The effects of handedness on lateralization,
spatial representation of pitch height and
transfer of learning in pianists
Supervisor: M. Sadakata Second reader: J.A. Burgoyne
Master Thesis for the Graduate School of Humanities 2016
The effect of handedness on hemispheric dominance, spatial representation of pitch height and transfer of learning in pianists was examined. Twenty-five pianists (12 right-handed and 13 left-handed) participated in a four-part experiment. Two questionnaires were used to determine four-participants’ level of handedness and their level of musical sophistication, and a dichotic listening task tested for hemispheric dominance. A performance test on a regular and reversed MIDI piano keyboard examined spatial representation of pitch height and in combination with a transfer of learning paradigm provided comprehension into the effects on sensorimotor behaviour. It was found that transfer of learning was affected most significantly by motor condition, whereas reversing pitch height did not have a significant effect. An interesting trend was found on handedness, which could indicate that left handed pianists are more accurate in adapting to different effectors. Analysis of errors indicated that right handed pianists made significantly more mistakes in the mirrored motor condition when playing with their left hand in comparison with their right hand. Also, overall performance of right handed pianists in the mirrored motor condition was significantly less accurate than performance of the left handed pianists. Future research could focus on transfer of learning differences between professional and novice pianists and dive into a more thorough analysis of the effect of playing errors on performance.
Acknowledgements
This thesis is the product of the final part of a master study and was made as a completion of the MA Arts & Culture: Musicology at the University of Amsterdam, department Graduate School of Humanities.
Several people have contributed and supported me throughout the process of experimenting, analysing and writing, for which I am grateful. Therefore, I would like to thank my supervisor Dr. Makiko Sadakata for all the time and effort she put in throughout the process. I would also like to thank Dhr. Ir. Dirk-Jan Vet for his help in the practical applications of the experiment itself and the second reader of this thesis, Dr. Ashley Burgoyne, for his constructive comments.
I hope you will enjoy reading this thesis.
Table of content
Abstract... 2 Acknowledgements... 3 Table of content... 4 Introduction... 6 General introduction... 6 Research... 7 Research questions... 8 Literature review... 9 The participant... 9 The musician... 9 Lateralization in musicians...10The left handed... 12
Lateralization in handedness...12
The (left handed) pianist...13
The experiments... 16 Dichotic listening... 16 SMARC effect... 18 Transfer of learning...20 Error... 22 Methods... 25 Participants... 25
Design and Instruments...25
Materials... 26
Equipment... 27
Procedure... 27
Results... 29
Dichotic listening test...29
Transfer of learning task...29
Training... 29
Test... 30
... 33
Linear Mixed Effects...34
Error... 36
Discussion... 38 Dichotic listening... 38 SMARC-effect... 40 Transfer of learning... 41 Errors... 43 Limitations... 45 Generalization... 45 Internal validity... 45 External validity... 45 Reliability... 46 Conclusion... 47 Main conclusion... 47 Research questions... 49 Future research... 51 References... 53 Appendices... 62 Appendix 1... 62 Appendix 2... 72 Appendix 3... 73
Introduction
General introduction
The musician is a typical object for research. It is diverse by nature, can take various forms, has a typical lifestyle and is therefore currently an interesting topic for research, especially with regard to the cognitive and psychological sciences. The musician does not only use its body, but its entire brain is involved in the process of music making and music listening. The effects that music can have on a person’s brain – not only on the brains of musicians – are enormous and have become of great interest for different fields of research. For example, the cognitive and psychological sciences have expressed their interest in the effect of music on the brain and on behaviour. Multiple debates are currently going on in neurosciences with regard to music. What is music? When can we perceive a stimulus as being music? Is music ability a genetic advantage or is it shaped by our environment? How is music shaped in our brain? Specifically, the mental representation of music-related tasks has become a dominant subject in neuroscientific research, especially with regard to lateralization and hemispheric dominance. Music is not only processed in one particular hemisphere, but it uses several parts of the entire brain and travels through different hemispheres. Music is often related to language, as being a similar process in the brain. However, there are theories suggesting that some aspects of music are mostly processed in one particular hemisphere, which is similar to certain theories of how language is processed. Is there really a dichotomous split of the hemispheres when it comes to music and language processing? Are both hemispheres equally used when processing musical information or is there one more dominant than the other? A closely linked topic to the notion of hemispheric dominance is handedness. Are theories of hemispheric dominance applicable to left handed people or are there differences between groups of handedness? If there are varieties between participants who are left handed and those that are right handed, this might suggest differences in hemispheric dominance. When this is the case, this might be affecting processing of musical information as well. Surprisingly, current music cognition research usually neglects varieties in handedness, as often is reported that merely right-handed participants were involved in experiments or information about the left handedness of participants is not included (e.g. Hirshkowitz, Earle & Paley, 1978; Patston et al., 2007; Schlaug et al., 1995).
Occasionally, left-handed subjects are being examined, but fluctuations in results caused by several levels of handedness are not further researched. It is therefore not yet certain whether there are even differences in hemispheric dominance of musical processing between left and right handed people. This gap of knowledge in research on left-handed musicians will be addressed in the current experiment.
This thesis will focus specifically on pianists, as their instrument requires a certain level of bimanual control, which is different in comparison with other instruments. The pianist has to use its hands both simultaneously, separately, parallel to each other and also in a symmetric fashion. Both hands could therefore have a similar level of performance, which might be independent from the handedness of the pianist. However, the right hand generally has a more virtuosic and melodic function, which automatically puts the left hand in a more submissive position. It is therefore possible that the left handed pianists have a disadvantage when learning to play piano, as the role of the right hand could be less natural to them. Reversing the pitch height on a keyboard, and therefore also the roles of the two hands, could potentially be a solution for the left handed pianist.
The direct inspiration for this research derives from an essay by Lutz Jäncke, who described a case of left handed pianist (C.S.) playing on a reversed piano (2002). The pianist involved, who was a professional pianist and used to the regular keyboard, appeared to easily adapt to the reversed keyboard. His quick adaptation to the reversed keyboard was brought into relation with his left handedness and raised thought to ideas that handedness might have an influence on piano performance. This observation raises the question that there might be some differences in performance between left and right handed pianists. The case of C.S. was further analysed using functional magnetic imaging techniques and neuropsychological tests (Jäncke et al., 2006). Although C.S. showed regular left dominance for language and was left handed, his professional performance level on both the regular as the reversed keyboard indicates a certain level of functional asymmetry being responsible for such outstanding abilities. Unfortunately, research on the reversed keyboard is very limited and lacks evidence from right handed pianists, but the case of C.S. opens doors for new research objectives for both left handed as right handed pianists. In what way is C.S. a ‘special case’ or are these abilities found in all left and even right handed pianists?
