The Effect of Physical Play Experiences on Early Childhood Non-Cognitive Skills Development

This study aimed to verify the hypothesis that the acquisition of non-cognitive skills is affected by physical play experiences in early childhood. Research reports from the Organization for Economic Co-operation and Development state that the development of non-cognitive skills is affected by factors such as the quality of care and play experiences in early childhood. However, there is insufficient evidence regarding this hypothesis. To provide concrete evidence on how non-cognitive skills develop, this cross-sectional retrospective study was conducted. First, a questionnaire survey was conducted with university students and structural equation modeling was used to study the effect physical play experiences in early childhood had on non-cognitive skills in university, as represented by the Big Five personality traits. Second, to examine the perceived benefits of physical play experiences, participants were asked to write freely about their autobiographical memories of physical play experiences in early childhood. The narratives were visualized through co-occurring network analyses with text mining using KH Coder. The results showed a correlation between sufficiently rich physical play experiences in early childhood and the adult personality trait of attachment. Additionally, a correlation between personality traits and the quantity and quality of the subjective benefits of physical play experiences was observed. These findings imply the importance of physical play experiences during early childhood as the determinants of the development of non-cognitive skills.


Introduction
Recently, the development and support of non-cognitive skills have become core issues in early childhood education and are being incorporated into early childhood education curricula worldwide (Cherrington, & McLaughlin, 2018;Cherrington, 2018;Organisation for Economic Co-operation and Development, 2018). Research affirms the importance of supporting the development of non-cognitive skills in children for positive short-and long-term outcomes (Shonkoff & Phillips, 2000). Additionally, non-cognitive skills are effectively developed in early childhood when brain plasticity is high (Cunha & Heckman, 2007), and research into the development of non-cognitive skills continues to advance globally. However, reports on the acquisition and development of non-cognitive skills in early childhood are limited to the impact of the quality of childcare and play experiences on these skills (Rosenthall & Gatt, 2010). The limited research in this area may be partially owing to the emphasis on improving the quality of play rather than the acquisition or development of non-cognitive skills in early childhood (Muto, 2016).
Many longitudinal cohort studies have examined the impact of non-cognitive skills on the social life of an individual. Such studies have been conducted not only in the United States but also in other countries including Australia (Marks, 2016), New Zealand (Silva, 1990), the United Kingdom (Goodman, Joshi, Nasim, & Tyler, 2015), and Norway (Magnus et al., 2006). However, Bolli and Hof (2014) noted that, although many studies suggested that non-cognitive skills substantially affect life outcomes, little is currently known about the impact of education on non-cognitive skills; thus, the authors focused on work-based education in Switzerland and asserted that such education has a greater impact on non-cognitive skills than school-based higher education. Carneiro, Crawford, and Goodman (2007) similarly analyzed the determinants of cognitive and non-cognitive skills among 11-year-olds in the UK; they found that both skills are strongly dependent on the family background and home learning environment of children, and that non-cognitive skills may be more affected by such factors.
However, the definitions of non-cognitive skills are diverse (Carneiro et al., 2007), and researchers question what "none" refers to in "non-cognitive skills." The term was originally coined in the field of economics. Given that non-cognitive skills were initially discussed in the field of psychology using existing psychological concepts, such discussions have become part of a multi-layered narrative with theoretical and empirical research significance (Nishida, Kubota, Tonegawa, & Endo, 2018). A collection of concepts have emerged that have been discussed in the context of individual studies under the blanket concept of "non-cognitive skills," creating conceptual overlaps and gaps. Heckman and Kautz (2012) called personality traits and preferences "non-cognitive skills" to distinguish them from cognitive skills. Given that non-cognitive skills have high predictive validity in economic and labor markets and are the basis for interventions in education, much attention has been given to better understanding personality traits. Subsequently, increasing discussion in the field of psychology has focused on whether personality traits, which are used as indicators of non-cognitive skills, are measurable factors that can be used to explain individuals' behaviors. Roberts (2007Roberts ( , 2009 argued that an individual's personality is a response to a situation and its analysis is possible as a stable and consistent quality that represents the individual's behavior, feelings, and thoughts. Despite ongoing debates in recent years regarding the impact of an individual's personality in any given situation, research supports the stability and consistency of personality, leading to the general acceptance of Roberts' claims. implies that personality traits or skills are in line with existing frameworks that suggest individual characteristics can be developed through educational practices (and particularly with the Big Five, which distinguishes five basic aspects of personality). Furthermore, both the OECD and Center for Educational Research and Innovation plan to conduct an international comparative study of non-cognitive skills, beginning in 2020, based on the definition of non-cognitive skills as personality traits (OECD, 2018). The Big Five has also been applied as personality traits and a measure of non-cognitive skills in previous studies, including one on the effect of university education on non-cognitive skills among students in Australia (Kassenboehmer, Leung, & Schuler, 2018). Additionally, in a study on non-cognitive skills in adolescents, Gutman and Schoon (2013) showed that grit, self-control, and creativity have tendencies similar to personality traits, suggesting that the "skills contents" of non-cognitive skills may share commonalities with personality traits.
The use of the Big Five personality traits as a measure of non-cognitive skills had a degree of validity in previous studies. Therefore, in this study, the Big Five-as measured using the standardized FFPQ-50 for Japanese university students (see the Construction of the Short-form of the Five Factor Personality Questionnaire; Fujishima, Yamada, & Tsuji, 2005)-was employed as a measure of non-cognitive skills.

