Measure – Developing the Observation Coding Scheme

The Repetitive Behaviour Coding Scheme (RBCS) was developed using the methods

described below. The final version of the Repetitive Behaviour Coding Scheme is in Table

2.2.

2.2.3.1 Pre-pilot and pilot observations. I conducted pre-pilot observations on 30

hours of video records (this was 15 infants). These preliminary observations were conducted

by watching one infant at a time, recording all movements made by each infant. I transcribed

a continuous narrative record of all repetitive behaviours made by each infant and this

narrative approach was used for the preliminary sub-sample of 15 infants. I then read over the

narrative records and the behaviours that resembled the motor stereotypies and repetitive

actions on objects from previous studies were extracted. Whilst focusing on Thelen’s

behavioural categories I read my transcripts and focused on extracting any behaviours that

resembled her previous work, whilst also noting any behaviours that were not recorded by

Thelen. This method resulted in a list of 8 categorical items (flap, bounce, rock, head

movements, bang toy against another toy, bang toy against another object, clap and arm

banging a surface [e.g. wall, sofa]). A repetition was operationally defined as a movement of

a part of the body that is repeated in the same way three times (or more) within a two second

period. Should flap, bounce, rock or head movements occur whilst the infant was holding or

70 distinction between motor stereotypies and repetitive actions with objects discussed in

previous sections on the thesis

In general, the onset of the behaviour occurred at the moment the particular movement

started and then the offset occurred the moment the child ceased the behaviours, engaged in a

different action with the same objects of a different object, or paused between repetitive

actions for a period longer than 5 seconds (e.g. if an infant flapped and then stopped flapping

for five seconds and then flapped again, the second instance is a separate behavioural event).

Different repetitive behaviours could be coded simultaneously (i.e. when an infant flapped

and bounced at the same time).

The initial observation coding scheme was then used in pilot observations, where a

different 10 participants were observed and coded by three independent observers (these 10

infants were randomly selected from the 100 in the study. The second coder was trained to

use the coding scheme and the third coder was not). The 10 participants were different from

the original 15 that were used to develop the scheme. Operational definitions for each item

were edited to ensure clarification and ease of use of the coding scheme, these can be seen in

Table 2.2. In Table 2.3 I have provided examples of behaviours occurring without object

(motor stereotypies) and with object (repetitive action with objects).

2.2.3.2 Applying the RBCS to the sample. For the purpose of the formal coding, I

started coding again and coded all 100 participants (including the ones used in the

preliminary observations). Each video was observed two times, each viewing recorded the

behaviours of one individual participant on an event-based coding. Initially observers

transcribed and coded the type of behavioural repetition exhibited by the infant (e.g. flapping,

71 behavioural repetition and were also instructed to count the number of behavioural repetitions

displayed per event. Subsequently, the RBCS allows measurement of the frequency of the

behavioural bouts of repetition, the duration of the behaviour and the number of repeats

within each behavioural event. A randomly selected transcript can be seen in Appendix II.

2.2.3.3 Establishing reliability. I coded all of the videos. Because the RBCS was a

newly developed measure of repetitive behaviours, a second observer coded 33% of the

videos. To measure reliability, intra-class correlation coefficients (ICC) were calculated for

the total number of behavioural repetitions per participant, ICC inter-rater agreement for the

total number of repetitive motor behaviour bouts per participant was .95. On the item level,

for the behavioural category label provided for the bout exhibited, Kappa coefficient

agreement was .91.

In order to ensure that coding had remained consistent throughout the thesis, I coded

5% of the sample (n=5 children) again, 36 months after the initial coding had been

completed. Test-retest reliability was established with the number of behavioural bouts per

participant (ICC = .98) and the type of repetitive behaviour exhibited (ICC = .99).

2.2.3.4 Creating composite variables. The total number of repetitive behaviours

exhibited was calculated for each participant. The total number of repetitive actions with

objects was calculated (flapping, bouncing and rocking transcribed with object, as well as

banging toy against toy and banging toy against another object). Similarly, the total number

of bouts of motor stereotypies was calculated (flapping, bouncing, rocking and head

movement transcribed without objects as well as arm banging against surfaces and clapping).

Composite variables were therefore calculated to provide a simple measure of whether or not

the participant engaged in repetitive behaviour at all, whether they engaged in repetitive

72 time of all behaviours were noted and therefore I was able to calculate the total time infants

engaged in repetitive behaviour.

Participants’ free play session lasted for 25 minutes. For ease of comparison with other

research and in order to compare the descriptive information with those presented throughout

the thesis, a rate per hour was calculated for total repetitive behaviour observed, sum of

motor stereotypies observed and sum of object based repetition observed. A rate per hour was

also calculated for the individual behavioural categories (flap, bounce, rock, head

movements, clap and banging categories). A rate per hour therefore gives a consistent time

frame over which data can be compared across the studies reported in this thesis and allows

other researchers to compare their data to mine simply.