Effects of color stimulation on handwriting performance ... - Springer Link

European Child & Adolescent Psychiatry (2004) 13:191–198 DOI 10.1007/s00787-004-0371-5

Margarete Imhof

Accepted: 3 July 2003

Dr. Margarete Imhof Johann Wolfgang Goethe-University Institute of Educational Psychology P. O. Box 11 19 32 60054 Frankfurt/Main, Germany E-Mail: [email protected]

ORIGINAL CONTRIBUTION

Effects of color stimulation on handwriting performance of children with ADHD without and with additional learning disabilities

■ Abstract Active behavior problems in children with ADHD are often aggravated in situations which require sustained attention. Building on the ‘optimal stimulation’ hypothesis [43], this study explored the effects of color stimulation on graphomotor control in children with ADHD.A sample of 66 children with ADHD (n = 19 from primary education, n = 28 children with additional speech disorders, n = 19 children with additional learning disabilities) and matched controls participated in the investigation. Subjects performed a copying task on standard white and on colored paper in balanced order

Introduction

■ Key words ADHD – optimal stimulation – graphomotor behavior – primary education learning disabilities

lems with self-regulation and stimulus control [8, 11, 12] caused by dysfunctional cortical activation and subsequent variations in stimulus processing may play an important role [30–32, 43]. Zentall and Zentall [36, 43] focused on the hypothesis that children with ADHD typically tend to display a chronic state of low cortical activation. Thus,“individuals with ADHD require more stimulation . . . to achieve and maintain an optimal level of arousal in a given context” ([24] p. 272 f.). Against this backdrop, the excessive motor activity and other stimulation seeking behavior is interpreted as compensatory activity to calibrate the ‘optimal stimulation level’ for efficient functioning. In a series of experimental studies including children of several age and ability groups, Zentall and colleagues found that both motor activity (e. g.,[1]) and academic performance (e. g., reading, arithmetic, speaking) of children with ADHD could be positively influenced when additional environmental stimulation was present. Learners

ECAP 371

In academic learning environments, the attention problems in children with ADHD result in a number of behavioral characteristics which may interfere with academic tasks: They have difficulty sustaining attention over a certain period of time, which would imply both maintaining an intention for selection and protecting this intention against distractions. They often forget what exactly they were supposed to do and fail to complete assignments. Especially in repetitive and (monotonous) practicing tasks, their error rates are comparatively high and the quality of their work varies greatly across time, e. g., as far as accuracy or completion are concerned [13, 17, 18, 33]. The etiology of ADHD is unknown, but various explanations have been proposed. It has been suggested that problems in behavioral inhibition [2, 26] and prob-

across classes. Positive effects of the color stimulation on graphomotor behavior control and, consequently, on qualitative aspects of the handwritings were expected. Results broadly confirm the predictions. Effects are explained as added external stimulation facilitating behavioral inhibition and regulation of selective attention and graphomotor coordination. Reduction of visual stress as an alternative explanation is considered.

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European Child & Adolescent Psychiatry (2004) Vol. 13, No. 3 © Steinkopff Verlag 2004

with ADHD performed, in many cases, at the same level as control children, when extra stimulation, such as background noise [42] or an extra motor task [41], was included in the learning environment. Initial studies on the effects of color stimulation, however, yielded mixed results as the application of color was confounded with task complexity [35, 37, 40]. A case study (n = 3 students with ADHD) reported by Belfiore, Grskovic, Murphy, and Zentall [4] yielded encouraging results for the effect of nonspecific color added to a reading task by using colored typefaces. Lee and Zentall [24] used a series of single-digit additions to test the effects of color stimulation which was induced by colored computer screens and animation effects. The authors found that in the condition of high within-task stimulation, ADHD students had more completed problems and more correctly solved problems than in the low stimulation condition with black numbers on a grey computer screen. In our own experimental study with eight children with ADHD and an equal number of controls from a special education setting for children with speech disorders, it was shown that children with ADHD performed significantly better when color stimulation not affecting task complexity was added [20, 22]. The children with ADHD had fewer mistakes and took more time to complete the task when they worked on colored paper than on standard white paper. In addition, teachers also reported the impression that the quality of the handwriting had improved on the colored sheets. None of these effects, however, were visible in the control group. Iovino, Fletcher, Breitmeyer, and Foorman [23] detected a similar trend in their study on the effects of colored overlays used to facilitate reading. The ADHD group in their sample improved on their word recognition and reading comprehension performance when they used the overlays, whereas none of the other groups were affected. Taken together, there is evidence that individuals with ADHD react to color stimulation in a very specific manner. Further exploration of the utility of color stimulation would be of practical relevance, because this rather unobtrusive form of stimulation would be easily compatible with a variety of learning contexts in a typical classroom. The current study was designed to validate previous findings with a larger sample including both normal controls and ADHD children with comorbid speech disorders (SD) and learning disabilities (LD) to evaluate more closely the qualitative aspects of the handwriting. It is expected that the characteristics of the handwriting of children with ADHD improve with the added color stimulation, due to a better control over (grapho)motor behavior. This expectation is based on the assumption that changes in cortical activation, which are elicited by the color stimulation, have an influence on behavioral inhibition and facilitate motor coordination [6], attention regulation [27], and the effective monitoring of cog-