Physical Play in Early Childhood
"Physical play" was defined as a general term for "play" in which children perform by vigorously moving their entire body, including their mind. The term encompasses activities conducted in nursery settings, including physical, movement, group games, and physical expression, as well as outdoor play and nature experiences. In this section, the significance of the relationship between physical play experiences in early childhood and non-cognitive skills is discussed based on the results of prior studies.
To address the decline in the level of and willingness to engage in physical activity among children, Susuki (2016) elaborated on the concept of "fully playable (Japanese: a-so-bi-ko-mu)" (Akita, 2009) and developed the Playability Scale of Young Children to clarify the factors that regulate "fully playable" and improve the quality of children's play. In this scale, being fully playable involves five factors: "smooth transition between reception, empathy, and reaction;" "adaptability to surroundings;" "motivation for exploration;" "creativity and imagination with focus;" and "affinity and cooperation." Thereafter, the scale was used to examine how changes in fully playable situations might improve the quality of play by using dodgeball (Suzuki & Suzuki, 2017) and physical expression play (Susuki, 2019) during free play. Compared to traditional physical activity goals that relies on physical effects (e.g., strength and motor skills), focusing on the psychosocial aspect of "fully playable" raises the motivation for physical play activities and producing physical effects (Takenaka, 2017). Although such studies did not delve into the abilities that children acquire by entering into a "fully playable" state or the impact of such states on their lives afterward, they suggest the possibility that non-cognitive skills may result from physical activities, thereby directing future research on physical play activities.
To date, few studies have directly addressed non-cognitive skills by focusing on physical play activities during childhood. Two possible means exist for measuring the effect of specific physical activities on non-cognitive skills: using an index of non-cognitive skills and examining its relationship to 1) personality traits as non-cognitive skills or 2) physical strength/motor skills. The former approach was taken by Yamakita, Ando, Sato, Suzuki, and Yamagata (2017), who examined the relationship between the affiliation to sports clubs and the non-cognitive skill of grit (Duckworth, Peterson, Matthews, & Kelly, 2007) in elementary school children and reported that grit was higher in children who were affiliated with sports clubs dedicated to group sports. Similarly, Nakano, Tanaka, Ikeda, and Yamauchi (2020) examined the effect of an outdoor summer camp on the personality traits of middle school students and found that the experience had a significant effect on personality traits as social and emotional skills and its degree of impact depended on participants' individual characteristics. Additionally, Ito et al. (2018) positioned safety, autonomy, creativity, cooperation, and interest as non-cognitive skills to evaluate the development of young children in play settings centered around their physicality.
Several studies have taken the latter approach of examining the relationship between physical strength and motor skills. Kasuga (2019) and Nakano (2019) both found a close relationship between physical strength and motor skills, based on the Big Five personality traits in young children. These studies were based on guardians' evaluations by proxy of non-cognitive skills and reported that fostering non-cognitive skills can have a positive effect on later physical strength improvement. Both Goto and Kasuga (2017) and Minami, Kasuga, and Goto (2019) reported that differences in physical strength and motor skills among 5-year-old girls can affect non-cognitive skills, and performing physical activities while following rules or practicing communication with multiple people increases coordination, extraversion, and integrity.
These findings suggest that non-cognitive skills may be developed through the promotion of exercise in early http://journal.julypress.com/index.php/jed Vol. 4, No. 3;December, 2020 childhood. In this study, we expected that new value to children's physical play activity may be added by demonstrating the relationship between physical play experiences in childhood and non-cognitive skills, thereby filling a noted gap in the research.

