Expressive language

The decision to measure e>q)ressive language sküls rather than, for example, receptive language skills, proved to be especially illuminating for the cognitive-emotion task and the higher-order task. As was predicted, children's expressive language skills most rehably

distinguished children's abihty to provide verbal explanations for their answers to the two tasks, that is, the two justification questions in the cognitive-emotion task and the justification question m the higher-order task. The effect did not quite reach significance for the higher-order task, and one could invoke the 'floor' effect again to explain this, since there is no other obvious plausible interpretation.

The finding that children with greater expressive language skills are better at predicting someone's emotions fi'om a joint consideration o f their behefs and desires merits close consideration. It could be that these two measures are both actually assessing the child's general intellectual abihties. Since the Bus Story and the Bayley are significantly correlated, it would appear that expressive language skills are in fact a part o f overall mental abihty. However, assuming that the Bayley MDI can be seen as an index o f general intehectual abihty, and given the absence o f any association between children’s theory o f mind performance and this construct, the possibihty that the association between expressive language skihs and theory o f mind abihty is due to the fact that they are both tapping general intehectual abihty can be dismissed.

There are several altemative accounts o f the observed association between children’s theory o f mind performance and their expressive language skihs. First o f ah, it could be, as was suggested in Chapter One, that there is a fimdamental causal relation between language and theory o f mind, such that linguistic development promotes theory o f mind development. For exarpple, it has been argued that children’s increasing abihty to generate and use symbohc representations underhes their improvement in performance on theory o f mind tasks as they get older (Plant & Karmhoff-Smith, 1993). This argument is based on ideas outlined in Chapter One, ideas that learning language - the principal symbohc, conceptual system to which the preschool aged chhd has access - makes it possible for the child to form rules and

to think abstractly. Such a causal relation from language to theory o f mind is suggested in a recent study o f prelingually deaf 8 to 13 year olds o f normal intelligence who were given a frlse-belief task using sign language they had learned after entering school (Peterson & Siegal, 1995). Despite perfect performance on the control questions, most children failed the task. O f course, this study could equally be interpreted as supportive o f a social interaction hypothesis o f the influence o f language on the development o f a theory o f mind. However, the correlational data o f the present study cannot address the issue o f the causal relation o f language to theory o f mind, an issue which remains ambiguous m the empirical literature (Astington & Jenkins, 1995b).

A related interpretation o f the association observed in this chapter resides within the domain o f narratives and language. As was described in the introduction to this chapter, Lewis et al. (1994) have theoretically proposed and empirically demonstrated that there is a relationship between narrative fluency (the child retelling the theory o f mind scenario) and false-behef reasoning, and it seems appropriate to extend this theory to the present findings^. Such a narrative account would interpret the present findings as suggesting that those children Wio are able to recount the Bus Story more fluently and coherently, and thereby gain higher scores on the Bus Story variables (especially the quality o f information variable), have a better understanding o f narratives in general - via particular aspects o f language, such as story grammars (Schank & Abelson, 1977) and mental models (Gamham, Oakhill & Johnson-Laird,

^However, there are obviously irrportant differences, which could also be limitations on the apphcability o f Lewis et aL's theory as an e?q)lanation for the present results: firstly, the narrative fluency under consideration here is the child's abihty to retell a story other than the theory o f mind scenario (i.e. the Bus Story - see Appendix 3.3 for the fuU dialogue); and secondly, one o f the measures o f theory o f mind here involves emotions based on false-behefs, rather than simply false-behefs alone, and the other is based on higher-order representations.

1983) - and that this understanding o f narratives gives specific access to theory o f mind abilites, since the theory o f mind scenarios are quintessentially about such information (for exanq)le, see Bruner, 1986^).

There is, however, an equally plausible altemative narrative account. This interpretation would argue that those children with higher scores on the Bus Story are demonstrating a greater abihty to formulate and access detailed and enmeshed accounts o f a story. This generic skih o f narrative fluency helps them to perform a number o f tasks, including theory o f mind ones, but is not uniquely related to an understanding o f mental state information.

A third explanation could be that children’s theory o f mind performance and their expressive language skills were observed to be correlated because they are both dependent on some third common variable - that is, some underlying factor brings about development in both theory o f mind and language. One such possible common variable is children’s early attachment security, which, as was described in Chapter One, has been found to be predictive o f children’s development across a wide range o f domains. Whether such an explanation can account for the present findings will emerge in the multivariate analyses o f Chapter Eight.

As the results stand at the moment, however, the findings regarding the role o f parents' verbal skills may add an interesting dimension to the explanations proposed thus far.