Infant music perception: domain-general or domain-specific mechanisms?

Integration of auditory and tactile inputs in musical meter perception

Musicians often say that they not only hear but also "feel" music. To explore the contribution of tactile information to "feeling" music, we investigated the degree that auditory and tactile inputs are integrated in humans performing a musical meter-recognition task. Subjects discriminated between two types of sequences, "duple" (march-like rhythms) and "triple" (waltz-like rhythms), presented in three conditions: (1) unimodal inputs (auditory or tactile alone); (2) various combinations of bimodal inputs, where sequences were distributed between the auditory and tactile channels such that a single channel did not produce coherent meter percepts; and (3) bimodal inputs where the two channels contained congruent or incongruent meter cues. We first show that meter is perceived similarly well (70-85 %) when tactile or auditory cues are presented alone. We next show in the bimodal experiments that auditory and tactile cues are integrated to produce coherent meter percepts. Performance is high (70-90 %) when all of the metrically important notes are assigned to one channel and is reduced to 60 % when half of these notes are assigned to one channel. When the important notes are presented simultaneously to both channels, congruent cues enhance meter recognition (90 %). Performance dropped dramatically when subjects were presented with incongruent auditory cues (10 %), as opposed to incongruent tactile cues (60 %), demonstrating that auditory input dominates meter perception. These observations support the notion that meter perception is a cross-modal percept with tactile inputs underlying the perception of "feeling" music.

Music and movement share a dynamic structure that supports universal expressions of emotion

Music moves us. Its kinetic power is the foundation of human behaviors as diverse as dance, romance, lullabies, and the military march. Despite its significance, the music-movement relationship is poorly understood. We present an empirical method for testing whether music and movement share a common structure that affords equivalent and universal emotional expressions. Our method uses a computer program that can generate matching examples of music and movement from a single set of features: rate, jitter (regularity of rate), direction, step size, and dissonance/visual spikiness. We applied our method in two experiments, one in the United States and another in an isolated tribal village in Cambodia. These experiments revealed three things: (i) each emotion was represented by a unique combination of features, (ii) each combination expressed the same emotion in both music and movement, and (iii) this common structure between music and movement was evident within and across cultures.

Feeling music: integration of auditory and tactile inputs in musical meter perception

Musicians often say that they not only hear, but also "feel" music. To explore the contribution of tactile information in "feeling" musical rhythm, we investigated the degree that auditory and tactile inputs are integrated in humans performing a musical meter recognition task. Subjects discriminated between two types of sequences, 'duple' (march-like rhythms) and 'triple' (waltz-like rhythms) presented in three conditions: 1) Unimodal inputs (auditory or tactile alone), 2) Various combinations of bimodal inputs, where sequences were distributed between the auditory and tactile channels such that a single channel did not produce coherent meter percepts, and 3) Simultaneously presented bimodal inputs where the two channels contained congruent or incongruent meter cues. We first show that meter is perceived similarly well (70%-85%) when tactile or auditory cues are presented alone. We next show in the bimodal experiments that auditory and tactile cues are integrated to produce coherent meter percepts. Performance is high (70%-90%) when all of the metrically important notes are assigned to one channel and is reduced to 60% when half of these notes are assigned to one channel. When the important notes are presented simultaneously to both channels, congruent cues enhance meter recognition (90%). Performance drops dramatically when subjects were presented with incongruent auditory cues (10%), as opposed to incongruent tactile cues (60%), demonstrating that auditory input dominates meter perception. We believe that these results are the first demonstration of cross-modal sensory grouping between any two senses.

Amusia results in abnormal brain activity following inappropriate intonation during speech comprehension

Pitch processing is a critical ability on which humans’ tonal musical experience depends, and which is also of paramount importance for decoding prosody in speech. Congenital amusia refers to deficits in the ability to properly process musical pitch, and recent evidence has suggested that this musical pitch disorder may impact upon the processing of speech sounds. Here we present the first electrophysiological evidence demonstrating that individuals with amusia who speak Mandarin Chinese are impaired in classifying prosody as appropriate or inappropriate during a speech comprehension task. When presented with inappropriate prosody stimuli, control participants elicited a larger P600 and smaller N100 relative to the appropriate condition. In contrast, amusics did not show significant differences between the appropriate and inappropriate conditions in either the N100 or the P600 component. This provides further evidence that the pitch perception deficits associated with amusia may also affect intonation processing during speech comprehension in those who speak a tonal language such as Mandarin, and suggests music and language share some cognitive and neural resources.

