Measurement of temperament. Parent-report temperament Developmental scientists have designed several questionnaires based on different theoretical conceptualisations of temperament (e.g., Xxxxx & XxXxxxxx, 1995; Xxxxxxxxx, 1996; Xxxxxxxx, Xxxxx, Xxxxxxx, & Xxxxxx, 2001). These questionnaires are often implemented in research due to good psychometric properties and practicality of the administration (e.g., cost and time efficiency; Xxxxxxxx et al., 2013; Xxxxx et al., 2014). Parents are rich sources of information as they are the primary caregivers and have the most contact with their child. Therefore, they have the most opportunity to see temperamental tendencies in different contexts and gather generalised perspectives on trait level temperamental dispositions (Xxxxxxxx & Xxxxx, 2002). However, parental judgements may also be affected by rater bias for several reasons. Firstly, parents who have a single child may have a lack of calibration with average child behaviour to evaluate the child’s temperamental traits (Xxxxxxxxx & Xxxxxx, 2003). Secondly, in families with multiple children, parental judgement may be affected by contrasting sibling behaviour. The results of twin studies have highlighted this tendency (e.g., Saudino, 2003). Given that temperament traits are constitutionally based individual tendencies (Xxxxxxxx & Xxxxxxxxxx, 1981) and co-twins share genetic variations, similarities in temperament traits are expected. Xxxxxxx (2003) argued that low correlations in parent-rated temperament of dizygotic twins and moderate correlations in monozygotic twins might partly be explained by that parents exaggerate differences (contrasting effect). On the contrary, high correlations between co-twins may be the result of magnified similarities (assimilation effect). Thirdly, parental characteristics such as personality traits and psychopathology (e.g., anxiety and depression) influence parental perceptions of the child’s temperament (Xxxxx, Xxxxxxxxxx, de Vente, & Xxxxxx, 2013; De Los Xxxxx & Xxxxxx, 2005). For example, Xxxxxxx, Xxxxxxxx, Xxxxxx, and Xxxxx (2013) found that parents with depression perceived their child’s temperament to be more difficult than parents without depression. Parental intrusiveness, stress (Mäntymaa, Xxxxx, Xxxxx, Xxxxxxxx, & Xxxxxxxx, 2006) and their own childhood experiences, such as being exposed to over- protective parenting, also affects their perception about their children’s negative temperament (Xxxxxxx et al., 2016). Finally and importantly, using pa...
