Assessing time processing ability in People with an intellectual disability, by using the KaTid Child

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Running Head: TIME PROCESSING ABILITY IN PEOPLE WITH AN INTELLECTUAL DISABILITY

Assessing Time Processing Ability in People with an Intellectual Disability, by using the KaTid Child

Masterthesis Orthopedagogiek Pedagogische en onderwijskundige wetenschappen University of Amsterdam M. Buiten Supervisor: Prof. dr. X. Moonen Second reviewer: Dr. H. R. Rodenburg Amsterdam, January 2019

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TIME PROCESSING ABILITY IN PEOPLE WITH AN INTELLECTUAL DISABILITY 2

Abstract

Skills in time perception, time orientation and time management, also known as time processing ability (TPA), are important skills people need to function well in current society. People with a mild intellectual disability (MID) or a moderate intellectual disability (MOID) often experience difficulties in TPA. In this study it was assessed whether the Dutch version of the KaTid Child, a Swedish instrument to assess TPA in children, can be used by children and adults with a MID (n=21) and children and adults with a MOID (n=15). Cronbach’s alpha analysis showed that the KaTid was a reliable instrument to use (α=.98). Based on MANOVA analysis it can be concluded that people with a MID scored significantly higher on the Dutch version of the Katid Child than people with a MOID, although average age of people with a MOID was higher. Considering the feasibility of the instrument when used with people with an ID, it can be concluded that several adjustments are due (e.g. implementation of a stopping rule; adjusting items so they are recognizable for people with ID). Overall, the Dutch version of the KaTid Child is to be considered a promising instrument to measure TPA in people with an ID. Keywords: time processing ability, TPA, mild intellectual disability, moderate intellectual disability, validity

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Samenvatting

Vaardigheden in tijdsperceptie, tijdsoriëntatie en tijdsmanagement, oftewel time

processing ability (TPA), zijn belangrijke vaardigheden in de huidige samenleving. Mensen met een verstandelijke beperking (VB) ervaren vaak problemen met betrekking tot TPA. In deze studie is gekeken of de Nederlandse vertaling van de kinderversie van de KaTid, een Zweeds instrument dat TPA meet bij kinderen, ook geschikt is om te gebruiken bij mensen met een lichte VB (n=21) en met een matige VB (n=15). De Cronbach’s alfa analyse liet zien dat het instrument betrouwbaar was om te gebruiken (α =.98). Uit de resultaten van de MANOVA kan worden opgemaakt dat mensen met een lichte VB significant betere resultaten behaalden op de KaTid in vergelijking tot mensen met een matige VB, hoewel deze laatste categorie significant ouder was. Daarnaast moet worden vastgesteld dat er verschillende aanpassingen nodig zijn om de deze versie van de KaTid een geschikt instrumenten te laten zijn voor het testen van TPA bij mensen met een VB (e.g. implementatie van een stopregel, het aanpassen van items aan de

belevingswereld van mensen met een VB). De Nederlandse vertaling van de kinderversie van de KaTid lijkt een veelbelovend instrument om TPA te meten bij mensen met een VB.

Sleutelwoorden: time processing ability, TPA, lichte verstandelijke beperking, matige verstandelijke beperking

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Assessing Time Processing Ability in People with an Intellectual Disability, by Using the KaTid Child

In today’s society everybody has a tight time schedule. Therefore it is thought to be an important skill to be able to manage and plan one’s time. This is one of the aspects of time process ability (TPA). To become an autonomous and well-functioning person, children start learning about time order and telling time already when they are toddlers. But does the same account for people with an intellectual disability? In the DSM 5 (American Psychiatric

Association, 2013) an intellectual disability (ID) is described as a disorder which is, among other characteristics, characterized by deficits in intellectual and adaptive functioning, including planning. So it is to be expected that people with intellectual disabilities experience difficulties in their TPA. It was shown that understanding the concept of time can be difficult for people with an ID (Davies, Stock, & Wehmeyer, 2002). Not getting the concept of time can increase their feelings of powerlessness and anxiety (Owen & Wilson, 2006).

