The focus of physical therapy in early intervention is to enable children to use their perceptual-motor skills to explore, learn, and interact with objects and people in the environment. This focus is based on current theoretical support and disabilities models. Specifically, support has been growing over the last decade that everyday perceptual-motor experiences are critical for building, shaping, and maintaining cognitive, social, and communicative abilities for individuals across the life span and particularly for young children.1–3 For example, object interaction, sitting, and locomotion experience all advance developmental outcomes across domains and time.4 In addition, support is growing for interventions that focus on improving activity and participation rather than those working solely to reduce impairments. For example, early powered mobility interventions provide young children the means for early exploration and for enjoyment, socialization, and play.5,6 Therefore, we propose that pediatric physical therapy is more than a child performing a target behavior in an isolated, controlled environment. Rather, children perform behaviors in a social, natural environment in a manner that encourages them to explore, learn, interact, and participate. One potential model of how early learning and development is influenced by the interactions among action, people, and objects is presented in Figure 1.
Emphasis on embedding task performance goals of physical therapy in other domains is growing.4 Literature informing therapists about the relationships among physical activity (PA), play interactions, and object use in early development, however, is lacking. Physical activity is defined as “...any bodily movement produced by skeletal muscles that requires energy expenditure.”7 Play interactions are defined as direct and indirect social interactions that are generally “purposeless,” meaning that interactions occur for their own sake without external considerations.8 Previous studies have assessed exploration behaviors related to specific uses of objects.9–11 For the purpose of this study, object use is defined more generally to include a child touching, holding, or using a portable object with his or her hands. In reality, very little is known about how toddlers with typical development (TD) use these 3 categories of behavior in their typical day.
Researchers in the field of kinesiology have studied PA of young children and typically report PA in isolation of other important exploratory and social behaviors.12–15 Studies have primarily focused on describing the relationship of anthropometric measures such as body composition to the amount and intensity of PA levels of toddlers through self-reported measures,14 accelerometry,15 or energy expenditure.16 One study that addressed the connection of PA to the social environment found that the presence of larger group sizes was associated with higher-intensity PA; however, social and play behaviors were not observed at the interaction level.12 These studies included children without disabilities and do not shed light onto the potential gap between their behaviors and those of children with disabilities.
In contrast, researchers in the fields of developmental psychology and pediatric rehabilitation have taken a broader view of PA, emphasizing how PA is used to participate, explore, and engage in the physical environment and the social world.17–19 There is a rich history within these fields of describing the typical qualitative development of children's behaviors, and recently researchers have begun to quantitatively assess these processes.20–22 For example, recently Adolph et al23 found that toddlers with TD walk 2368 steps daily and fall 17 times per hour on average. In recent decades, some researchers have aimed at describing how these developmental experiences differ for those with disabilities. For example, for 2- to 3-year-old children with disabilities, a greater number of strides per day has been shown to be associated with increased social participation.16 In terms of interaction with objects, children with disabilities often interact with objects less often and with less variability of behaviors and these early differences in object exploration and information gathering are associated with poorer performance on cognitive tasks such as object discrimination and causal learning tasks.10,24,25
Literature comparing PA, play, and object-related behaviors for children with and without disabilities within the same study is lacking. The 3 purposes of this study were (1) to describe the performance of PA, play, and object-related behaviors for toddlers with and without disabilities; (2) to describe the co-occurrence of PA, play, and object-related behaviors for toddlers with and without disabilities; and (3) to compare the performance and co-occurrence of PA, play, and object-related behaviors for toddlers with and without disabilities. We hypothesized that the behavioral landscapes would differ between toddlers with and without disabilities across the 3 categories of behavior. We also hypothesized less co-occurrence of the 3 different categories of behavior and that behaviors would occur more in isolation. These hypotheses were based on a proposed model (Figure 1), suggesting that the inability to initiate actions to engage, explore, and interact would be related to decreased interaction with people and objects in the dynamic social context of an early childcare setting. Together, this diminished behavioral performance would be expected to negatively affect early learning and cognitive development.4,26 We planned to interpret our results within the dynamic systems and grounded cognition frameworks.
Participants included 23 toddlers. Twenty-one were toddlers with TD, 11 boys and 10 girls participated (mean age = 23.5 ± 4.9 months old). Participants' parents reported their ethnicities as Caucasian (48%), African American (38%), and Asian (14%).
