«Assessing handedness in pre-schoolers: Construction and initial validation of a hand preference test for 4-6-year-olds URSULA KASTNER-KOLLER1, PIA ...»
After a thorough course of training, three examiners conducted the tests in Viennese Kindergartens. Two to three testing dates were needed for each child, and the test was administered in a quiet room.
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3.1. Item statistics and reliability coefficient Within the context of the test, the hand preference of children was observed for 16 tasks, each of which was carried out three times. Thus, a total of 48 observations on hand use were available for each child. Tasks carried out using the right hand were marked with a 1, those with the left hand with a -1. A negative overall score thus indicated left-hand dominance, while a positive overall score indicated right-hand dominance.
An initial reliability analysis of all 48 observations resulted in an alpha of.96. Four observations showed item-total correlations lower than.3. All three trials of the item Finger counting as well as one trial of the item Pointing to a dot were concerned. Both items were removed from further analyses. Table 3 contains the item difficulties and item-total correlations before and after selection. The internal consistency of the reduced handedness scale with 42 items (14 tasks x 3 trials) amounts to a Cronbach’s alpha of.97. The overall score ranges from -42 to +42, although the sample only achieved values of -40 to +42. Figure 2 shows the distribution of the total scores, which exhibits the J-shape typical of preference tests (cf. Bishop, 1990).
The consistency of hand use over all three trials was checked task per task. The codes were added up for each task. A value of –3 indicated that the corresponding activity was carried out with the left hand in all three runs. A value of +3 resulted if the right hand was used all three times. Children who attained a score of –3 or +3 consistently performed a task using the same hand. Table 4 clearly shows that at least 60% of the children accomplished the items consistently. The highest consistency was shown in the activity of Drawing. In this case, 119 out of 120 children always used the same hand. On average, the children performed 11 of the 14 activities consistently with one hand, so that it can be assumed that children of this age group already show a very clear preference for one hand.
3.2 Validity A whole host of information on the handedness and hand preference of the children was available from other sources for assessing the validity of the newly developed hand preference test. As was already mentioned, the parents had performed a global assessment on whether their child was left or right-handed when providing written consent (Global handedness). Moreover, a questionnaire was used to determine hand preference in five common every day activities, using a five-point rating scale (Parents’ estimate) and a drawing assignment conducted independently of the hand preference test was observed by the test examiner (Observation of drawing hand). Table 5 provides the inter-correlations of these three variables and the hand preference test. The assessment of hand preference made by the parents was clearly based on their observations regarding which hand the child uses to draw.
Thus, the global statement of whether the child is left or right-handed (Global handedness), corresponds precisely to the use of the Drawing hand observed within the course of testing.
Even the more detailed Parents’ estimates primarily report hand preference when drawing.
In contrast to this, the inter-correlations of the three measures of handedness with the hand preference test do not only support the validity of the test, but also demonstrate that the hand preference test registers aspects of hand preference beyond those indicated by the drawing hand.
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3.3 Hand preference and visual-motor skills The overall score of the hand preference test was used to allocate the children to the groups left-handed, right-handed and ambidextrous. The range of values of the test goes from a possible raw score of -42 to +42. Children who performed more than two thirds of all tasks administered using one particular hand (left or right) were assigned to either the groups right-handers (RH) or left-handers (LH). For the left-handers this corresponded to scores of
-42 to -15, and for the right-handers, a range of +15 to +42. Children attaining a total score of -14 to +14 were assigned to the group ‘ambidextrous’ – both hands (BH). The total sample comprised 18 left-handers, 17 ambidextrous and 85 right-handers (cf. Table 6). Test data concerning developmental status gathered using the Vienna Developmental Test was available for 96 children. The distribution of left, ambidextrous and right-handers in this sample is also shown in Table 6. The three groups differed significantly with respect to the consistency of hand preference. As expected, ambidextrous children tended to switch among the right and left hand most frequently, even when performing the same task. Right-handers exhibited the most prominent hand preference, while hand use was significantly less lateralized in the case of left-handers.
As previous empirical studies have shown, the visual-motor skills of left-handed children are less developed than those of right-handed children. For the sample at hand, we wanted to check whether left-handed, ambidextrous and right-handed children differed in terms of their overall level of development and whether left-handed children performed worse on visualmotor tasks. To this end, the children had to complete the subtest Nachzeichnen (a tracing task) which tests visual and graphic motor skills in a very narrowly defined sense. Furthermore a score out of all WET-subtests containing activities requiring visual-spatial and visual-motor skills was calculated. This Visual-motor score comprised the two subtests of the functional areas Visual perception/Visual-motor-coordination (Bilderlotto and Nachzeichnen), as well as the subtest Schatzkästchen of the area Learning and memory, which tests U. Kastner-Koller, P. Deimann & J. Bruckner 250
visual-spatial memory and the subtest Bunte Formen of the area Cognitive development, which aside from placing demands on inductive reasoning, also entails processing of visualspatial information. Moreover, the overall developmental score of the WET (WET-Total) was used as a measure of the child’s general developmental level. Since left-handed, ambidextrous and right-handed children differed with respect to the consistency of their hand preference, this variable was used as a covariate in the analyses of covariance.
Table 7 shows the results of the univariate analyses of covariance with handedness as an independent variable, the total Centil values (WET-Total), the Centil value from the subtest Nachzeichnen, the Visual-motor score and the Verbal score as dependent variables, as well as Hand consistency as a covariate. The Verbal score comprised mainly tasks from the areas Language, Psychosocial development as well as the verbal subtests of the functional area Cognitive development. Level of type-1-error was set.05.