nitive functions, such as working memory and motivational regulation [2, 3].

Method ■ Participants Participants came from various second and third grade classes in a South German school district. In this particular federal state, students are assigned to categorical schooling when specific problems arise. The general idea is to provide a school environment which is tailored more closely to the learning needs, e. g., of children with speech disorders and learning disabilities. These arise typically during the first year of elementary school (RE). After a sound diagnosis, an individual education plan is developed which includes transfer to a different type of school. Schools for children with normal intelligence and speech disorders (SD) cater to those who display expressive language and articulation problems. They are taught the same curriculum as children in regular education, but in smaller classes. In addition, they receive remedial language instruction. Children with learning problems and below normal intelligence scores (but not retarded) are assigned to yet a different type of schools (LD). Their instruction also follows the identical curriculum, but the material is covered over a considerably longer period of time, e. g., the content of the first two years in RE is spread out over a three-year period in LD schools. The rationale for using the same core curriculum in all schools is to keep the doors open for everybody to return to RE schooling. To avoid exposing “problem children”, entire classes with an ADHD child were asked to take part in the experimental tasks which were actually treated like regular class work. Thus, a total of 144 girls and boys from regular primary education (RE, 2nd grade), 103 children from schools for children with speech disorders (SD, 2nd grade), and 73 students from schools for children with learning disabilities (LD, 3rd grade) participated in the study. The numbers of children with an ADHD diagnosis within the total sample were n = 19 children in RE, n = 28 from SD schools, and n = 19 from LD schools. All children with ADHD had been diagnosed based on DSM-IV criteria by a child psychiatrist and a school psychologist, and had been unanimously reported by their teachers and their parents on the Conners scale ([9], German translation of the short version, adapted for teachers and parents, respectively) to have active behavior problems. Data of children who were known to be on medication for ADHD and of those who were of the predominantly inattentive type had been excluded from further processing, because differential patterns in executive functions are known for different subtypes of ADHD [19] and no predictions could be made on how

M. Imhof Effects of color stimulation on handwriting performance of children with ADHD

these conditions would interact with the color stimulation. Also, the data for the remaining girls (n = 4) were eliminated, because the data base for group comparisons with reference to gender would lack power. So, the final sample consisted of 44 boys with ADHD and included 12 pairs of boys from RE, 20 from SD, and 12 from LD. All participating children with ADHD had had at least one interview with a school psychologist prior to the experiment. Data of children who were known to be on medication for ADHD were excluded from further processing. The mean age of the RE and SD students was between 7 and 8 years, whereas the LD children were about one year older. Information on the general cognitive abilities of the participants was available through the records of school entrance assessments and later assessments of individual educational needs. For the RE and SD children, general IQ measures (Kaufman-Test) were found to be within the norm (IQ > 90), whereas children from the LD schools were tested below average (75 < IQ < 90). The distribution of IQ measures reflects the general policies for the assignment to the different categories of schooling in this particular federal state. Each boy with ADHD was matched with a non-ADHD partner on the basis of gender, class, and time used for the task in the neutral condition.All statistic procedures involving group comparisons were performed based on this selection.

