Creative Education 2013. Vol.4, No.9, 41-50 Published Online Septe mber 201 3 in SciRes (http ://www.scirp.org/journal/ce) http://dx.doi.org/10.4236/ce.2013.49B009 Copyright © 2013 SciRes. Language Development: The Effect of Aquatic and On-Land Motor Interventions Ronit Ram-Tsur1, Michal Nissim1, Michal Zion1, Tal Dotan Ben -Soussan2,3, Zemira Mevarech1 1School of Education, Bar-Ilan University, Ramat-Gan, Israel 2The Gonda (Goldschmied) Multidisiplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel 3Research Institute for Neuroscience, Education and Didactics, Patrizio Paoletti Foundation for Development and Communication, Assisi (PG), Italy Email: ronitram@netvision.net.il Received July 2013 The aim of the current prelimina ry research was to examine the relationship between aquatic motor activ- ities and language abilitie s. Our hypothesis suggests that changing the environment to water may improve motor and linguistic abilities. The study included 94 children between the ages of four and six. Thi rty-one children who participated in aquatic motor activitie s were compared to 41 children who participated in on-land motor activities and to 21 children who participated in non-motor a ctivitie s. Developmen- tal-functionality tests, including gross and fine motor, time estimation and language tests, were used to diagnose participants’ abilities before and after six months of intervention. We found significant im- provement in gross motor, fine motor and time estima tion abi litie s for the aquatic motor activities group. Moreover, improvement in gross motor and time estimation abilities moderated the association between aquatic motor activities and children’s naming ability, suggesting the positive effect of aquatic motor ac- tivities on language abilities. Based on these novel findings, child-development professionals can have a better understanding of relation between language abilities and motor abilities, possibly leading to an im- provement of intervention methods with early-childhood patients. Early childhood intervention could aid in reducing primary differences between children in motor abilities, and especially in motor-development disorders, which in turn are thought to lead to additional learning disabilities. Keywords: Early Childhood Intervention; Physical Activity; Aquatic Environment; Language; Time Estimation Introduction Over the years, many studies have show n that physical activ- ity has menta l, cognitive and physical benefits (Cragg & Ca- meron, 2006; Ben-Soussan, Glicksohn, Goldstein, Berkovich- Ohana, & Donchin, 2013; Warburton, Nicol, & Bredin, 2006). Since t here is high neuroplasticity in early childhood (Hanna- ford, 2005) and the early yea r s are the most cost-effective time to intervene (Heckman, Stixrud, & Urzua, 2006), we wanted to examine the effects of physical activity in children. Appropriate motor performance at the ages 4-6 is a prerequisite for learning; deficient motor performance is thought to be a sign of possible academic problems in the future (L osse et al., 1991). Although every child has a unique developmental pattern, development is influenced by the interaction between life experiences and the environment in which these occur. For exampl e, according to the dynamic-sy stem theory, the interaction between the indi- viduals, the purpose of the task and the environmental conditions contribute to the child’s development (Smith & Thelen, 2003). It is thus theoretic al ly possible that changing the training envi- ronment from non-aquatic to aquatic, may enhance the child’s capabilities, improve existing skills and/or introduce new ones. In fact, throughout history, water has been used for many pur- poses, including physical therapy , sport, and physical hygiene. These activities have been made possible by the advantages of water’s special qualities (Becker & Cole, 1997; Becker, 2009; Campion, 1997). Consequently, we chose to examine the changes in language abilities following Aquatic Motor Activi - ties (AMA) in comparison w ith On Land Motor Activities (OLMA) and Non Motor Activities (NMA) in children. Be- cause of the unique qualities of water, a child can be exposed to new skills such as diving and floating, whic h cannot be per- formed on land. In addition, AMA provides multisensory sti- mulation combining three sensory systems: vestibular, proprio- ception and tactile. This multisensory stimulation may improve balance and coordination (Ahrendt, 1999; Devereux, Robertson, & Briffa, 2005). Immersion improves balancing abilities by in- creasing the proprioceptive input to the immersed body and provides greater body alignme nt and s tability. Sensory feed- back is increased by promoting a sense of body awareness, as resistance to movement through water is greater than resistance through air (Roth et al., 2006). AMA also exposes the child to sensorimotor stimuli, including floating boards and sinking ob- jects, which can be use d onl y in an aquatic environment. Thus, AMA during ea r ly childhood constitutes a unique plat- form for working on skills related to sensorimotor development, such as automatic movements and balance, which could be im- proved through aquatic activity by training on different depths without the interference of gravity (Campion, 1997). Moreover, sensorimotor integration may be stimulated more effectively in the aquatic environment, since the water provides three dimen- sions of movement: forward-backward, up-down and right-left.