Research
The central aim of this thesis is to find out whether there are significant differences between left and right handed pianists on a behavioural level which might affect certain aspects of cognition. The thesis is structured as follows. First, an extensive literature review will provide the theoretical background necessary to back up the experiment. The population groups of the musician, the pianist and the left handed will thoroughly be discussed as well as the behavioural measures on which the experimental part of this thesis is based.
The purpose of the experimental part of this thesis is to provide a research objective in which different experimental approaches are combined involving ideas of lateralization in right- and left handed subjects, spatial mapping of pitch height and transfer of learning. The first approach of lateralization will attempt to find out whether left and right handed pianist show differences in which hemisphere is involved in the processing of musical information. Musical information is represented in the brain in a certain manner, which will be related to spatiality and handedness. The transfer of learning paradigm uses theories of learning and how learning is affected by the use of different effectors, e.g. different hands. These three approaches will be thoroughly explained in the literature review.
The main research question of this study will be formulated as follows: Is there an effect of handedness on lateralization, spatial representation of pitch height and transfer of learning in pianists? Multiple behavioural measures will be used in order to find answers to the questions whether left-handed pianists are privileged or disadvantaged when learning to play piano. It is hypothesized that there is a difference in the degree of lateralization of musical stimuli between left-handed and right-handed pianists and that this could have an effect on sensorimotor behaviour. Hemispheric dominance will be tested using a dichotic listening test, whereas a transfer of learning paradigm will provide insight into the effects of handedness on sensorimotor behaviour.
Subsequently, results of the experiment will be discussed and will show how this experiment contributes to the field of cognitive musicology and hopefully shed a new light on current existing theories and findings related to this field of research. Limitations of this experiment and ideas for further research will show how this experiment could potentially still be improved and
extended in the future.
Research questions
Main research question:
Is there an effect of handedness on lateralization, spatial representation of pitch height and transfer of learning in pianists?
Sub questions:
1. Is there a difference in hemispheric dominance in left and right handed pianists?
2. Is there a difference in spatial representation of pitch height in left and right handed pianists?
3. What are the effects of different effectors (such as reversing the pitch height or the motor condition) on transfer of learning in left and right handed pianists?
Literature review
As mentioned during the introduction section, this thesis attempts to involve different experimental approaches in one experiment. Apart from those, two specific types of participant bodies are used, who both need an extensive review of literature. Musicians are a special group of participants, especially with regard to cognitive and psychological research. The development of musical abilities often starts at a young age and therefore goes hand in hand with the development of other cognitive skills (e.g. linguistic skills, planning abilities, development of personality (Miendlarzewska & Trost, 2014)). It is difficult to separate the development of one ability from the other, but the effects of developing music abilities on a musician’s brain are currently a hot debate. A second typical group of participants are the left handers. Often neglected in experiments, but nonetheless extremely interesting. The origins and the function of being left handed has not been found yet, making this group of participants
even more interesting. The first part of this literature review will be devoted towards explaining cortical differences in musician’s brains and the brains of left handed people. After laying out the overview of research on the populations of musicians and the left handed, the different experimental approaches will be discussed.
The participant
The musician
What exactly makes the musician such an interesting type of participant? Multiple studies have indicated that there are structural and functional differences in brains of professional musicians in comparison with non-musicians, such as sensorimotor brain regions (Elbert et al., 1995; Hund-Georgiadis and von Cramon, 1999; Schlaug, 2001; Gaser and Schlaug, 2003), auditory areas (Pantev et al., 1998; Zatorre, 1998; Schneider et al., 2002; Gaab and Schlaug, 2003; Bermudez and Zatorre, 2005; Lappe et al., 2008), and regions in the brain where input from multiple sensory areas are integrated (Münte et al., 2001; Sluming et al., 2002, 2007; Gaser and Schlaug, 2003; Lotze et al., 2003; Bangert and Schlaug, 2006; Zatorre et al., 2007).
One preliminary critical point that has to be made regarding most of the studies mentioned in this thesis is the facile use of the terms ‘musician’ and ‘non-musician’. Studies often provide some demographic information about their participant body, including providing an estimate of the amount of musical experience of years of musical study, but this is quite problematic in itself. Researches have used numerous of different ways to measure ‘musicality’, complicating generalizing results from different studies. Up until 2014, there was not one specific tool to measure one’s musical capacity or level of music training, which is both accurate and relatively easy to use when dealing with a lot of participants. Recently, the Goldsmiths Musical Sophistication Index was created by Müllensiefen et al. (2014), including a self-report questionnaire and auditory tests to measure one’s musical sophistication. Even though it can also be debated why this test should be used for all future studies involving ‘musicians’ or ‘musicality’, as any test cannot be stated to be perfect, it would certainly be beneficial to use one tool for all studies. Apart from a non-systematic use of different measurement tools, the easy manner in which the term musical is used
is problematic as well. Also, the term non-musician implies a certain lack of musicality, whereas a person not practising music as a profession can be as musical as a musician. Therefore, for this particular experiment, the decision to include only pianists is convenient as it avoids problems of categorization of musicians. This thesis also does not claim to use a correct form of the term musician, but for the sake of clarity and because of a lack of a better term, the terms musician and non-musician will systematically be used.
Lateralization in musicians
There is a general view in literature suggesting a functional division between the brain’s two hemispheres; the left being involved in language processing and the right being responsible for processing musical input (Kallmann & Corballis, 1975). Although, the situation is not as black and white as often stated in colloquial articles on scientific-related topics, there is a certain degree of lateralization to be found (Bangert & Schlaug, 2006; Gates & Bradshaw, 1977). Usual hemispheric asymmetry is shifted in musician’s brains, having more bilateral neural connectivity than non-musicians (Patston et al., 2007). Anatomic evidence was found for a positive correlation between midsagittal callosal size and the amount of fibres in the corpus callosum of musicians as opposed to non-musicians (Schlaug et al., 1995a). This indicated structural difference in corpus callosum size leads to changes in interhemispheric communication and a possible hemispheric asymmetry of sensorimotor areas (Schlaug et al., 1995a). Supernormal musical abilities, such as perfect pitch, have been associated with hemispheric asymmetry as well. Schlaug, Jäncke, Huang & Steinmetz have used in vivo magnetic resonance morphometry to measure levels of anatomical asymmetry of the planum temporale (1995b). The planum temporale is part of the auditory association cortex and associated with structural and functional asymmetry. It was shown that musicians with perfect pitch have stronger leftward planum temporale asymmetry than musicians without perfect pitch or non-musicians (Schlaug, Jäncke, Huang & Steinmetz, 1995b).