■ Tasks As part of the regular spelling instruction, students would on a regular basis, according to the mandatory curriculum, work extensively with series of 10 ‘words of the week.’ It was part of the classroom routines that, at the end of each week, practice was concluded by having the students copy a coherent text, in which the target words were embedded, from an overhead projection onto a worksheet. For the experimental study, this same far copying task was employed. In addition to spelling skills, the copying task demanded a high degree of selective attention, perceptual and memory skills, perceptive and semantic segmentation of the stimulus material, and coordination of visual and motor functions. For the purpose of the experimental study, two texts were composed which contained the 10 target words of the respective weeks and which were matched for a number of criteria: The texts consisted of 140 and 141 characters respectively to be copied (counting individual letters and punctuation marks). One text contained 28 words and 45 syllables, the other 29 words and 43 syllables. The number of possible impulsivity ‘traps’ was also adjusted for the two texts, namely (a) one long word made up of eleven letters; (b) eight times the letter ‘t’ which often leads children to omitting the horizontal

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line; (c) ten diphthongs and (d) three double consonants which are all considered to be particular problems in German spelling.

■ Procedure The texts were presented in cursive handwriting on an overhead transparency in the same manner that the students were accustomed to. The instruction for the children was to copy the text both correctly and completely and to make sure to mind the ‘words of the week’ just as carefully as the remainder of the text. They were allowed to choose their preferred type of writing utensil.All children in RE and SD classes had advanced to cursive writing, whereas some of the LD children still printed their letters. No time limit was set for the task. When a child was obviously no longer working after a period of 15 minutes, the task was considered completed. The independent variable of the investigation was the intensity of color stimulation by the worksheets. The children received either standard white paper or were free to select colored paper ranging from a variety of pastel to fluorescent colors. It had been found in an earlier study [20] that ADHD children had a preference for saturated and very bright colors. All papers were ruled with the standard supporting lines which were used in class on a regular basis for all kinds of writing tasks. The dependent variable was the quality of the children’s handwriting which should be taken as an indicator for graphomotor control. The two texts were given one week apart in order to avoid practice transfer. It was also taken care that the students had done some other classwork with the colored paper before to mitigate the novelty effect, e. g., make their own invitation cards for a birthday party using the colored paper. This step was important especially in the light of the strong reaction of children with ADHD to novel situations. To control for serial effects, the order of colored and white paper was counterbalanced across classes. The classes were assigned the order of color presentation, before the day of testing, so that no individual preferences would come into the picture. The texts, however, were presented in the same order in all classes; thus, each text appeared for part of the sample on the standard white paper and for the other part on the colored paper, so that possible effects of text difficulty would be washed out. All writing tasks were given in the second period in the morning to ensure that participating children were at a comparable level of mental alertness. The experimental task was instructed by the teacher with a neutral observer being present in the classroom.

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■ Hypotheses Children with ADHD typically have problems to control and fine-tune motor behavior [28, 29], which may impede the execution of pertaining tasks, such as handwriting [25]. If the effect of the enhanced color stimulation on attention processes is mediated through cortical stimulation, and since efferent motor functions and selective attention have been shown to interact [10, 21], it is reasonable to assume that, as a consequence, motor regulation is facilitated, which may become visible in the characteristics of the handwriting. The following hypotheses can be stated: 1. Children with ADHD produce a more coherent and legible handwriting when writing on colored paper than on standard white paper. 2. This effect is not present for control children. Building on the results from earlier studies, the hypotheses and related statistical tests are administered one-tailed, because the children with ADHD are expected to benefit from the color stimulation.

■ Measures A system of descriptive categories to evaluate the quality of the handwriting was developed. Based on earlier research, the following aspects were considered [15]: ■ Letter formation. Deficient letter formation was scored when the writer failed to clearly mark individual letters, e. g., when letters were formed in a way that they might be confused with others; fell apart and each part would create a distinct grapheme; were blurred and possibly misread to represent a different sound; or were corrected in a way that resulted in degraded legibility. ■ Alignment. Whenever one of the horizontal supporting lines or the end of a line was crossed, an error was tallied. ■ Slant. Frequent changes of slant are taken as an indicator of problems with graphomotor control. In a sample of 10 words taken from the text, the number of changes from a left slant to a right slant within a single word was counted. ■ Spacing. The number of deviations from the continuity of the writing flow was scored.All stops performed within a single letter or word, resulting in an inappropriate space, and all visible marks of subsequent weldings applied to fill the space were counted in. ■ Neatness. The impression of neatness was rated on a four-point Likert scale, the low score being defined as containing smudges, strikeouts, incomplete erasures,