Autobiographical Memory
The Big Five personality traits were measured for adults (i.e., university students) as non-cognitive skills fostered by the promotion of exercise in childhood. Therefore, autobiographic memory was used to examine factors related both to personality traits and to the type and content of physical play experiences in early childhood. However, memory is difficult to evaluate objectively since it is accompanied by forgetting, fluctuation, and modification and also can include various biases and rationalizations. This section discusses the validity and limitations of memory.
Almost 40 years have passed since autobiographical memory was first studied (Csikszentmihalyi & Beattie, 1979). In developmental research, autobiographical memory is defined in episodic memory as a memory that can form one's own story that is meaningful to the story of one's life (Nelson, 1992). Singer and Salovey (1993) proposed the concept of "self-defining memory" in autobiographical memory, arguing that memory is the basis of one's self. Additionally, autobiographical memory is closely related to personal identity; i.e., a memory that symbolizes one's self. Moreover, research has demonstrated that autobiographical memories are less concerned with the accurate recall of past events than with relaying stories imbued with meaning regarding the core of one's identity (Neimeyer, & Metzler, 1994). Since 2000, research on the function of autobiographical memory has become active, and several journals (Applied Cognitive Psychology, 2009;Memory, 2003Memory, , 2013Memory, , 2015 have continued to address the function of autobiographical memory (Bluck, 2003(Bluck, , 2009Memory, 2013;Nicole & Wang, 2015). In the process, Singer and Blago (2004) stated that autobiographical memory comprises information that has a strong connection with one's past self. In addition, Rubin, Schrauf, and Greenberg (2003) showed that there are two subjective sensations associated with the recall of autobiographical memory: the feeling of re-experiencing an event and the belief that the memory of it is correct. At present, autobiographical memory is considered to have three functions: self, direction, and society (Bluck, 2003;Sato, 2008). "Self" is the function by which memory guarantees self-consistency and maintains a favorable self-image; "direction" is a function that makes use of past problem-solving and decision-making experience; and "society" is a function that uses past experiences as a material for conversation, reminding one of relationships with people and deepening bonds with them.
Specific memories available for recall, among the vastness of past experiences, tend to have high personal significance. They reinforce a consistent sense of self and are highly likely to affect one's life going forward. Based on their analysis of the life histories of adult participants，Habermas and Bluck (2000) specifically emphasized adolescence as the period when the motivation and ability to conceptualize one's life as a consistent life story emerges. Reports suggest that humans begin recalling episodic memories with context at around four-years-old (Bruce, Phillips-Grant, Wilcox-O'Hearn, Robinson, & Francis, 2007). Therefore, childhood memories recalled upon entering adulthood are reliable. In this study, the autobiographical memories for physical play experiences in early childhood were interpreted as "the subjective benefits" of physical play and were used as a qualitative measure.
Conversely, research relying on autobiographical memories becomes a cross-sectional retrospective study owing to the research methods employed. Measurement accuracy tends to be relatively low in such studies compared to intervention and prospective cohort studies. Specifically, bias regulation (the confounding factor) will impact personality traits relative to the relationship between the causal variable of physical play experiences in early childhood and the resultant variable of personality traits in adulthood. Given that it is difficult to determine confounding factors that indirectly influence personality traits, the factors and degree of influence cannot be clarified. Furthermore, although it may be possible to clarify the existence of the relationship and trend between physical play experiences in early childhood and the resultant personality traits in adulthood, the limitations of this study prohibit a description of their level, degree, or causality. To address these limitations, longitudinal prospective studies are required. Therefore, this study should be considered a pilot study, with an objective of furthering the direction of future research; specifically, it examines the cohorts to be used as participants and factors to be measured and presents the resulting perspectives.