One could object to these findings by assuming that hemispheric specialization is related to acoustic properties of stimuli and can therefore not be caused or affected by structural brain differences amongst different participants groups. However, it was found that hemispheric specialization is accompanied by
perceptual processing and experience (Hirshkowitz et al., 1978). Differences between musicians and non-musicians related to lateralization and structural brain differences can therefore not be accounted to acoustic or other external aspects of the stimuli itself, but there are processes happening at the cerebral level.
Structural brain differences between musicians and non-musicians were found in several parts of the auditory and motor cortex (Schlaug et al., 1995a,b; Amunts, 1997; Zatorre et al., 1998; Schlaug, 2001; Schneider et al., 2002; Hutchinson et al., 2003; Lee et al., 2003). Whether these structural differences can be attributed to innate or genetic predisposition or whether the found differences can be fully attributed to the practice and performance of music is a legitimate concern. Gaser and Schlaug (2003) found increase of gray matter volume in different motor, auditory and visual-spatial regions for professional piano players as compared to a group of amateur musicians and non-musicians. More specifically, a positive correlation was found between professional musicianship and gray matter volume in primary motor and somatosensory areas, premotor areas, anterior superior parietal areas, the interior temporal gyrus bilaterally cerebellum, left Heschl’s gyrus and the left inferior frontal gyrus. These results suggest a particular association between several left-hemispheric brain regions. Particularly, the significant results showed in the left inferior frontal gyrus is interesting to further discuss. Both the left as the right inferior frontal gyrus are playing a critical role in response inhibition for inappropriate motor responses (Swick, Ashley, & Turken, 2008; Hampshire et al., 2010). Gaser and Schlaug reported to have only used right-handed participants in their research (2003). Perhaps, this could have caused a bias for left hemispheric brain areas, resulting in a seemingly non-activation of right hemispheric areas.
A strong association was found between these structural differences, musician status and practice intensity defying the hypothesis of the effect of innate predisposition (Gaser and Schlaug, 2003). Generally, there is a lack of studies examining structural behavioural brain changes caused by long-term music training (Hyde et al., 2009). Hyde et al., tested young, right-handed children to demonstrate regional structural blain plasticity occurring with only 15 months of instrumental music training (2009). Although, 15 months were found to be too short for permanent structural brain changes, some changes were found in motor and auditory areas correlating with behavioural improvements on motor and auditory musical tests. There were no initial structural brain
differences found between the tested groups of children prior to the experiment. Instrumental practice therefore had a profound effect on the development of aforementioned brain regions.
From the aforementioned studies, it can be concluded that musicians reveal differences in structural and functional brain regions. There is a tendency towards supporting the hypothesis that these differences are not caused by genetic predispositions, but that long-term training in music can have a profound and lasting effect on the brain’s structures. However, there is a strong bias towards the participant population, as most of these studies report to have used only right-handed participants.
The left handed
The second particularly interesting subject group used in this thesis are the left handed. The origins of handedness and differences in its types are not consistent. For example, it is thought that certain happenings, such as the preferred hand while thumb sucking in prenatal development plays an important role for the development of handedness (Hepper, Wells & Lynch, 2005). Other theories are related to hemispheric specialization (Banich, 1997) or genetic factors (Annett, 2009). However, none of the theories provide an overall and complete explanation of the phenomenon left handedness. For this thesis, theories of differences in lateralization between left and right handed people are particularly important and those will be more thoroughly discussed in the following section.
Lateralization in handedness
Differences in lateralization for left-handed subjects have been found to a certain extent (Vingerhoets et al., 2012). The situation of hemispheric dominance in left-handed musicians is complex, but this should not lead towards a neglect of the left-handed participant as a whole.
Studies have shown that there are differences in at least the degree of brain asymmetry for left and right-handed subjects. For example, the aforementioned study by Vingerhoets et al., examined brain activation patterns for recollection and pantomiming of learned gestures in both left and right-handed participants (2012). It was found that right-handedness did not influence the
direction of asymmetry, but that it did have a strong effect on the strength of the lateralization. Lefthanders showed a reduced degree of lateralization, mostly in the posterior parietal region. This is in consensus with findings of other studies, suggesting that there is a general left lateralized network guiding learned gestural behaviour of both hands (Choi et al., 2001; Johnson-Frey et al., 2005; Moll et al,. 2000). Handedness, or the hand used to complete the task, did not affect the left hemispheric lateralization.
An essential aspect of music performance in general is the stream of information floating between sensory processing and motor planning areas (Janata & Grafton, 2003). The interaction between audio and motor areas was investigated by amongst others Haueisen and Knösche (2001) and Popescu et al. (2004). By using MEG, it was found that there is a level of activation in motor areas in musicians and non-musicians while performing a purely auditory task. These results suggest that there is at least an indirect, or even a direct, interaction between auditory and motor areas (Haueisen & Knösche, 2001; Popescu et al., 2004; Baumann et al., 2007). An important aspect of this interaction is whether this happens voluntary or involuntarily. In the case of voluntary activation of transmodal information, participants could consciously decide to involve this interaction when performing a task. This could be beneficial when performing musical tasks that deviate from normal. However, it was found that there is at least an involuntary aspect in the transfer of information from the auditory to the motor system (Haueisen & Knösche, 2004; Popescu et al., 2004; Baummann et al., 2007). Even the imagery of sound appears to have a positive effect on the activation of parts of the auditory cortex (Bunzeck et al., 2005; Halpern and Zatorre, 1999; Janata, 2001; Zatorre et al., 1996) and that imagery of motor performance activates parts of the motor areas (Kristeva et al., 2003; Lotze et al., 2003; Meister et al., 2004). Considering pianists and cortical activations of motor areas, Jäncke, Shah and Peters found that long term extensive skill training of finger and hand movements as found in professional pianists lead to a lesser degree of activation in primary and secondary motor areas, meaning that there is are larger degree of efficiency in neural activity (2000). However, the network combining audio and motor information seems to be more activated in skilled pianists in comparison with non-musicians when one modality is missing (Baumann, et al., 2007). Overall, these results indicate a level of plasticity to be happening at the neuronal level which can be influenced by intensive skill training. Whether handedness plays a role in these processes is not
specified, which is a point of critique. Since it was found that handedness has an effect on the strength of the degree of lateralization, any studies related to finger movements and neural activity should include handedness as a factor.
