Jamshed J. Bharucha

Music Cognition and Perceptual Facilitation: A Connectionist Framework

The mind internalizes persistent structural regularities in music and recruits these internalized representations to facilitate subsequent perception. Facilitation underlies the generation of musical expectations and implications and the influence of a musical context on consonance and memory. Facilitation is demonstrated in experiments showing priming of chords: chords that are harmonically closely related to a preceding context are processed more quickly than chords that are harmonically distant from the context. A tonal context enhances intonational sensitivity for related chords and heightens their consonance. Facilitation occurs even when related chords don9t share component tones with the context, and even when overlapping harmonics are eliminated. These results point to the indirect activation of representational units at a cognitive level. In a parallel study conducted in India, tones considered to play an important role in a rag but absent from the experimental rendition of that rag were facilitated in the same way. In a connectionist framework, facilitation is a consequence of activation spreading through a network of representational units whose pattern of connectivity encodes musical relationships. In a proposed connectionist model of harmony, each event in a musical sequence activates tone units, and activation spreads via connecting links to parent chord units and then to parent key units. Activation reverberates bidirectionally until the network settles into a state of equilibrium. The initial stages of the activation process constitute the bottom-up influence of the sounded tones, while the later, reverberatory stages constitute the top-down influence of learned, schematic structures internalized at the cognitive level. Computer simulations of the model show the same pattern of data as human subjects in experiments on relatedness judgments of chords and memory for chord sequences.

Activation of the inferior frontal cortex in musical priming.

Musical contexts influence the processing of target events. Our study investigated the neural correlates of processing related and unrelated musical events presented as the last chord of eight-chord sequences.

The representation of harmonic structure in music: Hierarchies of stability as a function of context

Abstract The ability to appreciate most Western music presupposes cognitive structures capable of abstracting an underlying harmonic structure from a complex string of musical events. In this paper we provide a description of the listeners knowledge of hierarchies of harmonic stability. The organization of harmonic information may be summarized by six principles. Three of these principles—Key Membership, Intrakey Distance and Intrakey Asymmetry—govern harmonic organization independent of context. Three principles—Contextual Identity, Contextual Distance and Contextual Asymmetry—govern harmonic organization in the presence of a tonal context. Chords that are members of the same key are represented in a hierarchy of stability that is independent of context. Chords from different keys are represented in a hierarchy of stability that is dependent upon the prevailing context. Two different experimental tasks were used to provide convergent evidence for these principles: 1) multidimensional scaling of chords in the absence of any context or in the presence of different tonal contexts, and 2) recognition memory for chords in random and tonal contexts. It is suggested that harmonically stable chords function as cognitive reference points for the system as a whole. The importance of representations of hierarchies of harmonic stability is discussed with respect to generative accounts of musical competence.

Reaction Time and Musical Expectancy: Priming of Chords

The cognitive processes underlying musical expectation were explored by measuring reaction time in a priming paradigm. Subjects made a speeded true/false decision about a target chord following a prime chord to which it was either closely or distantly related harmonically. Using a major/minor decision task in Experiment 1, we found that major targets were identified faster, and with fewer errors, when they were related than when unrelated. An apparent absence (and possible reversal) of this effect for minor targets can be attributed to the primes biasing effect on the targets stability. In Experiments 2 and 3 we tested this hypothesis by employing an in-tune/out-of-tune decision for major and minor targets separately. Both major and minor in-tune targets were identified faster when related than when unrelated. We outline a spreading activation model which consists of a network of harmonic relations. Priming results from the indirect activation of chord nodes linked through the network.

Judged displacement in apparent vertical and horizontal motion

The judged vanishing point of a target traveling along a vertical or horizontal trajectory at uniform velocity was examined. In Experiments 1 and 2, subjects indicated the vanishing point by positioning a cross hair. Judged vanishing point was displaced forward in the direction of motion, and the magnitude of the displacement increased with the apparent velocity of the target. Displacement was greater for horizontal than for vertical motion. In Experiment 3, similar patterns were found using a forced-choice paradigm. Experiments 4 and 5 assessed the role of knowledge of the target’s likely behavior. In Experiment 4, the target bounced within the confines of a square frame. Judged vanishing point was displaced in the anticipated direction, even 9 when the anticipated direction was opposite to the current path of motion. Experiment 5 was a control experiment that ruled out the presence of the frame as the sole cause for displacement. The results suggest that displacement from the true vanishing point is due to a high-level cognitive mechanism capable of utilizing knowledge about probable target location.