Objectives
The ultimate goal of this study was to clarify the determinants and mechanisms involved in the development of non-cognitive skills in physical play experiences in early childhood. As the first stage of the larger study, the following smaller studies were conducted to verify that physical play experiences in early childhood impact http://journal.julypress.com/index.php/jed Vol. 4, No. 3;December, 2020 non-cognitive skills.
Study I aimed to determine the physical play experiences in early childhood and the degree that such experiences affected non-cognitive skills in adulthood. Using a quantitative approach, the effect was analyzed and examined using structural equation modeling (SEM). In Study II, the quantitative confluent relationships obtained in Study I were qualitatively visualized. The autobiographic memory of physical play activities in early childhood was treated as a "subjective benefit" of physical play, and its relationship to non-cognitive skills was analyzed using co-occurrence network analysis.
This study was a mixed-methods study consisting of an explanatory sequential design (Teddie, & Tashakkori, 2009) and connects the individual experiences and stories detailed in Study II to the statistical results obtained in Study I. In both cross-sectional retrospective studies, it was difficult to establish the confounder in retrospect, when compared to longitudinal prospective studies. Therefore, a major shortcoming of the study is its difficulty in determining bias regulation. However, to satisfy the urgent need for evidence related to this particular topic within the early childhood education field, this study attempted to provide at least some evidence on non-cognitive skills despite this noted challenge.

Study I
Study I utilized the quantitative approach of SEM to investigate the degree that physical play experiences in early childhood influence non-cognitive skills in adulthood. 1) Physical play experiences in early childhood consisted of four elements-Types, Characteristics, Motivation ("full playability"), and Location-that were adopted based on existing scales, classification schemes, and theories. Participants rated their reflections of early childhood for each item using a five-point Likert-type scale that ranged from 1 (never) to 5 (very often). The initial 27 items (74 sub-items) for physical play experiences in early childhood were subjected to factor analysis (maximum likelihood method), leading to the latent variables being reorganized as 5 factors of 22 items (58 sub-items) (see Table 1).
2) Big Five personality traits (non-cognitive skills) were evaluated with the FFPQ-50, which consisted of 50 five-factor items (see Construction of the Short-form of the Five Factor Personality Questionnaire; Fujishima et al., 2005). Responses ranged from 1 (strongly disagree) to 5 (strongly agree). The FFPQ-50 is compliant with other global and standard personality tests that utilize the five-factor model, such as the NEO Personality Inventory (Costa & McCrae, 2008), but was specifically designed to reflect a Japanese understanding of personality. The scale quantifies five so-called "super traits"-Extraversion, Attachment, Controlling, Emotionality, and Playfulness-each consisting of five component traits (25 total; Table 2). Before the SEM analysis, FFPQ-50 items with a factor loading < 0.5 were excluded from the model.

