The development of temporal orienting of attention and its role in language rule learning
After only a few years of life, children are able to understand and produce their language effortlessly and without the need to receive any specific instruction. Understanding how children achieve such an extraordinary landmark is the ultimate goal of a language acquisition researcher. Previous research suggests that the attention system, which allows the brain to select certain stimuli for further processing and ignore others, influences language processing, and as a consequence, it affects its learning. Although a considerable progress on the understanding of the role of attention in language have been reached, the under-specification of the attentional mechanisms involved in language learning calls for the necessity of developing new frameworks on how this relationship might work. For this reason, the current doctoral thesis takes a cognitive neuroscience perspective to investigate the putative attention mechanisms that may scaffold language development. Given the intrinsic temporal characteristics of speech, this doctoral thesis proposes that temporal aspects of attention may be of critical relevance in oral language acquisition.
This dissertation encloses four different studies, by combining eye-tracking and behavioural measures in four different populations; infants, typically developing (TD) children, children diagnosed with Specific Language Impairment (SLI) and adults. The experimental data are presented in Chapters 3, 4, 5, and 6 that enclose Study 1, Study 2, Study 3, and Study 4, respectively. The first two studies address temporal orienting of attention, by investigating its emergence in infancy (Study 1) and its developmental trajectory throughout childhood and adulthood (Study 2). Study 1 demonstrates that the ability to endogenously orient attention in time emerges at 15 months of age. Study 2 reveals that differences in executive function demands modulate the effects of temporal orienting of attention. More specifically, the temporal orienting effects seem to be due to a flexible mechanism of temporal orienting. The last two studies focus on the temporal attention mechanisms involved in language rule learning (Study 3), and the role of executive functions in infant language rule learning (Study 4). The results of Study 3 reveal that better temporal orienting abilities are related to better language rule extraction abilities in adults and TD children. In addition, differences in temporal orienting are observed in children with SLI when compared to an age and gender matched control group. Finally, Study 4 provides evidence on the relationship between the development of executive functioning and language rule learning in infancy, showing that the different patterns of language rule discrimination observed seem to depend the development of executive functions at the age of 15 months.
Taken together, the research presented in the current doctoral thesis supports the idea that the attention system acts as a modulatory system assisting language learning. The current doctoral thesis proposes that temporal orienting may involve at least two developmental stages, a more rigid one and a more flexible one, engaging executive attention, and that flexible mechanisms of temporal orienting benefit language rule learning.