Cognition and the evolution of music: pitfalls and prospects

What was the role of music in the evolutionary history of human beings? We address this question from the point of view that musicality can be defined as a cognitive trait. Although it has been argued that we will never know how cognitive traits evolved (Lewontin, 1998), we argue that we may know the evolution of music by investigating the fundamental cognitive mechanisms of musicality, for example, relative pitch, tonal encoding of pitch, and beat induction. In addition, we show that a nomological network of evidence (Schmitt & Pilcher, 2004) can be built around the hypothesis that musicality is a cognitive adaptation. Within this network, different modes of evidence are gathered to support a specific evolutionary hypothesis. We show that the combination of psychological, medical, physiological, genetic, phylogenetic, hunter-gatherer, and cross-cultural evidence indicates that musicality is a cognitive adaptation.

Without it no music: beat induction as a fundamental musical trait

Beat induction (BI) is the cognitive skill that allows us to hear a regular pulse in music to which we can then synchronize. Perceiving this regularity in music allows us to dance and make music together. As such, it can be considered a fundamental musical trait that, arguably, played a decisive role in the origins of music. Furthermore, BI might be considered a spontaneously developing, domain-specific, and species-specific skill. Although both learning and perception/action coupling were shown to be relevant in its development, at least one study showed that the auditory system of a newborn is able to detect the periodicities induced by a varying rhythm. A related study with adults suggested that hierarchical representations for rhythms (meter induction) are formed automatically in the human auditory system. We will reconsider these empirical findings in the light of the question whether beat and meter induction are fundamental cognitive mechanisms.

Behavioral methods in infancy: pitfalls of single measures

This paper outlines the principal behavioral methods used to study music processing in infancy. The advantages of conditioning procedures are offset by high attrition rates and restrictions on the stimuli that can be used. The head-turn preference procedure is more user-friendly but poses greater interpretive challenges. In view of the multidimensional nature of infant attention, no single response measure, whether behavioral, physiological, or neural, can provide unambiguous information about music processing in infancy. Greater use of ecologically valid stimuli is likely to generate increased cooperation from infants and greater generality of the findings.

Effects of culture on musical pitch perception

The strong association between music and speech has been supported by recent research focusing on musicians' superior abilities in second language learning and neural encoding of foreign speech sounds. However, evidence for a double association—the influence of linguistic background on music pitch processing and disorders—remains elusive. Because languages differ in their usage of elements (e.g., pitch) that are also essential for music, a unique opportunity for examining such language-to-music associations comes from a cross-cultural (linguistic) comparison of congenital amusia, a neurogenetic disorder affecting the music (pitch and rhythm) processing of about 5% of the Western population. In the present study, two populations (Hong Kong and Canada) were compared. One spoke a tone language in which differences in voice pitch correspond to differences in word meaning (in Hong Kong Cantonese, /si/ means ‘teacher’ and ‘to try’ when spoken in a high and mid pitch pattern, respectively). Using the On-line Identification Test of Congenital Amusia, we found Cantonese speakers as a group tend to show enhanced pitch perception ability compared to speakers of Canadian French and English (non-tone languages). This enhanced ability occurs in the absence of differences in rhythmic perception and persists even after relevant factors such as musical background and age were controlled. Following a common definition of amusia (5% of the population), we found Hong Kong pitch amusics also show enhanced pitch abilities relative to their Canadian counterparts. These findings not only provide critical evidence for a double association of music and speech, but also argue for the reconceptualization of communicative disorders within a cultural framework. Along with recent studies documenting cultural differences in visual perception, our auditory evidence challenges the common assumption of universality of basic mental processes and speaks to the domain generality of culture-to-perception influences.