spots, wrinkling of the paper. The high score was used when none of these characteristics were present. The size of the letters was not considered (as suggested by [15]), because all children used ruled paper with supporting lines supplied to limit letter size. Letter formation was evaluated with reference to the standard letter forms that were mandatorily taught in all schools [16]. In contrast to the procedure suggested by Graham et al. [15], the criteria were operationalized as countable features, except for neatness. All analyses were performed on the original material produced by the children in order to avoid any contamination by photocopying. The handwriting samples were rated independently by graduate students who had been trained in handling the criteria. The students had normal or corrected to normal vision. None of them reported symptoms, such as headaches or blurred letters when working on the colored paper. They had been instructed to take regular breaks in order to avoid eye strain and to control observer drift to more and more meticulous evaluation of the handwriting samples. They received the colored and white papers in separate stacks so that they would not be able to identify corresponding pieces by the same participant. Reliability measures obtained from independent ratings of selections of the samples with raters blind to both hypotheses and diagnostic status of the subjects yielded satisfactory results with coefficients (Pearson product-moment correlations) ranging from r = 0.79 to r = 0.97 for inter-rater agreement (calculated for the LD and SD samples) and from r = 0.81 to r = 0.99 for intra-rater agreement (calculated for the RE sample).

Results Before the results of the graphomotor analysis are presented, some specifications need to be made. The analysis of the handwritings from LD had to be separated from that of RE and SD due to specifics of the LD group: First, while data from RE and SD were evaluated by parametric procedures, non-parametric statistical tests had to be used for the LD data to accommodate for the deviance from normal distribution of the raw scores. Consequently, for the LD group the Wilcoxon test was administered for within group and the Mann-Whitney U-test for between groups comparisons. Second, because some LD students had been taught to print letters, the spaces criterion did not apply and was omitted. Third, in the same line, the continuity of slant could not be measured, but was replaced by a five-point rating of overall legibility (low score: very clearly legible; high score: very poorly legible). Fourth, as it turned out too late in the process to be amended, the ruled lines on the colored paper for the LD group were slightly off the right


angle and some sheets contained an extra line which had certainly been confusing, so that the line transgressions had to be excluded from scoring the LD children’s handwritings. Prior to hypothesis testing, the graphomotor performance of the groups in RE and SD was analyzed using a 2 2 ANOVA procedure with types of schools (RE and SD) and diagnostic status (hyperactive vs. normal control) as between subjects factors.As it turned out that the handwriting characteristics of the children ADHD in RE and SD were not statistically different for letter formation, alignment, and neatness, the data from these two groups were collapsed for these categories. The evaluation of the children’s handwriting in the combined group validated the a priori assumption that children with ADHD in RE and SD performed more poorly in the control condition (standard white paper) than their peers concerning letter formation, alignment, and neatness (Table 1). The hypotheses were tested for the three criteria letter formation, alignment, and neatness in the combined RE and SD sample using a MANOVA procedure with paper type (standard white paper vs. colored paper) as within subjects factor and diagnostic status (hyperactive vs. normal control) as between subjects factor. Results show a significant main effect for color stimulation and a significant interaction for color stimulation with diagnostic condition for all three criteria (Table 2). Closer inspection using post hoc t-tests reveals an improvement for the children with ADHD under the condition of working with color as compared to standard white paper. The handwriting samples of children Table 1 Assessment of handwriting criteria of ADHD and control children in the different categorical samples and experimental conditions

Table 2 Multivariate analysis of variance for effects of color (repeated measure) and on handwriting characteristics of ADHD and control children from RE and SD Criteria

