Effects of piano training on executive functions: evidence for the mediation hypothesis in 4- to 5-year-old children

Efectos de lecciones de piano sobre las funciones ejecutivas: evidencia de la hipótesis de mediación en niños y niñas de 4 a 5 años

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Multiple studies have suggested a relation between music and the development of different skills, including language abilities (Chen et al., 2021;Hille & Schupp, 2015) and IQ tests (Barbaroux et al., 2019; Schellenberg & Weiss, 2013) have identified three different kinds of possible links between music and cognition: the association between music abilities and cognition, the effect of listening to music on cognitive tasks, and the improvement of cognitive skills after music training.

Different studies regarding cognitive variables associated with musical aptitude have found a significant correlation with language (Milovanov et al., 2010), arithmetic processing (Foncubierta et al., 2020;Hoch & Tillmann, 2012) and higher order cognitive ability (Swaminathan & Schellenber, 2018).

A second potential relationship between music and cognitive ability would be the enhancement of cognitive performance after or while people listen to music, as described by the controversial so-called Mozart effect, originally reported in connection with visuospatial reasoning (Hetland, 2000). A similar issue has been found in the study of the effects of background music on cognitive performance; for instance, on memory (Richards et al., 2008; Salamé & Baddeley, 1989). Evidence in this area is unclear and, at times, contradictory, yielding different results depending on the population studied. This suggests that personality and musical preferences, type of music, and other conditions of the experimental conditions could affect the results (Cooper, 2020; Schellenberg & Weiss, 2013;Swaminathan & Schellenberg, 2018, Swaminathan et al., 2019).

Finally, Schellenberg, Weiss, and Swaminathan point to a possible effect of music training on cognition (Schellenberg & Weiss, 2013; Swaminathan & Schellenberg, 2018, 2019). Moreno et al. (2011) analyzed the effect of computerized visual art, as well as a music training program on a sample comprising children between the ages of 4 and 6: a significant effect was found for both the verbal intelligence test (WPPSI-III) and on the Go/No-go task for the music training program; but not for the visual art program.

The effect of music training has been shown not only on literacy skills (Slater et al., 2014) and phonological awareness (Degé & Schwarzer, 2011), but in longitudinal studies on different perceptual variables (Fujioka et al., 2006; Strait et al., 2013; Swaminathan & Schellenberg, 2021). In addition, performance was also positively impacted by this type of training when keeping the beat in a finger-tapping task (Slater, et al., 2013; Swaminathan & Schellenberg, 2021).

Regarding the potentially strictly cognitive effects of music training, two different kinds of cognitive variables have been considered: executive functions and higher order cognitive abilities, as measured by IQ tests or academic achievement.

A link between music training and general cognitive abilities (Schellenberg & Weiss, 2013) has been substantiated by several studies involving child (Degé, 2021; Kragness et al., 2021; Norton et al., 2005), and adult populations (Chaddock-Heyman et al., 2021; MacRitchie et al., 2020); for instance, in connection with higher IQ scores (Bilhartz et al., 2000; Schellenberg, 2011; Swaminathanm et al., 2017). Furthermore, studies show that both musicians outperform non-musicians in different executive functions, as well as the impact of musical training on executive functions (Degé, 2021; Degé et al., 2011; Hernández et al., 2021; Moreno et al., 2011; Schellenberg, 2011; Strait et al., 2010; Yurgil et al., 2020).

Executive functions are cognitive processes involved in conscious control. Miyake et al. (2000) and Friedman (2019) claim that three factors underlie executive functions in adult populations: shifting, updating and inhibition. However, some research suggests that structure of these functions differs between children and adults: the existence of a one-factor structure at an early stage has been suggested (Wiebe et al., 2011); that is, when the child turns 10, it splits into 2 specific factors: working memory (WM) updating, and inhibition/shifting (Brydges et al., 2014; Messer et al., 2018). Other research proposes that the same two factors (WM updating and inhibition/shifting) might appear as early as 3 years of age (Miller et al., 2012). Miyake and Friedman (2012) highlight that there is no real evidence of a specific inhibition factor. Thus, the difference in inhibition tasks would be better explained by a general factor of executive functions, while updating tasks would correspond to a combination of this common factor with specific skills. Studies on the development of executive function could therefore point to the existence of an initial general capacity, after which a specific updating capacity would appear.