Rhythm evokes action: early processing of metric deviances in expressive music by experts and laymen revealed by ERP source imaging

To examine how musical expertise tunes the brain to subtle metric anomalies in an ecological musical context, we presented piano compositions ending on standard and deviant cadences (endings) to expert pianists and musical laymen, while high-density EEG was recorded. Temporal expectancies were manipulated by substituting standard "masculine" cadences at metrically strong positions with deviant, metrically unaccented, "feminine" cadences. Experts detected metrically deviant cadences better than laymen. Analyses of event-related potentials demonstrated that an early P3a-like component (~150-300 ms), elicited by musical closure, was significantly enhanced at frontal and parietal electrodes in response to deviant endings in experts, whereas a reduced response to deviance occurred in laymen. Putative neuronal sources contributing to the modulation of this component were localized in a network of brain regions including bilateral supplementary motor areas, middle and posterior cingulate cortex, precuneus, associative visual areas, as well as in the right amygdala and insula. In all these regions, experts showed enhanced responses to metric deviance. Later effects demonstrated enhanced activations within the same brain network, as well as higher processing speed for experts. These results suggest that early brain responses to metric deviance in experts may rely on motor representations mediated by the supplementary motor area and motor cingulate regions, in addition to areas involved in self-referential imagery and relevance detection. Such motor representations could play a role in temporal sensory prediction evolved from musical training and suggests that rhythm evokes action more strongly in highly trained instrumentalists.

Audiotactile interactions in temporal perception

In the present review, we focus on how commonalities in the ontogenetic development of the auditory and tactile sensory systems may inform the interplay between these signals in the temporal domain. In particular, we describe the results of behavioral studies that have investigated temporal resolution (in temporal order, synchrony/asynchrony, and simultaneity judgment tasks), as well as temporal numerosity perception, and similarities in the perception of frequency across touch and hearing. The evidence reviewed here highlights features of audiotactile temporal perception that are distinctive from those seen for other pairings of sensory modalities. For instance, audiotactile interactions are characterized in certain tasks (e.g., temporal numerosity judgments) by a more balanced reciprocal influence than are other modality pairings. Moreover, relative spatial position plays a different role in the temporal order and temporal recalibration processes for audiotactile stimulus pairings than for other modality pairings. The effect exerted by both the spatial arrangement of stimuli and attention on temporal order judgments is described. Moreover, a number of audiotactile interactions occurring during sensory-motor synchronization are highlighted. We also look at the audiotactile perception of rhythm and how it may be affected by musical training. The differences emerging from this body of research highlight the need for more extensive investigation into audiotactile temporal interactions. We conclude with a brief overview of some of the key issues deserving of further research in this area.

Auditory-nerve responses predict pitch attributes related to musical consonance-dissonance for normal and impaired hearing

Human listeners prefer consonant over dissonant musical intervals and the perceived contrast between these classes is reduced with cochlear hearing loss. Population-level activity of normal and impaired model auditory-nerve (AN) fibers was examined to determine (1) if peripheral auditory neurons exhibit correlates of consonance and dissonance and (2) if the reduced perceptual difference between these qualities observed for hearing-impaired listeners can be explained by impaired AN responses. In addition, acoustical correlates of consonance-dissonance were also explored including periodicity and roughness. Among the chromatic pitch combinations of music, consonant intervals/chords yielded more robust neural pitch-salience magnitudes (determined by harmonicity/periodicity) than dissonant intervals/chords. In addition, AN pitch-salience magnitudes correctly predicted the ordering of hierarchical pitch and chordal sonorities described by Western music theory. Cochlear hearing impairment compressed pitch salience estimates between consonant and dissonant pitch relationships. The reduction in contrast of neural responses following cochlear hearing loss may explain the inability of hearing-impaired listeners to distinguish musical qualia as clearly as normal-hearing individuals. Of the neural and acoustic correlates explored, AN pitch salience was the best predictor of behavioral data. Results ultimately show that basic pitch relationships governing music are already present in initial stages of neural processing at the AN level.

Functional development in the infant brain for auditory pitch processing

Understanding how the developing brain processes auditory information is a critical step toward the clarification of infants' perception of speech and music. We have reported that the infant brain perceives pitch information in speech sounds. Here, we used multichannel near-infrared spectroscopy to examine whether the infant brain is sensitive to information of pitch changes in auditory sequences. Three types of auditory sequences with distinct temporal structures of pitch changes were presented to 3- and 6-month-old infants: a long condition of 12 successive tones constructing a chromatic scale (600 ms), a short condition of four successive tones constructing a chromatic scale (200 ms), and a random condition of random tone sequences (50 ms per tone). The difference among the conditions was only in the sequential order of the tones, which causes pitch changes between the successive tones. We found that the bilateral temporal regions of both ages of infants showed significant activation under the three conditions. The stimulus-dependent activation was observed in the right temporoparietal region of the both infant groups; the 3- and 6-month-old infants showed the most prominent activation under the random and short conditions, respectively. Our findings indicate that the infant brain, which shows functional differentiation and lateralization in auditory-related areas, is capable of responding to more than single tones of pitch information. These results suggest that the right temporoparietal region of the infants increases sensitivity to auditory sequences, which have temporal structures similar to those of syllables in speech sounds, in the course of development.