All four analyses of covariance yielded significant results, although hand preference and consistency of hand preference proved to have different effects. While hand preference had the largest effect on graphic-motor (subtest Nachzeichnen) as well as visual-motor and visual-spatial skills (Visual-motor score), consistency of hand preference influenced overall development (WET-Total, Verbal score, Visual-motor score).
The three hand preference groups did not differ significantly with respect to the total Centil values of the WET (WET-total). All three groups of children exhibited an average level of development (cf. Table 7). In contrast, the mean of the Visual-motor score of the group of left-handed children was significant below the mean of the ambidextrous and righthanded children. The lower visual-motor skills of left-handers especially came into play in the subtest Nachzeichnen. With an average Centil value of 3.67, the left-handed children were in need of remedial training concerning their graphic skills.
As described above, Hand consistency scores the amount of tasks required of the hand preference test that were performed using the same hand in all three runs. Children with high consistency scores always used either the left or right hand when performing a specific activity, but may have switched hands when changing to another activity (e.g. always drawing with the right hand, but throwing a ball with the left in all three runs). Children with low Assessing handedness in pre-school children 251
consistency scores switched hands even within the three attempts of the same task (e.g. rubber-stamping twice using the right hand, and once with the left). Children with consistent hand preference generally exhibited higher scores in overall development than did children with inconsistent use, i.e. frequent changes of hand within an activity.
The aim of this study was the construction of an objective, reliable, valid, but also ageappropriate preference test for analyzing handedness among four to six year old children.
The assessment of preschoolers’ handedness seems to be relevant since left-handed children often develop poor visual-motor skills which may further affect graphic and writing skills.
Operationalization of the construct of handedness was intended to go beyond the oberservation of the drawing hand, a method common for this age group but often criticized. Therefore, items were developed according to the Steenhuis and Bryden’s (1989) concept, which allows task analysis with regard to the movements involved and the quality of execution.
Validation was based on information concerning handedness from independent sources: A global estimate of handedness and a detailed rating of hand preference when performing U. Kastner-Koller, P. Deimann & J. Bruckner 252 everyday tasks were requested from the parents; the examiner was asked to observe the drawing hand outside the scope of the hand preference test.
The claim of developing an appealing age-appropriate and motivating hand preference test was realized by designing the test as an adventure and embedding the tasks within the context of a treasure hunt. Test objectivity was ensured in several ways: instructions were given via an audio cassette, and the positions of the test materials were pre-determined, as was the location of the child while performing the individual tasks. Since the examiner only had to record whether the child used its right or left hand, adequate objectivity can be assumed. As test analyses have shown, high internal consistency can be assigned to the hand preference test, item statistics were satisfactory throughout.
In order to ensure content validity, the hand preference test was designed as a preference test, thus eliminating the influence of fine motor skills on the test score. The medium to high correlations of the hand preference test to other measures of handedness underline the high concurrent validity of the test. Anyhow, the test does not merely assess hand preference with drawing but with a broader range of activities.
Estimates of handedness performed by the parents provided insight into their mental concept of the construct of handedness, which is obviously determined by the child’s drawing hand. While the global estimate of the parents exhibited a relatively high correlation with the result of the hand preference test, the correlation was considerably lower when the parents tried to provide a detailed analysis. This is typical for the reliability of parents’ estimates: they yield more precise estimates of their child’s development and behavior when asked for a global assessment than for a detailed evaluation (cf. Deimann, Kastner-Koller, Benka, Kainz & Schmidt, 2005; Glascoe & Sandler, 1995).
As in other studies, left-handed children scored lower on visual-motor and visual-spatial tasks in this study (cf. Bonoti et al., 2005; Giagazoglu et al., 2001; Karapetsas & Vlachos, 1997; Olsson & Rett, 1989), even though they did not differ from right-handed or ambidextrous children in terms of other developmental domains. In tracing geometric figures such as an x-mark, circle or triangle (the subtest Nachzeichnen of the WET), left-handers scored so low as to indicate a need for remedial training. Although the administration of the hand preference test did not put left-handed children at a disadvantage, these children may still have experienced unfavorable conditions in an environment which is tailored to righthanders. From a social-ecological perspective such experiences might not have been conducive to the left-handers’ previous visual-motor development (cf. also Gallo, Angioletti & Viviani, 2000).
Taking into account not only handedness but also consistency of hand use, a detailed view on the connection between hand preference and development of pre-school children emerges. Irrespective of lateral preference, children who tended to repeatedly perform a task with the same hand, were generally better developed than children whose use of hands was less consistent. Although ambidextrous children showed the least consistency and righthanders the greatest, as was expected, all three groups contained children with higher and lower levels of consistency. Thus, the consistent use of a particular hand to perform the tasks of the hand preference test can be seen as an indicator of lateralization. The pronounced lateralization of right-handers in comparison to ambidextrous or left-handers has been welldocumented (cf. Polemikos & Papaeliou, 2000; Bishop, 1990).
The lower level of development of children with inconsistent handedness, which was especially apparent in the WET-subtests with verbal components, may be due to a less proAssessing handedness in pre-school children 253 nounced functional specialization of the cerebral hemispheres. It is interesting to note, however, that the total score of the hand preference test does not suffice to identify differences in developmental level. This approach has been used in other studies, e.g. by classification into definite or less definite right-handers, also leading to differences in cognitive ability (cf.