R. RAM-TSUR ET AL. Copyright © 2013 SciRes. The experience of the se spatial concepts depends on the partic- ular kind of individuals’ body, and how that body learns to interacts with its surroundings (Lakoff & Johnson, 1999). A recent study investigating the influence of water immer- sion on cortical activation, using functional near-infrared spec- troscopy, has found tha t water immersion induced cortical acti- vation in both somatosensory and motor areas. These results suggest that water immersion may enhance motor learning dur- ing the period of acquisition of motor skills (Sato et al., 2012). The results of the Zel az o & Weiss experiment (2006) for initial five-test trials for infants aged four-, eight-, twelve- and six - teen-months were similar for kicking, arm flexion, the righting response, turning 180 degrees, and grasping the pool wall. In- fants at all four ages ini t ia lly displayed disorganized behaviors. The s tudy showed that training improved all behaviors during the initial five test trials for all four age groups. The data from Zelazo’& Weiss’s experiment impl i e s tha t early neuro-motor development is a bi-directional process, in which the infant’s movement results in feedback from the environment, which then influences both central and peripheral nervous system de- velopment. The integration of the sensorimotor information learned in controlling the aquatic environment is made possibl e by the plasticity of the nervous system, which enables it to develop a network of neural connections as a response to experiences in life. These neural groups create communication patterns whi ch develop into neural paths, particularly after repetition. It ha s been observed that brain structure undergoes changing through- out life. These changes are influenced by the environment, by the individual’s exposure to different stimulus, and by genetics (Blakemore & Frith, 2005). One of the investigated areas in the brain is the neuroplastic- ity of the cerebellum (Grossman et al., 2002). It has long been known that it is involved in the coordination of movements, balance and posture, visually-guided movements, and motor- learning (Stoodley & Stein, 2011). In the last decades, evidence has indicated its importance in timing processes (Harrington & Haaland, 1999). Studies have shown that pat ient s with cerebel- lar lesions display e d poor performance in time-estimation task (Ivry, Keele, & Diener, 1988; Ivry & Keele, 1989; Ivry & Di- ener, 1991). Several studies have shed light on additional func- tions of the cerebellum (Stoodley & Stein, 2011). One study , which explored a population with reading disabilities (dyslexia), suggested that cerebellar deficits can lead to phonological and processing-speed problems. The cerebellar deficits are thought to affect articulation and working memory, due to deficits in the timing functioning which interfere wi th the automatization of function development. These findings have constituted the “ce- rebellar deficit hypot hesis of dyslexia ” (Nicolson, Fawcett, & Dean, 2001). In support of this hypothe s is, Specif ic Language Impairment (SLI) in children was found to be related to low motor performance (Hill, 2001), and impaired motor function is further evident in Developmental Language Impairment (DLI) (Webster, Majnemer , Plat t, & Shevell, 2005). Despite the above findings, the connection between motor experience, language development and cerebellum functionality is still debated. This is also probably due to the fact that the re is a dearth of evidence for the comparative effects of differing environments on lan- guage development. More specifically, in addition to the scar- city of studies aimed at understanding of the possible motor aspects important for the cognitive enhancement, there have been very few researches in the field related to AMA’s contri- bution to physiological or motor-related functioning. Conse- quently, the current study combined motor- and language-re- lated research, in order to provide practica l understanding of the importance of AMA. We posited a neurobiological hypo thesis for the relationship between AMA and language processes. To this end, we aime d at examining three mai n questions: 1) Do the changes in the fine motor and time estimation abil- ities mediate the effect st ud y group on the gross motor abilities? 2) Do the changes in the fine motor and time estimation abil- ities mediate the effect st ud y group on the language abilities? 3) Do the changes in the gross motor abilities mediate the effect of study group on the linguistic abilities? Method Participates and Procedure Study participants were recruited from a regional kindergar- ten-complex serving 350 children between the ages of four and six. Participants were recruited from September 1 through Oc- tober 31, 2011. The research was approved by the Ministry of Education’s Chief Scientist in Israel and by the Bar-I la n Uni- versity ethics committee. In order to ascertain if the child was appropriate for the current study, and whic h grouping best re- presents the chi ld, parents of potential research participants were requested to complete a developmental and background questionnaire. Criteria for the child’s eligibility included: (a) participation in only one additional extracurricular activity pro- vided by t he local c ommunity center after October 31, 2011; ( b) in order