Tonal Hierarchies in the Music of North India

Cross-culturally, most music is tonal in the sense that one particular tone, called the tonic, provides a focus around which the other tones are organized. The specific organizational structures around the tonic show considerable diversity. Previous studies of the perceptual response to Western tonal music have shown that listeners familiar with this musical tradition have internalized a great deal about its underlying organization. Krumhansl and Shepard (1979) developed a probe tone method for quantifying the perceived hierarchy of stability of tones. When applied to Western tonal contexts, the measured hierarchies were found to be consistent with music-theoretic accounts. In the present study, the probe tone method was used to quantify the perceived hierarchy of tones of North Indian music. Indian music is tonal and has many features in common with Western music. One of the most significant differences is that the primary means of expressing tonality in Indian music is through melody, whereas in Western music it is through harmony (the use of chords). Indian music is based on a standard set of melodic forms (called rags), which are themselves built on a large set of scales (thats). The tones within a rag are thought to be organized in a hierarchy of importance. Probe tone ratings were given by Indian and Western listeners in the context of 10 North Indian rags. These ratings confirmed the predicted hierarchical ordering. Both groups of listeners gave the highest ratings to the tonic and the fifth degree of the scale. These tones are considered by Indian music theorists to be structurally significant, as they are immovable tones around which the scale system is constructed, and they are sounded continuously in the drone. Relatively high ratings were also given to the vadi tone, which is designated for each rag and is given emphasis in the melody. The ratings of both groups of listeners generally reflected the pattern of tone durations in the musical contexts. This result suggests that the distribution of tones in music is a psychologically effective means of conveying the tonal hierarchy to listeners whether they are familiar with the musical tradition. Beyond this, only the Indian listeners were sensitive to the scales (thats) underlying the rags. For Indian listeners, multidimensional scaling of the correlations between the rating profiles recovered the theoretical representation of scales described by theorists of Indian music.(ABSTRACT TRUNCATED AT 400 WORDS)

Anchoring effects in music: The resolution of dissonance ☆

Abstract Most pieces of music induce in the listener a sense that some pitches sound consonant, stable, or final, while others sound more dissonant, unstable, or transient. A psychological account of the intuition that the dissonance of an unstable tone is sometimes “resolved” by following it by a stable tone that is close in pitch is provided. The perceived hierarchy differentiating tones on the basis of stability may be construed as a cognitive schema, which facilitates the encoding of some tones relative to others. A cognitive principle, melodic anchoring, which specifies the ordered relationships (between tones) that govern (i) the activation of one tonal schema over another and (ii) the assimilation or anchoring of unstable tones to the tonal schema once it has been activated is presented. In a forcedchoice paradigm, the principle is invoked to predict which chord is perceived to “underlie” a sequence that is tonally ambiguous in all respects except the ordered relationships between its tones. In a same-different task, subjects were presented with a pair of tonal sequences. When a stable tone was replaced by an unstable tone, more confusions occurred when the latter was anchored than when it was not. The accuracy advantage when the unstable tone was in the comparison as opposed to the standard sequence was lower when the unstable tone was anchored than when it was not. Finally, subjects rated how well a sequence and a chord sounded together. Melodies that contained an unstable tone were given higher ratings when the unstable tone was anchored than when it was not. Each paradigm was used to demonstrate first immediate and then delayed anchoring.

Listening to polyphonic music recruits domain-general attention and working memory circuits

Polyphonic music combines multiple auditory streams to create complex auditory scenes, thus providing a tool for investigating the neural mechanisms that orient attention in natural auditory contexts. Across two fMRI experiments, we varied stimuli and task demands in order to identify the cortical areas that are activated during attentive listening to real music. In individual experiments and in a conjunction analysis of the two experiments, we found bilateral blood oxygen level dependent (BOLD) signal increases in temporal (the superior temporal gyrus), parietal (the intraparietal sulcus), and frontal (the precentral sulcus, the inferior frontal sulcus and gyrus, and the frontal operculum) areas during selective and global listening, as compared with passive rest without musical stimulation. Direct comparisons of the listening conditions showed significant differences between attending to single timbres (instruments) and attending across multiple instruments, although the patterns that were observed depended on the relative demands of the tasks being compared. The overall pattern of BOLD signal increases indicated that attentive listening to music recruits neural circuits underlying multiple forms of working memory, attention, semantic processing, target detection, and motor imagery. Thus, attentive listening to music appears to be enabled by areas that serve general functions, rather than by music-specific cortical modules.

Priming of chords: Spreading activation or overlapping frequency spectra?

A chord generates expectancies for related chords to follow. Expectancies can be studied by measuring the time to discriminate between a target chord and a mistuned foil as a function of the target’s relatedness to a preceding prime chord. This priming paradigm has been employed to demonstrate that related targets are processed more quickly and are perceived to be more consonant than are unrelated targets (Bharucha & Stoeckig, 1986). The priming experiments in the present paper were designed to determine whether expectancies are generated at a cognitive level, by activation spreading through a network that represents harmonic relationships, or solely at a sensory level, by the activation of frequency-specific units. In Experiment 1, prime-target pairs shared no component tones, but related pairs had overlapping frequency spectra. In Experiment 2, all overlapping frequency components were eliminated. Priming was equally strong in both experiments. We conclude that frequency-specific repetition priming cannot account for expectancies in harmony, suggesting that activation spreads at a cognitive level of representation.

Perceived Harmonic Structure of Chords in Three Related Musical Keys.

Harvard UniversityThis study investigated the perceived harmonic relationships between the chordsthat belong to three closely related musical keys: a major key, the major keybuilt on its dominant, and the relative minor key. Multidimensional scaling andhierarchical clustering techniques applied to judgments of two-chord progressionsshowed a central core consisting of those chords that play primary harmonicfunctions in the three keys. Th& separation of chords unique to the keys and themultiple functions of chords shared by the different keys were simultaneouslyrepresented. A regular pattern of asymmetries was also found that suggests ahierarchy among different types of chords. In addition, there was a preferencefor sequences ending on chords central to the prevailing tonality. Comparisonwith earlier results on single tones points to differences between melodic andharmonic organization.