AWA: Academic Writing at Auckland

The huge popularity of iPods and the ease of access to music online means that music can be with us at all times, even while we work and study. British office workers in one recent sample were found to listen to music for 36% of their working week, usually through headphones (Haake, 2011). A glance at the students in the University of Auckland libraries shows the high prevalence of music listening while studying for tests and working on assignments in this population group. However, it is unclear what effect this infiltration of background music into academic and working life has on working memory, and whether musicians are affected differently to non-musicians. This study will use functional magnetic resonance imaging (fMRI) to test the hypotheses that background music has a greater negative effect on working memory in musicians than non-musicians, and that musicians display different patterns of neural activation when completing a working memory task compared to non-musicians.

Many respondents to Haake’s office worker survey (2011) observed that listening to music helped them to focus on their work, but others reported that listening to music had a deleterious effect on their concentration. Similarly, a large study of school and university students in several countries found great variability between respondents in both their listening habits and the students’ perceptions of the effect their listening was having on their study (Kotsopoulou & Hallam, 2010). In my own experience, I have found that the presence of music is a significant distraction. However, many of my undergraduate peers choose to study with music playing and find that it improves their memorisation ability.

Research studies into the quantitative effect of background music on task performance and memory have also yielded mixed results. Nearly seventy years ago, Henderson, Crews, and Barlow (1945) found that background pop music distracted students, lowering their reading comprehension scores, but that background classical music had no effect. Hallam, Price and Katsarou (2002) found that playing ‘calming’ music (a string adagio in a minor key) in the background while primary school students completed memory and maths tasks increased their performance, while ‘aggressive’ music (a chaotic instrumental track from Coltrane’s ‘Meditations’) decreased their scores.

One explanation for these varying results is that in many cases the background music has an effect, but one that is not of great enough magnitude to alter the participant’s reading comprehension, word recall or other such behavioural measure of memory. Perhaps these measures are simply not finely graded enough to reflect the subtle effects that background noise can have on an individual’s cognitive processes.

Several electroencephalogram (EEG) studies support this explanation. For example, Jäncke and Sandmann (2010) found that background music had no significant effect on performance in a verbal memory task. However, their EEG data showed stronger event-related desynchronisations in parieto-occipital and frontal areas about 1000ms after stimulus presentation in the presence of fast, in-tune music, and stronger synchronisations in fronto-parietal areas about 1800ms after presentation in the presence of out-of-tune music. This suggests that background music does affect cognitive processes involved in memory, even if this effect is too small to alter performance. Stronger effects are also observed when the task in question is more difficult, as shown by Gisselgård, Petersson, and Ingvar (2004). The use of fMRI in this proposed study will allow a far more in-depth comparison of the effect of background music on working memory in musicians and non-musicians than a simple behavioural study.

Musical expertise may also have a major role in determining the effect of background music on working memory. Schmithorst and Holland (2003) used fMRI to show that musicians and non-musicians employ different cognitive processes when attending to music. Several differences were observed, but the most relevant to this study is that activation in the inferior parietal lobules (an area implicated in auditory working memory) was seen only in musicians. This study aims determine whether such differences are also present when music is playing in the background while another task occupies conscious attention, and is not deliberately attended to.

Methods

Participants

Forty participants (twenty musicians and twenty controls) will participate in this research. All of the subjects will be right-handed native English speakers, and will have no neurological or hearing impairments. This study will have a between-subjects design, with musicians being contrasted with non-musician control participants. The musicians will be undergraduates from the Bachelor of Music (Performance) programme, and will have commenced musical training at or before the age of ten years. The controls will be undergraduate students from outside the School of Music who have not had any musical training aside from compulsory music classes in the primary and secondary school curricula. Any musicians who have previously performed Pleyel’s Symphony in C, B128, will be excluded from the study as in-depth knowledge of the musical stimulus could be a confounding factor.

Level of musical experience, including age of first music lesson and number of hours spent playing and listening to music per week, will be assessed using a survey prior to the beginning of the research. Self-reports of current study habits regarding background noise will be obtained after the fMRI data has been collected. Informed consent to take part in a study approved by The University of Auckland Human Participants Ethics Committee will be obtained from each potential participant prior to the commencement of the study.