Source

df

dferror

F

p

η2

Letter formation

color color ADHD

1 1

62 62

22.81 9.09

0.000 0.004

0.269 0.128

Alignment

color color ADHD

1 1

62 62

10.50 10.89

0.002 0.002

0.145 0.149

Neatness

color color ADHD

1 1

62 62

13.89 8.02

0.000 0.006

0.183 0.115

with ADHD writing on the colored paper contained fewer poorly marked letters (t (31) = 4.46, p < 0.001), fewer line transgressions (t (31) = 3.94, p < 0.001), and the worksheets were also rated to be superior in neatness (t (31) = –4.34, p < 0.001). The same comparisons for the control group yielded no significant results (all F-values were returned with p > 0.05), which means that the handwriting performance of the children with ADHD was differentially affected as compared to the control children. Analysis for those two criteria for which RE and SD samples could not be collapsed, yielded similar results. Due to the relatively low number of students in RE, however, statistical analysis was restricted to within group comparisons. For children in RE with ADHD, paired ttests yielded significant differences both in the number of inappropriate spaces (t (11) = 3.36, p < 0.01) and in the variability of slant (t (11) = 2.11, p < 0.05). The control children performed equally well in both conditions with no significant differences being observed. ADHD children

Paper type

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white M

controls colored

white

colored

SD

M

SD

M

SD

M

SD

Regular primary education Letter formation 10.83 Alignment 40.75 Spaces 16.17 Slant 4.17 Neatness 2.33

7.21 31.99 7.15 3.86 0.78

7.17 22.75 11.25 2.67 3.33

6.63 12.09 5.40 4.23 0.78

7.50 30.25 17.42 3.33 2.92

5.74 19.05 6.64 4.03 0.90

6.75 31.83 14.50 3.08 3.08

5.03 22.29 8.34 4.01 0.90

Children with speech disorders Letter formation 11.15 Alignment 50.15 Spaces 43.25 Slant 11.35 Neatness 2.40

7.80 27.49 19.68 9.13 0.75

6.05 39.10 29.00 8.45 2.90

3.93 21.00 17.34 6.53 0.64

5.90 29.80 35.60 9.25 2.95

3.99 25.23 16.62 7.48 0.76

4.70 29.05 27.80 8.25 3.00

3.88 20.71 17.30 6.86 0.73

16.37 7.69 22.29 (does not apply) (does not apply) 2.92 0.56 3.00 2.08 0.67 1.75

12.69

21.42

15.17

1.13 0.62

2.88 2.13

1.00 0.71

Children with learning disabilities Letter formation 26.33 Alignment Spaces Slant/legibility1 3.37 Neatness 1.71

8.35

0.91 0.40

1 Legibility scores for this group represent average ratings on a five-point Likert scale

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In the SD group, a main effect of color on the handwriting was also visible with respect to slant (F (1,38) = 4.15, p < 0.05) and inappropriate spaces (F (1,38) = 44.77, p < 0.001). In this case, however, the interaction with diagnostic status was not significant, so it must be concluded that both SD children with ADHD and SD controls improved on spaces and slant in the color condition. Results from the LD sample mirror the pattern as reported above. The handwriting performance of LD students with ADHD improved significantly on colored paper as compared to their performance on white paper. Letter formation was clearer (Z = –2.94, p < 0.01), and overall legibility was rated more favorably (Z = –1.84, p < 0.05), as well as neatness (Z = –1.91, p < 0.05). No significant differences were returned for the LD students without ADHD (all Z-values with p > 0.05). Between groups comparisons for the scores for the handwriting samples of children without and with ADHD from the LD sample did not yield significant differences in either condition.

Discussion and conclusions In this study, an attempt was made to check on possible effects of added external stimulation on graphomotor control of children with ADHD and two different comorbidities. The handwriting quality of second-grade students in regular primary education and in schools for children with speech disorders and third graders in schools for children with learning disabilities was assessed in two different conditions, using a set of criteria which are assumed to be indicators of motor control processes. Results show that typical features of handwriting improve with the colored writing paper and lead to a better overall legibility of the work. This supports the conclusion that some control or monitoring processes must have been exerted more efficiently than in the standard situation. The predictions which had been based on results from earlier studies could be largely confirmed and are in line with other empirical evidence suggesting more efficient information processing in the presence of increased stimulation, especially through the visual channel [2, 5, 7, 8, 14]. In particular, the results are in line with results reported from other studies using color as a means of external stimulation. Iovino et al. [23] found an advantage in both word recognition and reading comprehension when children with ADHD used colored overlays in a reading task. Similarly, Lee and Zentall [24] found color and animation effects in the presentation of math problems to be beneficial for both behavior and performance. In the present study, children in the SD group also seem to respond to the color in some way as seen in the inappropriate spaces and slant categories. This may