Participants also included 2 toddlers with disabilities. They will be referred to as “Child A” and “Child B.” Cognitive function was not measured for either child. We cannot rule out a cognitive influence on each child's behaviors observed for this study. Child A was a Caucasian girl (age = 31 months old). Her primary diagnosis is cerebral palsy with secondary diagnoses of microcephaly, hypotonia, and cortical vision impairment/persistent fetal vascular syndrome. She had the ability to interact with cause and effect toys such as those that light up or make sounds. She could also distinguish between different types of animals and colors. She also was able to recognize and respond to different people such as her teacher, physical therapist, and parent/caregivers. She had the ability to roll on the floor. She was able to sit on the floor with close supervision and hands-on support. She was unable to pull to stand or walk (even with the use of an assistive technology device). She used a wheelchair throughout the day since it provided the additional support she required. She was unable to move the wheelchair independently from place to place and required assistance for this task. She vocalized often but did not say words. Her Gross Motor Function Classification was level IV.
Child B was an African American boy (age = 33 months old). His primary diagnosis is developmental delay with secondary diagnoses of mild hearing loss in the left ear and epilepsy (type: electrical status epilepticus during sleep). Similar to Child A, he responded to cause and effect toys, had the ability to categorize objects and responded to the people with whom he interacted on a regular basis. He had the ability to respond to and follow instructions although he demonstrated difficulties related to self-regulation. He could independently sit, stand, and walk without assistance. However, his movements were ataxic, and he usually required physical and/or verbal prompts and assistance to initiate movements. He vocalized often but said few words, primarily names of people or objects. His Gross Motor Function Classification was level I.
Approval from the university Institutional Review Board and written parent/guardian consent were obtained prior to data collection. Twenty-one toddlers were video recorded for 20 minutes in each of 3 contexts—classroom, gym, and playground (60 minutes total per child). Child A and Child B were each video recorded for 60 minutes per context. Video recording occurred from 8:30 AM (after breakfast) until 11:30 AM (before lunch) at the Early Learning Center, a daycare and preschool that serves approximately 230 children from the broader community. At the time of the study, 2 children with disabilities were enrolled in the Early Learning Center and they were included in the study.
Data coding was performed for video of each child using momentary time sampling to avoid excessive and unnecessary coding time while obtaining large samples of the data. This means video was broken down into consecutive 15-second intervals where experimenters coded the first 5 seconds of each interval. The protocol was adapted from Brown et al,27 who used a 5-second observation and 25-second recording interval. Research has shown that PA of young children tends to occur in short, intermittent bouts.28–30 Thus, we shortened the recording interval for this study so that more frequent observations were collected. Behaviors across the 3 categories of PA, play, and object use were all coded during each 5-second coding interval. This allowed for the description of the co-occurrence of behaviors.
A mutually exclusive coding protocol was used within each assessment of PA, play, and object-related behaviors. Thus, within each of the 3 categories only 1 behavior was recorded for each observation interval. For example, if during a 5-second observational period a child sat for 3 seconds and stood for 2 seconds, only sitting was coded since that behavior was demonstrated a majority of the time. Four observation intervals were coded each minute. This resulted in 5040 observation intervals for the children with TD and 720 intervals for each Child A and Child B. All data were descriptive and we did not perform statistical analyses to compare behaviors between children with and without disabilities. Interpretations and comparisons of the data were based on visual analysis. To meet the purposes of the study, we present results as a percentage of time. Standard error bars are provided on the bar graphs for children with TD. Data are presented individually for each child with a disability.
Two experienced and trained coders analyzed all video recordings. Inter- and intrarater reliabilities of at least 85% agreement were established for each variable on 10% of the video recordings using the ratio of (agreements/[agreements + disagreements] × 100) to establish a percentage of agreement.
Assessment of Physical Activity
Physical activity level was classified according to the Observational System for Recording Physical Activity in Children-Preschool version.27 This protocol has been used previously to measure PA of 2- to 3-year-old children in the early childcare setting.12 This system classifies PA by type and level of exertion (ie, intensity). Activity type was defined as lying down, crawling, kneeling, sitting, squatting, cycling, standing, walking, and running. Activity-level categories include stationary/motionless, stationary with trunk and limb movement, slow-easy, moderate, and fast movement. Slow-easy, moderate, and fast movements require locomotion from 1 location to another defined as at least 3 steps in any direction at varying intensity.
Assessment of Play
Play behaviors were defined according to the Howes Peer Play Scale.31 This scale includes the following types of play: solitary—a child is more than 3 feet away from peers and teachers and is not engaged in verbal or physical interaction with anyone; parallel—a child is within 3 feet of a peer or teacher but with no direct verbal or physical interaction; peer interaction—direct verbal and/or physical interaction with a peer; and teacher interaction—direct verbal and/or physical interaction with a teacher.