SEM Data Analysis
The degree that a person's physical play experiences in early childhood influenced their non-cognitive skills in adulthood was examined using SEM, based on our hypothesized model. Excel software was used for statistical analysis.

Study II
Study II utilizes a qualitative approach to connect physical play experiences during early childhood (recounted as autobiographical memories) to specific subjective benefits in adulthood (in the form of enhanced non-cognitive skills) using co-occurrence network analysis. 2) Non-cognitive skills in adulthood (i.e., at university age) were measured using four question items, corresponding to the four Big Five personality traits measured on the FFPQ-50, which achieved significant path coefficients in the model tested in Study I: i.e., Extraversion vs. Introversion, Attachment vs. Separateness, Controlling vs. Naturality, and Playfulness vs. Practicality. Participants rated themselves in each dimension on a six-point Likert scale that ranged from 6 (very extroverted) to 1 (very introverted) based on their current personality as an adult university student.

Data Analysis for Text Mining Using KH Coder
Data were analyzed by text mining using KH Coder (Higuchi, 2014a(Higuchi, , 2014b statistical software. Text mining is a collection of analytic methods often employed in qualitative research to systematically process, quantify, and visualize textual information. This approach was utilized because it allows qualitative text data to be treated similarly to numerical data and can reduce the analyst's bias.
Specifically, analysis was conducted according to the following procedure: 1) Participants' written responses detailing the subjective benefits of their physical play experiences in early childhood were converted into digital text data.
2) All text data were morphologically parsed using ChaSen software. The resulting data were cleaned as follows: I. Words that imply the prompt itself (e.g., "remember" and "memory"), and words without a clear meaning in isolation were not extracted. II. Some words (e.g., "climbing pole" and "tag" (Japanese: oni-asobi) were manually extracted as compound words. III. Synonymous words were collapsed into a single term.
3) Morpheme analysis was conducted via text mining. 4) Co-occurrence network analysis can be used to visualize associations between words in a dataset and was conducted to visualize the associations between words and non-cognitive skills (personality traits). Co-occurrence networks represent words as circles ("nodes"), whose size corresponds to their usage frequency in the dataset. Word pairs that "co-occur"-i.e., appear in similar contexts or locations-are connected by a line ("edge"). The strength of an association is represented by the thickness of the edge, rather than the relative http://journa position of Jaccard ind

Ethica
These surv this study considerat Participant  The effects of physical play experiences in early childhood on non-cognitive skills in adulthood were analyzed using SEM in three parts.

Study
1) First, the relationship between the overall factors of physical play experiences and the overall factors of non-cognitive skills was analyzed. The path coefficient from physical play experiences in early childhood to non-cognitive skills was high (0.701; Figure 1).
2) Second, the relationship between the overall factors of physical play experiences in early childhood and each latent variable of non-cognitive skills was analyzed (Figure 2). The overall factors of physical play experiences in early childhood had the strongest effect on "Attachment" with a path coefficient of 0.350, followed by "Extraversion" (0.276) and "Playfulness" (0.241).
3) Finally, the relationship between the latent variables of each physical play experience in early childhood and the latent variables of non-cognitive skills was analyzed. Physical play experiences in childhood had effects on the latent variables of non-cognitive skills. The strongest positive association observed was between Motivation ("full playability") and Attachment (0.701), followed by Characteristics ("highly active") vs. Extraversion (0.611), Type ("active") vs. Playfulness (0.412), and Motivation ("full playability") vs. Controlling (0.312). The model had inadequate goodness-of-fit (GFI = 0.831, AGFI = 0.803, RMR = 0.150, RMSEA = 0.061), perhaps because many of the sub-items were excluded when the variables were reorganized before testing. However, some of this lack of fit might be forgivable since the model purports to describe relationships based on childhood recollections, a bias-prone metric that is difficult to control for.