Apparent motion enhances visual rhythm discrimination in infancy

Many studies have demonstrated that infants exhibit robust auditory rhythm discrimination, but research on infants' perception of visual rhythm is limited. In particular, the role of motion in infants' perception of visual rhythm remains unknown, despite the prevalence of motion cues in naturally occurring visual rhythms. In the present study, we examined the role of motion in 7-month-old infants' discrimination of visual rhythms by comparing experimental conditions with apparent motion in the stimuli versus stationary rhythmic stimuli. Infants succeeded at discriminating visual rhythms only when the visual rhythm occurred with an apparent motion component. These results support the view that motion plays a role in infants' perception of visual temporal information, consistent with the manner in which natural rhythms appear in the visual world.

Association of the arginine vasopressin receptor 1A (AVPR1A) haplotypes with listening to music

Music is listened in all cultures. We hypothesize that willingness to produce and perceive sound and music is social communication that needs musical aptitude. Here, listening to music was surveyed using a web-based questionnaire and musical aptitude using the auditory structuring ability test (Karma Music test) and Carl Seashores tests for pitch and for time. Three highly polymorphic microsatellite markers (RS3, RS1 and AVR) of the arginine vasopressin receptor 1A (AVPR1A) gene, previously associated with social communication and attachment, were genotyped and analyzed in 31 Finnish families (n=437 members) using family-based association analysis. A positive association between the AVPR1A haplotype (RS1 and AVR) and active current listening to music (permuted P=0.0019) was observed. Other AVPR1A haplotype (RS3 and AVR) showed association with lifelong active listening to music (permuted P=0.0022). In addition to AVPR1A, two polymorphisms (5-HTTLPR and variable number of tandem repeat) of human serotonin transporter gene (SLC6A4), a candidate gene for many neuropsychiatric disorders and previously associated with emotional processing, were analyzed. No association between listening to music and the polymorphisms of SLC6A4 were detected. The results suggest that willingness to listen to music is related to neurobiological pathways affecting social affiliation and communication.

Identification of Changes along a Continuum of Speech Intonation is Impaired in Congenital Amusia

A small number of individuals have severe musical problems that have neuro-genetic underpinnings. This musical disorder is termed "congenital amusia," an umbrella term for lifelong musical disabilities that cannot be attributed to deafness, lack of exposure, or brain damage after birth. Amusics seem to lack the ability to detect fine pitch differences in tone sequences. However, differences between statements and questions, which vary in final pitch, are well perceived by most congenital amusic individuals. We hypothesized that the origin of this apparent domain-specificity of the disorder lies in the range of pitch variations, which are very coarse in speech as compared to music. Here, we tested this hypothesis by using a continuum of gradually increasing final pitch in both speech and tone sequences. To this aim, nine amusic cases and nine matched controls were presented with statements and questions that varied on a pitch continuum from falling to rising in 11 steps. The sentences were either naturally spoken or were tone sequence versions of these. The task was to categorize the sentences as statements or questions and the tone sequences as falling or rising. In each case, the observation of an S-shaped identification function indicates that amusics can accurately identify unambiguous examples of statements and questions but have problems with fine variations between these endpoints. Thus, the results indicate that a deficient pitch perception might compromise music, not because it is specialized for that domain but because music requirements are more fine-grained.

Free will debates: Simple experiments are not so simple

The notion that free will is an illusion has achieved such wide acceptance among philosophers and neuroscientists that it seems to be acquiring the status of dogma. Nonetheless, research in this area continues, and this review offers a new analysis of the design limitations and data interpretations of free-will experiments. This review presents 12 categories of questionable conclusions that some scholars use to promote the idea that free will is an illusion. The next generation of less ambiguous experiments is proposed.

