This thesis aims to investigate how well associative learning can account for human sequence learning under incidental conditions. It seems that we can learn complex sequential information about events in our environment, for example language or music, incidentally, without being aware of it. Awareness is, however, a complex issue with arguments for (Dienes, 2012) and against (Shanks, 2005) the existence of implicit learning processes. A dual process account proposes that there exist two different learning systems, one based on conscious, controlled reasoning and rules, and the other based on automatic association formation, which can take place outside of awareness (McLaren, Green, & Mackintosh, 1994). This thesis attempts to use the predictions of an associative account in conjunction with a suitable method for investigating implicit learning: sequence learning (Destrebecqz & Cleeremans, 2003). The research involves a collection of serial reaction time (SRT) tasks whereby participants respond to on-screen stimuli that follow a sequence that they were (intentional learning) or were not (incidental learning) informed of. Following on from the experimental design of Jones and McLaren (2009) this thesis provides evidence that humans differ in their ability to learn different sequential contingencies. After training sequences of trials where the current trial location was twice as likely to be either: the same as (Same rule); or different to (Different rule) the location two trials before this, participants were far better at learning the latter rule. I found that this result was not adequately simulated by the benchmark associative model of sequence learning, the Augmented SRN (Cleeremans & McClelland, 1991), and present a revised model. This model, amongst other attributes, represents all the stimuli experienced by participants and can therefore learn stimulus-response contingencies. These seem to block learning (to some extent) about the Same rule thus providing an associative explanation of the advantage for acquisition of the Different rule. Further predictions regarding the role of additional stimuli alongside sequence learning were then derived from this associative account and tested on human participants. The first of these was that additional stimuli within the task will interact with sequence learning. I found that human participants show increased Same rule learning when additional, concurrently presented stimuli follow the previous element in the sequence. I demonstrate that when participants perform an SRT task where responses are predicted by the colour of a cue, they are able to learn about this relationship in the absence of awareness. Using this cue-response learning I further investigate cue-competition between sequences and colours under incidental conditions and find evidence that suggests between cue associations may alter the influence of cue competition. These results altogether suggest that stimuli – both simple and sequential – can be learned under incidental conditions. This thesis further proposes that learning about simple and more complex relationships between stimuli interacts according to the predictions of an associative account and provides evidence that contributes to a dual process understanding of human learning.

The procedural deficit hypothesis (PDH) posits that a range of language, cognitive and motor impairments associated with specific language impairment (SLI) and developmental dyslexia (DD) may be explained by an underlying domain-general dysfunction of the procedural memory system. In contrast, declarative memory is hypothesized to remain intact and to play a compensatory role in the two disorders. The studies in the present thesis were designed to test this hypothesis. Study I examined non-language procedural memory, specifically implicit sequence learning, in children with SLI. It was shown that children with poor performance on tests of grammar were impaired at consolidation of procedural memory compared to children with normal grammar. These findings support the PDH and are line with previous studies suggesting a link between grammar processing and procedural memory. In Study II, the same implicit sequence learning paradigm was used to test procedural memory in children with DD. The DD group showed a learning profile that was similar to that of children with SLI in Study I, with a significant impairment emerging late in learning, after extended practice and including an overnight interval. Further analyses suggested that the DD impairment may not be related to overnight consolidation but to the effects of further practice beyond the initial practice session. In contrast to the predictions of the PDH, the sequence learning deficit was unrelated to phonological processing skills as assessed with a nonword repetition task. Study III examined declarative memory in DD. The performance of the DD group was found to be not only intact, but even enhanced, compared to that of the control children. The results encourage further studies on the potential of declarative memory to compensate for the reading problems in DD. In sum, the results lend partial support for the PDH and suggest further refinements to the theory. Collectively, the studies emphasize the importance of going beyond a narrow focus on language learning and memory functions in the characterization of the two disorders. Such a broader cognitive, motor and language approach may inform the development of future clinical and pedagogical assessment and intervention practices for SLI and DD.

