JCPSLP Vol 17 No 3 2015

contingent communicative style was a positive one. In contrast to a contingent communicative environment is one with increased parental control. A longitudinal study investigating parental control conducted by Lederberg and Everhart (2000) compared the number of directives given to 20 children who were D/HH and 20 children who were NH, at 22 months and 3 years of age. The study involved three measures of maternal directives. The number of direct behavioural commands (“Stop that.”), was significantly different between the groups. At both points in time, the mothers of children with a hearing loss were significantly more likely to use the direct behavioural commands, with the number used by the mothers of children who were D/HH the same as the number the mothers of the NH children used at 22 months (Lederberg & Everhart, 2000). The authors attribute the increased maternal control to the delayed language abilities of the children who were D/HH. Lam and Kitamura (2010) reported similar results in a twin study, linking differences in maternal control to the decreased responsiveness of the twin who was D/ HH. To the twin with a hearing loss, the mother was less responsive, more controlling, and more directive during interactions. Despite the ability of a twin study to more closely control for individual variation and environmental factors, the generalisability of the study is limited, and the findings were not supported by statistical analyses. These studies indicate the likelihood of a difference in caregiver behaviour and control due to the impact of hearing loss on child behaviour. An important measure of the quality of HLE is the presence of rich conversational experiences, including opportunities to learn linguistic rules (Chouinard & Clark, 2003). Supportive caregiver behaviours such as expansions, repeats, recasts, and requests for clarification enable children to learn language during conversation (Chouinard & Clark, 2003). Ruter (2011) found that for 21 children following cochlear implantations, parental expansions increased their acquisition of grammatical structures, with a significant correlation between an expansion of a grammatical structure and the children’s subsequent usage. Children who are D/HH have more profound difficulties in syntax and grammar compared with vocabulary acquisition (Boons et al., 2013) and therefore this study highlights the valuable role that parental expansions have for language development and informing intervention strategies in this population. The results of these studies can be grouped into three major themes: those indicating differences in parental conversational control (Lam & Kitamura, 2010; Lederberg & Everhart, 2000), parent–child responsiveness (Harrigan & Nikolopoulos, 2002; Morgan et al., 2014; Most et al., 2010), and the richness of the linguistic environment (Ruter, 2011). Interaction quantity The number of adult words a child is exposed to in the HLE is acknowledged as a key facilitator of language acquisition (Zimmerman et al., 2009). In terms of typical language development, the number of adult words a child hears has been found to be relatively stable, while conversational turns and child vocalisations increase as the child ages and language skills develop (Greenwood, Thiemann-Bourque, Walker, Buzhardt & Gilkerson, 2010). Extrapolating these findings to children who are D/HH, a reduction in conversational turns and child vocalisations compared to children who are NH may be expected, due to decreased spoken language competence in this population. Additionally, no significant differences in the number of adult words may be anticipated. However, according to

experiences (Vigil et al., 2005). The scope of the current study is therefore closely underpinned by the theory of emergentism. This theory acknowledges the interaction between the “external language environment and the internal learning capabilities of the child” (Morgan et al., 2014, p. 47). Emergentism indicates that there is a likely compounding effect of a less supportive linguistic environment in addition to language learning difficulties associated with hearing loss. Consequently, the quality and quantity of interaction in the HLE is considered in this paper. Interaction quality Demonstrating emergentism theory in this population, Lam and Kitamura (2010) summarised research surrounding the impact of hearing loss on the communicative behaviour of caregivers of children who are D/HH. They suggested caregivers are more controlling and dominant during conversation, and that communicative breakdowns occur more frequently due to decreased responsiveness from the child (Lam & Kitamura, 2010). Similarly, Morgan et al. (2014) examined the quality of conversational turns between 30 children who were D/HH and 19 children who were NH aged between 17 and 35 months, and their caregivers. The measures of conversational quality were based on those proposed by Ensor and Hughes (2008), and included coding exchanges as connected, initiated, failed, or unclear. Connectedness is a measure of how semantically related an utterance is to the previous turn. It provides an indication of how often topics are continued, and how responsive conversational partners are to each other’s communicative attempts (Ensor & Hughes, 2008). As such, it can be used to measure how supportive the HLE is for language development, as children engage more enthusiastically and frequently in topics initiated by them (Harrigan & Nikolopoulos, 2002). In contrast, more failed or unclear utterances indicate less successful interaction experiences and conversational partners who are less responsive (Harrigan & Nikolopoulos, 2002). The study found the NH group displayed more connected conversational turns, initiated communication more often, and had fewer failed or unclear turns (Morgan et al., 2014). Although the study did not account for non-verbal communication, the authors suggest the conversational exchanges were “impoverished” (Morgan et al., 2014, p 47). These findings are supported by Most, Shina-August, and Meilijson (2010). Out of 24 children receiving amplification, appropriate connected interactions were not displayed consistently between any children who were D/ HH and their caregivers. In contrast, such interactions were displayed by 11 of the 13 NH children and their caregivers. It should be noted that the authors viewed this discrepancy as a difference in pragmatic function between the two groups, and they acknowledged the impact on the success of the communicative interactions. According to the literature, the quality of interaction in the HLE is improved when caregivers expand on their child’s utterances, use self-talk, promote conversational turn-taking, limit parental initiations, and follow their child’s communicative initiations (Vigil et al., 2005). A study conducted by Harrigan and Nikolopoulos (2002) involved teaching caregivers of children with cochlear implants these supportive behaviours. Parental utterances were assigned to one of two categories: an initiation or a response. Post- course, the parents responded significantly more to their child rather than initiating a conversational turn (Harrigan & Nikolopoulos, 2002). Although the study did not assess the impact this might have had on the children’s language abilities, the authors suggested that the shift towards a

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JCPSLP Volume 17, Number 3 2015

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