to control the motivation and willingness of each sub- ject to part ic i pate in each activity, the choice of the a ct i vity wa s the child’s and not the parent’s according to the questionnaire given to the parents; (c) there was no absence longer than one week from the kindergarten before October 31, 2011. The study further excluded children who were receiving additional thera- pies such as occupational, speech, or ph ysical therapies. One- hundred and twenty-nine parents returned the questionnaire and a total of 111(86%) children were found appropriate for the cur- rent study. Testing of motor abilities, cognitive abilities and time estimation ability w ere conducted during personal meet- ings with the children prior to the activities and after six months of parti cipation. The act ivi ty took the form of a weekly training session of 45 minut e s ’ duration. Training Groups Aquatic Motor Activities (AMA) The AMA occurred in a hydrotherapy pool (14 meters long and 5 mete rs wide and kept at 33˚C. The pool depth ranged from 80 centimeters to 140 centimeters). One swimming in- structor accompanied five children in the water. The children learned how to control the aquatic environment in activities including standing and walking in water up to the chest, float- ing on the back/stomach, rolling over from stomach to back (and vice versa) while kicking with legs and moving the hands, and diving. Thirty-three children were in this group at the be- ginning; two left the activity during the experiment. Therefore, the group included 31 children. On-Land Motor Activities (OLMA ) The second intervention group included 45 children who par-
R. RAM-TSUR ET AL. Copyright © 2013 SciRes. ticipated in OLMA (basketball, football, judo, general gymnas- tic or ballet). Four left the activity during the experiment. There - fore, the OLMA group included 41 children. Non-Motor Activities (NMA) The third intervention group consist ed of 33 children partic- ipating in NMA (chess, dra ma or art ) . Four left t he activi ty and six added another motor activity during the study and so were left out of the sample . Another child had medical problems and was also not included in the sample. Therefore, the NMA group included 22 children. Tasks The cognitive protocol included the following test: The Raven’s coloured progressive matrices we re used to es- timate differences between study groups at baseline. This is a well-known assessment battery of nonverbal intelligence using the a bi li ty of matching appropriate colors and patterns. The outcome is the number of correct answers and the total time taken (Raven, 1965). The language protocol included the following tests (for a de- tailed explanation about punctuation in Hebrew, see (Ram-Tsur, Faust, & Zivotofsky, 2008): Semantic Fluency test (Kave, 2006) which measures ability to retrieve information from sema nt i c me mory . The child has to name as many words in a category as he/she could within one minute. Semantic fluency was measured in the categories of “animals” and “food”. These are categories used in most studies on semantic fluency (Hurks et al., 2006; Riva, Nichelli, & De- voti, 2000). The outcome is the number of correct answers for both categories combined. The Automatic Picture-Naming test and the Automatic Col- or-Naming test of the Assessment Battery Sahtil (Sahtil, 2002) were used to measure ability in automatic naming. T he auto - matic picture-naming test consists of 21 pictures that the child is requested to identify as quickly as possible. The outcome is the number of correct answers and the time needed for execu- tion. The automatic color-naming cons ist s of 21 colors with the child requested to name all the colors as quickly as possible. The outcome is the time needed for execution. The Automatic Digit Naming of the Assessment Battery “Aleph-Taph” (Shany et al., 2005) was used to measure the ability of automatic digit naming. T he child had to name 50 digits as fast as possible. The outcome is the executive time . The Phonological Awareness test of the Assessme nt Battery Sahtil (Sahtil, 2002) was used to measure phonological aware- ness. The child had to repeat the first phonemic sound of a non- word. The stimuli were 16 non-words. The outcome is the num- ber of correct answers. The motor protocol included the following tests: The Test of Gro ss Mot o r Development (TGMD) (Ulrich, 1985) was developed to score obj e ct i vely the qual i ty and qua n- tity of movement in children. It can be used to assess changes as a function of increasing age, experience, instruction or inter- vention. We used the Israeli version (Hotzler, 1995a, 1995b). The tes t includes locomotion and object-control abilities. The locomotion pa rt consists of four consecutive items: running, horizontal jumping, sliding and galloping. The object-control subtest consists of four consecutive items: catching, kicking, bouncing and overhand throwing. All data collection was con- ducted in the kindergarten facility. Prior to testing, an accurate demonstration and verbal description of the skill were provided to the chil d by an experienced adult. The child was given on e practice trial to insure t hat the child understood wha t to do. If the child did not appear to understand the task or had not per- formed cor rect ly in the pr ac tic e trial, additional demonstration and instructions were provided by