Distributed recognition of natural songs by European starlings

Individual vocal recognition behaviors in songbirds provide an excellent framework for the investigation of comparative psychological and neurobiological mechanisms that support the perception and cognition of complex acoustic communication signals. To this end, the complex songs of European starlings have been studied extensively. Yet, several basic parameters of starling individual vocal recognition have not been assessed. Here we investigate the temporal extent of song information acquired by starlings during vocal recognition learning. We trained two groups of starlings using standard operant conditioning techniques to recognize several songs from two conspecific male singers. In the first experiment we tested their ability to maintain accurate recognition when presented with (1) random sequences of 1–12 motifs (stereotyped song components) drawn from the training songs, and (2) 0.1–12-s excerpts of continuous song drawn from the training songs. We found that song recognition improved monotonically as more vocal material is provided. In the second experiment, we systematically substituted continuous, varying length regions of white noise for portions of the training songs and again examined recognition accuracy. Recognition remained above chance levels for all noise substitutions tested (up to 91% of the training stimulus) although all but the smallest substitutions led to some decrement in song recognition. Overall, above chance recognition could be obtained with surprisingly few motifs, short excerpts of song, and in the absence of large portions of the training songs. These results suggest that starlings acquire a representation of song during individual vocal recognition learning that is robust to perturbations and distributed broadly over large portions of these complex acoustic sequences.     

Recognition memory for text and melody of songs after unilateral temporal lobe lesion: evidence for dual encoding.

The role of left and right temporal lobes in memory for songs (words sung to a tune) was investigated. Patients who had undergone focal cerebral excision for the relief of intractable epilepsy along with normal control subjects were tested in 2 recognition memory tasks. The goal of Experiment 1 was to examine recognition of words and of tunes when they were presented together in an unfamiliar song. In Experiment 2, memory for spoken words and tunes sung without words was independently tested in 2 separate recognition tasks. The results clearly showed (a) a deficit after left temporal lobectomy in recognition of text whether sung to a tune or spoken without musical accompaniment, (b) impaired melody recognition when the tune was sung with new words following left or right temporal lobectomy and (c) impaired melody recognition in the absence of lyrics following right but not left temporal lobectomy. The different role of each temporal lobe in memorizing songs provides evidence for the use of dual memory codes. The verbal code is consistently related to left temporal lobe structures, whereas the melodie code my depend on either or both temporal lobe mechanisms, according to the type of encoding involved.     

Two-way interactions between music and language: Evidence from priming recognition of tune and lyrics in familiar songs

A priming technique was employed to study the relations between melody and lyrics in song memory. The procedure involved the auditory presentation of a prime and a target taken from the same song, or from unrelated but equally familiar songs. To promote access to memory representations of songs, we varied the format of primes and targets, which were either spoken or sung, using the syllable /1a/. In each of the four experiments, a prime taken from the same song as the target facilitated target recognition, independently of the format in which it occurred. The facilitation effects were also found in conditions close to masked priming because prime recognizability was very low, as assessed in Experiment 1 by d' measures. Above all, backward priming effects were observed in Experiments 2, 3, and 4, where song order was reversed in the prime-target sequence, suggesting that words and tones of songs are not connected by strict temporal contingencies. Rather, the results indicate that, in song memory, text and tune are related by tight connections that are bidirectional and automatically activated by relatively abstract information. Rhythmic similarity between linguistic stress pattern and musical meter might account for these priming effects.     

Amplitude modulation of sexy phrases is salient for song attractiveness in female canaries (Serinus canaria)

Song discrimination and recognition in songbird species have usually been studied by measuring responses to song playbacks. In female canaries, Serinus canaria, copulation solicitation displays (CSDs) are used as an index of female preferences, which are related to song recognition. Despite the fact that many studies underline the role of song syntax in this species, we observed that short segments of songs (a few seconds long) are enough for females to discriminate between conspecific and heterospecific songs, whereas such a short duration is not sufficient to identify the syntax rules. This suggests that other cues are salient for song recognition. In this experiment, we investigated the influence of amplitude modulation (AM) on the responses (CSDs) of female canaries to song playbacks. We used two groups of females: (1) raised in acoustic isolation and (2) raised in normal conditions. When adult, we tested their preferences for sexy phrases with different AMs. We broadcast three types of stimuli: (1) songs with natural canary AM, (2) songs with AM removed, or (3) song with wren Troglodytes troglodytes AM. Results indicate that female canaries prefer and have predispositions for a song type with the natural canary AM. Thus, this acoustic parameter is a salient cue for song attractiveness.     

