1 ISCRAT Congress Amsterdam 2002 Symposium June 18, 2002 The Continuous Performance Test (CPT) as an Assessment of Voluntary Attention in Preschool Children at High Risk for Learning Disabilities Akira Midorikawa 1, 2, Kiyoshi Amano 2 1 Japan Science and Technology Corporation, Japan 2 Faculty of Literature, Chuo University, Japan Correspondence to: Prof. K. Amano. Department of Education, Chuo University 742-1, Higashi-nakano, Hachioji-shi, Tokyo, , Japan (Tel), (Fax)
2 Dr. A.Midorikawa ABSTRACT Disturbances of voluntary attention are very common in school age children with learning disabilities (LD). However, developmental disorders of voluntary attention can also easily be observed in some children in the preschool period. Therefore, it is important to evaluate voluntary attention in this period. In order to study the development of voluntary attention of children in the preschool period, Midorikawa (1997) developed a continuous performance test (CPT) for preschool children. In Experiment I, we utilized this CPT to assess the development of voluntary attention in five-year-old preschool children, in addition to eight other diagnostic tests (such as a vocabulary test, verbal regulation test, and memory test). In order to evaluate the validity of the CPT, we included three other attention tests: a visual search test, a maze test, and an inhibition test. As a result of Experiment I, we identified 15 five-year-old preschool children at high risk of LD. We confirmed the validity of the CPT for correctly discriminating among preschool children in the study. In Experiment II, using the above CPT, we evaluated the effect of a one-year experimental training program, the languagecognitive development program for children with suspected LD, on children's voluntary attention. The results of this study confirmed the positive effect of the experimental
3 training for children at risk for LD, not only on their verbal skills, but also on their cognitive functioning in the area of voluntary attention.
4 1. INTRODUCTION Disturbance of voluntary attention is diagnosed as Attention Deficit Hyperactivity Disorder (ADHD) and is defined independent of a Learning Disability (LD). Especially in the early years, however, distinguishing between ADHD and LD is difficult. Many children diagnosed as LD also have attention problem. Therefore, in the early period of childhood, it is especially important to evaluate attention. For this study, we designed two experiments. In Experiment I, four types of tasks were used to clarify the nature of preschool children s attention and to attempt to identify differences between suspected LD children and control children. In Experiment II, the effect of experimental training on the voluntary attention of children with suspected LD was evaluated using the continuous performance test (CPT). 2. EXPERIMENT I In Experiment I, in order to evaluate children s attention, we used four types of attention tasks. Three were paper and pencil tests designed to examine the attention function; one was a computer-based test that is a major diagnostic tool for LD or ADHD
5 children. In this study, we used the CPT, which was created by one of the researchers (Midorikawa, 1997) for use with preschool children (from 3- to 6-years-olds) Method Subjects: Sixty-one preschool children (five-years-old) participated in Experiment I. Materials: The Continuous Performance Test (CPT) developed by Midorikawa (1997) is a computer-based serial performance test. Children are instructed to respond to certain target stimuli (Figure 1) continuously for a sustained period of time. Stimuli consist of ten animal pictures which are presented successively for 333ms on a computer monitor (Figure 2). The target stimulus is a lion, which appears with only 20% frequency. The instruction to children is as follows: "You can see a lion and many other animals. The lion is a bully. When you see the lion, push the button as soon as possible in order to send him away from here to another place; otherwise the other animals may be bullied". The test lasts about eight minutes. Including 60 targets, the total number of stimuli is 300. Each stimulus appears in six different positions, (the center position and five peripheral positions), with varying probabilities. The stimuli appear in the center position with 50% probability and in each of five peripheral positions with 10% probability. The testing session has three time intervals. Each interval has 100 stimuli. One of the characteristics
6 of the CPT is its ability to assess three aspects of voluntary attention: selective, divided, and sustained attention. Selective attention is evaluated by performance during the first interval. Divided attention is evaluated by considering the difference between performance on stimuli in the center position and performance on items in peripheral positions. Sustained attention is evaluated by examining differences between performance in the first interval and performance in the third interval. Procedure: In addition to the CPT, three paper and pencil based tasks were used: the cancellation test (Lezak, 1995), the maze test (Wechsler, 1974), and the draw-a-line test (Levy, 1980). These three tests are thought to evaluate different dimensions of attention. The cancellation test evaluates visual searching ability (Lezak, 1995), the maze test evaluates allocation ability (Sivak, 1981), and the draw-a-line test evaluates inhibitory ability (Levy, 1980). Eight kinds of diagnostic tests (including a vocabulary test, a verbal regulation test, a memory test, etc.) were used to differentiate suspected LD children from non-suspected LD children. (See Amano (2002) for more information).
7 (a) (b) Figure 1: Example of stimuli in the center position (a) and in a peripheral position (b). Children were instructed to push a button, when the target lion appeared as soon as possible.