It is plausible that playing a musical instrument involves high-level skills to facilitate the real-time manipulation of complex information about pitch, harmony, and rhythm encoded in rich notation, as well as requiring the transformation of such information into different movement patterns across the central nervous system. (Soria-Urios et al., 2011; Zhu, 2018). From a neuropsychological perspective, there is some evidence of brain plasticity induced by musical practice (Kausel et al., 2020;Pascuale-Leone, 2003; Schellenberg, 2020).

Apparently, in order to select the correct response and activate the correct motor response, musical training demands access to cognitive functions such as working memory updating and inhibitory control (Bernal-Ruiz et al., 2020; Chen et al., 2020; Degé, 2021, by handling multiple rhythms, interacting with other musicians, and constantly updating the musical notes to be played. Trainor et al. (2009) report a greater induced gamma wave response to musical sounds in musicians compared to non-musicians, claiming that musical training affects oscillatory networks associated with executive functions in the brain, thus concluding that this could improve performance in a wide range of cognitive domains.

Although they come from different research traditions, executive functions and general intelligence have been shown to share a substantial relationship. In a Structural Equation Analysis, Wongupparaj et al. (2015) found that executive functions (Inhibition and Updating), together with short-term memory storage, explain approximately 60 % of the variance of general intelligence, suggesting executive function sub-processes as fundamental pieces of different components of intelligence.

Consistent with this interpretation, some authors have hypothesized that executive functions mediate the effect of music training on general cognitive abilities, claiming that musical training positively affects executive functions (Chen et al., 2021; Hannon & Trainor, 2007; Schellenberg & Peretz, 2008; Schellenberg & Weiss, 2013; Swaminathan & Schellenberg, 2019). These improved functions could in turn explain better results in several cognitive ability tests (Schellenberg & Weiss, 2013), while no direct relationship between music training and general cognitive abilities is apparent.

From a methodological perspective, this hypothesis implies three main predictions: a positive effect of music training on executive functions, a positive effect of musical training on general abilities, and finally, disappearance or decrease of this effect when executive function variables have been statistically controlled. As discussed, there are sufficient elements to support the prediction of said positive effect on general cognitive abilities (Swaminathan & Schellenberg, 2019) which, when found, tends to disappear if executive functions are statistically controlled, as expected in prediction 3. For example, Degé et al. (2011) report that, in a fluid intelligence test, the benefit of music training in a group of children aged 9 to 12 disappeared when five cognitive variables related to executive functions (set shifting, selective attention, planning, inhibition, and fluency from the NEPSY II test) were statistically controlled. Likewise, Franklin et al. (2008) found that the effect of music training on verbal memory in children under 10 disappeared when working memory was controlled.

The relationship between music training and executive functions is supported by some research: for example, a positive effect on auditory working memory tests was found under certain circumstances (Pallesen et al., 2010; Strait et al., 2012; Zhang et al., 2021.). Similarly, other studies report that musicians outperformed non-musicians inhibitory control tasks (Rodríguez-Gómez & Talero-Gutiérrez, 2022; Strait et al., 2010). In a quasi-experimental design with 9- to 12-year-old children, Schellenberg (2011) found a significant effect on a working memory test (Digit Span), but not in verbal fluency, Tower of Hanoi, Wisconsin, Card Sort Test, and Sun-Moon Stroop.

Most of these findings are based on non-experimental designs, resulting in only a small number of randomized experimental studies (Mehr et al., 2013; Swaminathan & Schellenber, 2019). While they have a clear advantage in terms of ecological validity, non-experimental designs also show an important limitation: the effects are measured using previously trained and untrained participants, making the direction of the effects indiscernible. The results could be explained because by musical training, but it could also be the case that subjects with higher abilities were more likely to have prior participation in musical activities. Therefore, an experimental design would be necessary that would allow differentiation between any of the two possible causal directions. Experimental studies evaluating the effect of piano lessons on executive functions have found a positive impact on these cognitive processes in older adults. (Bugos, 2019).