Assessment of Object-Related Behaviors
Object-related behaviors were classified by whether a child was touching, holding, or using a portable object with his or her hands. A portable object included any toy or other piece of equipment that could be moved by a child from place to place. For example, a pencil, ball, and a bicycle were all considered portable objects if manipulated in any way by a child. Although a bicycle is large, it was still considered a portable object since a child could move it from place to place. Examples of nonportable objects included stair rails, tables, and playground equipment.
Occurrence of Behaviors
For each assessment, the mean percentage of time spent in each behavior is described. Mean percentage of time was calculated by the following formula: (observed intervals for each behavior/total intervals × 100).
Co-Occurrence of Behaviors
To examine the co-occurrence of behaviors, a child's behavior for each observation interval was classified (1) as “movement” if the level of PA was coded as any level except for motionless or as “no movement” if coded as motionless; (2) “social” if the type of play was coded as any type except solitary play and “not social” if coded as solitary play; and (3) “object-related” if a child touched, held, or manipulated a portable object in any way and “not object-related” when portable objects were not being contacted.
Physical Activity Type
Toddlers With Typical Development
Toddlers engaged in various types of PA almost always associated with some level of play (see Figure 2). Standing (31%), walking (20%), and sitting (20%) occurred most frequently, whereas 29% of the assessment was spent in all other types of PA. At an individual participant level, 17 of 21 children with TD engaged in every type of PA. Three children did not engage in cycling at any point and 1 child did not engage in crawling during observation.
Toddlers With Disabilities
Child A engaged in limited types of PA, but this activity was almost always associated with some level of play (see Figure 2). Sitting (53%), standing (29%), and lying down (16%) occurred most frequently, whereas only 2% of the assessment was spent in all other types of PA. This participant was not observed engaging in kneeling, cycling, walking, or running.
Child B engaged in various types of PA, except for cycling, and was almost always associated with some level of play (see Figure 2). Sitting (38%), standing (21%), and walking (19%) occurred most frequently, whereas 22% of the assessment was spent in all other types of PA.
Physical Activity Level of Exertion
Toddlers With Typical Development
As seen with the types of PA, toddlers engaged in various PA levels almost always associated with some level of play (see Figure 3). Trunk and limb movements occurred most frequently (47%). Moderate movements occurred least frequently (5%). At an individual participant level, every child engaged in every level of PA at some point during observation.
Toddlers With Disabilities
Child A engaged in limited levels of PA, but this activity was almost always associated with some level of play (see Figure 3). Trunk and limb movements occurred most frequently (78%). She spent the remaining time (22%) motionless and did not engage in slow-easy, moderate, or fast movements at all.
Child B engaged in various levels of PA, except for fast movements, and was almost always associated with some level of play (see Figure 3). Trunk and limb movements occurred most frequently (67%). He spent the least amount of time in moderate (6%) movements.
Toddlers With Typical Development
Children engaged in various types of play that were almost always associated with movement (see Figure 4). Children spent on average the following percentage of time in each type of play: parallel (34%), solitary (28%), teacher interaction (27%), and peer interaction (11%). Children were engaged in movement (all PA levels except motionless) a majority of the time across all types of play, so play and movement co-occurred most of the time play was performed.
Toddlers With Disabilities
Child A engaged in all types of play, with the exception of peer interaction, and her play was almost always associated with movement (see Figure 4). She spent on average the following percentage of time in each type of play: teacher interaction (76%), solitary (12%), parallel (12%), and peer interaction (<1%).
Child B engaged in various types of play almost always associated with movement (see Figure 4). He spent on average the following percentage of time in each type of play: parallel (54%), teacher interaction (27%), solitary (17%), and peer interaction (2%).
Toddlers With Typical Development
Toddlers were often engaged in object-related behaviors and often these behaviors were associated with movement or play. On average, children spent 54% of the time engaged in object-related behaviors. Of the 54% of time engaging with objects, 52% of that time was also associated with movement or play.
Toddlers With Disabilities
Child A spent limited time engaged in object-related behaviors, and, when she did, these behaviors were not frequently associated with movement or play. On average, Child A spent 13% of the time engaged in object-related behaviors. Of that 13% of time engaging with objects, only 12% was also associated with movement or play.
Child B often engaged in object-related behaviors that were always associated with movement or play. On average, Child B spent 59% of the time engaged in object-related behaviors and 100% of that time was also associated with movement or play.
On the basis of an average of 10.2 hours awake per day,32 the occurrence of key behaviors of the present sample was translated to the number of hours per day, month, and year to provide practical relevance and meaning to the results (see Table 1).
