1. Introduction
Object play is a skill that emerges early in a child’s development. It is closely linked with the development of cognitive, language, motor, and visual skills [
1]. Object play develops gradually. One of its first forms is exploratory play or sensorimotor play, which usually involves manipulations of a single object. The primary goal of this type of play is to learn about the physical world [
2]. Exploratory play transitions into relational play, which involves more complex manipulations of two or more objects [
3]. Another form of object play is functional play, which includes the functions of objects in children’s play activities, with objects being used in accordance with their purposes. For example, the child uses a toy hammer to drive toy nails or uses a toy hair dryer. Functional play usually appears in the play repertoire at approximately 12 months of age [
4]. Between 18 and 24 months of age, children develop symbolic play. This type of play is more complex and qualitatively different from play activities in preceding forms. It involves symbolic thinking and mental manipulation of objects. One kind of symbolic play is pretend play [
5]. The development of object play is not hierarchical, and the kinds of play typical for a given age may be observed at other stages of development. However, object play becomes more complex over time, building on the elements of previous stages [
6]. This is why, given the development of functional and symbolic play, when comparing the way children play under 18 months and at over 24 months of age, we can expect significant differences in terms of form and complexity.
A number of studies have demonstrated a relationship between the development of language, symbolic skills, and object play, especially pretend play [
7]. Positive correlations were found between language development and symbolic play in children [
8]. Those who demonstrated more advanced symbolic play skills and presented more complex and sophisticated forms of object play were more likely to exhibit higher levels of language skills.
Children with autism spectrum disorder (ASD) and children at high risk for ASD differ from typically developing children and children with other developmental disorders with respect to object play [
9]. Children with ASD present repetitive patterns of behavior and difficulties in social communication, which are the core symptoms of ASD according to the Diagnostic and Statistical Manual of Mental Disorders [
10] criteria. Repetitive patterns of behavior define a broad spectrum of behaviors characterized by sameness, rigidity, and repetitiveness. The presence of repetitive behavior has an influence on the development of play skills in children with ASD [
11]. For example, Libby et al. [
12] argue that preoccupation with sensorimotor play might suppress the emergence of functional and symbolic skills. However, even though repetitive behaviors belong to the core symptoms of ASD, it should be noted that they also tend to be present in typically developing children [
13,
14] and children with other developmental disorders.
Research has shown that children with ASD are more likely to play in a more stereotyped, less varied, and less flexible way than their typically developing peers [
15]. Moreover, it has been noted that they tend to engage in more exploratory play and in stimulating activities compared with typically developing children and children with other developmental disorders [
2]. Children on the spectrum are also less likely to become involved in relational play, and their play is less complex than their typically developing counterparts [
12]. Studies have also shown that children with ASD experience difficulties engaging in more complex play behavior (e.g., pretend play). In comparison to typically developing children, children with ASD often lack the ability to present original ideas for pretend play, and their play often seems rote and less spontaneous [
3].
Untypical object play has been observed not only in children with ASD but also those diagnosed with ASD later in life and in siblings at risk of ASD [
16]. It has been noted that children at high risk of ASD are more likely to engage in less complex exploratory play, e.g., put objects in the mouth more often, demonstrate excessive visual fixation, present repetitive visual fixation, engage in the excessive spinning of objects versus children at low risk of ASD [
17,
18,
19]. In addition, children at high risk of ASD have been observed to present a play that was more repetitive and less functional [
15].
Even though a lot of studies addressed the issue of object play in children at high risk of ASD, as well as the methods of measuring object play in children [
9], our knowledge about the relationships between the severity of ASD symptoms and object play in children at risk of developmental disorders remains limited. Furthermore, studies of children at high risk of ASD mostly enroll participants less than 24 months of age and use objects familiar to children, such as popular toys. There is still insufficient data on the relationships between object play and ASD symptoms, either in children aged less than 18 months or more than 24 months. It is entirely possible that these relationships are somewhat different in both younger and older populations due to the development of symbolic skills. The purpose of this study was to investigate the relationships between object play and the severity of ASD symptoms in younger children aged 12-18 months and older children aged 24–36 months at high risk of developmental disorders. The study aimed to find answers to the following research questions: (1) How is object play related to ASD symptoms in children at risk of developmental disorders? (2) Are the relationships between object play and ASD symptoms different in younger and older children at risk of developmental disorders?
3. Results
To obtain answers for the research questions, data analysis was based on Spearman’s rho partial correlation coefficients. Next, the significance of correlation coefficients was compared between the younger and older children’s groups using the z-statistics. Correlations were calculated separately for the group of children aged 13–18 months and 24–37 months.
Table 3 present the percentage of intervals with observed behavior. In the younger group, the mean ADOS total was 4.04 (SD = 3.02), in the Social Affect scale 3.83 (SD = 2.95), and 0.41 (SD = 0.20) in the Limited and Repeated behavior scale. The mean ADOS total score in the older group was 4.53 (SD = 3.03), in the Social Affect scale 3.08 (SD = 2.98), and 0.71 (SD = 0.70) in the Limited and Repeated behavior scale.
Table 4 presents the values of Spearman’s rho partial correlation coefficients obtained in the younger group of children aged 13–18 months.