As plausible as this hypothesis is, further experimental studies are required to test it in different contexts and populations, including the analysis of a variety of executive functions and measures of general intelligence. This study has two main purposes: the first one is to assess the potential effect of music training with Bastien's piano method on general cognitive abilities. This study also seeks to test the hypothesis of mediation of music training on executive functions through Bastien's piano instruction method (Bastien, 1990) using an experimental design. Following the evidence of a 2-factor structure during childhood, two executive functions were considered: inhibitory control and working memory updating.

These results confirm the association between musical training and general cognitive abilities (MacRitchie et al., 2020; Schellenberg, 2020; Schellenberg & Peretz, 2008; Schellenberg & Weiss, 2013; Swaminathan & Schellenberg, 2019). Furthermore, the experimental nature of the study gives rise to a causal interpretation. As mentioned in the introduction, both experimental and non-experimental designs have their own advantages and disadvantages, which means that the convergent results from both designs give stronger support to the hypothesis suggesting that musical training increases general cognitive abilities.

Multiple studies using different populations, measurements, and aspects of general cognitive abilities, as well as different kinds of training, are important in order to understand the particularities of these effects. In this study, we show evidence of the effect of music training on general cognitive abilities, as measured by the Weschler Preschool and Primary Scale of Intelligence (WPPSI-R) through the vocabulary, comprehension, and arithmetic subscales.

Previous studies report contradictory results regarding the mediation of executive functions in the relationship between musical training and general cognitive abilities (Bowmer et al., 2018; Bugos et al., 2022; Schellenberg, 2011; Strait et al., 2010). A thorough analysis of the relevant literature reveals that the real challenge is to determine which aspects of executive functions play a role in mediation and, more specifically, to what extent and under what conditions. In this sense, these results can be interpreted as evidence of a particular case of mediation in a population of 4- to 5-year-old children trained in piano with the Bastien Method.

To evaluate the mediation hypothesis, we consider three of its main predictions and contrast them with our data: 1) the positive effect of executive function training; 2) the positive effect of higher order abilities training, and 3) the disappearance or reduction in the effect on general abilities when executive functions were statistically controlled. As for the second prediction, higher-order ability was affected by training in the expected direction: in one component of the WPPSI (Comprehension) the training effect was significant; in the others (Arithmetic and Vocabulary) they were marginally significant. (Table 1).

The first prediction was only partially verified. For Stroop, it was significant in the Neutral, the Man/Woman and the Emotional versions of the task (Table 2). For working memory updating tests, only when children had to maintain 8 rather than 6 stimuli in their memory in the Toys task was the effect significant (Table 2). This suggests that when the task requires less cognitive demand, as in the case of six stimuli tasks, the magnitude of the effect could not be detected with the sample size used in this experimental design. Karbach and Kray (2009) also report a case where an effect associated with training cannot be detected in tasks with a low cognitive demand but becomes significant in a similar task when cognitive demand increases. Furthermore, we found evidence of a positive effect of training on the Go/No-go scores, with significant differences in execution errors for the neutral version as well as in omission errors for the emotional version of the task (Table 2).

According to Johnstone et al. (2005) the effect size in omission errors discovered in the current study for the emotional form of the Go/No-go task reaches the level of a large effect, but the neutral version only approaches the level of a medium effect. A possible interpretation of this pattern would be that the emotional task involves a higher cognitive demand because of the facial expressions (Mancini et al., 2022). An alternative interpretation would be that the character of the music training specifically facilitates the manipulation of emotional stimuli. To evaluate the plausibility of both interpretations, studies including both emotional and no-emotional types of training as well as emotional and non-emotional stimuli should be conducted.