Co-Occurrence of All Behaviors
Toddlers With Typical Development
Toddlers were most often engaged in behaviors in which movement and play co-occurred either with or without objects (see Table 2). Movement and play co-occurred with an object 31% of time and without an object 25% of time. Children spent 77% of time engaged in at least 2 types of behaviors; movement, play, and/or object-related. Movement, play, and object-related behaviors co-occurred 31% of the time.
Toddlers With Disabilities
Child A most often engaged in behaviors in which movement and play co-occurred primarily without objects (see Table 2). Results indicate that movement and play co-occurred with an object 9% of time and without an object 60% of time. Child A spent 72% of the time engaged in at least 2 types of behaviors; movement, play, and/or object-related. Movement, play, and object-related behaviors co-occurred 9% of the time.
Child B most often engaged in behaviors in which movement and play co-occurred either with (44%) or without (31%) objects (see Table 2). Child B spent 90% of the time engaged in at least 2 types of behaviors; movement, play, and/or object-related. Movement, play, and object-related behaviors co-occurred 44% of the time.
This is the first study to describe the amount, variety, and co-occurrence of PA, play, and object-related behaviors of toddlers with TD and those with disabilities in their natural environment. Two main observations begin to provide a snapshot of the real-world doses of these behaviors. First, toddlers demonstrated a wide variety of behaviors. Second, all behaviors occurred and co-occurred with high quantity and frequency. Within each of these observations, children with TD and those with disabilities engaged differently throughout the day. In the following sections, we synthesize and discuss the results in more detail.
Toddlers With Disabilities Engaged in Less Variable Physical Activity
Toddlers with TD demonstrated a high variability of PA. Almost every child engaged in every possible type of PA. Every child engaged in all levels of PA. This behavioral and exploratory variability was not seen as readily in the toddlers with disabilities.
Each toddler with disabilities demonstrated relatively low variability in their PA behaviors. Child A spent a majority of her time sitting, standing, and lying down with limited time spent squatting and crawling. She never engaged in kneeling, cycling, walking, or running. Furthermore, Child A spent a majority of the time (78%) engaged in trunk and limb movements and did not engage in slow-easy, moderate, or fast movements at all. Child B also displayed limited variability in PA. He spent an increased amount of time in trunk and limb movements, and no time at all cycling or in fast movements. This suggests that regardless of level of impairment, variability was dramatically decreased for toddlers with disabilities.
Dynamic systems theory as applied to behavior provides a theoretical framework to interpret these results.33 In this framework, one's everyday experiences and behaviors shape his or her future developmental landscape and abilities. A key component of early dynamic development is the presence of variability. The idea is that a range of complex and varied experiences allows subsequent behavior to be shaped and optimized on the basis of characteristics of the environment. The contribution of variability to healthy development has been demonstrated across domains such as social interactions and play,34–36 motor abilities,37 and language development.38
Toddlers With Disabilities Interacted Less With Their Peers
Key differences emerged between toddlers with TD and those with disabilities in the occurrence of peer interactions. Toddlers with TD engaged in peer interaction 11% of the time compared with less than 1% and 2% for Child A and Child B, respectively. On the basis of an average of 10.2 hours awake per day,32 this amounts to about 1 hour of peer interaction per day in TD compared with about 6 minutes per day for Child A and 20 minutes per day for Child B (34 hours per month, 409 hours per year in TD vs 3 hours per month, 37 hours per year for Child A, and 6 hours per month, 74 hours per year for Child B). This result is especially disheartening. At first glance into a toddler classroom, children with disabilities often appear to be right in the middle of the action with their peers with TD. However, this finding quantifies a serious gap in peer interaction and play behaviors between toddlers with TD and those with disabilities. A lack of ability to participate in various PA behavior likely results in a lack of ability to seek out and initiate play experiences that are so important for social development in early childhood.
According to the grounded cognition perspective, limited function in 1 domain is likely to affect other domains.39 Previous research supports this concept through studies that demonstrate how impairment in 1 domain affects development in other domains.40 For example, children with cerebral palsy often have limited ability to participate in PA and have less than optimal social and participation experiences.41,42 Another example is children diagnosed with language impairment demonstrate less peer interaction and more withdrawn social behaviors on the playground compared with peers with TD. 43,44 Results of this study lend further evidence in support of previous findings.
Toddlers With Disabilities May Combine Their Physical Activity, Play, and Object-Related Behaviors Less Often
Children with TD play, PA, and object-related behaviors co-occurred 31% of the time compared with only 9% for Child A. This finding highlights the high co-occurrence of behaviors for toddlers with TD and how this co-occurrence is disrupted for a child with significant physical impairments associated with cerebral palsy. On the basis of an average of 10.2 hours awake per day,32 this amounts to co-occurrence of these behaviors about 3 hours per day in those with TD, 1 hour per day for Child A, and 4 hours per day for Child B (96 hours per month, 1153 hours per year in those with TD vs 28 hours per month, 335 hours per year for Child A and 136 hours per month, 1637 hours per year for Child B).