The concept of TPA covers three concepts. These categories can be linked to the International Classification of Functioning, Disability and Health: Children and Youth version (ICF-CY) edited by the World Health Organization (2007). The first concept of TPA is time perception. This includes the subjective experience of time by estimating the length of activities and the passage of time, in other words, the experience of time. Second is the concept of time orientation. This concept refers to the knowledge that people have with regard to the days of the week, months, the date of today etc. and being able to place those concepts in the right order and connect them to daily activities. Time management is the third category to be described. Time management is connected to the ability to make plans. More specific, to be able to allocate a certain time to an activity and to order those activities in a logical chronological sequence.

The three categories of TPA can be seen as in a hierarchical order to each other, starting with time perception and finally time management as the most difficult category to learn and use. This hierarchical order can be seen in research done with typically developing (TD) children in different age categories. Older children scored significantly higher on TPA than did younger children (Janeslätt, Granlund, Alderland, & Kottorp, 2008). Therefore it can be concluded that age is related to TPA scores in TD children. The same applies to children with disabilities, but when comparing a group of TD children with children with disabilities with the same TPA skills,

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the group with disabilities was significantly older than the TD group (Janeslätt, Granlund, Kottorp, & Almqvist, 2010). This can be explained with the concept of developmental or mental age. Children with disabilities mature at a slower pace compared to TD children, thus their developmental age is lower than their chronological age (Janeslätt, Granlund, Kottorp, & Almqvist, 2010).

An important benefit of good TPA skills is that it gives a person the ability to have control over his or her own life and to make decisions for one selves: it gives a person autonomy. A premise for this autonomy is being able to manage one's own time (Janeslätt et al., 2010;

Janeslätt, Granlund, & Kottorp, 2009). Janeslätt et al. (2009) claim that the three different aspects of TPA (time perception, time orientation and time management) are needed together to become able to manage one's own time. Because of the lack of skills to understand and manage their time, people with an intellectual disability are often strongly dependent on other people in society and they cannot be considered as entirely autonomous functioning persons (Janeslätt et al., 2008). It has been shown that people with developmental problems and difficulties with TPA experience little independency and autonomy (Arvidsson & Johnsson, 2006). In the same study it was concluded that independency and autonomy are different concepts that are not strictly related to each other. Independency is a more objective category: a certain person does not need another person to manage tasks in daily life. On the other hand autonomy is often subjective: everybody has a strict personal approach of experiencing one's own autonomy. For children with disabilities Janeslätt et al. (2009) found that TPA skills are related to their perceived autonomy. Surprisingly, this was not the case for TD children (Janeslätt et al., 2009). One of the explanations for this result is that the sample of TD children in this study was younger than the sample of children with disabilities. The children with disabilities might be living with relatively low TPA skills for a longer period of time. Therefore they are better in estimating the contextual demands of

autonomous acts (Janeslätt et al., 2009).

This lack of autonomy and independency causes difficulties in participating in social life for people with an ID (Janeslätt, Lindstedt, & Adolfson, 2015) and is a predictor for less

engagement in school activities (Skinner, Furrer, Marchand, & Kindermann, 2008). People with a moderate intellectual disability (MOID) are more at risk of being excluded from social life than people with a mild intellectual disability (MID; Dusseljee, Rijken, Cardol, Curfs, &

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To assess TPA in children the KaTid child (Kit for assessing time processing ability in children) can be used (Alderman & Janeslätt, 2004; Janeslätt et al., 2010). With this instrument TPA is assessed in the three different subcategories of TPA specified by the World Health Organization (2007). The KaTid child is validated and standardized for a Swedish population of children (Janeslätt et al., 2008). It’s not yet standardized for the population of Swedish people with an ID but some research on this topic is done (Janeslätt et al., 2009; Janelsätt et al. 2010; Janeslätt et al. 2015). In the Netherlands Hoeving (2017) made a first step in using the KaTid child in assessing TPA in people with an ID in the Netherlands. To be able to use the KaTid child for people with an ID in the Netherlands, more research and validation is needed.

