investigated by presenting alternatives either before, after, or both before and after a tachistoscopic stimulus. Study 1 (N = 12) showed that identification accuracy is best with alternatives both before and after the stimulus, poorest with alternatives after the stimulus, and intermediate with alternatives only before the stimulus. Study 2 (N = 3) indicated that performance with alternatives both before and after the stimulus varies according to where S is permitted to fixate prior to each exposure. The possibility of a central tuning mechanism was not strongly supported.     

Acoustic memory and the perception of speech

The nature of acoustic memory and its relationship to the categorizing process in speech perception is investigated in three experiments on the serial recall of lists of syllables. The first study confirms previous reports that sequences comprising the syllables, bah, dah, and gah show neither enhanced retention when presented auditorily rather than visually, nor a recency effect—both occurred with sequences in which vowel sounds differed (bee, bih, boo). This was found not to be a simple vowel-consonant difference since acoustic memory effects did occur with consonant sequences that were acoustically more discriminable (sha, ma, ga and ash, am, ag). Further experiments used the stimulus suffix effect to provide evidence of acoustic memory, and showed (1), increasing the acoustic similarity of the set grossly impairs acoustic memory effects for vowels as well as consonants, and (2) such memory effects are no greater for steady-state vowels than for continuously changing diphthongs. It is concluded that the usefulness of the information that can be retrieved from acoustic memory depends on the acoustic similarity of the items in the list rather than on their phonetic class or whether or not they have “encoded” acoustic cues. These results question whether there is any psychological evidence for “encoded” speech sounds being categorized in ways different from other speech sounds.     

躯体知觉的认知神经机制

摘 要：人类躯体是由各部位按照一定的空间关系组成的,与人类面孔相似,也是对称的。它也能提供个体身份和行为方式等信息,如年龄、性别、意图、情感状态等。它与面孔相辅相成,共同促成对个体身份的辨别。躯体知觉是指大脑对进入视觉加工系统中的人类躯体刺激的侦察,感知或识别。躯体知觉应当如面孔知觉研究一样受到更多的关注。文章概述、评价了躯体知觉相关的认知神经研究,着重介绍了躯体知觉的认知和神经机制,并提出了一些值得进一步研究的问题。     

The production and perception of long calls by cotton-top tamarins (Saguinus oedipus): acoustic analyses and playback experiments

The authors' goal was to provide a better understanding of the relationship between vocal production and perception in nonhuman primate communication. To this end, the authors examined the cotton-top tamarin's (Saguinus oedipus) combination long call (CLC). In Part 1 of this study, the authors carried out a series of acoustic analyses designed to determine the kind of information potentially encoded in the tamarin's CLC. Using factorial analyses of variance and multiple discriminant analyses, the authors explored whether the CLC encodes 3 types of identity information: individual, sex, and social group. Results revealed that exemplars could be reliably assigned to these 3 functional classes on the basis of a suite of spectrotemporal features. In Part 2 of this study, the authors used a series of habituation-dishabituation playback experiments to test whether tamarins attend to the encoded information about individual identity. The authors 1st tested for individual discrimination when tamarins were habituated to a series of calls from 1 tamarin and then played back a test call from a novel tamarin; both opposite- and same-sex pairings were tested. Results showed that tamarins dishabituated when caller identity changed but transferred habituation when caller identity was held constant and a new exemplar was played (control condition). Follow-up playback experiments revealed an asymmetry between the authors' acoustic analyses of individual identity and the tamarins' capacity to discriminate among vocal signatures; whereas all colony members have distinctive vocal signatures, we found that not all tamarins were equally discriminable based on the habituation-dishabituation paradigm.