Discussion
The experience of being "fully playable" has a strong effect on the personality traits of attachment (warmth, cooperativeness, trustfulness, empathy, respect for others) and controlling (meticulousness, persistence, responsibility, self-control, deliberateness). Further, the difficulty and variety of play has an effect on the personality traits of extraversion (activity, dominance, gregariousness, excitation-seeking, attention-getting) and playfulness (curiousness, imaginativeness, inner sensibility, rigidity). The results showed a correlation between sufficiently rich physical play experiences and the personality trait of attachment as an adult. A correlation between a high level of activeness during play and the trait of extraversion was also found.

Study II
In total, 349 episodes were recounted (average = 1.7 per participant). Text mining extracted a total of 43,545 words: 14,427 words excluding commonly used words such as particles and auxiliary verbs, 3,693 unique words, and 3,315 words used.   -rated Extraver " "ball," "tag, are well illus , and tag with on as an adul 3.71 1.

Results: Words Characterizing the Subjective Benefits of Physical Play Experiences in Early Childhood
sion "friends," "soc l memories. T y baseball, so rast, high selfand "dislike."  of attachment is linked to the development of diverse non-cognitive skills, and the perspective of individual development, of encountering different sorts of people and accumulating different sorts of experiences, is essential (Vaughn & Bost, 1999). Moreover, in early childhood, play that involves numerous other people is understood to affect the development of attachment. As seen in this study, attachment is fostered over a long period up to adulthood. Therefore, future studies should investigate not only the factors that mediate attachment but also models that incorporate adjustment factors in a complex manner (Kabaya, 2017). In contrast, participants who self-rated "separateness" highly as a personality trait cited autographical memories with experiences in which they sought to maintain high self-esteem, hated to lose, and became absorbed in honing their skills in isolation. Although their experiences differed from those described in the "attachment" cases, those closer to the separateness pole of Separateness-Attachment are said to demonstrate interpersonal separation and individuality (The Society for FFPQ 's Research, 2002, p. 6). Moreover, the commonality between separation and individuality tended to be high.
(2) Participants who self-rated "extraversion" highly as a personality trait possessed autobiographical memories of their devotion to play, characterized by vigorous physical activity that was performed in groups with older siblings and other children. Extraversion indicates proactiveness in interpersonal relationships as well as the tendency to seek intense stimulation and risk (The Society for FFPQ 's Research, 2002, pp. 4-5). Individuals who possess such qualities often talk about their active experiences encountered through baseball, soccer, and other games; their experiences of having played gregariously in groups; and of having pursued excitement. In contrast, participants who self-rated "introversion" highly characteristically recalled, as autobiographical memories, their experiences of "having played quietly indoors rather than outdoors" and "being alone or with brothers/sisters, instead of with many people." (3) Many participants who self-rated "controlling" highly as a personality trait possessed autobiographical memories of having become immersed in organized play outdoors with friends and their fathers, although they hated to lose. The fact that these participants often talked about their experiences of physical play in early childhood; of systematic, organized, and physical play that they felt comfortable with and regarded as a benefit, coincided with the controlling pole in personality traits, where people can consciously and purposively control the self and the environment. In contrast, participants who rated "naturality" highly as a personality trait possessed autobiographical memories of preferring the kinds of play where they could change the rules themselves. Those who are closer to the naturality pole reportedly do not try to artificially control their environment but instead respect natural frameworks (The Society for FFPQ 's Research, 2002, pp. 6-7). The fact that these participants talked about their experiences of preferring loose rules and playing haphazardly, non-competitively, and flexibly is thought to have commonality, as with "controlling" types, with their current personality traits and interest in the quality of experiences.
(4) Participants who self-rated "playfulness" highly as a personality trait possessed autobiographical memories of the fun and excitement, creating "hideouts" or "forts" with their friends, and competing among themselves to make things. Compared with the play experiences seen with the other personality traits, many of these individuals were more imaginative and freewheeling. They talked about innovative and enterprising pleasures. Those close to the playfulness pole are said to show a tendency to give themselves over to overflowing abundance and transcend play to out-of-the-ordinary experiences (The Society for FFPQ 's Research, 2002, p. 8). They showed a tendency to overlap the current self with these autobiographical memories. In contrast, participants who self-rated "practicality" highly showed a tendency to have had the experience, as an autobiographical memory, of immersing themselves in ball games that they played together with older children and older brothers. Those close to the practicality pole reportedly show a tendency to be steadfast and carry out actions without becoming bogged down in emotions (The Society for FFPQ 's Research, 2002, p. 9). However, although not as typical as those seen in the memories of playfulness, participants showed a tendency to talk about play that was steadfast, conservative, organized, and disciplined.
In summary, participants showed a tendency to talk about characteristic experiences of physical play in early childhood that had different tendencies according to both their personality trait factors and the opposite poles of each trait. Simultaneously, commonality was seen between a personality trait as one's current non-cognitive skills and the relationship with the quality perceived within their play. In other words, it became possible to identify the aspect of the participants perceiving specific subjective benefits derived from the play that they experienced in early childhood. liable to be reorganized to fit his/her self-schemata. Moreover, Cappeliez, O'Rourke, and Chaudhury (2005) as well as Cully, LaVoie, and Gfeller (2001) stated that the recall function for autobiographical memories is related to one's personality traits, sense of happiness, and degree of satisfaction with one's life, and is linked to the self in different forms. As to the question of what the assessment of one's personality traits is based on, the researchers cite the experiences that participants recalled as an example. As stated by Ota (2009), the content of past experiences recalled by university students is closely related to the formation and transformation of self-concept; thus, such content affects their personality traits.
Given that the quality of physical play experiences in early childhood, used in this study as autobiographical memories, showed a tendency to have a commonality with personality traits, supports the hypotheses of this study that (1) a relationship exists between the factors that form personality traits and the experiences of physical play in early childhood; and (2) despite the bias owing to various factors found both inside and outside the individual at that particular timepoint, as well as the time leading up to it, experiences of physical play in early childhood had an influence on adults. Our findings also suggest that experiences of physical play in early childhood affect the development of non-cognitive skills.

