Table 2.
Study 1: pattern matrix for principal components analysis of neurotypical data, percentage of variance explained, internal consistency and descriptive statistics for each component
| Rotated item loadings | Component 1 | Component 2 |
|---|---|---|
| Repetitive motor behaviour (RMB) | Insistence on sameness (IS) | |
| Like to arrange items in rows or patterns? | .447 | .140 |
| Repetitively fiddle with items? | .611 | .054 |
| Spin yourself around and around? | .713 | −.084 |
| Rock backwards and forwards, or side to side, either when sitting or when standing? | .871 | −.207 |
| Pace or move around repetitively | .718 | −.067 |
| Make repetitive hand and/or finger movements? | .686 | .029 |
| Have a fascination with specific objects? | .390 | .261 |
| Like to look at objects from particular or unusual angles? | .233 | .218 |
| Have a special interest in the smell of people or objects? | .178 | .308 |
| Have a special interest in the feel of different surfaces? | .383 | .250 |
| Have any special objects you like to carry round? | .181 | .424 |
| Collect or hoard items of any sort? | −.078 | .503 |
| Insist on things at home remaining the same? | .001 | .702 |
| Get upset about minor changes to objects? | −.103 | .695 |
| Insist that aspects of daily routine must remain the same? | −.102 | .716 |
| Insist on doing things in a certain way or re-doing things until they are “just right”? | .184 | .505 |
| Play the same music, game or video, or read the same book repeatedly? | .164 | .507 |
| Insist on eating the same foods, or a very small range of foods, at every meal? | −.041 | .438 |
| Percentage of variance explained: | 25.67 % | 10.16 % |
| Cronbach’s alpha (α): | .78 | .73 |
| Mean (SD) | 1.65 (.46) | 1.54 (.37) |
| Median (IQR) | 1.50 (.67) | 1.50 (.47) |
Bold denotes items that load on each factor (item loading > .4)