The (left handed) pianist
Apart from the musician being a remarkable, but particularly interesting subject for research, as earlier mentioned, the pianist is a special type within this category. Having to use both hands (and feet), while reading multiple lines of music, and occasionally being able to sing along when necessary as well, the pianist is required to multitask in an extreme fashion. What are the general advantages and disadvantages of being a pianist in comparison with other musicians or with not being a musician at all?
Playing piano requires extreme activity from the brain and the body. The movement of the fingers alone is already a quite complex activity, as pianists can reach a speed of 30 notes per second (Rumelhart and Norman, 1982). These motor actions involve automatic processes of task-learning, leading to a state of automaticity, in which information is formed into “chunks” (Globerson & Nelken, 2013; Logan, 1979; Miller, 1956). Because of this method of chunking, the necessary involvement of movement and cognitive control is reduced without the loss of performance (Cohen & Poldrack, 2008). Not only the process of chunking is important for fast learning of motoric movements and flexibility in controlling those. It was found by Bengtsson and Ullén that there is a dissociation between melodic and rhythmic processing during piano playing while reading the musical score (2006). Although it might seem plausible to consider that the musical information on a score is processed as a whole, it appears that a pianist decodes two sorts of information during playing, which are the spatial properties of the notes required to play the right pitch and the timing information. Bengtsson and Ullén have suggested that this dissociation is particularly helpful when it is required to learn motoric movements fast (2006).
Apart from controlling motoric information, auditory information needs to be processed as well. The processing of music is a complex cognitive system, which can hardly be compared to any other cognitive process. Music consists of many different elements, increasing its difficulty of processing and its difficulty of analysing and examining which events are occurring in which cortical area and when. All musicians cope with processing incoming musical information, but
pianists have to deal with playing multiple musical lines and multiple voices simultaneously. Could it be possible that they outperform other musicians when it comes to the hearing? No particular studies have been conducted comparing pianists and with other musicians on the level of hearing, but musicians have been found to have a more fine-tuned hearing than non-musicians (e.g. Parbery-Clark, et al., 2013).
Since there seem to be quite some cortical differences between musicians versus non-musicians and left handed versus right handed people, it only makes sense to combine those groups to see whether there are differences to be found there as well. However, conclusions drawn from experiments involving musicians are generalizations, because of the diversity of the musician group as mentioned before. The decision to use pianists for this experiment was specifically made mainly because their instrument required bimanual mastering. Both hands require similar motoric functioning, but are dissimilar when it comes to musical functioning. The left hand is usually associated with playing the harmony, whereas the right hand often plays the melody and is therefore often regarded as the more virtuosic and dominant hand. Analysing a group of pianists is in itself already particularly interesting, because of the previous discussed cortical differences and hemispheric asymmetry. Adding a layer of differences in the level of handedness only increases its interesting potential. Are left handed and right handed pianists different in the degree of dominance of their hands? One could also ask the question whether left handed pianists are at disadvantage, since their dominant hand is put in a position where it cannot use its dominant and virtuosic potential to the fullest. There have not been many studies focusing on these particular questions, but there are some examples. Kopiez et al. examined personal experiences of conservatory students and teachers - playing either piano or a string instrument – regarding their practice habits, discomfort during playing, history of injuries and personal feelings associated with their level of playing (2011). There was no association between left handedness and the amount of bodily discomfort or negative personal associations with the instrument. Interestingly, left handed musicians rated their playing more positive than right handed musicians. These findings suggest that there might not be a negative association of being left handed on the personal level, but one cannot rely on self-reported questionnaires only when drawing such conclusions. Performance abilities of left and right handed pianists should be measured and compared to see whether there are actual differences between the groups.
Another study by Jabusch, Vauth and Altenmüller examined pianists on sensorimotor skills. Participants played sequences of 10-15 repeats of a C major scale on 2 octaves. Duration time was measured and functioned as the indicator of performance. It was found that the right hand displayed a larger degree of equality between the notes, also for left handed pianists. Overall performance was similar for left and right handed pianists. Whether years of regular practice has an effect on hand dominance is doubted by Annett (2002), who stated that “years of practising scales with both hands may not remove the superiority of the preferred hand, whether right or left”. If this would indeed be the case, the results of the study by Jabusch, Vauth and Altenmüller should have been different. Different theories explaining the pianists’ outstanding ability of bimanual control were reviewed by Globerson and Nelken (2013). It is suggested that the pianist uses different strategies, or ‘mental scripts’ to avoid automatized motor behaviour and risk of making errors during performance, which is especially helpful for sequential information. In other words, there is an abstract representation of the sought musical information, relatively independent from the hand or the fingering required to perform it. Considering the complexity of performing bimanual movements, it was found that symmetric movements are easier to perform than parallel movements, causing a greater brain activation for the latter category (Sadato et al., 1997; Stephan, et al., 1999). However, this was found in a regular participant body, as it appears that the rules are different for professional pianists who did not show a greater brain activation for parallel movements as compared to symmetric movements (Haslinger, et al., 2004). These studies unfortunately do not mention differences between left and right handed pianists.
Even though the amount of studies conducted on the left handed pianists is not particularly large, there are discrepancies found in the idea whether left handedness is an advantage or a disadvantage when learning to play the piano. Left handedness amongst pianists in relation with their level of performance on their instrument is particularly worth examining, especially because of this disagreement among researches.
As briefly mentioned during the introduction, one particular subject has indicated that left handedness might not necessarily be a disadvantage, but that adapting the instrument certainly is advantageous. In the case of C.S., reversing the pitch height of piano in order to create a so-called ‘left handed piano’ might be a solution for left handed players. There have not been any studies conducted
yet analysing the differences of performance of pianists on a regular and a reversed keyboard. C.S. was tested by Jäncke et al. (2006) for neural control while playing the reversed and the normal keyboard, but this research is focused on merely on neural patterns rather than measuring C.S.’s actual performances and comparing those. To conclude the section on different participant groups related to this experiment, one can state that there definitely is a gap in research considering the question of the left handed pianist, which will hopefully be partially filled by the current experiment.