question the exclusive susceptibility of children with ADHD to color. If this observation is not attributed to a chance significance, it may be plausible to assume that color stimulation has an unspecific effect on cortical activation and attention regulation. Based on this assumption, it would not really be surprising when children in SD classes, though not fully diagnosed as ADHD, might still benefit from the added color, because part of their problems may actually be located in the areas of attention regulation and extend to motor timing. This, of course, needs further investigation. According to research on the effects of colored overlays on reading performance (cf. [34] for an overview), the facilitating effects of the colored paper could also be explained from a completely different angle, namely in terms of a reduction of visual stress. Color should mitigate strong contrasts of black print in a white page and thus puts less strain on the eyes and prevents tiring on the task. On the one hand, this might be a viable alternative route to explain the observed effects. The basic assumption here would be that for individuals with visual hyperexcitability perception is facilitated as the intensive contrasts are alleviated. On the other hand, this explanation would be somewhat incompatible with the observation that ADHD children select the papers with fluorescent colors which usually ‘flicker’ as one is focussing on them for a while, thus creating additional visual stimulation instead of smoothing visual perception. The stress reduction hypothesis would also challenge the results from those studies that show improved behavior control and performance in the presence of added external stimulation other than color, e. g., classroom noise [42], motor activity [41], movement effects [24], and increased self-attentional focus [39]. Additional research pitting the conflicting explanations would probably benefit from a sound operationalization of “level of arousal” and an identification of valid and reliable neuropsychological indicators for effects of different levels of stimulation. From the current study, the conclusion can be drawn that children with ADHD across different comorbidity groups respond to the color stimulation with improved control of attention and motor processes. The effects have been described for a spelling and handwriting exercise and it is open to further research if the effect generalizes to other academic or non-academic skills areas. It also needs to be borne in mind that participants in this investigation were relatively young writers. The question is if the additional stimulation can have a direct impact once learners have automatized the writing process more perfectly and personalized their handwriting more strongly. It is also not known how long the color stimulation would carry over time and if habituation to the color eliminates the demonstrated effect. Since color comes with a variety of attributes (hue, saturation, brightness), more research is needed to clar-


ify the differential impact of these presentation modes. As seen in the research on visual stress and the Irlen Syndrome, it should be worthwhile to further investigate the effects of color perception on different neuropsychological conditions. Practical implications of these findings are, quite obviously, to provide children with ADHD with additional, non-intrusive stimulation to support the regulation of attention. If children with ADHD respond positively to color stimulation, this may be used as diagnostic information and for intervention planning. If the results presented here hold, one might even expect that children with ADHD score differently on paper-and-pencil tests when they are printed on colored paper. Since penmanship is not an end in itself, but a means to an end [18], it is appropriate to ask what improved mechanics of handwriting do for a child. Depending on the overall situation, it is quite feasible that improved handwriting may contribute to an encouraging experi-

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ence for children with ADHD who are often frustrated by not being able to complete an assignment or by not being able to decipher their own notes which they have, undoubtedly, produced with some subjectively perceived effort. To offer students with ADHD colored sheets to write on may be only one option. Some children might prefer other kinds of stimulation and they might come up with their own ideas of how to create additional stimulation. Furthermore, it goes without saying that an intervention as described here can only represent one aspect of a more comprehensive individual education plan and that multiple interventions are needed to accommodate the range of learning needs of children with ADHD. If, however, children with ADHD respond to color stimulation, this is a convenient tool to facilitate performance on tasks which require selective and sustained attention, and motor control.