Stimuli

The three background auditory stimuli will be silence, white noise, and music (from Pleyel’s Symphony in C, B128, recorded by Capella Istropolitana under the direction of Uwe Grodd). An orchestral work has been chosen as the musical stimulus rather than pop music because the lyrics in pop music could act as a confound (Henderson, Crews, & Barlow, 1945). This symphony is a relatively rarely performed work which the participants are unlikely to have heard many times before, if at all. It is, however, a typical example of a classical period symphony and as such the results of this study will be able to be generalised to more popular background classical music such as the works of W.A. Mozart (Haake, 2011). Auditory stimuli will be presented binaurally through headphones, at an average intensity of 60dB  to reflect normal background music sound intensity (Cassidy & MacDonald, 2007). The stimuli in the working memory task will be visually presented shapes.

Experimental Design

A change-detection task will be used to test working memory in this study. In each trial, participants will view a display featuring nine shapes arranged in a 3 x 3 invisible grid. The display will be viewed for one second then erased. After a delay of three seconds in which the participant will fixate on a cross and attempt to remember the display, another display will be shown for one second, featuring two shapes. One of the shapes will be the same, and in the same location, as in the original display, the other shape will be in a different location to before. The shapes will be labelled 1 and 2, and as soon as this display disappears the participant will respond by pressing a buzzer corresponding to the item that is the same shape, colour and in the same location as in the original display. The subject will then have a five second rest period before the next trial. An example of this change-detection task is shown in Figure 1, below. In this example, the correct response would be to press Buzzer 1 as the item marked 1 is the same shape, colour and location as in the original display.

[Figure 1. Illustration of a trial sequence.]

Each participant will complete sixty trials in total, divided into three blocks of twenty. Each block will be conducted in a different auditory background condition (silence, white noise or music). The order of the background conditions will be randomised to control for practice effects in the working memory task, although these are not expected to be significant (Eng, Chen, & Jiang, 2005). Before starting the trials, each participant will complete three practice trials to familiarise them with the task and the response process. The practice trials will be conducted with the same background condition as that participant’s first block of trials. As such, the total scanner time will be seven hours (forty participants at ten minutes and thirty seconds per participant).

A major confound in fMRI studies requiring auditory stimuli is the presence of loud (typically 110-140dB) scanner background noise (Gaab, Gabrieli, & Glover, 2007). In this study, these loud sounds would render the ‘no background noise’ condition invalid. They would also interfere with the participants’ ability to hear the background stimuli in the ‘music’ and ‘white noise’ conditions. The sparse temporal sampling paradigm will be utilised to combat this confound. In this paradigm, fewer images are taken, ensuring that scanner background noise does not occur in the crucial time in which the participant attempts to memorise the word (Hall et al., 1999). This paradigm negatively affects temporal resolution (as far fewer images are taken) but has little significant effect on spatial resolution. As this study is more interested in the locations of cortical activations than their time course, the sparse temporal sampling paradigm is appropriate.  

After the scanning is complete, participants will be asked to complete a short questionnaire. This will be along the lines of that used by Ohnishi et al. (2001), and will determine whether participants had previously heard or performed the musical excerpt, and if they had imagined playing along with the symphony while hearing it in the scanner. It will also ask for their subjective opinions on the relative ease of completing the working memory task in the music condition compared with the other two conditions.

Preprocessing

Image preprocessing will be performed using SPM8 software. As this study will utilise a sparse temporal sampling paradigm, no slice timing correction will be required (Nebel et al., 2005). Participants’ heads will be restrained during scanning to minimise motion artefacts; any remaining head motion will be corrected for using a rigid body transformation. Individual structural differences between participants will be normalised to the Montréal Neurological Institute (MNI) template, and smoothed by application of a Gaussian kernel two voxels wide.

Data Analysis

Behavioural data will consist of correct and incorrect responses to the working memory task conducted in three auditory conditions. ANOVA will be performed on the data from each individual participant to determine whether their accuracy is affected by the background auditory condition. Two independent samples t-tests will be conducted on data from each of the three conditions to determine whether there are significant differences in mean accuracy of musicians compared with non-musicians. The significance value will be set to P < 0.05. These statistical analyses will allow analysis of the behavioural effect of differing background auditory conditions on working memory, both in individuals and between musicians and non-musicians. As participants will be required to respond immediately after the test display disappears, response time will not be analysed.

