Theoretical Implications

Study 1 has contributed to the theory of iconicity in symbol learning, suggesting that there is a threshold over and above which any enhancement to iconicity will not benefit performance. Previous research has theorised that children with ASC rely on a high level of iconicity to successfully map symbols with their intended referents (Hartley & Allen, 2015a). Greater pictorial realism (such as coloured photographs) has been found to improve

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1997; Hartley & Allen, 2015b). However, it was not known whether three-dimensional and interactive symbols presented on a screen would improve iconicity and the realism of the images beyond the realms of 2D coloured photographs – potentially increasing symbolic understanding in ASC. Study 1 found that 2D coloured photographs are enough to elicit successful symbol learning in ASC, and under such conditions children with ASC perform as well as their TD peers. Consequently, any additional measures to improve the iconicity of images are not necessary to foster symbolic understanding for children with ASC. This could potentially inform the teaching of new symbols to children with ASC within the classroom, suggesting that 2D coloured photographs are the optimal stimuli to foster symbolic understanding in this population.

Study 2 examined the theory that language (specifically labelling) scaffolds symbolic understanding in typical development (Callaghan, 2008). Previous research suggests that TD children demonstrate greater symbolic understanding and generalisation to different category members when a symbol is labelled compared to when it is unlabelled (Booth & Waxman, 2002; Preissler & Bloom, 2007; Waxman & Booth, 2003). However, Hartley and Allen (2015b) found that this was not the case for children with ASC, who exhibited no difference in symbolic understanding when the symbol was labelled compared to when it was unlabelled. The current study included both TD children and children with ASC and compared symbolic understanding between labelled and unlabelled conditions. No significant difference was found between conditions, with a high level of symbolic

understanding for both groups. It may be that naming is no more beneficial than other forms of information, such as description of function (Field, Lewis, & Allen, 2016b). As previously explained, a description of the target object’s function was provided alongside the symbol in the training phase regardless of condition, and consequently a linguistic cue was provided to every child. This may explain the high level of symbolic understanding across conditions. However, it is important to note that, as with Study 1 (iconicity and symbol learning), symbols used in this study were realistic coloured photographs and so it is difficult to know whether the high level of symbolic understanding is due to language or iconicity – which has been

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found to benefit symbolic understanding in ASC (Hartley & Allen, 2014b; Hartley & Allen, 2015a; Hartley & Allen, 2015b).

Study 3 contributed the theory of word/label learning in children with ASC and typical development. Previous research suggests that children with ASC do not possess

qualitatively different word learning mechanisms to TD children, however word learning mechanisms may be less efficient in ASC (Hartley et al., 2019; Hartley et al., 2020). Children with ASC may require multiple exposures to new words to facilitate successful delayed recall (Haebig et al., 2017; Hartley et al., 2019; Hartley et al., 2020) due to the language difficulties experienced by this population (Kjelgaard & Tager-Flusberg, 2001; Pelphrey, Shultz, Hudac, & Vander Wyk, 2011). In the current study, children with ASC and TD children were given two new labels for novel animals, repeated twice in a labelling activity. They were then tested on their label recall immediately and after a two-week delay. Robust label recall was examined – whether participants correctly recalled both labels immediately and after a delay. TD children performed above chance (11%), with approximately 26% of participants

correctly recalling both labels at both time points, compared to approximately 10% of

children with ASC. Despite comparable immediate recall between groups, TD children more often retained the new label information over time. This finding could potentially guide the teaching of new vocabulary to children with ASC within the classroom, suggesting that two exposures to a new word is not enough to facilitate successful label retention in some children with ASC. This finding also emphasises that successful immediate recall (fast mapping) is only the first step in the slow and effortful word learning process (Axelsson & Horst, 2014).

Study 4 has contributed to the theory of narrative comprehension in children with ASC. Specifically, that children with ASC have a deficit in inferential narrative comprehension (requiring the sequencing of key events and the integration of text information with the participant’s own knowledge) while performing as well as their TD peers on fact-based comprehension questions (Norbury & Bishop, 2002; Nuske & Bavin, 2011). Researchers have theorised that this disparity in performance is due to weak central coherence in ASC –

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the tendency to prioritise the processing of local information at the expense of the gestalt (Frith, 1989). In the current study, participants were administered multiple-choice questions (measuring knowledge of individual facts) and a picture ordering task (measuring the sequencing of key events) immediately after storybook reading. As expected, children with ASC performed as well as their TD peers on the fact-based questions. However, contrary to predictions, children with ASC also performed as well as their TD peers on the picture ordering task – requiring some inference-making abilities. This suggests that some children with ASC do not have a deficit in narrative comprehension compared to TD children on both fact-based and inferential comprehension questions. However, it is important to note that while the picture ordering task required some inference-making ability to allow for the

integration of temporal story information to create a coherent narrative (Oakhill & Cain, 2012) it did not fully tap into the inference-making abilities of children with ASC. For example, it did not require the integration of text information with the participant’s own knowledge – another key element of inference-making (Cain & Oakhill, 2014; LAARC & Muijselaar, 2008; Tarchi, 2015). To fully investigate this theory, future research could expand the multiple-choice question task used in the current study to include questions that require inference-making and the integration of the child’s own experience with storybook information.

Study 1 (iconicity and symbol learning) and Study 4 (narrative comprehension) provide further evidence to support the weak central coherence theory (Frith, 1989), in addition to the ‘Coherence Principle’ in multimedia learning (Harp & Mayer, 1997). Previous research suggests that the simultaneous presentation of information to multiple modalities can be conducive to learning when minimal miscellaneous information is included (Mayer & Moreno, 1998). Moreover, irrelevant information is particularly detrimental for individuals learning a new skill (Mayer & Moreno, 1998) and young children with limited cognitive resources (Kirkorian, 2018), potentially increasing cognitive load and subsequently adding strain to working memory (Sweller, 2005). Although the relevance of multimedia and interactive information was not directly manipulated in the current research, a different relationship between engagement and learning can be found between children with ASC

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and TD children in Studies 1 and 4. When symbols were presented one at a time on the screen against a blank background (Study 1), greater visual attention towards symbols was related to more robust symbolic understanding in children with ASC. In contrast, when both relevant and irrelevant information was presented on an e-book (Study 4), greater visual attention was only related to performance for the TD group.

The findings of Studies 1 (iconicity and symbol learning) and 4 (narrative

comprehension) suggest that the relevance of information may be particularly important for some children with ASC, as TD children in Study 4 were not impeded by the mixture of relevant and irrelevant interactive and multimedia features within the e-book. This may be due to the weak central coherence and executive dysfunction experienced by some children with ASC (Christ et al., 2007; Frith, 1989; Omar & Bidin, 2015; Richard & Lajiness-O’Neill, 2015). Although not directly measured within this thesis, the findings of Studies 1 and 4 are consistent with the weak central coherence theory of ASC, suggesting that children with ASC, who may have difficulty with global information processing, are more susceptible to the distracting influence of irrelevant information during a task.