To study the possible role of executive functions mediating the effect of training on general abilities, we decided to extract individual scores for two latent variables related with updating and inhibitory control. Using these scores, we found some support for the third prediction of the mediation hypothesis. Particularly, we found evidence of an indirect effect between training and arithmetic ability, caused by working memory updating (Table 3). Similarly, results suggest mediation of updating as well as of inhibitory control between training and comprehension ability (Table 3). These results agree with evidence from pure correlational studies, such as Degé et al. (2011), using a completely different set of tests

With the aim to understand the different patterns regarding the three general abilities, we analyze the particular traits of the three subtests through the WIPPSI. As for the Arithmetic score, participants had to solve a series of mathematical problems. These results (Table 3) are consistent with literature that reports a relation between mathematical abilities, specifically with respect to arithmetic problems and working memory (Allen et al., 2019; Kroesbergen & van Dijk, 2015). This relation seems to be explained by the important working-memory demand of arithmetic problems, as suggested by the strong correlation between children’s accuracy and the representational set size (maximum number of units required to be held in working memory to solve a given arithmetic problem) (Allen et al., 2019; Giofrè et al., 2018; Klein & Bisanz, 2000).

For the Vocabulary subtest, children had to give definitions for different words. This semantic demand clearly seems to be related to a searching process in long-term memory, rather than working memory as preview evidence has suggested (Artuso & Palladino, 2019; Otem, 2003). Furthermore, Rabbitt et al. (2007) found that different variables highly associated with decline of executive functions in adults (age, loss of brain volume, carotid and basilar artery blood flow, and white matter lesions) had only a very small effect on vocabulary. This finding could be interpreted as lack of effect of executive function on vocabulary, and would be in line with this study results, where no mediation effect from our executive function variables was found.

Finally, the Comprehension subtest requires explanations of a series of situations and activities that involve the management of general principles and social situations for decision-making. In general, subjects must decide between different options, some of them trivially correct. Presumably, children had to inhibit these trivial solutions to achieve higher scores in the subtest. However, relevant evidence seems to be unclear because studies in different populations using the Iowa Gambling Task (IGT) as a measurement for decision-making failed to show a correlation with executive functions (Frischen et al., 2022; Wongupparaj et al., 2015). Conversely, Brand et al. (2006), claim that, in situations under ambiguous conditions like the IGT, the role of executive functions could be negligible, but when it is possible to assess the risks of the decisions, those functions become relevant.

Giofrè et al. (2018) run a confirmatory factor analysis that showed that verbal and working memory can be differentiated and that these factors have a different predictive power in explaining unique portions of variance in reading and mathematics. These results point to the importance of distinguishing between working memory modalities in evaluating the relationship between mathematics or arithmetic skills and verbal abilities.

This study presents relevant information that confirms exposing preschool children to formal piano training, using the Bastien method, influences executive functions and general cognitive skills. By using an experimental design approach, a causal interpretation between piano training and improvements in general cognitive abilities and executive functions can be confirmed.

Specifically, an improvement was found in inhibitory control measured through the Stroop tests, particularly in the neutral, male/female and emotional versions of the task. Positive results were also found in inhibitory control measured through the Go/No-go tests, both in executive errors and in omission errors in the neutral version. Regarding working memory, better results were identified in the experimental condition in the more complex updating tests.

Regarding cognitive skills, differences were found between participants belonging to the experimental group compared to the control group in the three measures used, namely: comprehension, arithmetic and vocabulary.

Finally, the findings of this research partially support the mediation hypothesis for 4- to 5-year-old children. These results provide experimental evidence in favor of this hypothesis specifically for working memory updating as a mediating variable of arithmetic ability measured by WIPPSI. This conclusion follows from the clear advantage in WIPPSI scores in the group of children who receive musical training with the Bastien method and the tendency of this effect to disappear when executive function variables are statistically controlled, except in the case of arithmetic cognitive skills.

It is important that future research delves into the variation in executive function processing results when using tasks with affective versus neutral content.

Furthermore, future studies need to investigate what other training programs may have similar effects on executive functions as those found using piano training. One of the limitations of this study was the sample size. It would be valuable in future research to test the mediation hypothesis with a larger sample size to better understand whether the mediation between executive functions and cognitive skills is limited to arithmetic skills only or whether the results may vary with a larger sample size. These results allow for a better understanding of the development of executive functions at an early age, which contributes to the theoretical understanding of cognitive issues. This study also provides input for decision makers to better understand the impact that learning an instrument has on human and social development.

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