Do ferrets perceive relative pitch?

The existence of relative pitch perception in animals is difficult to demonstrate, since unlike humans, animals often attend to absolute rather than relative properties of sound elements. However, the results of the present study show that ferrets can be trained using relative pitch to discriminate two-tone sequences (rising vs. falling). Three ferrets were trained using a positive-reinforcement paradigm in which sequences of reference (one to five repeats) and target stimuli were presented, and animals were rewarded only when responding correctly to the target. The training procedure consisted of three training phases that successively shaped the ferrets to attend to relative pitch. In Phase-1 training, animals learned the basic task with sequences of invariant tone-pairs and could use absolute pitch information. During Phase-2 training, in order to emphasize relative cues, absolute pitch was varied each trial within a two-octave frequency range. In Phase-3 training, absolute pitch cues were removed, and only relative cue information was available to solve the task. Two ferrets successfully completed training on all three phases and achieved significant discriminative performance over the trained four-octave frequency range. These results suggest that ferrets can be trained to discern the relative pitch relationship of a sequence of tone-pairs independent of frequency.

Aesthetic judgments of music in experts and laypersons--an ERP study

We investigated whether music experts and laypersons differ with regard to aesthetic evaluation of musical sequences. 16 music experts and 16 music laypersons judged the aesthetic value (beauty judgment task) as well as the harmonic correctness (correctness judgment task) of chord sequences. The sequences consisted of five chords with the final chord sounding congruous, ambiguous or incongruous relative to the harmonic context established by the preceding four chords. On behavioural measures, few differences were observed between experts and laypersons. However, several differences in event-related potential (ERP) parameters were observed in auditory, cognitive and aesthetic processing of chord cadences between experts and laypersons. First, established ERP effects known to reflect the processing of harmonic rule violation were investigated. Here, differences between the groups were observed in the processing of the mild violation - experts and laypersons differed in their early brain responses to the beginning of the chord sequence. Furthermore, ERP data indicated distinctions between experts and laypersons in aesthetic evaluation at three different stages. Firstly, during the interval of task-cue presentation, a stronger contingent negative variation (CNV) to the beauty judgment task was observed for experts, indicating that experts invest more effort into preparation for aesthetic processes than into correctness judgments. Secondly, during the first four chords, preparation for the correctness judgment required more exertion on the laypersons' side. Thirdly, during the last chord, laypersons showed a larger late and widespread positivity for the beauty compared to the correctness judgment, indicating a stronger reliance on internal affective states while forming a judgment.

Phonological Knowledge Guides Two-year-olds' and Adults' Interpretation of Salient Pitch Contours in Word Learning

Phonology provides a system by which a limited number of types of phonetic variation can signal communicative intentions at multiple levels of linguistic analysis. Because phonologies vary from language to language, acquiring the phonology of a language demands learning to attribute phonetic variation appropriately. Here, we studied the case of pitch-contour variation. In English, pitch contour does not differentiate words, but serves other functions, like marking yes/no questions and conveying emotions. We show that, in accordance with their phonology, English-speaking adults and two-year-olds do not interpret salient pitch contours as inherent to novel words. We taught participants a new word with consistent segmental and pitch characteristics, and then tested word recognition for trained and deviant pronunciations using an eyegaze-based procedure. Vowel-quality mispronunciations impaired recognition, but large changes in pitch contour did not. By age two, children already apply their knowledge of English phonology to interpret phonetic consistencies in their experience with words.

Chimpanzee faces are 'special' to humans

A longstanding proposal is that primates, including humans, might have an innate representation of face structure. But, if humans have such a representation, how broad is its form: limited to coding conspecifics, or general enough to cover related species? The results reported here show adult humans process faces of chimpanzees in a way previously assumed to be exclusive to human faces. The composite effect was used to provide the first direct test of so-called holistic processing. Despite no lifetime experience of chimpanzees, adult humans showed a substantial composite effect for chimpanzee faces, and also an inversion effect. There was no similar evidence of holistic processing for faces of species of greater phylogenic distance from humans, including gorillas, spider monkeys, sheep, chickens, and Jacky lizards; nor was there any effect for non-face objects. In contrast to the holistic processing results, discrimination of chimpanzee faces was, as expected, poor. In the context of evidence that poor discrimination of heterospecific faces arises from a process of perceptual narrowing in infancy, our results suggest that adults retain some aspects of a broader bandwidth present in neonates (holistic processing) but lose others (discrimination).