Auditory temporal pattern learning by songbirds using maximal stimulus diversity and minimal repetition

The sequential patterning of complex acoustic elements is a salient feature of bird song and other forms of vocal communication. For European starlings (Sturnus vulgaris), a songbird species, individual vocal recognition is improved when the temporal organization of song components (called motifs) follows the normal patterns of each singer. This sensitivity to natural motif sequences may underlie observations that starlings can also learn more complex, unnatural motif patterns. Alternatively, it has been proposed that the apparent acquisition of abstract motif patterning rules instead reflects idiosyncrasies of the training conditions used in prior experiments. That is, that motif patterns are learned not by recognizing differences in temporal structures between patterns, but by identifying serendipitous features (e.g., acoustical cues) in the small sets of training and testing stimuli used. Here, we investigate this possibility, by asking whether starlings can learn to discriminate between two arbitrary motif patterns, when unique examples of each pattern are presented on every trial. Our results demonstrate that abstract motif patterning rules can be acquired from trial-unique stimuli and suggest that such training leads to better pattern generalization compared with training with much smaller stimulus subsets.     

Physical interaction and association by contiguity in memory for the words and melodies of songs

Three experiments were designed to investigate two explanations for the integration effect in memory for songs (Serafine, Crowder, & Repp, 1984; Serafine, Davidson, Crowder, & Repp, 1986). The integration effect is the finding that recognition of the melody (or text) of a song is better in the presence of the text (or melody) with which it had been heard originally than in the presence of a different text (or melody). One explanation for this finding is the physical interaction hypothesis, which holds that one component of a song exerts subtle but memorable physical changes on the other component, making the latter different from what it would be with a different companion. In Experiments 1 and 2, we investigated the influence that words could exert on the subtle musical character of a melody. A second explanation for the integration effect is the association-by-contiguity hypothesis, which holds that any two events experienced in close temporal proximity may become connected in memory such that each acts as a recall cue for the other. In Experiment 3, we investigated the degree to which simultaneous presentations of spoken text with a hummed melody would induce an association between the two components. The results gave encouragement for both explanations and are discussed in terms of the distinction between encoding specificity and independent associative bonding.     

The organisation of musical semantic memory: Evidence from false memories for familiar songs

By adapting a well-known paradigm for studying memory for words—the Deese-Roediger-McDermott or DRM paradigm (Deese, 1959, Roediger & McDermott, 1995)—the two experiments reported here explore memory for song titles and song clips. Participants were presented with five song titles (Experiment 1a) or five 30-second song clips (Experiment 1b) for each of nine popular artists (e.g., Robbie Williams). The most popular song identified for each artist in a pilot task was omitted from the sets of titles/clips. Following a distractor task, participants were asked to write down as many of the songs as they could recall. They were also asked to return a week later and complete a second recall task. Participants falsely recalled a significant number of the related but non-presented songs in both experiments and this increased a week later, while correct recall for presented items decreased. The results are discussed in terms of theory for musical memory as well as in the context of providing a novel method for exploring the organisation of musical memory.     

Integration of melody and text in memory for songs

Two experiments examined whether the memory representation for songs consists of independent or integrated components (melody and text). Subjects heard a serial presentation of excerpts from largely unfamiliar folksongs, followed by a recognition test. The test required subjects to recognize songs, melodies, or texts and consisted of five types of items: (a) exact songs heard in the presentation; (b) new songs; (c) old tunes with new words; (d) new tunes with old words; and (e) old tunes with old words of a different song from the same presentation (‘mismatch songs’). Experiment 1 supported the integration hypothesis: Subjects' recognition of components was higher in exact songs (a) than in songs with familiar but mismatched components (e). Melody recognition, in particular, was near chance unless the original words were present. Experiment 2 showed that this integration of melody and text occurred also across different performance renditions of a song and that it could not be eliminated by voluntary attention to the melody.     

成年雄性斑胸草雀高级发声中枢鸣声控制的右侧优势

鸣禽是研究语言功能的动物模型。鸣禽端脑的高级发声中枢(high vocal center, HVC)与人类布洛卡氏区具有功能同源性。利用电损毁与声谱分析相结合的方法, 对成年雄性斑胸草雀两侧HVC分别进行电损毁, 观察HVC控制鸣声的侧别差异。结果表明, 损毁左侧HVC对长鸣和鸣曲的频域和声强特征均无显著性影响。损毁右侧HVC导致长鸣的振幅、调频、幅度调制显著减小(p < 0.05), 鸣曲的振幅、平均频率、峰频率显著减小(p < 0.05)。损毁双侧HVC后均引起鸣曲时域特征的改变, 暗示鸣曲时域特征的编码需要两侧半球鸣唱系统的整合。HVC在控制鸣声频域和声强特征上具有右侧优势, 但对鸣曲时域特征的控制需要两侧HVC的共同参与。     

