Joint attention and word learning

In a classic word mapping study, Baldwin (1993) concluded that enhanced salience and temporal contiguity are not sufficient elements for establishing a new word-object link. Other researchers arrived to the same conclusions through different experimental methods (Akhtar, Carpenter, & Tomasello, 1996; Akhtar & Tomasello, 1996; Baldwin et al., 1996; Samuelson & Smith, 1998). As Bruner (1975) suggested in his social-pragmatic approach, something more is required by the infant to make a meaningful connection between word and object: joint attention, the act of sharing attention between the speaker and the listener, directing and following attention through different cues. In fact, joint attention is constructed on a set of cues embedded in the social interaction, which help in establishing the word-object link: gaze direction, head direction, body posture, voice direction, gestures, intonational quality, and facial expressions (Baldwin & Moses, 2001).

Recent studies testing Bruner’s (1975) proposal of joint attention being the linking element between preverbal and verbal communication, found that triadic

interaction skills are indeed strong precursors of language development (see Figure 1.5, Carpenter et al., 1998; Daum, Ulber, & Gredeback, 2013; Gliga & Csibra, 2009;

Morales et al., 2000; Mundy & Gomes, 1998; Mundy et al., 2007).

Figure 1.5. Lines represent prerequisite relations, while the direction of the arrows show the order of

emergence (Carpenter et al., 1998).

In particular, following joint attention (i.e., following gaze/head/posture movements and/or pointing gestures) at earlier months is related to later receptive vocabulary growth (Brooks & Meltzoff, 2005; Morales et al., 2000, 1998; Mundy, Fox, & Card, 2003; Mundy & Gomes, 1998; Mundy & Jarrold, 2010) and is fundamental for novel word learning in experimental settings, being the necessary base for referentially mapping the new word onto the correct object (Baldwin, 1993, 2000; Mundy et al., 2009). It has been shown that correct interpretation of gaze shifts and pointing gestures, rather than more basic features of the object itself (i.e., attention grabbing features, inherent salience) or of the situation (i.e., temporal contiguity, attentional enhancement caused by the gaze shift), facilitates the establishment of the word-object link (for a review see Baldwin & Moses, 2001). At the same time, IJA abilities have been shown to predict later language acquisition (Mundy, Fox, et al., 2003; Mundy & Jarrold, 2010), but not in such a strong way. There is therefore a distinction between these two aspects of joint attention and their role in language acquisition. However, this is not the same as saying that infants are passively receiving information, but rather that they are able to recognise stimuli denoting situations carrying new information and to act on these stimuli. For example, in a series of studies in which the experimenter provided a novel label for one novel and one known object vs. two novel objects, infants of 13 and 18 months of age, directed gaze more frequently towards the experimenter in the second

condition, when they in fact needed more disambiguating information to understand the situation (Vaish, Demir, & Baldwin, 2011).

Given the social nature of language acquisition and its bases in joint attention, caregivers play an important role in the process. The ability of mother-infant dyads of establishing and maintaining joint attentional bouts has been found to be associated with better language outcomes (Markus et al., 2000; Tomasello & Farrar, 1986). Also, children rely on adults’ feedback to evaluate their communicative efficacy and improve their knowledge of language’s conventions (Tomasello, 1992). At the same time, children play an active role in the building of their vocabulary. Researchers found that individual differences in infants’ receptive language skills at 12 months predicted the amount of time spent in joint attention interactions with the mother at 18 months and that expressive language skills at 12 months influenced the infants’ ability to initiate joint attention bouts during interactions at 18 months (Markus et al., 2000). Moreover, it has been shown that 2-year-olds can establish a novel word-object link by overhearing conversations (although the results were less clear for action-verb links) (Akhtar, Jipson, & Callanan, 2001).

1.3.5 Conclusions

Infants are actively gathering information from other people from very early on. From preferential attention to faces at 2 months, to proximal attention following

between 3 and 4 months, infants show the ability to orient their attentional focus in particular towards stimuli of a social nature. A continuous exchange between neural predispositions, accumulation of personal experience and feedback from caregivers and other people contribute to shape infants’ triadic attention skills.

Mundy’s view of joint attention as part of a continuum of social learning

(Mundy et al., 2000) highlights the importance of dyadic attention abilities developed in the first months of life as precursors of joint attention skills and therefore, later on, of

language skills. The conscious awareness that others are intentional beings seems to not be necessary to successfully navigate social interactions in the first year of life, while infants are able to identify the goal-directedness of others’ actions through experience, accumulating knowledge on intentionality.

The reciprocal influence of joint attention and language adds another element to the interconnected system of social stimuli and abilities that surrounds infants. In particular, establishing correct referential connections between words and their correspondents in the material world relies heavily on the ability of successfully responding to joint attentional bids.

1.4 Summary

This chapter introduced the two main topics on which this thesis is based on: prematurity and social attention and communication.

Premature birth is a common event worldwide and is not showing clear signs of diminishing. Negative developmental outcomes linked to prematurity affect also infants born at later gestational ages and can last well into childhood and later on. However, infants born closer to the 37 weeks mark have been neglected by

developmental psychology research until recently. In particular, there is very little knowledge on the socio-cognitive development of this population.

Socio-cognitive skills play an important role in infants’ development and are influenced by caregivers, as well as the infants themselves. Dyadic and triadic attention skills flourish during the first year of life, providing infants with powerful tools to interact with the surrounding environment. The continuous development of these skills supports the growth of receptive and productive language in the second year of life.

The next chapter describes the longitudinal study on which this thesis is built, providing details on its aims, experimental measures and procedures, together with a description of the participants’ samples.