In the younger group, the analyses showed moderate positive correlations between the ADOS total score and putting three objects together in various configurations and putting four objects together in various configurations. Positive correlations between the ADOS Social Affect score and putting three objects together in various configurations and putting four objects together in various configurations were also observed. Low positive correlations have been observed between the ADOS total score, ADOS Social Affect score, and putting two objects one on top of the other. Low negative correlations have been observed between ADOS total score, ADOS Social Affect score, and putting two objects together in a row. Nevertheless, statistically significant correlations have been observed only between connecting three and four objects and ADOS measures.
In the older group (
Table 5), low positive correlations were found between ADOS total score, ADOS Social Affect score, and looking towards the object and hitting the object. Between ADOS Repeated Behavior score and rotating the object, moderate correlations were found. However, no correlations in the older group were statistically significant.
Next, the significance of correlation coefficients was compared between the younger and older children’s groups using the z-statistics. The results of these analyses are shown in
Table 6.
Statistically significant differences between the correlation coefficients have been observed regarding looking at objects (negative correlations in the younger group), putting two objects in a row (negative correlations in the younger group), and connecting three objects in any configuration (positive correlations in the younger group) in ASD Total Score and Social Affect.
4. Discussion
The aim of the present study was to analyze the relationships between object play and ASD symptoms in children at risk for developmental disorders. For that purpose, we analyzed correlations between the severity of ASD symptoms and object play using novel objects designed to encourage children to manipulate and combine them in various configurations. The analyses were conducted separately in younger (13–18 months) and older participants (24–37 months).
The expectation was that the severity of ASD symptoms would be related to the complexity of play in the children at risk for developmental disorders. The results partially confirm this hypothesis. In addition, it was noted that these relationships are different in younger and older children. Numerous studies on children with ASD have found that they are more likely to engage in exploratory play and stimulating activities [
3]. In contrast to typically developing peers, their play is usually more restricted and repetitive [
17,
18,
19]. Some authors have linked this fact with the presence of stereotyped behaviors in children with ASD [
12]. Exploratory play and stimulating activities often involve the manipulation of single objects [
3]. It could, therefore, be expected that in this study as well higher severity of ASD symptoms would correlate with a greater frequency of manipulating single objects. However, the relationships found in the study group between ASD symptom severity and single-object manipulation, such as turning an object around its axis, were weak. Much stronger, positive correlations were obtained between the severity of ASD symptoms and combining objects and more complex play behaviors. They were the strongest when the child was manipulating three or four objects. In other words, younger children demonstrating more social function problems engaged more often in relational play and manipulated several objects combining them into various structures. This stays in opposition to some studies regarding object play in children with ASD [
28]. Another notable fact was that these relationships were found between object play and ADOS total score and ADOS SA score, but not between object play and ADOS RRB score. We might expect [
12] that the severity of stereotyped behavior would demonstrate the strongest relationships with object play. Our findings suggest otherwise, at least in the case of play of children at risk of developmental disorders.
5. Conclusions
One reason for the actual pattern of these relationships may be the fact that children at risk of developmental disorders whose social functioning is more impaired probably engage in relational play more often and initiate social interaction less often than typically developing children [
18,
19]. It should be noted, however, that in other studies, children with ASD often demonstrated difficulties with respect to relational play, and their play was usually less complex than that of their typically developing peers [
12]. Still, the present study enrolled children not diagnosed with ASD, with ADOS-2 scores below the cut-off point, and thus the severity of symptoms was in all likelihood lower than in children with ASD diagnosis. However, we cannot conclude that children in the study who demonstrated greater severity of symptoms in the SA subscale were less likely to engage in social interaction in the present study since there was no control for social interaction.
On the other hand, the results may have been affected by the characteristics of objects used in the present study. Studies on play activity in children differ to a large degree regarding methodology and objects used in the observation of play behavior, which may have a relevant impact on the results [
7]. Their design motivated children to combine them in various configurations. In addition, the procedure required that neither the experimenter nor the parent initiates interactions with the child. Consequently, younger children may have been more highly motivated to engage in that type of play, especially those children that demonstrate social function problems.
In turn, the relationships between object play and autism symptom severity observed in the older group were not statistically significant. The associations between relational play, i.e., manipulation of multiple objects, and ASD symptoms were very weak. Stronger relationships in this group were found between the variables associated with looking toward objects and the manipulation of a single object. It is worth pointing out that a comparison of the correlation coefficient has shown significant differences between the younger and older children regarding looking at objects, putting two objects in a row, connecting three and four objects in any configuration, and ASD Total Score and Social Affect.
These findings suggest that the relationships between the severity of ASD symptoms and object play may differ depending on children’s age. Perhaps older children, who would be expected to possess higher levels of symbolic skills and engage in more pretend play, were less motivated to engage in relational play. However, the symbolic play was not controlled for in the present study. On the other hand, the design of objects used in the study was not meant to motivate children to engage in symbolic play.
One of the limitations of the present study was the fact that social interactions between the child and experimenter, and caregiver were not measured. It would be a good idea to take into account this aspect of play when studying children of various ages and analyzing relationships between ASD symptoms and object play, given that social communication is one of the core symptoms of ASD. Another limitation was that the study did not control for the child’s mental age/level of development. This factor may have significantly affected the complexity of the participants’ play.