With an easy to use and validated instrument, difficulties in TPA in people with an ID could be dealt with more easily. First of all, this could lead to better understanding of the

development of TPA in people with an ID in general and specifically in a certain person. Second, these insights in the level of TPA can help to improve TPA, and finally, it could enhance

autonomy and self-determination. This can lead to a positive effect on once perceived quality of life (McDougall, Evans, & Baldwin, 2010) and to improvement of independency and autonomous behavior. Finally leading to better functioning and engagement in daily life. The aim of this study was to make the next step in validating the Dutch version of the KaTid child for people with an ID. First, the reliability of the KaTid child used in the Netherlands for people with an ID was measured. Second, possible differences were assessed in people with a MID and a MOID concerning the three aspects of TPA. Finally, the feasibility of the Dutch version of the

instrument was subject of research. Because the Katid was original designed to use with children, it could be expected that the instrument was not entirely suitable for using with people with an ID. So the question to be answered was if and if so what modifications should be made to make it more suitable for using in people with an ID. To assess this, it was important to look at the administration of the items and to determine whether they are suitable for people with an ID. To answer those research questions, the following three hypotheses were tested:

1. The KaTid has a high reliability, when used in Dutch people with an ID. 2. People with a MID will have better TPA performance and will perform

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3. The KaTid needs to be adapted to be used in people with a MID and a MOID.

Method Procedure

Prior to the start of this study, it was approved by the ethical committee of the University of Amsterdam. Before taking part in the study, participants and their parents/caretakers were informed by a letter and were asked to sign an informed consent. The assessment of the Dutch version of the KaTid child was performed in one time in a quiet room either at a school in an institution or at the home of the participant. Participants in this research had to meet several criteria. Inclusion criteria were that the participants had to be Dutch speaking and their level of cognitive development had to be comparable with those of people with a MID or a MOID. Exclusion criteria for participating were severe auditory and/or visual impairment because this interferes with TPA skills.

Participants were recruited in four different daycare facilities and 24 hour facilities for people with an ID in the Netherlands. Professionals working in these institutions selected participants on the basis of the inclusion and exclusion criteria. People who met the criteria received an invitation to join the study. All potential participants agreed to participate. Participants were rewarded with a small treat after the assessment of their TPA skills.

The professionals in the institutions, where the clients received care, provided the information about the severity of the ID that could be classified as either mild or moderate. To gather information about actually handling the materials and the questions of the Dutch version of the KaTid child by the participants, log notes were taken during every assessment procedure. Participants

In this study 36 people participated ranging in age from 9 to 61 years. T-test show a few differences between the the groups. The MOID and the MID groups differed significantly concerning mean age and gender. People in the MID group were significantly younger and there were significantly more women in this group then in the MOID group. In table 1 the descriptive statistics of the participants are presented.

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Table 1

Descriptive Statistics of the Participants

N Age Male Female

MID 21 18.3* (SD= 4.04) 5* 10*

MOID 15 27,2* (SD= 12.79) 11 10

Note: MID= mild intellectual disability, MOID= moderate intellectual disability *p < .05

Measures

KaTid. Data was collected using the Dutch version of the KaTid child (Janeslätt et al., 2010). The original Swedish version was translated to English by the Swedish authors. The version used in this research project was translated from English to Dutch by Hoeving (2017) in collaboration with Janeslätt. After Hoeving translated the KaTid child in Dutch, it was translated back to English by an English language teacher to make sure the translation was done correctly. Three items were changed in the Dutch version of the KaTid child compared to the original Swedish version. First a picture used in two items (A2.2 and A2.5) represented a typical Swedish activity which is unknown in the Netherlands and therefore was replaced by a picture of ‘having breakfast’. Furthermore, in item C2 participants are asked to place numbers on an empty clock face. In the Swedish version this was done by using stickers, in the current study small tiles with numbers were used. Furthermore, for the current studyto improve the fluency and understanding of the items, a few modifications were made by the author of this paper in the Dutch introduction sentences of the Dutch version of the KaTid child Hoeving used.

The Dutch version of the KaTid child contains of 51 items with a maximum score of 61 points (16 in time orientation, 35 in time perception and 10 in time management). Most items are presented by using a flipbook with two or three pictures on each page. The pictures are there to support the questions asked by the professional. This way of presenting the items makes the test suitable for children and adults with an ID with and without disabilities. Also children and adults with with reading difficulties can use the Dutch version of the KaTid. Children and adults with an

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ID can point at the right picture if answering verbally is (too) difficult or impossible for them. Besides those items the Dutch version of the KaTid child has several questions to be asked in an interview-format. The item score format is mostly dichotomous, can (1 point), or cannot (0 points), with a few items scored in a 3 point rating scale format.