Neural correlates of consonance, dissonance, and the hierarchy of musical pitch in the human brainstem

Consonant and dissonant pitch relationships in music provide the foundation of melody and harmony, the building blocks of Western tonal music. We hypothesized that phase-locked neural activity within the brainstem may preserve information relevant to these important perceptual attributes of music. To this end, we measured brainstem frequency-following responses (FFRs) from nonmusicians in response to the dichotic presentation of nine musical intervals that varied in their degree of consonance and dissonance. Neural pitch salience was computed for each response using temporally based autocorrelation and harmonic pitch sieve analyses. Brainstem responses to consonant intervals were more robust and yielded stronger pitch salience than those to dissonant intervals. In addition, the ordering of neural pitch salience across musical intervals followed the hierarchical arrangement of pitch stipulated by Western music theory. Finally, pitch salience derived from neural data showed high correspondence with behavioral consonance judgments (r = 0.81). These results suggest that brainstem neural mechanisms mediating pitch processing show preferential encoding of consonant musical relationships and, furthermore, preserve the hierarchical pitch relationships found in music, even for individuals without formal musical training. We infer that the basic pitch relationships governing music may be rooted in low-level sensory processing and that an encoding scheme that favors consonant pitch relationships may be one reason why such intervals are preferred behaviorally.

Infants detect cross-modal cues to identity in speech and singing

Little is known about infants' perception of cross-modal cues to identity, but the importance of recognizing familiar individuals makes it likely that this skill would be evident early in life. Infants 6-8 months of age were tested on their ability to link dynamic cross-modal cues to the identity of unfamiliar speakers and singers. After exposure to speech or singing, infants watched two silent videos, one featuring the previously heard speaker or singer. Infants looked significantly longer at the video of the person heard previously, which indicates that they can match auditory and visual cues to the identity of unfamiliar persons.

What Can Experiments Reveal About the Origins of Music?

The origins of music have intrigued scholars for thousands of years. In this article I discuss the role of experiments in discussions of these issues. I argue that potentially useful kinds of evidence are those that address the innateness and the specificity of different components of musical behavior. At present there is some evidence for innate influences on music, but little evidence for capacities that are clearly specific to music. Although future experiments could potentially alter this picture, there is currently little unambiguous support for the notion that music is an adaptation.

The neurocognitive components of pitch processing: insights from absolute pitch

The natural variability of pitch naming ability in the population (known as absolute pitch or AP) provides an ideal method for investigating individual differences in pitch processing and auditory knowledge formation and representation. We have demonstrated the involvement of different cognitive processes in AP ability that reflects varying skill expertise in the presence of similar early age of onset of music tuition. These processes were related to different regions of brain activity, including those involved in pitch working memory (right prefrontal cortex) and the long-term representation of pitch (superior temporal gyrus). They reflected expertise through the use of context dependent pitch cues and the level of automaticity of pitch naming. They impart functional significance to structural asymmetry differences in the planum temporale of musicians and establish a neurobiological basis for an AP template. More generally, they indicate variability of knowledge representation in the presence of environmental fostering of early cognitive development that translates to differences in cognitive ability.

Early electrophysiological correlates of meter and rhythm processing in music perception

The two main characteristics of temporal structuring in music are meter and rhythm. The present experiment investigated the event-related potentials (ERP) of these two structural elements with a focus on differential effects of attended and unattended processing. The stimulus material consisted of an auditory rhythm presented repetitively to subjects in which metrical and rhythmical changes as well as pitch changes were inserted. Subjects were to detect and categorize either temporal changes (attended condition) or pitch changes (unattended condition). Furthermore, we compared a group of long-term trained subjects (musicians) to non-musicians. As expected, behavioural data revealed that trained subjects performed significantly better than untrained subjects. This effect was mainly due to the better detection of the meter deviants. Rhythm as well as meter changes elicited an early negative deflection compared to standard tones in the attended processing condition, while in the unattended processing condition only the rhythm change elicited this negative deflection. Both effects were found across all experimental subjects with no difference between the two groups. Thus, our data suggest that meter and rhythm perception could differ with respect to the time course of processing and lend credence to the notion of different neurophysiological processes underlying the auditory perception of rhythm and meter in music. Furthermore, the data indicate that non-musicians are as proficient as musicians when it comes to rhythm perception, suggesting that correct rhythm perception is crucial not only for musicians but for every individual.