Limitations and Challenges
This study had the following limitations and challenges. First, although the hypothesis that physical play experiences in early childhood affect the development of non-cognitive skills was supported, the evidence did not sufficiently illustrate what or how many physical play experiences were engaged in by the participants.
Second, from a methodological point of view and based on the first limitation, it was necessary to remove the influence of incentive and culture, which are other key factors that can modify behaviors, when analyzing the effect of personality on the behavior of individuals. However, distinguishing the effect of non-cognitive skills from incentives and motivations, which differ depending on the situation, was challenging, and the controls for doing so were insufficient in this study. Simultaneously, this was a limitation related to having used autobiographic memories as data. Despite these limitations, the presence of a relationship was investigated, first using quantitative analysis and then through qualitative analysis of participants' free-writing samples regarding subjective benefits. The significance of this study was confirmed; it visualized an interrelationship between physical play experiences in early childhood and the development of non-cognitive skills through the employment of the text mining method. This method was used to remove the complexity of individual qualitative data as well as the arbitrariness of the researchers.
Third, the study enrolled only university students between the ages of 18 and 26 years. Children's play styles continue to evolve: video games were invented in the 1970s, which were typically played while seated. The subjective benefits of physical play, and how individuals self-appraise non-cognitive skills, likely depends on their generation. Future studies could be enhanced by adding a cross-sectional survey component, to narrow down the beliefs and participants to be analyzed.
Ultimately, a positive longitudinal prospective investigation is required. However, this study was able to acquire suggestive viewpoints and narrow down the relationship between personality traits as non-cognitive abilities and physical play experiences in early childhood that may enable the execution of a study. In the future, the authors would like to continue research in this area to contribute to further knowledge regarding the development of non-cognitive skills and the development of intervention programs to promote them.