Song syllable discrimination by song sparrows (Melospiza melodia)

A habituation test paradigm was used to examine the responses of free-living territorial adult male song sparrows (Melospiza melodia) to a range of synthetic songs. The three-phrased test songs differed from one another in having either conspecific or heterospecific (swamp sparrow, M. georgiana) syllables, or silence, in the second phrase. Subjects were exposed to repeated presentations of one song type until their approach distance to a loudspeaker increased. In one experiment, birds were habituated with a song consisting of three phrases of song sparrow syllables and then tested for generalization to either novel song sparrow syllables in the second phrase, swamp sparrow syllables, or silence. Birds discriminated between song sparrow syllables on two response measures, and between song sparrow and swamp sparrow syllables on one measure. In a second experiment, after habituation to a song with swamp sparrow syllables in the second phrase, birds did not generalize to novel song sparrow syllables, but they did generalize to novel swamp sparrow syllables. Thus song sparrows make finer distinctions among conspecific syllable variants than with alien syllables. The results further suggest that subtle species-specific differences in note structure within syllables are discriminated by song sparrows and potentially provide an adequate basis for individual recognition by song.     

Timing and classifying brief acoustic stimuli by songbirds and humans.

The durations of animals' brief vocalizations provide conspecifics with important recognition cues. In the present experiments, zebra finches and humans (trained musicians) were rewarded for responding after S+ (standard) auditory signals from 56 to 663 ms and not for responding after shorter or longer S- (comparison) durations from 10 to 3684 ms. With either a single standard (Experiment 1) or multiple standards (Experiment 2), both zebra finches and humans timed brief signals to about the same level of accuracy. The results were in qualitative agreement with predictions from scalar timing theory and its connectionist implementation in both experiments. The connectionist model provides a good quantitative account of temporal gradients with a single standard (Experiment 1) but not with multiple standards (Experiment 2).     

The cult of experiment: the Psychological Round Table, 1936-1941

The Psychological Round Table (PRT) was an important yet anomalous society founded by young American experimental psychologists. Although it was secretive, it encouraged contact among young experimental psychologists. Although it was motivated by perceived inequities in professional psychology, it was governed by an autocratic minority. And although it was self-consciously informal and irreverent, it clandestinely used formal selection procedures. These aspects of the PRT are documented and explained (counter to L. Benjamin, 1977) as manifestations of the PRT's devotion to psychological experimentation, specially understood. Secrecy, specifically, served not to protect PRT participants from senior colleagues but to create an environment free of political and professional influences and thus taken to be well suited to the vetting of experiments. In this regard, the PRT is distinguished from more familiar scientific societies.     

Perception of temporal properties in self-generated songs by Bengalese finches (Lonchura striata var. domestica)

In the songbird forebrain, neuronal selectivity for temporal properties of each bird's self-generated song has been well described, but the behavioral and perceptual correlates of this selectivity are not known. By operant procedures, the authors trained Bengalese finches (Lonchura striata var. domestica) to discriminate between songs that were played normally and in reverse. Male Bengalese finches learned the discrimination quicker when their self-generated song was used as a stimulus than when a song of another conspecific bird was used. When the global note order was retained but each note was locally reversed, the song was more likely to be regarded as a forward song by the singer himself, but not by other birds. These results provide psychophysical evidence that the special processing of the self-generated song observed at the neural level might reflect an individual's perception of his self-produced song.     

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.     

Changes in stereotyped central motor patterns controlling vocalization are induced by peripheral nerve injury.

Adult male zebra finches (Taeniopygia guttata), as closed-ended learners, normally crystallize their songs at 90 days of age, and the song remains fixed throughout life (Price, 1979). We show that injuring the tracheosyringeal nerve(s) (each of which innervates the ipsilateral half of the syrinx, the avian vocal organ) results in a short-term deficit in the syllables forming adult male song; this deficit disappears after ts nerve regeneration. However, when adult males were followed for a period of several weeks after unilateral tracheosyringeal nerve injury, long-term changes occurred in the temporal patterning of song. Syllables were deleted, remaining portions of the song were linked, and new syllables were added. Syllables with call-like morphology were less likely to be deleted from and more likely to be added to the song. Deletions were most often contiguous chunks of syllables. Changes in the temporal patterning of song occurred during specific periods following nerve injury, were completed within 100 days after nerve transection, and were not dependent upon regeneration of the ts nerve. The resulting newly formed song patterns were stable, remaining unchanged up to 1 year later. The ability of adult male zebra finches to make specific types of changes to crystallized song indicates that some form of vocal plasticity remains even after song learning is completed, though this plasticity may be restricted to a subset of song characteristics. The limitations on the types of changes that are possible may reflect how song is centrally organized.     