As in the original version of the KaTid, the Dutch version of the KaTid child has four subcategories. The category time orientation is such a broad concept that it is specified in two subcategories. Category A is time perception. The subjective experience of time by estimating the length of activities and the passage of time is measured. (e.g. ‘This picture means swimming and this picture means eating a banana. Which picture shows the activity that takes a long time to complete?’).

Category B is time orientation. Time concepts are measured, i.e. the knowledge that people have of the days of the week, months, the date of today etc. (e.g. ‘What day is it tomorrow?’ ).

Category C is time orientation; refers to objective time. In this category participants are tested on being able to place the concepts used in category B in the right order and connect them to daily activities. (e.g. ‘What is the time in this picture?’ and ‘How does your teacher know when the school begins?’)

Category D is time management, refers to the ability to make plans. More specific, to be able to allocate a certain time to an activity and to order those activities in a logical chronological sequence (e.g.‘If your mum/dad says that he/she is gonna read a story to you in 5 minutes, what can you do in the time left? Go to a party or brush your hair?’).

The original Swedish version of the KaTid child was validated and standardized for Swedish children by Janeslätt et al. (2008) by using a Rasch analysis.

Administration/ log notes. Feasibility of using the KaTid in people with an ID was assessed by keeping a log and noting observations during testing. Difficulties were noted per item for each participant. Examples of difficulties are: not understanding the question, items that did not match the daily life experiences of the participant, the participant being distracted.

Data analysis

KaTid. Because the Dutch version of the Katid child was not standardized for Dutch people with an ID yet, and this study being a pilot with a limited number of participants, no

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Rasch analysis was used. The scores on the instrument used were analyzed by using the percentages of correct answers for each subcategory. Percentages of correct answers were calculated per person in each subcategory in Microsoft Excel. Data analysis were performed in IBM SPSS statistics version 25. Reliability of the Dutch version of the Katid child was assessed using Cronbach’s alpha. Cronbach’s alpha was chosen because it is the most commonly used method to measure internal consistency and reliability of an instrument. Besides that it is very convenient and it can be calculated easily (McCrae, Kurtz, Yamagata, & Terracciano, 2011).

To determine if there were differences in the level of TPA between participants with a MID and a MOID a MANOVA was performed on the mean percentages of correct answers for each subcategory comparing the MID and the MOID group. The MANOVA was chosen because there are three dependent variables to compare in two different groups (Timeperception,

-orientation and -management).

Log notes. Log notes were analyzed by counting the amount of difficulties per item in both groups. Besides that, a distinction was made for the nature of the different problems. Percentages of the number of participants with the same kind of difficulties were calculated.

Results Hypothesis 1

The first hypothesis tested was that the KaTid has a high reliability, when used in Dutch people with an ID. This hypothesis was accepted, since the reliability found was high (Cronbach’s alpha = .98). The item total statistics showed that removing specific items did not benefit the reliability of the test.

Hypothesis 2

The second hypothesis stated that people with a MID will have better TPA performance and will perform significantly higher on all of the subscales of the KaTid than people with a MOID. This was tested using a MANOVA analysis. The data from the KaTid and the participants met all assumptions for using a MANOVA test, except for the subgroup of participants with an MID. This data did not meet the assumption of normality. This implies that we have to be careful with interpreting the results. In table 2 the percentages of correct items are shown for the two groups in the three different categories and for the total TPA score. By applying Wilks Λ (to test if there

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were differences between groups) a significant difference between the two groups could be calculated (Λ = .544, F(3,32) = 8.949, p = 0.000). Participants with a MID had significantly higher total scores on the Dutch version of the Katid child than the participants with a MOID, as on all 3 subscales (Time perception: F(1, 34) = 13.278, p = .001, eta-squared = .281; time

orientation(1, 34) = 25.266, p = .000, eta-squared = .426; time management: F(1, 34) = 23.879, p = .001, eta-squared = .413). Therefore the second hypothesis that people with a MID will have better TPA performance and will perform significantly higher on all of the subscales of the KaTid than people with a MOID was accepted. However, the results have to be interpreted with great care, because this results were obtained by using the KaTid child without any adaptations for people with MID of MOID.