The experiments
Dichotic listening
The dichotic listening task is a behavioural test often used in experiments related to hemispheric dominance and lateralization. Previous results of experiments involving lateralization in musical tasks have indicated that there is a left hemispheric specialization for language and a right hemispheric dominance for music information processing (e.g. Josse & Tzourio-Mazoyer, 2004; Perani et al., 2010; Springer & Deutsch, 1998). McKee et al. have observed higher alpha ratios in left and right during musical task performance in four right handed participants (1973). Comparable results were found by Schwartz et al., who stated that that relative right hemispheric activation happened during musical activities, such as singing and whistling, whereas light left hemispheric activation occurred during reciting of the lyrics of a song (2004). Both of these results suggest that there is a right hemispheric dominance for the processing of musical information.
The dichotic listening task was used by e.g. Tramo and Bharucha, who examined lateralization for musical structure processing (1991). Participants were presented with either a chord sequence or a spoken syllable sequence. For the chord sequence, the final chord was either harmonically expected or less expected. Subjects had to identify final syllables or the timbre of the chord. It was found that a left-ear advantage revealed itself for tonal function, whereas identification of final tonic chords presented in the right ear was faster for harmonically more expected chords (such as the tonic). These findings suggest that there is a right-hemispheric specialization for musical structure processing when subjects are presented with both a musical and a speech stimulus (Tramo &
Bharucha, 1991).
The dichotic listening paradigm has been used by multiple other studies to test perceptual differences between musicians and non-musicians. Nelson, Wilson and Kornhass (2003) tested 24 musicians and 24 non-musicians on their perception of dichotic chords (free recall and directed recall) and nonsense syllables (CVs). Although, there was a significant right-ear advantage found on the dichotic CV and dichotic-digit free-recall tasks in both groups and a left-ear advantage with the dichotic-chords in free-call condition, there were no surprising significant differences between the groups. Only with directed recall for the dichotic chords, musicians performed slightly better. This particular experiment does not provide specific insights into perceptual differences between musicians and non-musicians, but it puts forth an important notion needing consideration when setting up a dichotic listening test. As discussed by Obrzut, Bolie and Obrzut (1986), the level of perceptual asymmetry found can be severely influenced by the category of stimuli which was used, but even more so by the attentional strategy employed. The type of questioning is therefore important and should not be picked randomly, since it can have a great effect on the results. Strouse and Wilson (1999) have shown that in healthy participants (without cognitive or hearing deficits) recognition performance should be relatively similar for one-, two-, and three-pair digits under both free- and directed-recall response conditions. For the dichotic listening test used in this experiment, it was chosen to use a directed-recall response condition. This decision is supported by the fact that the test was in the English language whereas the participant body was international, therefore a free-recall response condition would have provided too much freedom for participants to respond in different languages.
Another dichotic listening test relating musicians and non-musicians was conducted by Milovanov, Tervaniemi, Takio and Hämäläinen (2007), who compared adults and children on their performance. The hypothesis that “musical expertise affects the laterality of the musical and linguistic processing in the human brain” could be confirmed to a certain extent. It was found that the score of musical aptitude had a positive correlation with the laterality index score.
Most of these studies are focused around differences in lateralization of music versus language processing or differences in processing of simultaneously presented stimuli in brains of musicians versus non-musicians. However, essential for this particular experiment is also possible differences in hemispheric
dominance between left and right handed subjects, and more specifically pianists. Generally, it is expected that there is not necessarily a reversed hemispheric dominance happening for left handed participants, but the degree of specialization might be decreased (Vingerhoets et al., 2012). Several studies have looked into this difference of lateralization by using the dichotic listening paradigm.
The left-handed brain is uncanny and its mysteries have not yet been solved. The idea that hemispheric dominance in left-handed might be switched stems from the 90s. Works of Springer and Deutsch (1998), Damasio and Damasio (1992), and others, found out that the association of a completely switched hemispheric specialization in the left-handed population does not exist. However, around 19% of left-handed have a right-hemisphere dominance for language, whereas 20% processes language in both hemispheres. The majority of left-handers therefore have similar hemispheric dominance for language as right-handed people, which is situated in the left-hemisphere.
Several studies have attempted to unravel the mysteries of the left handed by using the dichotic listening test. A reoccurring finding is a right-advantage in both left handers and right-handers, which cause some disturbance amongst researchers (Van der Haegen et al., 2012). Even though, it was established that the majority of left-handed people have similar hemispheric dominance for language stimuli as right-handed people, the question why this is the case remains. Van der Haegen et al., examined the effect of handedness on hemispheric dominance in a dichotic listening task with consonant-vowel syllables (2012). It was found that left-handers with right-hemispheric dominance did show a left ear advantage. Left-handers with left-hemispheric dominance, and right-handers showed the expected right ear advantage. Ear advantage was therefore not predicted by handedness, but by language dominance. The directionality of causality remains questionable. Is handedness at all related to these hemispheric differences?
The question whether handedness influences performance skills for musicians on certain tasks was examined by Kopiez et al., who conducted a survey study on sensorimotor skills and tested for performance in scale playing (2011). An expected disadvantage for left-handed string players and pianists could not be confirmed, as it was found that “handedness-based asymmetry in motor performance is compensated, and even over-compensated, for by intensive and long-lasting practice on a non-inverted instrument” (Kopiez et al.,
2011). The right hand was found to have higher temporal precision in general, for both right-handed as well as left-handed musicians. However, left-handed musicians seem to be in advantage for certain music-related tasks. For example, it was found that they outperform right handers on a pitch memory task, as it appears that disruptive effects of interpolated tones have less effect on task performance when participants are left-handed (Deutsch, 1980; Deutsch, 1985). Other studies examined differences in lateralization of musician´s brains of those that were either right or left handed or ambidextrous (Oldfield, 1969; Byrne, 1974; Gates & Bradshaw, 1977; Fry, 1990; Hassler & Birbaumer, 1988; Götestam, 1990; Aggleton, Kentridge & Good, 1994). The statement by Kopiez et al. (2011) can be contradicted by findings of several other studies. Peters (1985a, b) found that there is a reduced hand asymmetry in some piano players on a bimanual tapping task. However, it is suggested that there is a stability in this asymmetry even after extensive practice (Annett, Hudson & Turner, 1974; Annett, 1970; Peters, 1981). In other words, extensive practice of the non-dominant hand might improve its performance, but the prior existing asymmetry cannot be completely compensated for. Jäncke, Schlaug and Steinmetz (1997) confirm this notion with their findings on a reduced level of hand skill asymmetry in musicians and non-musicians. The found reduced degree of right-hand superiority was caused by an increase of performance in the left-right-hand instead of a loss in the right hand.
