The psychometric properties of the Socio-Moral Reflection Measure - Short Form and the Moral Theme Inventory for men with and without intellectual disabilities

Drawing conclusions from the literature regarding the moral development of people with

intellectual disabilities (IDs) is difficult because of the use of unstandardised and

idiosyncratic measures. In order to address this short-coming, a moral reasoning

production measure (the Socio-Moral Reflection Measure – Short Form; SRM-SF) and a

recognition measure (the Moral Theme Inventory; MTI) were presented to men with and

without IDs who had no known history of engaging in illegal behaviour. The instruments

were completed on two occasions, separated by a two-week interval, in order to

investigate their basic psychometric properties. The results indicated that there was a

strong relationship between the MTI and the SRM-SF, suggesting that the MTI has

convergent validity. The internal consistency of the MTI and the SRM-SF ranged from

moderate to substantial for both men with and without IDs. However, the test–retest

reliability of the MTI was poor formen with IDs, while it was good formen without IDs. The

test–retest reliability of the SRM-SF was good for both men with and without IDs.

Comparison of the moral reasoning abilities of men with and without IDs suggested that

many of the differences between the two groups could be accounted for by general

intellectual functioning. The exception was overall score on the SRM-SF and moral

reasoning in relation to the law, where men with IDs scored at stage 2(1), when

intelligence was controlled. The results were interpreted by suggesting that the

relationship between moral reasoning and illegal behaviour may take an inverted U

curve shape, moderated by intelligence.