Grounded cognition places an emphasis on the embedded and interconnectedness of cognitive, social, language, and motor experiences. The behaviors associated with these experiences continually shape development and are occurring constantly throughout daily life. This study provides further evidence for the relatedness of developmental domains at a micro-level, real-time embedding of PA, play, and object-related behaviors.
Application to Clinical Interventions
We suggest that the quantity and frequency of behaviors of children with TD be considered a general reference standard to compare the effectiveness of technology and training in children with disabilities. The results of this pilot study begin to describe and quantify these behaviors. Therapy should focus on improving a child's abilities, providing supports, and removing environmental and cultural barriers to maximize PA, social interaction, and play. This study suggests that children with TD engage in various behaviors and those behaviors occur and co-occur in a high quantity and frequency during daily life. Other recent research confirms a high level of intensity and variability for play in those with TD throughout the first 2 years of life and that the amount and variability of play is less for infants and toddlers at risk for or with disabilities.24
Given this information and the confirmation that typical behavioral development requires an intense amount of practice, clinicians should focus on ways to use technology and training to maximize behavioral performance in children with disabilities both within and outside of therapy sessions. These data suggest that education aimed at changing everyday behaviors and interactions is likely the most important task of pediatric physical therapists. This can involve changing how young children are handled and positioned, changing play and social interactions with caregivers and children, and adapting everyday tasks to promote performance of key behaviors.9,45,46 Novel, inexpensive technologies that can enter the real world may also be increasingly helpful in increasing the amount of behavioral performance between therapy sessions to enhance early learning and development. For example, modified ride-on cars may be used to promote mobility and interaction with people and objects in young children with disabilities.5,6 The associated experience with this self-initiated mobility may also have broad benefits for early development and cognition (see Figure 1). Affordable exoskeletons47 and “smart garments” are also becoming available that have potential to promote behavioral performance, play with objects, and interaction with peers.48–50
A limitation of this study includes the descriptive study design that does not allow for causal inferences for differences observed between children with TD and those with disabilities. Another limitation is the low sample size (n = 2) of children with disabilities, and results should be interpreted cautiously and without generalization to larger populations. Also, we did not formally assess cognition for the children in this study so it is not clear if/how cognition affected children's PA. It is possible that children with severe cognitive issues may engage differently in PA, play, and object-related behaviors. This question can be addressed in future research by including a larger sample size of children with various cognitive and physical impairments to determine how these impairments may be a confounding variable in engaging in PA, play, and object-related behaviors. Future research should continue to study toddlers with TD to establish accurate expectations of the variety, occurrence, and co-occurrence of behaviors to inform the design and implementation of technology and intervention strategies for children with disabilities.
Future research could move in many potential directions. This study is descriptive and provides basic information regarding the variety, occurrence, and co-occurrence of PA, play, and object-related behaviors. Future studies that include a larger sample size would allow for statistical analyses to provide further understanding to the relationship among these behaviors and test more specific hypotheses related to providing technology and training to children with disabilities. Also, it is important to examine how children engage in different behaviors across contexts. For this study, all observations were combined across the classroom, gym, and playground. It is important to examine these behaviors in home and community contexts to further understand the daily life of toddlers. For example, car rides, trips to the grocery store, meals, and bedtime routines are all important aspects of daily life and likely a gap exists between children with TD and those with disabilities.
A recent position statement of the American Physical Therapy Association republished in Pediatric Physical Therapy states “The physical therapy profession will transform society by optimizing movement for all people of all ages to improve the human experience.”51(p129) This suggests that the quantity and frequency of movement should be optimized on an individual basis. Understanding the intensity of behavioral practice that occurs in typical development, for instance, that PA, play, and object-related behaviors co-occur 4.3 hours per day, 133 hours per month, and almost 1600 hours per year, reminds early intervention professionals of the high level of accumulated experience that intervention should address. Our pilot data highlight a potentailly large gap in the amount and variability of PA, play, and object-related behaviors for children with motor disabilities. The goal for early intervention should be to use educational techniques and rehabilitative technologies to effectively bridge this gap and optimize everyday PA, play, and interaction with people and objects. To reach this goal, early intervention providers will likely need to embed treatment within dynamic, social settings such as classrooms, playgrounds, and other community spaces where children typically spend their day exploring rich and dynamic environments.
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