The Spatial Properties of Music Perception: Differences in Visuo-spatial Performance According to Musicianship and Interference of Musical Structure

Spatial cognition has been implicated in the perception and production of music within both behavioral and neurological experimental paradigms. Using performance on mental rotation of a three-dimensional object, the present study examined the visuo-spatial abilities of conservatory and non-conservatory students. Participants performed the rotation task under no distraction followed by performance with an interference task, which consisted of detecting either tempo or pitch changes. Conservatory students performed better on the mental rotation task both with and without interference. Musical structure (Western classical versus Indian classical) and musical aspect (tempo changes and pitch changes) influenced how much interference was produced in the mental rotation task. The results confirm the relation between music cognition and spatial cognition with the complexity introduced by the musical structure itself. THE SPATIAL PROPERTIES OF MUSIC PERCEPTION 3 The Spatial Properties of Music Perception: Differences in Visuo-spatial Ability According to Musicianship and Interference of Musical Structure Take a moment to close your eyes while imagining humming your favorite tune. As the melody progresses, where are the notes? Left, right, down, or up? Most people represent music as high or low, up or down, even though there is nothing spatially higher or lower in the composition of sound frequencies. Foster and Zatorre (2010) assert that just as we ascribe spatial qualities to visual stimuli and its parameters, we assign these same spatial qualities to the relations between musical properties. Our tendency to represent pitches on a spatial dimension raises a question regarding the type of cognition that is involved in representing music and how it might extend beyond the auditory dimension. Perhaps the same cognitive mechanisms involved with spatial representations are employed in the perception and manipulation of musical information. The present study examined whether processing music would interfere with a person’s ability to concurrently process visual-spatial information. Additionally, the present study addressed whether conservatory and non-conservatory differ in their visual-spatial abilities and their abilities to concurrently process visual-spatial information and music. The connection between musical ability, musical cognition, and spatial cognition has been demonstrated across several paradigms. Zatorre, Perry, Backett, Westbury, and Evans (1998) showed that the right inferior frontal cortex was activated in musicians who were relative pitch possessors, but not those who were identified as absolute pitch possessors. Perhaps the relative pitch possessors were establishing a degree of spatial distance between the two pitches, a task that presumably requires spatial cognitive resources, thus activating an area of the brain associated with the processing of visual images. Absolute pitch possessors were not using their THE SPATIAL PROPERTIES OF MUSIC PERCEPTION 4 visual-spatial working memory, as shown by their fMRI scans – instead their left posterior dorsalateral frontal cortex was activated when asked what a given pitch was in terms of notation, which is a region of the brain associated with making conditional verbal responses. The spatial representation of musical pitch is not limited to musicians. Rusconi, Kwan, Giordano, and Umilità (2006) demonstrated that both musicians and non-musicians responded faster and more accurately to decide which of two instruments played a higher pitched note when the mapping of the response to that instrument was higher on the response keyboard. For example, participants were faster (and more accurate) to identify that the marimba played a higher note than the french horn when the button representing the marimba was higher on the keyboard than the button representing the french horn. Everyone seems to be spatially mapping musical pitch onto the visual world, otherwise it would not matter whether the higher musical pitch was on a higher key or the lower musical pitch was on a lower key. Douglas and Bilkey (2007) demonstrated further support for the spatial representation of music with a mental rotation paradigm. Their participants exhibited impairment in mental rotation tasks of visual stimuli when simultaneously presented with the task of differentiating between pitches. Perhaps not surprisingly participants who had amusia (“tone-deafness”), specifically those who scored under par in the melodic contour portion of the MBEA test, showed no impairments in their mental rotation performance while engaging in the pitch perception task. More suggestive was their other finding that these participants with amusia did show impairment in the mental rotation task alone when compared with the performance of participants without amusia. Despite amusia being an auditory condition affecting one’s THE SPATIAL PROPERTIES OF MUSIC PERCEPTION 5 perception of tones or pitches it is associated with a deficit in visuospatial abilities. Together, their results suggest that the same spatial cognitive mechanism being employed in the task of representing and manipulating visual images is employed when representing auditory stimuli, specifically pitch. If people are using their spatial cognitive resources in the act of music perception and these same resources are used in visual-spatial tasks, explaining why amusia is associated with poorer performance, then perhaps frequent music perception and/or music production, (i.e. being a musician), should be associated with enhanced visual-spatial abilities. One study demonstrated an association between musical ability and spatial ability but only for orchestral musicians (Sluming, Brooks, Howard, Downes, & Roberts, 2007). These orchestral musicians showed superior performance on a three-dimensional mental rotation task relative to non-musicians. Relative to non-musician’s, FMRIs of the orchestral musicians showed increased activity in an area of the brain implicated in visual-spatial imagery. The experimenters concluded that the sight-reading skills of orchestral performance rewires brain circuitry such that these professional musicians gained a cognitive benefit of highly developed visual-spatial abilities, which are nonmusical in nature. Yet, other studies have failed to show an association between musical ability and mental rotation performance (Brandler 2003; Helmbold, 2005). Building on the Sluming, et al. (2007) methodology, the present study used an object rotation task to engage participants’ visual-spatial processing. Simultaneously, participants listened to melodies and were asked to count the number of pitch changes or the number of THE SPATIAL PROPERTIES OF MUSIC PERCEPTION 6 tempo changes, keeping the number in their head while they rotated the images. The degree of interference of the pitch task was compared to that of the tempo task, in order to determine which element of music perception has more of detrimental effect on the object rotation task. The task that had more of a detrimental effect on mental rotation was presumed to make a greater use of visual-spatial mechanisms. Additionally, both conservatory and non-conservatory students’ baseline performance of the mental rotation was compared, as well as their ability to perform the two simultaneously.