Table 2

Mean and SD of Percentage of Correct Answers for children and adults with a Mild and a Moderate ID, in Total TPA and in the Subcategories: Time Perception (TP), Time Orientation (TO) and Time Management (TM)

TPA TP TO TM

n M SD M SD M SD M SD

MID 21 63.35 29.65 81.55 24.24 75.24 27.60 54.76 32.95 MOID 15 38.60 19.96 50.42 26.67 32.76 20.71 11.33 11.26

Note: MID = mild intellectual disability, MOID = moderate intellectual disability Hypothesis 3

In the third hypothesis it was presumed that the KaTid needs some adaptations if used with people with a MID or a MOID. This hypothesis was tested by analyzing log notes and observations during testing. The log notes and observations were analyzed by looking if they applied to two or more participants.

First of all, certain items (A1.1, A2.5, B3.3, D1.2) did not fit the experiences in daily life of the adults tested. In this study 72% of all participants were over 18 years of age and most of them did not attend school anymore. Item A1.1 shows a picture of doing PE in school. Item A2.5

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shows a picture of playing with toy blocks (Lego), most of the participants do not play with those toy blocks anymore. Item B3.3 contains the question: ‘What are your days off from school?’ while most participants did not attend school anymore and were also working in the weekends. In the introduction of item D1.2 the participant is asked what he/she is able to do if his/her mom or dad is going to read them a story in five minutes. This introduction does not fit in the daily life experience of the participants targeted in this study. First of all because a lot of them were too old to have their parents read stories to them, but also because a lot of the participants did not live with their parents anymore. It is plausible that the remarks apply for more future participants with a MID and a MOID.

Besides the items that did not match the daily life experiences of the participants, item C6.1 is age dependent. This item uses two time frames. The first one is a timeframe from 40-100 years ago and the second timeframe is from 100-140 years ago. The participants have to point at the timeframe of when their grandma was born. Because there is a wide age range in the

participants of this study and of future participants, the right answer to this question will differ for every person. Besides that, we had and will have no information about the real birthdate of the grandmother.

Furthermore, two items (B6.1: ‘If today is Wednesday and you have been sleeping the whole night and you wake up, what part of the day is it? Morning, noon or afternoon?’ and C1.1: ‘How does your teacher/mentor know that the school/work starts in the morning?’) appeared to be difficult to explain and to understand. Often participants did not know what answer to give because they signaled that they did not understand the question. In the MID group 60% of the participants had difficulties understanding at least one of those two items addressed in the question. In the MOID group this percentage was 24%.

During the assessment, the researcher noticed that the lack of a stopping rule caused some difficulties. In the KaTid manual it is described that: “If the child is unable to answer more items in the same category, you can choose not to ask the more difficult items, if you think the child is not able to answer those items. If so, you fill in “Cannot” (0 points).” In 48% of the assessments with participants on a MOID level, the researcher hesitated whether to stop or to go on with presenting items because they seemed too difficult. Besides that, in 33% of the assessments in the group participants with a MID the researcher noticed that the participants found it very easy and got bored of answering questions. In 78% of the assessments where the researcher had doubts

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about continuing the test, it applied to part C3 of the test, which includes telling time. Altogether, the third hypothesis was accepted, adaptation of the KaTid is needed to be used in people with an ID.

Discussion

The aim of this study was to investigate the reliability of the instrument, the differences in scores of the KaTid between people with a MID and a MOID and whether the KaTid is suitable to use in assessing TPA in people with ID. Because the Katid is constructed to be used in

children, it was important to look at the administration of the items and to determine whether they were suitable for people with an ID as a first step in a process of validating the KaTid for people with a MID and a MOID. It was expected that a few modifications were needed to make the KaTid suitable to use in people with an ID. The expectations were that the Dutch version KaTid child used in people with a MID and a MOID would be a reliable instrument, that people with a MID on average would have better TPA, and that adaptations would be needed to make the KaTid more suitable for people with a MID and a MOID.