SMARC effect
A second approach to handedness in musicians can be related to spatial mapping of pitch height. In general, basic elements of musical cognition appear to be mapped onto a mental spatial representation, which is visible in linguistic elements as well. Semantically speaking, the words ‘high pitch’ and ‘low pitch’ suggest a certain place in space. Or, in other words: “high tones are phenomenologically higher in space than low ones” (Rusconi et al., 2006). The association between pitch height and its vertical spatiality was already examined by Stump in 1883, as he initially observed that this association exists across languages and could therefore have a psychological origin. Although this association appears to be striking, Stumpf was not convinced that this particular spatial distinction is intrinsic to the ideas of tonality, but merely functions as an effective metaphor (Stumpf, 1883; Rusconi et al., 2005). Pratt was in 1930 the
first to hypothesize that there is in fact a real connection between pitch and spatiality. He discovered that an upward or downward musical phrase can evoke a movement in a certain direction (Pratt, 1930; Rusconi et al., 2005). This findings opened new doors for the pitch-space correspondence and nowadays it is generally thought that this connection is in fact quite robust.
The effect of this spatial mapping due to linguistic elements on motor behaviour was examined in several studies (Akiva-Kabiri et al., 2014; Lidji et al., 2007; Rusconi et al., 2006; Stewart et al., 2012). Responses were quicker when congruent pitch and response types appeared (e.g. high pitch with upper key), which is usually referred to as the SMARC effect (Spatial-Musical Association of Response Codes). In other words, mental representation of pitch affects motor responses, which was found by multiple studies (Rusconi et al., 2006; Lidji et al., 2007; Nishimura and Yokosawa, 2009; Cho et al., 2012). Moreover, horizontal mapping in musicians was found when pitch height was task irrelevant (Rusconi et al., 2006).
The SMARC effect is a domain specific concept, specifically applicable to music. This does not mean that music-related cognitive information is the only type of abstract knowledge represented spatially. Other types of abstract processes are found to be cognitively represented in a similar fashion, such as the SNARC effect (Spatial-Numerical Association of Response Codes). Interestingly, both effects seem to function similarly for only half of the participants (Beecham, Reeve & Wilson 2009). The experiment by Beecham, Reeve and Wilson showed that, when participants were explicitly told to focus on the spatiality of stimuli, that for both the numerical and the musical tasks, there was a clear division between response patterns (2009). These findings suggests that there are individual differences when tested for the SMARC and the SNARC effect. Testing different types of participant groups could potentially show very interesting results. One idea of the current experiment is that there might a SMARC effect in the congruency of the directionality of pitch and the keys of the piano. Since evidence suggests that there might be a horizontal and vertical spatial representation of pitch height (Lega et al., 2014), any incompatibility between pitch height results and requested response types is plausible.
Transfer of learning
The process behind learning a new musical piece is extremely complex. Especially pianists, who are often exposed to pieces having multiple melodic lines and difficult harmonies, can experience trouble with the perception, production and remembering of all this information.
“When musicians learn to perform a novel melody, they must
learn what events (pitches or chords) to produce, when to produce the
events (timing), and how to produce the events (motor movements)” (Meyer & Palmer, 2003).
As stated by Meyer and Palmer in the quote presented above, there are several layers of information involved in learning a new melody. If one looks at one simple note only, the what, when and how -question can already be asked. Imagine examining all the events related to an entire musical piece. However, that is not the purpose of this thesis, but it is related to the types of processes involved in melodic learning. Cortical processing does not stop after one has learned a particular melody. What happens with that type of information and what type of processes are generated when learning sequences of previous learned melodies? In other words, how is a melody represented in the brain after it has been learned and in what way is this representation preserved best when the melody is repeated? Is the mental representation of melody restricted to the exact type of factors used to produce the melody? For example, a melody can be learned by the right hand with a certain type of fingering. If by repetition, the hand used or the type of fingering changes, does this mean that it will not be possible to reproduce the same melody from memory? If this would be the case, then it would also be quite difficult for pianists to perform a musical piece on a different piano then where the piece was learned on. It is safe to say that there could indeed be restrictions to the mental representation of a melody, but it might be more abstract than one thinks. Certain types of effectors (e.g. changing the piano, the hand or the type of fingering) might not be affecting reproduction of a melody. This experiment uses different effectors to see the effect on transfer of learning. The transfer of learning paradigm, originally introduced by Thorndike and Woodworth (1901), explains the effects of performance on prior experience.
Their original idea involved the transfer of information from similar contexts, which is nowadays usually referred to as the identical element theory. This theory implies that “identical elements are concerned in the influencing and influenced function”, therefore depending on a task’s similarity (Thorndike & Woodworth, 1901). In the current study, a distinction is made between three types of transfer conditions. When a task performance in these conditions is facilitated by the training task in another situation, this is referred to as positive transfer. The opposite can be stated as negative transfer. No facilitation or hindrance is known as zero or neutral transfer. Thorndike and Woodworth’s original idea involved the transfer of information from similar contexts, which is nowadays usually referred to as the identical element theory. This theory implies that “identical elements are concerned in the influencing and influenced function”, therefore depending on a task’s similarity (1901). Other transfer theories exist, for example Judd’s theory of generalization of experience (1903), but it is hypothesized that this identical element theory will be most applicable to the results of this particular experiment.
It is proposed by some theories that the effector movements used for a specific task are not determining the representations necessary for a transfer of learning effect (Ivry, 1996; Keele, 1981; MacKay, 1982; Meyer & Palmer, 2003; Semjen & Ivry, 2001). If this is correct, then there would not be a significant difference in whether a task is performed with e.g. the left or the right hand in comparison with the initial task. For example, several studies examined the effects of different effector movements for keypress sequences (Cohen et al., 1990; Keele, Cohen & Ivry, 1990). It appears that a part of the encoding during learning of a sequence happens in an abstract manner independently from the effectors (Grafton et al., 1998; Meyer and Palmer, 2003). Palmer and Meyer tested experienced pianists on their effector independence (2000). During the training session of their experiment, pianists performed a novel melody as quickly as possible. In the test phase, a sequence of this melody was performed with but with either the same or different melodic structure or either the same or different motor movements. It was found that the stronger transfer of learning took place when tested melodies were similar to the trained ones and, importantly, performance was not affected by motor changes. The results from this experiment show that melodies are learned through abstract representations rather than motoric memory (Palmer & Meyer, 2000; Meyer & Palmer, 2003). This experiment was extended by studying the representation of temporal structure
and motor movements in music performers (Meyer & Palmer, 2003). In three experiments, Meyer and Palmer showed that:
1) Meter and motor movements remained in the representation of musical melodies. When meter or motor assignments changed from the training to the test session, performance was slower.