References 1. Antrop I, Roeyers H, van Oost P, Buysse A (2000) Stimulation seeking and hyperactivity in children with ADHD. J Child Psychol Psychiatry 41:225–231 2. Barkley RA (1997) Behavioral inhibition, sustained attention, and executive functions: Constructing a unifying theory of ADHD. Psychol Bull 121:65–94 3. Barkley RA (1998) Attention-deficit hyperactivity disorder: A handbook for diagnosis and treatment. New York: The Guilford Press 4. Belfiore PJ, Grskovic JA, Murphy AM, Zentall SS (1996) The effects of antecedent color on reading for students with learning disabilities and co-occurring attention-deficit/hyperactivity disorder. J Learning Disabil 29:432–438 5. Brandeis D (1995) Psychophysiologie der hyperkinetischen Störungen (Psychophysiology of hyperkinetic disorders). In: Steinhausen H-C (ed) Hyperkinetische Störungen im Kindes- und Jugendalter. Stuttgart: Kohlhammer, pp 71–89 6. Cammann R (1985) Evoked potentials in children with impaired and normal powers of concentration. In: Klix F, Näätänen R, Zimmer K (eds) Psychophysiological approaches to human information processing. Amsterdam: Elsevier, pp 269–278 7. Cammann R, Spiel G (1991) Neuropsychologische Grundlagen von Aufmerksamkeits- und Konzentrationsleistungen (Neuropsychological foundations of attention and concentration). In: Barchmann H, Kinze W, Roth N (eds) Aufmerksamkeit und Konzentration im Kindesalter. Berlin: Verlag Gesundheit, pp 11–26

8. Castellanos FX (1999) The psychobiology of attention deficit/hyperactivity disorder. In: Quay HC, Hogan AE (eds) Handbook of disruptive behavior disorders. New York: Kluwer Academic/ Plenum Publishers, pp 179–198 9. Conners CK (1973) Rating scales for use in drug studies with children. Psychopharmacol Bull, Special Issue 9: 24–29 10. Coquery JM (1978) Selective attention as a motor program. In: Requin J (ed) Attention and performance VII. Hillsdale, NJ: Lawrence Erlbaum, pp 505–514 11. Döpfner M (2000) Hyperkinetische Störungen (Hyperkinetic disorders). In: Petermann F (ed) Lehrbuch der Klinischen Kinderpsychologie und -psychotherapie. Göttingen: Hogrefe, pp 151–186 12. Douglas VI (1980) Treatment and training approaches to hyperactivity: Establishing internal or external control. In: Whalen CK, Henker B (eds) Hyperactive children. The social ecology of identification and treatment. New York: Academic Press, pp 283–317 13. Douglas VI, Peters KG (1979) Toward a clearer definition of the attentional deficit of hyperactive children. In: Hale GA, Lewis M (eds) Attention and cognitive development. New York: Plenum Press, pp 173–247 14. Farrace Di Zinno A, Douglas G, Houghton S, Lawrence W, West J, Whiting K (2001) Body movements of boys with attention deficit hyperactivity disorder (ADHD) during computer video game play. Br J Educational Technol 32: 607–618

15. Graham S, Boyer-Shick K, Tippets E (1989) The validity of the handwriting scale from the Test of Written Language. J Educational Res 82:166–171 16. Gramm D (1995) Maßstäbe für die objektive Bewertung der Schreibleistungen (Criteria for objective assessment of handwriting performance). In: Schorch G (ed) Schreibenlernen und Schriftspracherwerb. Bad Heilbrunn: Klinkhardt, pp 120–125 17. Hallahan DP, Kauffman JM (2000) Exceptional learners. Boston: Allyn and Bacon 18. Hallahan DP, Kauffman JM, Lloyd JW (1999) Introduction to learning disabilities. Boston: Allyn and Bacon 19. Houghton S, Douglas D, West J, Whiting K,Wall M, Langsford S, Powell L, Carroll A (1999) Differential patterns of executive function in children with attentiondeficit hyperactivity disorder according to gender and subtype. J Child Neurol 14:801–805 20. Imhof M (1995a) Beeinflussung des Arbeitsverhaltens hyperaktiver Kinder bei Rechtschreibübungen durch den Stimulationsgehalt des Arbeitsmaterials (The influence of stimulation-enhanced materials on hyperactive children’s work behaviors during spelling practice).Psychologie in Erziehung und Unterricht 42:234–239 21. Imhof M (1995b) Mit Bewegung zu Konzentration? (Minor) motor activity and concentration in listening situations. Münster: Waxmann