The reliability of the Dutch version of KaTid Child used in people with a MID and a MOID appears to be excellent, with a high Cronbach’s alpha (α = .98). An alpha greater than .80 is commonly accepted as a great internal reliability (Bryman, 2016). Because of this high

reliability, the KaTid is to be considered as a promising instrument to measure TPA. People with a MID have a better TPA than people with a MOID. They had a better performance on all three subcategories. Those results have to be interpreted with care because there was a significant difference in age between the two groups and because adaptations are needed when the KaTid is used in people with a MID or a MOID. In earlier research it was found that there is a correlation between TPA score and age in TD children (Janeslätt, Granlund,

Alderland, & Kottorp, 2008). But the same does not apply to children with disabilities. Those children mature at a slower pace compared to TD children, thus their developmental age is lower than their chronological age (Janeslätt et al., 2010). The current results meet the results of

Janeslätt (2010), not the chronological age but the developmental age is related to TPA. In the MID group there also was a significant difference in the number of men and women (Table 1). Therefore the results need to be interpreted carefully. There is yet no information about possible differences in TPA in men and women with an ID.

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Feasibility of the instrument was assessed by analyzing log notes and observations during testing. Several shortages in the Dutch version of the KaTid child, when used for people with an ID, were noted. The first finding in the log research was that certain items do not fit with the daily experiences of adults with an ID. The more a test approaches the daily life of the participant, the higher the ecological validity of a test will be. It is suggested to replace these items by items that fit in their daily life experiences. In the appendix suggestions for changing those items are attached. It would be useful to discuss the changes with the Swedish authors of the KaTid, so an international standard can be developed for using the KaTid in people with a MID and a MOID. Second, item C6.1 is age dependent, participants have to make an estimation of their grandmothers year of birth. According to the information of the Dutch Statistic

Authorities (Centraal Bureau voor Statistiek (online consulted, November 8th_{2018), the average} age of Dutch mothers when delivering their first child in the past 47 years is age 27.6. Because this is the first child, the age of mothers delivering their second, third child etc. will be higher. We used this information as an indicator for the birthdate of the grandmothers of the participants. When a participant is 35 years or older there is a big change that the birthdate of his/her

grandmother is around 100 years ago. This makes that older people have to make a more precise estimation of the birthdate of their grandmother than younger people. Furthermore researchers do not have a possibility to control for the correct answer. Therefore this item is only suitable when the KaTid is administered in children. Furthermore two items were considered to be difficult to understand. This might be due to the way the items are worded. It would be important to take notice of these items and to correct them for further research when using the KaTid in adults with an ID.

One of the strengths of this research was the combination of qualitative and quantitative research. Furthermore, the KaTid was administered by only one researcher. This benefits the interrater reliability.

Besides the strengths of the research there are also a few limitations. In the analysis of the KaTid scores is not taken into account that a lot of the items are multiple choice questions. Participants have a 50% chance of guessing the right answer. This implies that someone who does not have any skills in TPA theoretically could achieve a maximum 50% score just by guessing.

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Besides that, a stopping rule is lacking. The KaTid manual is not precise concerning the stopping rule. This could influence inter-rater reliability scores and bears the risk of asking too much of an participant. Second, the researcher has to make an estimation of what a person

potentially knows, to decide whether to keep on going or to stop if the items seem too difficult. In this project this appeared to be difficult to make this decision, as it is a subjective decision. This could influence the outcomes and the standardization of the test. The Dutch committee on test matters (Commissie Testaangelegenheden Nederland: COTAN) states that a test must be fully standardized or adaptive with explicit decision rules (Evers, Lucassen, Meijer, & Sijtsma, 2010). And that adaptive testing, when items are adapted according to the previous answers, results in a more correct estimation of the tested domain. Thereby, when a person is asked to answer a lot of difficult items which he/she cannot answer, he/she will be less motivated and less confident, which could also influence the test scores(Steinmayr & Spinath, 2009). Such a situation can be prevented by introducing a stopping rule.