the experienced adult. Each child then performed three trials for each gross motor skill; first, all the locomotion subtest abilities and then all the object-con- trol abilities. When the performance was correct, a scor e of 1 was marked; incorrect performances were scored 0. The sum of both performances represents the final score for each item. The outcome is the score for each part. Tests of fine motor skills: Bead-threading test (Fawcett & Nicolson, 1996): the child had to thread 15 beads as quickly as possible. The outcome was the total time taken, and was assessed twice. Finger-to-thumb test (Dow & Moruzzi, 1958): the child plac - ed the index fi nger of one hand onto the thumb of the other hand and vice-versa. Then, keeping the top t humb and finger together, the child rotated one hand clockwise and the other anti-clockwise until the finger a nd thumb touched again, and so on. The tas k wa s demonstrated and subjects trained until they completed the movement fluently five times. They we re then asked to perform ten such movements as quickly as possible. The outcome was the time take n for ten movements, and wa s assessed twice. Repetitive finger tapping (Denckla et al., 1985) the children were asked to press repeatedly and as fast as possible a button on a response box with the index finger for 1 min. all presses were recorded and the outcome is the average duration between two presses, the number of presses and standard deviation. Time estimation included the following test: The time estimation test was inspired by the t est of Nicolson et al. (1995), whi ch was itself inspired by Ivry & Keele (1989). In each time-estimation trial, two tones were presented succes- sively , and the task wa s to say whether the second tone was longer or shorter t han the first one. T he standard stimulus, al- ways presented first, was a 1200 ms-long pure tone of frequen- cy 392 Hz. Fifteen comparison tones had respective durations of 400, 700, 800, 900, 950, 1000, 1050, 1200, 1350, 1450, 1500, 1600, 1700 and 2000 ms. The two tones were separated by a 1000-ms silence interval. Each trial was repeated twice, amoun- ting to 30 te st trials presented in a random order. The test block was preceded by a practice block of eight trials (using only the eight extreme comparison tones), during which feedback was provided. No feedback was provided during the test block. The stimuli were presented by a computer through headphones at about 75 dB SPL. Af ter each pair of sounds, subjects had to say whether the second one was longer or shorter than the first on e. The outcome is the number of correct answers. Data Analysis The groups were compared on background characteristics. The AMA group and OLMA group were 51.6% and 53.5% fe- male, respecti vely , while the NMA group was 54.5% ma le. No significant differences were found between the groups w ith regard to age and Raven colored progressive matrices score (Raven, 1965) at baseline (see Table 1).
R. RAM-TSUR ET AL. Copyright © 2013 SciRes. Table 1. Sample characteristics. F(1, 91) NMA (n = 22) OLMA (n = 41) AMA (n = 31) 0.18 53.5 (7.5) 57.1 (8.5) 57.2 (7. 8) Chronological age (months) 0.61 13 (2.89) 13.56 (3.12) 12.87 (3.24) Raven score at baseline Results Do the changes in the fine motor and time estimation abili- ties mediate the effect study group on the gross motor abilities? In this section, we examined whether the change in the fine motor abilities and time estimation ability medi ate d the effect of stud y groups (AMA, OLMA, and NMA) on gross motor abilities (locomotion and object control). To this end, we em- pl oyed mediation analyses by Preacher and Hayes’s (2008) procedure. This procedure follows Baron and Kenny’s (1986) 4-step method. The progression from one step to the next is contingent on obtaining significant results in the preceding step. In the first step, we examined whether study group (X; the pre- dictor) predicts the change in the fine motor abilities and time estimation ability (M; the mediators). In the second step, we examined whether the change in the Fine motor abilities and time estimation ability predict the change in gross motor abili- ties (Y; the outcome s) while controlling for the effect of the study group. In the third step, we examined whether t he media- tion paths from the study group via the change in the fine motor skills and time estimation ability to the change in gross motor abilities were significant. A significant bi a s-corrected bootstrap analysis would support mediation. Finally, in the fourth ste p, we examined whether the direct links from study group to the change in gross motor abilities remained significant while con- trolling for the change in the fine motor abilities and time esti- mation ability. A significant direct link would support partial mediation, whereas a non-significant link would support full mediation. In the present analyses, we forgo Baron and Ke n- ny’s (1986) traditional first ste p in which one nee ds to establish a significant direct link from the predictor to the outcome vari- able as recommended by Preacher and colleagues (2010) and several other scholars (e.g., Shrout & Bolger, 2002; MacKin- non, Krull, & Lockwood, 2000). Step I. To examine whether study group predicts the change in the fine motor abilities and time estimation ability, we first effect-coded the study group variable. This coding enabled us to