Stability in temperament and emotional expression in 1- to 3-year-old children

I examined the stability of emotional expression in 18 toddlers aged 1 year, 2 years, and 3 years using laboratory observation. The children were presented with 5 social stimuli. Their emotional expressions were video recorded and later behaviorally coded by 2 independent raters. Average latency, intensity, and duration scores for emotional expression for each child were calculated at ages 1, 2, and 3 years and compared using Friedman's test. Intensity of emotional expression in the children showed stability over the 3 years; no significant differences were found between ages 1, 2, and 3 (c2(2) = 1.78, p = .41). Additionally, based on parental questionnaires for each year, from 1 to 3 years of age intensity, mood, activity, approach, and adaptability were 5 dimensions of temperament that showed stability.Keywords: emotional expression, intensity, temperament, stability, toddler.Temperament has been defined in a number of ways (Buss & Plomin, 1984; Rothbart, 2011; Strelau, 2008; Thomas & Chess, 1977). Although definitions vary, these theorists all agree that temperament refers to early individual differences in how each person reacts to stimuli. Emotional reactions are also part of early individual differences in how each person reacts and, therefore, emotional reactions are considered to be part of temperament.Emotional reactions are observed in emotional expressions. James (1981) defined an emotional expression as a reaction to a particular stimulus that is evident in bodily expression. In humans that bodily expression includes facial expression, vocal expression, gestures, and posture (Goldsmith, 1993; Goldsmith & Campos, 1986). These outward emotional expressions all reflect and communicate inner states to others and are often referred to as state emotion (Lewis, 1998).Emotional expressions are reactions that vary in their temporal characteristics (Buss, 1991; Denham, Lehman, Moser, & Reeves, 1995; Hudlicka, 2002; Losonczy, 2001; Strelau, 2008), such as latency in responding, intensity of expression, and duration of expression. There may be variations in these temporal characteristics from one individual to another. Additionally, individuals may also develop tendencies to react in specific ways; these tendencies are often viewed in terms of trait emotion (Strelau, 2008). For example, a particular individual may typically express anger intensely and be recognized for that trait. According to Hudlicka (2002, p. 616) "traits contribute to the dynamic characteristics of the affective states themselves," that is, their generation, intensity, duration and expression. This means that traits (or tendencies) contribute to the latency, intensity, and duration of emotional expressions. In other words, trait emotion may influence state emotion. If trait emotion influences state emotion then one would expect that, over time, there would be stability in the emotional aspects of temperament as well as stability in the dynamic characteristics of emotional expressions.Previous researchers on the emotional aspects of temperament have reported stability. Some researchers have focused on infants (Carranza Carnicero, Perez-Lopez, Del Carmen Gonzalez Salinas, & Martinez-Fuentes, 2000; Goldsmith & Campos, 1990; Riese, 1987; Rothbart, Derryberry, & Hershey, 2000; Sullivan, Lewis, & Alessandri, 1992; Wachs, Pollitt, Cueto, & Jacoby, 2004). Two studies have been conducted in which researchers have examined the stability of the emotional aspects of temperament in childhood (Durbin, Hayden, Klein, & Olino, 2007; Van den Akker, Dekovic, Prinzie, & Asscher, 2010). Similarly, there are only two studies in which researchers have examined the stability of the emotional aspects of temperament from one developmental period to another (Casalin, Luyten, Vliegen, & Meurs, 2012; Neppl et al., 2010). All of these researchers examined the emotional aspects of temperament in various ways. …