Investigating driver reactions to movements of autonomous vehicle in permitted right turn through driving simulator experiments

Traffic safety has always been a hot topic for human-driven (HDV) and autonomous vehicles (AV) mixed flow. The conflict between permitted right-turn vehicles (PRT) and opposing through vehicles (TH) at signalized intersections (left-handed traffic) is extraordinarily critical. AVs with aggressive behaviors are able to accept short gap time without losing safety. However, such a turning maneuver may lead to dangerous feelings and cause unexpected reactions of approaching drivers. This study aims to investigate and model drivers’ reactions in TH movements to PRT AVs considering the trust degree of drivers to AVs. Questionnaire surveys and driving simulator experiments were conducted for 41 participants. Results reveal that the right turn timing of PRT AV will significantly influence drivers’ reactions. Basically, TH drivers will brake with a high probability under the situation of small expected post encroachment time (PET). It is also found that female drivers and drivers with low trust in AVs are more vigilant to PRT AVs than other drivers. Based on this finding a two-layer model for reproducing TH drivers’ reactions to PRT AVs is proposed. The first layer is to determine the braking decision and the second layer is to calculate the parameters of braking behaviors (brake lag, braking time, and speed drop). The significance and coefficients variables in these models proved that the trust in AV will influence drivers’ decisions and braking behaviors (brake lag and braking time). The more the drivers trust AVs, the smaller the expected PET to AVs they can accept for passing without braking, and the more gently they will brake (longer brake lag and shorter braking time) due to the cutting in of PRT AVs. This effect will become significant after drivers have experienced several interactions with AVs.     

Visual form recognition threshold and the psychological refractory period

Two experiments studied the effect of a reaction time response (RT) on visual form recognition threshold when the temporal interval separating the RT stimulus and the recognition stimulus was short. In Experiment 1 an initial RT response to an auditory signal did not impair the subsequent forced-choice visual form recognition threshold. Interstimulus intervals (ISI) of 0, 50, 100, 150, and 200 msec were used; S was always aware of the ISI under test. In Experiment 2 a visual stimulus was used to elicit the R T response; this shift to an intramodal stimulus did not alter the recognition threshold. These data were interpreted as supporting the hypothesis that two stimulus events can be processed simultaneously even when the temporal interval between them is short.     

Experience with songs in adulthood reduces song-induced gene expression in songbird auditory forebrain

Male songbirds learn to produce song within a limited phase early in life; however they continue to learn to recognize songs in adulthood. Studies looking at Zenk activation after exposure to songs learned early in life for song production and songs learned in adulthood show opposite patterns of activation, suggesting distinct neural mechanisms may be involved in these two forms of learning. In this study, we look at IEG Zenk activation in auditory regions NCM and CMM of song sparrows (Melospiza melodia) to see whether recent exposure to song in adulthood leads to greater or decreased Zenk activation upon hearing that song versus a novel song. We found significantly lower activation in birds exposed to previously heard songs versus novel songs in vNCM but not dNCM, though further analysis suggest an overall trend in NCM. We found no significant difference in the amount of activation to previously heard songs vs. novel songs in CMM. These results support previous findings suggesting that activation is reduced to learned stimuli; we discuss possible implications of these findings in relation to song production learning early in life and song recognition learning in adulthood.     

Temporal integration of vibrotactile patterns

Three experiments were conducted to measure the temporal integration of vibrotactile patterns presented to the fingertip. In Experiment 1, letters were divided in half and the time between the onsets of the first half of the letter and second half of the letter, stimulus onset asynchrony (SOA), was varied. The recognizability of the letters declined as the SOA was increased from 9 to 100 msec. In Experiment 2, the time between two patterns constituting a masking stimulus was varied and the stimulus effectiveness in interfering with letter recognition was determined. The amount of masking increased as the SOA increased from 9 to 50 msec. In Experiment 3, the SOA between a letter and its complement (the portions of the tactile array not activated by the letter) was varied. Increasing SOA from 9 to approximately 50 msec led to increasingly accurate letter recognition. The results of the three experiments suggest that the skin is capable of complete temporal integration over a time period of less than 10 msec, and that the temporal integration function becomes asymptotic in 50 to 100 msec. The results also suggest that the onset of a vibrotactile pattern is critical for generating contours. The implications of the results for modes of generating tactile patterns and for temporal masking functions are discussed.