198


22. Imhof M, Scherr L (2000) Farbiges Schreibpapier verringert die Fehler hyperaktiver Kinder bei Schreibübungen in Grundschulen und Förderschulen (Colored paper reduces error rates of ADD-H children in writing practice in primary education and in special education). German J Educational Psychol 14:63–71 23. Iovino I, Fletcher JM, Breitmeyer BG, Foorman BR (1998) Colored overlays for visual perceptual deficits in children with reading disability and attention deficit/hyperactivity disorder: are they differentially effective? J Clin Experimental Neuropsychol 20:791–806 24. Lee DL, Zentall SS (2002) The effects of visual stimulation on the mathematics performance of children with Attention Deficit/Hyperactivity Disorder. Behav Disord 27:272–288 25. Monastra VJ, Lubar JF, Linden M, van Deusen P, Green G, Wing W, Phillips A, Fenger TN (1999) Assessing attention deficit hyperactivity disorder via quantitative electroencephalography: an initial validation study. Neuropsychology 13:424–433 26. Oosterlaan J, Logan GD, Sergeant JA (1998) Response inhibition in AD/HD, CD, comorbid AD/HD + CD, anxious, and control children: a meta-analysis of studies with the stop task. J Child Psychol Child Psychiatry 39:411–425 27. Rockstroh B, Elbert T (1990) On the regulation of excitability in cerebral cortex – A bridge between EEG and attention? In: Geissler H-G (ed) Psychophysical explorations of mental structures. Toronto: Hogrefe & Huber Publishers, pp 323–332

28. Rubia K, Noorloss J, Smith A, Gunning B, Sergeant J (2003) Motor timing deficits in community and clinical boys with hyperactive behavior: the effect of methylphenidate on motor timing. J Abnorm Child Psychol 31:301–313 29. Rubia K, Taylor A, Taylor E, Sergeant JA (1999) Synchronization, anticipation, and consistency in motor timing of children with dimensionally defined attention deficit hyperactivity behaviour. Perceptual and Motor Skills 89: 1237–1258 30. Scheres A, Oosterlaan J, Sergeant JA (2001) Response execution and inhibition with children with AD/HD and other disruptive disorders: the role of behavioral activation. J Child Psychol Psychiatry 42:347–357 31. Sergeant JA, Oosterlaan J, van der Meere J (1999) Information processing in Attention-Deficit/Hyperactivity Disorder. In: Quay HC, Hogan AE (eds) Handbook of disruptive behavior disorders. New York: Kluwer Academic/ Plenum Publishers, pp 75–104 32. Tannock R (1998) Attention deficit hyperactivity disorder: advances in cognitive, neurobiological, and genetic research. J Child Psychol Psychiatry 39: 65–99 33. Weyandt LL (2001) Attention deficit hyperactivity disorder: an ADHD primer. Boston: Allyn and Bacon 34. Wilkins A (2003) Reading through colour. Chichester: John Wiley & Sons, Ltd

35. Zentall SS (1986) Effects of color stimulation on performance and activity of hyperactive and nonhyperactive children. J Educational Psychol 78:159–165 36. Zentall SS (1989) Attentional cueing in spelling tasks for hyperactive and comparison regular classroom children. J Special Education 23:83–93 37. Zentall SS, Dwyer AM (1989) Color effects on the impulsivity and activity of hyperactive children. J School Psychol 27:165–173 38. Zentall SS, Falkenberg SD, Smith LB (1985) Effects of color stimulation and information on the copying performance of attention-problem adolescents. J Abnorm Child Psychol 13: 501–511 39. Zentall SS, Hall AM, Lee DL (1998) Attentional focus of students with hyperactivity during a word-search task. J Abnorm Child Psychol 26:335–343 40. Zentall SS, Kruczek T (1988) The attraction of color for active attention-problem children. Exceptional Children 54: 357–362 41. Zentall SS, Meyer MJ (1987) Self-regulation of stimulation for ADD-H children during reading and vigilance task performance. J Abnorm Child Psychol 15: 519–536 42. Zentall SS, Shaw JH (1980) Effects of classroom noise on performance and activity of second-grade hyperactive and control children. J Educational Psychol 72:830–840 43. Zentall SS, Zentall TR (1983) Optimal stimulation: a model of disordered activity and performance in normal and deviant children. Psychol Bull 94: 446–471