2) Rhythmic structure and motor movements remained in the representation of musical sequences. Transfer of rhythm remained under speed conditions, and motor movements seemed to be independent from rhythm. 3) Transfer of learning effects from one melody to another were greater for rhythm than meter in representation of melodies. When rhythm changed, performance was slower.
From these experiments, it can be concluded that there is no interaction between temporal structure and movement, indicating an independency between temporal and motor components in mental representations of melodies (Meyer & Palmer, 2003). From the different effectors, rhythmic complexity had the most impact on performance rate, at least for skilled pianists. It could be possible that there might be a different result for beginner pianist, as they might focus on different aspects of playing while performing such an experiment. This second experiment by Meyer and Palmer showed that there is more to the situation than simply motoric memory having a transfer of learning effect. The extension to meter and rhythmic changes showed that there a differences in the amount of transfer of learning and that there are limitations to the abstract representation of a melody involved. The current experiment will further investigate those limitations by looking at different effectors as well, with special regards to the limitations related to auditory and motoric memory instead of differences in temporal aspects.
Error
During the experiment, participants certainly will make some errors. In studies testing musical performance, errors are often discarded from the results (e.g. Meyer & Palmer, 2003). However, errors are affecting performance and can have psychological consequences on the performer. General theories of error management will be explained and subsequently, current research on error making related to musical performance will be discussed.
Errors are unintentional happenings that deviate from the initial intended goal (Frese & Keith, 2015). The field of Error Management is involved in dealing
with errors after they have occurred. Error Management attempts to reduce negative effects of errors and to deal with their consequences as quickly as possible after their occurrence. The theory of Error Management also acknowledges that errors are human and they cannot be completely avoided, which is the case for the theory of Error Prevention. These theories are used as approaches for the development of software systems or for management in organization, but can be applied to musicianship as well. Musicians generally attempt to play as little errors as possible. However, as it was just concluded that errors are human, errors cannot be completely prevented and will therefore always happen. What are the neurological bases and psychological effects of errors during musical performance and is there anything known about strategies of dealing with these errors?
Studies measuring brain activity related to correct and incorrect responses to general stimuli are often using fMRI and EEG techniques and it was found that each response elicits a small negativity on the ERP level, but that this negativity is enhanced when preceded by an error (Hoffmann & Falkenstein, 2012). This research takes an interesting approach, since one would expect to measure ERP after an error was made, rather than prior to. This negativity is also found in musical tests, for example Maidhof, Rieger, Prinz and Koelsch (2009) examined ERP effects occurring prior to an error in musicians. Apparently, there are neural processes active before the error related to prediction mechanisms. This was examined by Malekshahi et al., who analysed different neural mechanisms for the detection of late and early predicted errors (2016). It was stated that visual processing is facilitated by several levels of perception enabling the correct type of response. When reading sheet music, this means that a pianist should be able to predict well in advance which notes he/she has to play. Malekshahi et al. found that when the visual input is different than prior expectations, this is processed in a relatively late stage causing prediction errors (2016). This could be interesting in musical research, especially when musical stimuli differ from expectation (e.g. on a harmonic level). To go back to the article by Maidhof, Rieger, Prinz and Koelsch, differences in ERPs ranged up to 100ms before the onset of a note in comparison with notes that were correctly played and errors were played more slowly and caused a delay in time (2009). The experiment was extended in 2013 by Maidhof, Pitkäniemi and Tervaniemi, since previous results could have been caused by the use of different tempi. Previous assumptions thought that the observed pre-error negativity occurring at 70-100 ms before the error is related
to predictive control processes comparing predicted happenings with actual consequences. This experiment used data of ERPs and 3D movement of pianists’ fingers, performing melodies from memory. It was found that the pre-error negativity was visible for errors even with comparable tempi. An interesting finding was that correct notes which were played immediately before an error was played, also elicited a negativity. These results indicate that motoric feedback is important during piano performance when it comes to managing errors and it might be helpful for the prediction of errors.
A negative peak in ERP for the production of errors might be affecting duration time of performance when playing melodies as well. Since duration time is often used as indicator of performance in behavioural tests related to instrumental playing, it is important to find out whether simply discarding errors from the results is not affecting the data. It was found that erroneous keys were pressed with a lower amount of velocity, causing that the wrong notes were played with a decreased intensity (Herrojo Ruiz et al., 2009; Maidhof et al., 2009; Herrojo Ruiz et al., 2011; Strübing et al., 2012). Also, not only the errors themselves, but also the subsequent notes were played slower (Maidhof, Pitkäniemi & Tervaniemi, 2013). Results from these studies indicate that errors might cause a delay in duration time when occurring often during the performance of a melody. Discarding errors from the results in such a behavioural experiment could therefore show a shifted image than what the results otherwise would say.
Psychological effects of dealing with errors was examined by Kruse-Weber and Parncutt (2014), who claimed that current musical pedagogy is often neglecting issues related to error making. How one deals with errors is an important aspect of musicianship and this should be made more discussable. The manner in which a person deals with errors can affect their musical performance, which might even have an influence in behavioural experiments. An important step towards error management in musical practice is to acknowledge that nobody is perfect. Previous research found that expertise in general does not lead towards perfection in performance (Flossmann et al., 2011; Kruse-Weber & Parncutt, 2014; Maidhof, 2013; Zapf et al., 1999). It is thought that experts are better in detecting errors and more quick in correcting them, which can lead to the impression that they are not making errors when their performance is far from perfect (Repp, 1996). With current techniques, it is possible to track errors, so that nothing stays hidden. Once it is accepted that everybody makes mistakes,
steps can be taken towards how to deal with these mistakes. Kruse-Weber and Parncutt (2014) suggest a pedagogical approach towards error management in which it is important to realize when an error is made, what the cause is of this error and how future errors can be prevented.
Methods
The following section will lay out the methodology behind the experiment conducted for this thesis. Overall, the experiment was based on a study by Meyer and Palmer (2003), but was adapted in order to suit the research objectives of
this thesis.
Participants
Two groups of participants were selected for this experiment: left-handed and right-handed pianists. A total of 27 musicians (25 with piano as their main instruments, 2 with piano as second instrument) with different ethnical backgrounds, but resident in either the Netherlands or Belgium, between the ages of 18 and 36 participated. Pianists were selected according to their handedness. Participants were students or alumni from conservatories in the Netherlands or Belgium or advanced amateur pianists. Subjects under the age of 18 were not considered, due to possible effect of higher levels of cerebral plasticity at an earlier age. Participation was voluntary. Informed consent was obtained from all subjects, and the study was approved by the Ethical Committee of the Faculty of Humanities of the University of Amsterdam.