The imaging data from each participant will be analysed to determine whether different brain areas are active when completing a working memory task in the presence of music, white noise or silence. Within the musician and non-musician groups, imaging data will be contrasted to determine whether there is a significant difference between the average activation seen in each of the three background conditions. Contrasts will also be run between groups, to determine whether musicians’ responses to white noise, silence and music are, on average, different to or the same as those of non-musicians.

The data from correct-response trials and incorrect-response trials will also be compared, to determine whether the brain regions identified in previous contrasts are involved with working memory and background auditory stimulation in general, or specifically successful or unsuccessful use of working memory. Incorrect and correct trials in each condition will be contrasted in each participant, and average response for incorrect and correct trials will also be contrasted within and between groups. These many contrasts will allow conclusions to be drawn about the effects of background auditory conditions on the neurological processes involved in completing a working memory task in musicians and non-musicians.

If any musicians have played the symphony before, report being familiar with the symphony, or report consciously attending to the musical stimulus and imagining playing along, their behavioural results and images will be removed from the ‘musician’ cohort prior to analysis due to the likely confounding nature of these factors. The differences between each of these individuals’ silence, white noise, and music scores and images will still be analysed, as this may provide leads for further study in the area of working memory and music.

Discussion

This study will make a valuable contribution to the body of literature exploring the relationship between background auditory stimuli and working memory. As yet, no published research has used fMRI to show cortical activation patterns associated with completing working memory tasks under different auditory conditions. Given the mixed results of behavioural studies in this area, and the poor spatial resolution of EEG, this fMRI study could be instrumental in determining which brain regions are activated in the presence of different background auditory stimuli. Furthermore, no published studies have explicitly compared musicians to non-musicians in this way, despite a significant body of evidence that suggests that musicians process music differently to non-musicians (Tervaniemi et al., 2009, for example).

If the hypothesis that musicians are more negatively affected by background music than non-musicians is correct, then we can expect to see significant differences between musicians and non-musicians in the music condition, but not necessarily in the white noise and silence conditions. It is also possible that musicians respond differently to white noise as well as music, which would suggest that they are more affected by background sound in general than non-musicians. 

A significantly lower mean accuracy in the musician group compared with the control group in the music condition would support this hypothesis. It is possible that musicians will involuntarily pay more attention to the background music than their non-musician peers. Working memory has been implicated as the controlling force behind involuntary attention switching, so it follows that this increased division of attention could impair performance on the working memory task (Berti & Schröger, 2003).

Lack of behavioural effect would not, however, refute the hypothesis. Musicians may process background music differently without suffering decreased accuracy; neural activity is not necessarily mirrored by behavioural changes (Jäncke and Sandmann, 2010). It is therefore likely that the most significant results will come from comparison of the activation patterns in musicians compared with non musicians as shown by fMRI. Increased frontal lobe activation in musicians in the music condition would suggest increased attention switching (Cowan et al., 2005), which would in turn support the hypothesis.   

Gisselgård, Petersson, Baddeley, and Ingvar (2003) used positron emission tomography (PET) to determine that the dorsolateral prefrontal cortex is activated when completing a working memory task whilst distracted by irrelevant speech. It is thought that activation in this area is related high working memory load, rather than specifically to irrelevant speech (Manoach et al., 1997). As such, greater dorsolateral prefrontal cortical activation may be seen in individuals who are devoting more working memory capacity to inadvertently processing the background auditory stimuli. Therefore, increased dorsolateral prefrontal cortical activation in musicians would support the hypothesis that musicians are more affected by background music than non-musicians.

If musicians do indeed process background music differently to non-musicians, activation may be seen in the inferior parietal lobules of musicians but not non-musicians. This differential activation pattern has been shown using fMRI in a passive listening paradigm (Schmithorst & Holland, 2003) but not in an unattended music paradigm. If such activation was to be shown in this study, it would suggest that the inferior parietal lobules respond to music in musicians even without conscious thought about the music being heard.

Overall, it is hoped that this study will help to clarify current knowledge about the effects of background music on memory. Specifically, the use of fMRI will allow visualisation of the anatomical areas used when attempting a working memory task in the presence of differing auditory stimuli. This new information may lead to improved understanding of the process of working memory and the effects of auditory distraction. The comparison of musicians and non-musicians aims firstly to further understanding of the complex effects that musical training has on the brain, but also to determine whether musical training is a serious confound that must be taken into account in future studies into auditory distraction and memory. Practically, if significant behavioural differences are noted, this study could encourage individuals to take their musical experience into account when deciding whether or not to listen to music while they work and study.

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