8 Figure 2: The display schedule of the CPT. The target and the distracter stimuli appear for 333ms following 1500ms intervals Results Diagnostic tests differentiated 15 children with suspected LD from non-suspected LD (control) children. Then, we compared the suspected LD group and control groups using four kinds of attention tests. Figure 3 shows the results of Experiment I. Scores ranged from zero point zero (0.0) for superior ability to one point zero (1.0) for inferior ability. In the paper-based tests, a significant difference between the suspected LD group and the control group was observed only in the visual searching test (Mann-
9 Whitney U, p <.05). In the maze test (Mann-Whitney U, p =.35) and in the draw-a-line test (Mann-Whitney U, p =.39), there were no significant differences between the two groups. However, the computer based CPT showed significant differences in all three factors. In particular, selective attention was dramatically impaired in the children with suspected LD (Mann-Whitney U, p <.01). As described above, a significant difference was observed in both paper based visual searching test and the computer based CPT; however, the distribution of results was dissimilar. In the visual searching test, results of both groups were distributed widely (Figure 4). On the other hand, the results of the CPT were distributed differently, depending on the group. The control group results were clustered close to the highest point (0.0), whereas the results of the suspected LD group were distributed widely over the entire range (Figure 5-7).
10 Corrected Score * suspected LD Control VS Maze DAL CPT Sel CPT Div CPT Sus ** * * V S: visual search test; Maze: maze test; DAL: draw-a-line test; CPT Sel: CPT selected attention; CPT Div: CPT divided attention; CPT Sus: CPT sustained attention. (Mann-Whitney U, * p <.51; ** p <.01) Figure 3: The results of the four tests. In order to compare scores with each other, the test scores were adjusted so that zero point zero (0.0) was the best score and one point zero (1.0) was the worst. Between the suspected LD group and control group, there was a significant difference on all dimensions of the CPT (p <.05 ~ p <.01).
11 Corrected Score Control suspected LD Figure 4: The results of the visual search test. Statistical analysis shows a significant difference (Mann-Whitney U, p <.05); there is also a wide range of scores in each group.
12 Corrected Score Control suspected LD Figure 5: The results of the selective attention portion of the CPT. There is a highly significant difference between the two groups (Mann-Whitney U, p <.01).
13 Corrected Score Control suspected LD Figure 6: The results of the divided attention portion of CPT. There is a significant difference between the two groups (Mann-Whitney U, p <.05).
14 Corrected Score Control LD-Suspected Figure 7: The results of the sustained attention section of the CPT. There is a significant difference between the two groups (Mann-Whitney U, p <.05). 3. EXPERIMENT II In Experiment I, it was determined that the CPT is a powerful tool for discriminating suspected LD children from control children. Therefore, in Experiment II, the effect of experimental training for at-risk children was evaluated using the above computer-based test.
15 3.1. Method Subjects: Eleven five-year-old children participated in Experiment II. They were evaluated as having suspected LD and participated in training through our project. Materials: In order to evaluate the effects of training, the CPT, described in Experiment I, was used. Procedure: The CPT was administered twice, i.e., during a pre-training session and a post-training session. The training consisted of a language-cognitive development program. The interval between the two testing sessions was approximately one year (See Amano (2002) for more information) Results After one year of experimental verbal-cognitive training, subjects had improved significantly in all three elements of the CPT (Figure 8: selective attention (t (10) = 4.41, p <.001), Figure 9: divided attention (t (10) =.07, p <.07), Figure 10: sustained attention (t (10) = 1.92, p <.05)). All suspected LD children showed a training effect and improvement of scores converging on the range of scores for the control group (Figure 5-7).
16 Corrected Score Pre-Training Post-Training Figure 8: The results of the selective attention section of the CPT. There is a significant difference between the two sessions (t (10) = 4.41, p <.001).
17 Corrected Score Pre-Training Post-Training Figure 9: The results of the divided attention section of the CPT. There is a significant difference between the two sessions (t (10) =.07, p <.07).
18 Corrected Score Pre-Training Post-Training Figure 10: The results of the sustained attention section of CPT. There is a significant difference between the two sessions (t (10) = 1.92, p <.05). 4. DISCUSSION The objectives of this study were to estimate the validity of the CPT developed to identify preschool children with suspected LD and to evaluate the effect of our experimental verbal-cognitive training on voluntary attention using the CPT. In Experiment I, in order to discriminate a suspected LD group from a control group, we compared performance on paper-based attention tests with performance on the computer-based attention test. As a
19 result, it was found that the computer-based test was a more powerful predictive tool than the paper and pencil tests. It was also suggested that the selective attention portion of the CPT was the most powerful measurement for discriminating suspected LD children from controls. Based on the above results, we can conclude that the children with suspected LD had far inferior abilities in selective attention than the control children. In Experiment II, we examined the effect of cognitive training on voluntary attention in suspected LD children. After our training, all three elements of the CPT were improved. The most statistically meaningful effect was observed on the selective attention section of the CPT (Figure 8). Our experimental training (see Amano, 2002, for more information) includes mainly reading and writing training. Specific voluntary attention training is not included in this experimental training. Our results showed that practical activities such as reading and writing training in a formal situation might have an effect on the development of voluntary attention. 5. REFERENCES 1. Amano, K. (2002) 2. Levy, F. (1980). The development of sustained attention (vigilance) and inhibition in children: Some normative data. Journal of Child Psychology, and Psychiatry. 21, 77-84
20 3. Lezak, M.D. (1995). Neuropsychological Assessment. 3rd ed. Oxford: Oxford University Press 4. Midorikawa, A. (1997). The Experimental Study of Development of Voluntary Attention in Preschool Children. Master s Thesis, Chuo University. 5. Sivak, M., Olson, P.L., Kewman, D.G., Won, H., Henson, D.L. (1981). Driving and perceptual/cognitive skills: behavioral consequences of brain damage.archives of physical medicine and rehabilitation. 62, Wechsler, D. (1974). The Wechsler Intelligence Scale for Children - Revised. San Antonio, TX: The Psychological Corporation.