Design and Instruments
The experimental design consisted of a questionnaire study in combination with two behavioural tests. A handedness questionnaire, based on research by Oldfield (1969) and Annett (1970) was used to establish the degree of left-handedness of participants. In this manner, it became possible to evaluate left-handedness and to rate handedness level on a continuous scale. Problems of self-declared left-handedness will then be avoided and it offers room for a variety in the degree of handedness. Secondly, a dichotic listening test will offer insights in hemispheric dominance. Competency of both ears, to recognize double auditory stimuli, is tested, as stimuli are presented simultaneously.
A transfer of learning paradigm, as suggested by Meyer and Palmer, was used for the last part of the experiment (2003). For this part, pianists played simple melodies on a regular and reversed keyboard. Duration of their performances was used as test measure. A MIDI piano keyboard was used to simplify the process of reversing pitches. This test functions to see which elements of learning are transferred when motor behaviour and melodic material is reversed.
Materials
The Edinburgh Inventory Handedness Questionnaire was conducted online, and is an, by Mark Cohen, adapted version of the Oldfield handedness questionnaire (Cohen, 2008; Oldfield, 1971). For the establishment of participant’s levels of musical sophistication, the Goldsmiths Musical Sophistication Index was used (Müllensiefen, et al., 2014). For the first behavioural test, an online dichotic listening test was used which was retrieved from the Online Psychological Laboratory (n.d.).
Eight sets of melodies were composed for the second behavioural test. Criteria for the melodies were based on experiment materials from the study by Meyer and Palmer (2003). Melodies consisted of 13 quarter-notes and were all composed in C major. Sequences contain one specific difficulty (e.g. one necessary repositioning of the hand), but were overall designed to be relatively simple (i.e. without large intervals, no direct repetitions). The decision to use C major for all melodies can be supported by the desire to avoid black keys, which would have created another layer of difficulty. Even though, quarter-notes were structured by four per bar, no meter was indicated to avoid metrical complexity. In general, melodies were designed to have an equivalent level of difficulty.
One melodic set consists of four variations representing several conditions, in which either the sound of the melody is congruent to the original or motor behaviour is congruent to the original. A melody can be presented as follows:
1) Original melody on normal keyboard (sound and motor congruent)
2) Reversed melody on normal keyboard (sound incongruent, motor incongruent)
3) Original melody on reversed keyboard (sound incongruent, motor congruent)
4) Reversed melody on reversed keyboard (sound congruent, motor incongruent)
These variations were played by both the left and the right hand, resulting in eight different conditions. These were randomly presented to the participants. When motor is congruent, this will be referred to as the motor normal condition, whereas when motor is incongruent it is referred to as the motor mirror condition. Keyboard condition refers to whether the participant played the melody on the reversed or normal keyboard. Hand condition signifies the hand that is used to
play the melody, not the handedness of the participant. An example of the four conditions of a melody is presented in the figure below, and a complete overview of the eight melodies with their sequences in the different conditions can be found in Appendix 1. The questionnaires used for this study are presented in Appendix 2 and 3.
Figure 1: Example of the four conditions of Melody 1 as played by the right hand
Equipment
Participants performed the dichotic listening test online. Due to logistic difficulties, it was not possible to have participants tested on the exact same computers. The same set of headphones was used for all participants. Participants performed the performance test on a MIDI-keyboard (M-Audio Keystation MIDI 32). This type of keyboard was specifically chosen for its flexibility to be moved around. Computer software determined keypress onsets and offsets and the keyboard condition (reversed or regular) was scripted. Pitch errors were determined manually afterwards.
Procedure
All participants were tested individually. The two questionnaires were sent prior to the experiment, which allowed the experimenter to select participants who fit the requested criteria the best. The three tests were divided in two experimental rounds. The dichotic listening test formed the first round. The second round, consisting of motor behavioural tests on the MIDI piano keyboard, consisted of a warming-up, a practice and a test session. First, participants were instructed to play on the MIDI-keyboard for 2 minutes, in order to get used to the keyboard itself. To structure the warming-up and to ensure that all participants receive an equal amount of practice on the keyboard, they all had to play the C-major scale 10 times as quickly as possible on both the normal and the reversed keyboard. During the practice session, participants were given the possibility to become familiar with the test melodies on the regular piano. They were presented with one of the test melodies and were instructed to play this melody 10 times as quickly as possible with the left and the right hand. The order of which hand was used first was randomized. During the test phase, the melody from the practice session was presented with its variations in the different conditions. These melodies will have to be played 4 times as quickly as possible. All participants were randomly assigned to two of the eight melodic sets and therefore performed the second round of the experiment twice.
Test melodies were selected according to several criteria, based on Meyer and Palmer’s study (2003). Wrong notes were treated as errors and were included in the results. A separate analysis will be used for the total amount of errors played.
The data was pre-processed before any analysis was conducted. Participants played two sets of melodies with their variations. The training phase for one melody consisted of 20 trials (10 for the left hand and 10 for the right hand), whereas the test phase accounted for a total of 32 trials (4 times 4 trials per condition per hand). Occasionally, participants started a trial but stopped early without finishing. These trials were not included in the analysis and were removed from the data immediately. After this process, a total of 35,928 data points remained. Mistakes made during the course of a trial were encoded as errors and included for the error analysis. The beginnings and endings of trials were manually indicated after which the total duration per trial was calculated. Independent variables were handedness, motor condition, hand condition and
keyboard condition and duration was used as dependent variable for the transfer of learning analysis. For the error analysis, independent variables were the same, but the amount of errors was used as dependent variable.
Results
Dichotic listening test
Based on previous literature, a general left-hemispheric dominance for the dichotic listening test was expected. Table 1 shows the amount of correct answers for left and right handed participants. There was a roughly equal distribution of the level of handedness amongst participants. Notoriously, right hemispheric dominance was found in most left handed and right handed participants, which is not according to general expectation. According to previous conducted research, left hemispheric dominance would be the most expected results from such a dichotic listening test.
Table 1: Mean correct answers of the dichotic listening test
Handedness Mean Handedness Level Mean Correct Responses Left Mean Correct Responses Right Left (12) -71.9 8.15 5.98 Right (13) 82.38 7.14 4.76