compare the effect of the AMA group (coded 1) with those of the OLMA group (coded −1) and NMA (coded −1). Unstandardized regr ession coeffi- cients are presented in Figure 1. The analyses revealed that the AMA group was relate d with a shorter tapping average duration between two presses and with a better time estimation than the NMA group. AMA group wa s al so related with a quicker com- pletion of the beading ta sk and with a better time estimation than the OLMA group. Therefore, we continue to assess the mediation processes only via these Fine motor skills and time estimation ability. Step II. Unstandardized regression coeffi- cients are presented in Table 2. The analyses revealed that the quicker the completion of the beading t ask, the better the loco- motion, but not the object control a bi li ty . This effect was sig- nificant above and beyond the contribution of the study group to the prediction. Steps III to IV. The bias-corrected bootstrap -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 Figure 1. Unstandardized regression coefficients for predicting the change in the fine motor abilities and ti me estimation ab ility by study group . Note: *p < .05, ***p < .001. Table 2. Unstandardized regressio n coefficients for predicting the change in the motoric-related abilities by the fine motor abilities and time estimation ability a nd s tudy group. Object control Locomotion −.08 −.23* Beading task −.04 −.04 Finger-to-thumb −.11 −.07 Tapping average .05 .01 Tapping variabil it y .15 .12 Time estimation .25* .12 AMA vs. NMA .45*** .54*** AMA vs. OLMA Note: *p < .05, ***p < .001. analysis revealed that the mediation pa th from the AMA (verses the OLMA) via the time to complete the beadi ng task to partic- ipants’ locomotion was significant: the 95% confidence interval (CI) did not include the value zer o (i.e., no effect), CI .01 to .15. In addition, as can be seen in Table 2, the link between study group and participants’ locomotion remained significant after
R. RAM-TSUR ET AL. Copyright © 2013 SciRes. the inclusion of the fine motor abilities and time estimation ability . Thus, t he mediati on path was only partial. Figure 2 presents the diagram of the mediating model between AMA (verses the OLMA) via time to complete the beading task to participants’ locomotion abilities. Do the changes in the fine motor and time estimation abili- ties mediate the effect study group on the language abilities? In this section, we examined whether the change in the fine motor abilities and time estimation mediated the effect of study groups ( AMA, OLMA, and NMA) on linguistic abilities (lan- guage fluency, object naming time, color naming time, digit naming time, phonological awareness). To this end, we em- pl oyed mediation analyses by Preacher and Hayes’s (2008) procedure, as in our first research question. Step I. To examine whether study group predicts the change in the fine motor abili- ties and time estimation ability, we used the effect-coding that compare the effect of the AMA group (coded 1) with those of the OLMA group (coded −1) and NMA (coded −1). Unst andar- dized regression coefficients are presented in Figure 1. The analyses revealed that the AMA group was related with a quicker tapping time and with a better time estimation than the NMA group. AMA group wa s al so related with a quicker com- pletion of the beading ta sk and with a better time estimation than the OLMA group. Therefore, we continue to assess the mediation processes only via these fine motor abilities and time estimation ability. Step II. Unstandardized regression coeffi- Figure 2. Conceptual diagram of the mediating models. cients are presented in Table 3. The analyses revealed that an improvement in the time taken to complete the finger-to-toe task was linked with an improvement i n the phonological a ware- ness score. Never thele ss, be c ause study group did not predict the performance in the finger-to-toe ta sk, mediation processes could not have occurred. Conversely, an improvement in the time estimation ability was relate d with an improvement in the time taken to complete the object naming task. The other paths were not significant. Ste ps III to IV. Bias-corrected boot-strap analyses revealed that the mediation paths from the AMA group (verses the OLMA and NMA) via the abili ty to assess time to participants’ object naming time were significant: the 95% confidence intervals (CI) did not include the val ue zero, CI −.21 to −.03 for NMA, and CI −.32 to −.05 for OLMA. In addition, as can be seen in Table 3, the link between study group and participants’ object naming time was not significant after the inclusion of the Cerebellum related abilities. Thus, the time estimation ability f ully mediated these paths. Figure 2 pre- sents the diagram of the mediating model between AMA (verses the OLMA training and/or NMA group) via time esti- mation ability to participants’ object naming ability. Does the change in the gross motor abilities mediate the ef- fect of study group on the linguistic abilities? In this section, we examined whether the change in the gross motor abilities mediated the effect of study groups (AMA, OLMA, and NMA) on linguistic abilities (language fluency, object naming time, color naming time, digit naming time, pho- nological awa rene ss). To this end, we employed mediation ana- lyses by Preac he r and Hayes’s (2008) procedure, as in the first research question. Step I. To examine whether study group pre- dicts the change in the gross motor abilities, we first effect- coded the study group variable. This coding enabled us to com- pare the effect of the AMA (coded 1) with those of the OLMA (coded −1) and NMA (coded −1). Unstandardized regression coefficients are presented in Figure 3. The a nalyses revealed that the AMA was related with a better locomotion and object control abilities than both the NMA and OLMA conditions. Therefore, we continue to assess the mediation processes via all of the gross motor abilities. Step II. Unstandardized regression coefficients are presented in Table 4 for linguistic abilities. The analyses revealed that better object control abilities were linked with a quicker naming ability . This effect was significant above and beyond the contribution of the study group to the predic- tion. Steps III to IV. The bias-corrected bootstrap analyses re- vealed that the mediation paths from the AMA (verses the OLMA training and/or NMA group) via ob ject control abilities to participants’ overall naming score (95% CI .06, .45 for AMA vs. NMA, 95% CI .03, .22 for AMA vs. OLMA) were signifi- cant. In addition, as can be seen in Table 4, the path between study group and participants’ overall naming score remained significant aft e r the inclusion of the gross motor abilities, the thus the motor-related abilities only partial ly media ted this path. Figure 2 presents the diagram of the mediating model between AMA (verses the OLMA training and/or NMA group) via ob- ject control abilities to participants’ overall naming a bi li ty. Discussion The aim of this study was to investigate the effects of AMA on motor and language abilities, as well as to examine whether the change in the fine motor abilities and time estimation ability
R. RAM-TSUR ET AL. Copyright © 2013 SciRes. Table 3. Unstandardized regression coefficients for predicting the change in the linguistic abilities by the fin e motor abilities and time estimation ability and study group. Phonological Awareness Digit Naming Color Nam i ng Object Naming Language Fluency −.09 −.02 .15 .01 .05 Beading −.23* .15 .36** .28** .02 Finger-to-toe .02 .06 .02 −.13 .02 Tapping a verage .07 −.04 .10 .13 −.08 Tappi ng var ia bil ity −.15 −.19 −.13 −.30** −.01 Time Estimation −.08 −.13 −.06 .05 .02 AMA vs. NMA .20 −.25 −.06 .04 .14 AMA vs. OLMA Note: *p < .05, ***p < .001. 0.52 0.54 0.56 0.58 0.6 0.62 0.64 0.66 0.68 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 Figure 3. Unstandardized regression coefficients for predicting the change in the motor-related abilities by study group. Note: *p < .05, **p < .01, ***p < .001. Table 4. Unstandardized regression coefficients for predicting the change in the linguistic-related abilities by the gross motor abilities and study group. Phonological Awareness Naming Digit Naming Color N aming Object Naming Language Fluency −.11 −.04 −.19 −.17 −.18 −.02 Locomotion .13 .32* −.24 .08 −.06 −.05 Object Control .16 −.12 −.16 −.16 −.03 .03 AMA vs. NMA −.10 −.25* −.06 −.16 .03 .18 AMA vs. OLMA Note: *p < .05, ***p < .001. can explain change in language abilities in children. To this aim, we examined 94 four- to six-year-old children attending a nor- mal kindergarten. To our knowledge, this is study the fir st to examine the extent to which cerebellum-related abilities such as gross motor, fine motor abilities and time estimation ability may be medi at or in the relationship between language aspects and AMA. First, we found that the AMA group was related with better gross motor a bilities than both the NMA and OLMA conditions. in contrast to Becker (2009: p. 865), who claimed that it is un- likely that aquati c training can substantially improve dry la nd performance in adults (Killgore, Wilcox, Caster, & Wood, 2006; Robinson, Devor, Merrick, & Buckworth, 2004), our results suggest that AMA during early childhood significantly im- proved gross motor abilities as compared to NMA and OLMA. We suggest that the unique combinations of multisensory sti- muli that characterize the aquatic environment and high neuro- plasticity accessibl e during ear ly childhood are responsible for this difference. The aquatic environment activates a combina- tion of the vestibular syst em and the ta ct i le system, due to cha- racteristics of water such as density , hydrostatic pressure, buo- yancy, etc. The physi c al conditions of the aquatic environment allow training on different depths with different gravity. More- over, t he aquatic environment provides three dimensions of movement rather than the two present on land. This has proba- bly resulted in more and/or new sensory information during