On the role and origin of isochrony in human rhythmic entrainment

Wherever human beings live, and however they may organise their affairs, they gather from time to time to sing and dance together, often in a ritual setting. In doing so they synchronise their voices and bodily movements to a shared, repeating interval of time, the musical pulse, beat or tactus. We take this capacity to "entrain" to an evenly paced stimulus (isochrony) so much for granted that it may come as a surprise to learn that from a biological point of view such behaviour is exceptional. But it is not altogether unique. There are a number of other species, none of them closely related to humans, that also engage in group synchrony of behaviour through entrainment to an isochronous pulse. Despite their evolutionary distance from us their life circumstances throw an interesting light on the possible origin and nature of our own entrainment capacity. Here we consider this capacity in terms of its possible origin, functional mechanisms, and ontogenetic development.

Evidence of beat perception via purely tactile stimulation

Humans can easily tap in synchrony with an auditory beat but not with an equivalent visual rhythmic sequence, suggesting that the sensation of meter (i.e. of an underlying regular pulse) may be inherently auditory. We assessed whether the perception of meter could also be felt with tactile sensory inputs. We found that, when participants were presented with identical rhythmic sequences filled with either short tones or hand stimulations, they could more efficiently tap in synchrony with strongly rather than weakly metric sequences. These observations suggest that non-musician adults can extract the metric structure of purely tactile rhythms and use it to tap regularly with the beat induced by such sequences. This finding represents a challenge for present models of rhythm processing.

Genome-wide linkage scan for loci of musical aptitude in Finnish families: evidence for a major locus at 4q22

Background:

Music perception and performance are comprehensive human cognitive functions and thus provide an excellent model system for studying human behaviour and brain function. However, the molecules involved in mediating music perception and performance are so far uncharacterised.

Objective:

To unravel the biological background of music perception, using molecular and statistical genetic approaches.

Methods: 15 Finnish multigenerational families (with a total of 234 family members) were recruited via a nationwide search. The phenotype of all family members was determined using three tests used in defining musical aptitude: a test for auditory structuring ability (Karma Music test; KMT) commonly used in Finland, and the Seashore pitch and time discrimination subtests (SP and ST respectively) used internationally. We calculated heritabilities and performed a genome-wide variance components-based linkage scan using genotype data for 1113 microsatellite markers.

Results:

The heritability estimates were 42% for KMT, 57% for SP, 21% for ST and 48% for the combined music test scores. Significant evidence of linkage was obtained on chromosome 4q22 (LOD 3.33) and suggestive evidence of linkage at 8q13-21 (LOD 2.29) with the combined music test scores, using variance component linkage analyses. The major contribution of the 4q22 locus was obtained for the KMT (LOD 2.91). Interestingly, a positive LOD score of 1.69 was shown at 18q, a region previously linked to dyslexia (DYX6) using combined music test scores.

Conclusion:

Our results show that there is a genetic contribution to musical aptitude that is likely to be regulated by several predisposing genes or variants.

The capacity for music: What is it, and what’s special about it?

We explore the capacity for music in terms of five questions: (1) What cognitive structures are invoked by music? (2) What are the principles that create these structures? (3) How do listeners acquire these principles? (4) What pre-existing resources make such acquisition possible? (5) Which aspects of these resources are specific to music, and which are more general? We examine these issues by looking at the major components of musical organization: rhythm (an interaction of grouping and meter), tonal organization (the structure of melody and harmony), and affect (the interaction of music with emotion). Each domain reveals a combination of cognitively general phenomena, such as gestalt grouping principles, harmonic roughness, and stream segregation, with phenomena that appear special to music and language, such as metrical organization. These are subtly interwoven with a residue of components that are devoted specifically to music, such as the structure of tonal systems and the contours of melodic tension and relaxation that depend on tonality. In the domain of affect, these components are especially tangled, involving the interaction of such varied factors as general-purpose aesthetic framing, communication of affect by tone of voice, and the musically specific way that tonal pitch contours evoke patterns of posture and gesture.