In this study two categories of an ID were identified, people with a MID and a MOID. The MID group showed heteroscedastic variance, which means that there was a lot of variance in TPA scores between the participants. This can be explained by the range of severity of an ID in people with a MID (IQ scores 85-50). Furthermore, 72% of all participants had a psychiatric classification besides the an ID. Examples of classifications were: Attentional Deficit

Hyperactivity Disorder, Autistic spectrum disorder, Down’s syndrome, Charge syndrome etc. For those two reasons we have to be careful when interpreting the results of this research project. In further research it is recommended to us a larger sample, based on the normal distribution of intelligence.

Using the Dutch version of the KaTid child in people with an ID who are not able to communicate verbally was difficult. In the category time perception, participants were able to point at the right picture, but participant were not able to answer open ended questions. Some participants were able to use gestures. It would be better to exclude people with an ID and speech impairments from administration of TPA skills with the KaTid and to develop a tailor-made version for them.

From current research it is hard to answer the research question whether the results found meet the expectation that the KaTid is more suitable to use in people with a MID in contrast to people with a MOID. More research is needed on this topic.

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Future research using the Dutch version of the KaTid in people with an ID should look closer at several items and adjust them to fit with the daily experiences of the participants. Furthermore a stopping rule should be introduced for each of the categories. Finally, not only people with a severe auditory or a visual impairment should be excluded from administration of this version of the KaTid, but also people with a verbal/speech impairment. Overall the KaTid is a promising instrument to assess TPA in people with an ID, but more research is needed. The KaTid can enhance understanding of TPA skills of people with an ID and can help to improve their TPA and as a result could improve their quality of life.

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Acknowledgement

First of all, I would like to thank all participants in this study and the professionals in the institutions, who helped me find participants for the study. Further I would like to thank Prof. dr. Xavier Moonen for introducing me to the subject of time processing ability and the target

population of people with an intellectual disability and for his honest feedback on my thesis. I would also like to express my appreciation to Simone van der Burg for the mental support she gave me during the process and for all the useful feedback she gave me. I’d also like to extend my gratitude to Gunnel Janeslätt for developing the KaTid and for explaining the underlying meaning of this instrument and why it is so important to do the research and start using the KaTid all over the world. Also Fiona Hoeving deserves special thanks for the research that she had already done concerning TPA in the Netherlands, for all her help with the KaTid and for helping me to find participants. Finally, I would like to thank Dr. Roos Rodenburg for being the second reviewer of this thesis.

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Appendix 1

Suggestions for changing items that do not fit the daily life experiences of people with a MID and a MOID

A1.1 (old): Brushing your teeth Going to PE in school

Which picture shows the activity that takes a long time to complete? A1.1 (new): Brushing your teeth Going to the gym/playing sports

Which picture shows the activity that takes a long time to complete? A2.5 (old): Having breakfast Playing with Lego Putting your coat on

Which picture shows the activity that takes a short time to complete? A2.5 (new): Having breakfast Cleaning your bathroom Putting your coat on

Which picture shows the activity that takes a short time to complete? B3.3 (old): On which days are you free from school?

B3.3 (new): On which days is the weekend?

B6.1 (old): If today is Wednesday, and you have been sleeping the whole night and you wake up, what part of the day is it? Morning, noon or afternoon?

B6.1 (new): If you go to sleep on a weekday, and you are sleeping the whole night and you wake up, what part of the day is it? Morning, noon or afternoon?

C1.1 (old): How does your teacher know that the school begins in the morning?

C1.1 (new): How can you make sure that you are on time when you have an appointment? C6.1 (old): This is a picture of 40-100 years ago and this is a picture of 100-140 years ago.

How long ago do you think your grandma was born? Point at the right answer. C6.1 (new): This is a picture of 50-150 years ago and this is a picture of 150-250 years ago.

How long ago do you think your grandma was born? Point at the right answer. D1.2 (old): Watching a whole movie reading a story

If your mom/dad call the school and tell that they come to pick you up in a quarter of an hour, what can you do in the time until your parents are at school? Watch a whole movie or read a story?

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If your friend calls you to pick you up in a quarter of an hour, what can you do in the time until your friend arrives? Watch a whole movie or read an article from the