R. RAM-TSUR ET AL. Copyright © 2013 SciRes. AMA, which could account f or the difference between the OLMA and AMA groups. The current results of enhancing gross motor-related abilities, are in line with previous studies which reported a similar enhancement, which was claimed to be mediated by increased cortical activation motor areas which was induced by water immers ion ( Sat o et al., 2012). Second, AMA was related with a shorter tapping average duration be tw een t wo pre sses tha n the NMA group. AMA group was also related with a quicker completion of the beading task than the OLMA group. The development of the human bo- dy follows a proximo-distal and cephalo-caudal direction (Shar- ma, 2005). Thus , children who evidence greater improvement in the gross motor abilities, in the AMA group, may have grea- ter capacity for some fine motor abilities, as evidenced by the scores in bead-threading and the tapping ta sk which are a f ine motor task. A possible mediat i ng mechanism for our finding regarding to the motor abilities and the time estimation ability might be increased cerebellar activity, as will be discussed be- low. AMA provides multisensory stimulation combining thes e three sensory syst ems: the vestibular, the proprioception and the tactile. Immersion increases the proprioceptive input and sensory feedback to the immerse d body (Roth et al., 2006). The vestibular syst em is in the inner ear and reacts to head move- ments relative to gravity, and is connected to the cerebrum via the brain stem and cerebellum. The system operates in integra- tion with the proprioceptive system and produces the sense of balance and stability. The vestibular system influences regula- tion of muscle tension, body-movement coordination, and con- trol of eye movements which ensure a s ta bl e field of vision while moving (Bundy & Murray, 2002). The proprioceptive sys tem refers to the sensation provided by musc le s, ligaments and joints, and is created as a result of body movement. Proprioception allows ongoing awareness of posture and body movements in space, and the rhythm and timing of these movements (Williamson & Anzalone, 2001). Thus, it is a sys- tem providing external feedback to the cere be llum , allowing regulation of motor a c ti vi ty. The tactile system has receptors in the skin, serving as a mediator between self and environment (Williamson & Anzalone, 2001). Thus, the tactile system pro- vides the cerebellum with external feedback, allowing improv- ed reaction time and precision of movement via the cerebellum. Third, AMA was related with a better time estimation than both the NMA and OLMA conditions. Timing-processing is di- vided into two separate aspects: motor timing, which refers to the timing aspects of motor, speech and cognitive acts; and time perception, which refers to the discriminative aspects of cogni- tive time management, such as the ability to est ima te temporal delay s (Fuster, 1990). The intermediate cerebellum, through its direct connections with the motor syst em, mediates the motor aspects of timing, while the lateral cerebellar hemispheres and their output nuclei mediate the cognitive or perceptual aspects of timing through their connections with the fronto-parietal association cortex (Middleton & Strick, 1994). However, func- tional neuroimaging studies showe d activation of both the medial and the lateral zones of the cerebellar cortex during tasks requiring the precise representation of temporal informa- tion (Kawashima et al., 2000; Ramnani & Passingham, 2001; Harrington et al., 2004). Thus, it is still unclear if the cerebellar sys tem me dia te s ti me -perception independently from motor be- havior or other cognitive functions. Our findings suggest that time-estimation is associated with motor activities and motor behavior. However, how these results relate to cerebellar acti- vation and neuroplasticity requires additional investigation. Forth, we did not find differences between the study groups in language abilities. Interestingly, we confirmed association between motor activities in gross motor abilities aspects, but only part ia lly in fine motor a spe cts. Previous studies found that by kindergarten, fine motor tasks are better predictors of read- ing achievement than gross motor tasks (Wolff, Gunnoe, & Cohen, 1985). In longitudinal study, children with composite gross and fine motor abilities in preschool attained higher levels of third-grade reading achievement (McPhillips & Jordan-Black, 2007). Moreover, Grissmer et al. (2010) found that gross motor abilities did not predict achievement, but fine motor abilities did predict later achievement in math and reading. It seems that fine motor, rather than gross motor abilities are more significant in predicting language abilities. Thus, it seems reasonable to hypothes ize that our results about no differences between the three study groups in linguistics abilities could be due to the partial ly differences in fine motor aspects. Fifth, an improvement in the time estimation ability was re- lated with an improvement in the time taken to complete the object naming task. In addition, better object control abilities were linked with a quicker na ming ability . Appropriate naming development is essential for normal reading acquisition (Norton & Wolf, 2012). In fact, difficulties in naming ability have been found to be the most significant precursor of developmental reading disability (Georgiou, Parrila, & Liao, 2008, Tan et al., 2005). Reading has been reported as a sensitive process (Brez- nitz, 2006), which can be affected by timing abilities. It has been proposed that a lack of well -timed, automated, motor abil- ities inhibits the normal development of articulator gestures (Nicolson, Fawcett, & Dean, 2001). Therefore, children with dyslexia have been found to be slower in the automatic tempor- al abilities (Overy, Nicolson, Fawc et t, & Clarke, 2003). Ram- Tzur et al. (2006) found longer saccadic reaction times in stu- dents with reading disabilities, and suggested some theories for explaining the possible mechanism of t hese findings. A com- mon element of these theories is the conviction that timing abi- lities are a fundamental problem area in dyslexia. T he cerebel- lum has a function in the neural mechanism of timing, and this might explain our findings relating ti me -estimation to color- naming ability. Many neuroimaging st udi es, most of whi c h are on normal adul ts (Desmond et al., 1997; Mechelli Gorno-Tem- pini & Price, 2003), support t he role of the cerebellum in lan- guage abilities. The findings of the current st udy support the role of neurobiological mec ha nisms in the t heory of the rela- tionship between language abilities and motor performances. Finally, we have demonstrated that the mediation paths from the AMA group (versus the OLMA and NMA) via the ability to assess time to participants’ automatic picture-naming were sig- nificant. In addition, the link between AMA group and partici- pants’ automatic picture-naming was not significant after the inclusion of the time-estimation ability. Thus, the time-estima- tion ability fully mediated this path. Moreover, we have dem- onstrated that the mediation path from the AMA (verses the OLMA training and/or NMA group) via ob ject control abilities to participants’ overall naming score (including sum of the ob- ject naming and color naming scores) was significant. In a ddi- tion, t he path between study group and participants’ overall naming score remained significant aft er the inclusion of the motor-related abilities, thus the motor-relat e d abilities only partial ly mediated this path. These mediation pat hs suggest the
R. RAM-TSUR ET AL. Copyright © 2013 SciRes. positive effect of AMA on language abilities. It is important to remember that motor abilities are also cerebellum-related abili- ties. These novel findings shed light on the normal develop- ment of the neural network controlling reading-rel a te d abilities, which empha s ize the importance of t he cerebellar activity. Moreover, intervention that enhances functions traditionally re- lated to cerebellum activity leads to improvements in automatic naming ability . Study Limitations Up to now, there ha s be e n very little research in the field of AMA, especi a lly in regard to the contribution of aquatic activi- ties to areas of functioning that are not physiological or mo- tor-related. The current exploratory study provides a neurobio- logical hypot hesis for the relationship between an aquatic envi- ronment and language proce sses. This is a new concept for research, and one having great importance for developing our understanding of the contribution of aquatic activities. Never- theless, the study has limitations that should be acknowledged. First, the s mall sample size limited the power of the study and prevents further sub analyses, such as examination of family history of learning disabilities. Second, we are aware of the po- tential differences between various ty pe s of motor and non- motor activities that are non-aquatic and that the allocation of the groups was not random. However, this is a preliminary re- search aimed to examine the relationship between AMA and language abilities in normal population during early childhood, as the research related to AMA in this population is scarce. Third, we used gross motor, fine motor and time estimation test as “cerebellum-related” abilities. The claim should be accom- panied by the examination of exercise on brain morphology and internal connectivity (MRI or TDI). Further research is needed to conduct a study that includes this possibility for validating our results. We are currently examining working in this direc- tion. Conclusion In conclusion, data from our study supported the “cerebellar deficit hypot hesis of dyslexia” (Nicolson et al., 2001) suggest- ing that motor and non motor cerebellar-related abilities are associated with naming abilities. In addition, time-estimation ability moderat ed the association between AMA and children’s picture naming a bility, whil e obj ect control abilities moderated the association between aquatic motor activities and children’s overall naming score, suggesting the positive effect of AMA on language abilities. Together, the study may contribute to the understanding of the possibilities of different motor interven- tion in different environments. The combination of the advan- tages of an aquatic environment for children may provide use- ful knowledge for physic al -education teachers and could be uti- lized in the development of motor interventions for pre school children. According to our study , early aquatic motor intervention may help reduce early motor difficulties, thereby possibly preventing additional motor disorders which can lead to associated educa- tional problems. Thus, our findings might be the basis for new interventions for naming-related disabilities, such as dyslexia . Acknowledgements The results of this research are part of Michal Nissim’s thesis, Bar-Ilan University in partial fulfillment of the requirements toward her Ph.D. degree. Michal Nissim is grateful to the Azrieli Foundation for the award of an Azrieli Fellowship. The authors also wish to thank The Ministry of Education’s Chief Scienti s t in Israel for the approval and support in con- ducting this research. REFERENCES Ahrendt, L. (1999). 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