Procedural learning abilities have been shown to be deficient in children who meet criteria for Developmental Dyslexia (DD) and those who meet criteria for Specific Language Impairment (SLI; Lum et al., 2010; Menghini et al., 2006). Further, grammatical understanding has been linked to implicit sequence learning abilities across SLI and typically developing children (Lum, 2012). The present study examined implicit sequence learning, measured by the Serial Reaction Time Task (SRTT), in children who met criteria for DD with or without SLI. Implicit sequence learning was modeled using multi-level growth models of initial reaction time and learning slope across the repeated sequences of the SRTT. We further examined the predictive contributions of grammatical understanding, vocabulary abilities, phonological awareness, and diagnostic groups on implicit learning performance on the SRTT. Results showed language abilities and diagnostic group did not relate strongly to rates of implicit learning.

<p>Cognitive psychologists have long been interested in the nature of the representations that underlie human behaviours. In the domain of human memory, two main accounts have been forwarded to explain how memory is represented. The multiple memory systems account posits that different phenomenological experiences of memory are the result of separate and distinct representations. In contrast, the processing account posits that there is one memory system, and that different phenomenological experiences of memory are the result of the processes engaged in when probing memory. The explanatory power of these two accounts has been evaluated in a number of domains, where it has been shown that a processing view can accommodate many of the key findings that previously led researchers to propose a separate systems framework. The goal of this thesis was to extend this work by assessing the nature of the representations that underlie implicit sequence learning. The empirical portions of this thesis provide preliminary evidence suggesting that contextual features are incorporated into implicit sequence learning. Overall, the results reported in the empirical chapters of this thesis are consistent with a processing account, as they indicate that the episodic representations that are involved in explicit remembering also support performance in implicit memory tasks.</p> / Doctor of Philosophy (PhD)

Dyslexi är en form av läs- och skrivsvårighet som inte kan förklaras av t.ex. bristfällig undervisning, låg begåvning eller synproblem. Orsaken till dyslexi anses vanligen vara nedsatt förmåga av fonologiskt processande. Flera studier har dock visat att dyslexi även är förknippat med språkliga, kognitiva och motoriska svårigheter som inte kan förklaras av nedsatt förmåga av fonologiskt processande. Det procedurella minnessystemet engageras vid inlärning, processande och konsolidering av kognitiva och motoriska färdigheter. Enligt the procedural deficit hypothesis (PDH) orsakas de svårigheter förekommande vid dyslexi av en nedsättning i detta minnessystem. Forskningen inom området är inte entydig då det har rapporterats om både intakt och nedsatt procedurellt minne hos personer med dyslexi. Föreliggande studie var den första att undersöka procedurellt minne hos svenska universitetsstuderande med dyslexi. Syftet var att testa PDH med hjälp av alternating serial reaction time task (ASRT), samt att undersöka relationen mellan procedurellt minne, närmare bestämt implicit sekvensinlärning, och läsförmåga samt aspekter av språklig/fonologisk förmåga. I studien deltog totalt 37 universitetsstuderande, 11 med dyslexi och 26 utan dyslexi. Resultatet indikerade att förmågan till inlärning och konsolidering i det procedurella minnet inte skilde sig åt mellan grupperna. Resultatet ger således inte stöd åt PDH. Vidare kunde inga signifikanta korrelationer påvisas, vilket tyder på att det inte föreligger något samband mellan procedurellt minne och respektive läsförmåga, fonologisk medvetenhet och snabb benämning (rapid automatized naming, RAN). / Developmental dyslexia is characterized by reading and writing difficulties that do not derive from poor education, low intelligence or visual impairment. The disorder is commonly explained as a result of an underlying phonological deficit. However, studies have shown that dyslexia is also associated with linguistic, cognitive, and motor impairments that can not be explained by a specific phonological deficit. The procedural memory underlies learning, processing and consolidation of motor and cognitive skills. The procedural deficit hypothesis (PDH) suggests that an impairment of procedural memory is the underlying cause of developmental dyslexia. Previous research has yielded inconsistent results as studies have reported intact as well as impaired procedural memory in dyslexics. This study was the first to examine procedural memory in Swedish university students. The aim was to test the PDH, by using an alternating serial reaction time task (ASRT), and to examine the correlation between procedural memory and reading ability as well as aspects of linguistic/phonological ability. In this study there was a total of 37 university students, 11 dyslexics and 26 nondyslexics. The result showed learning and consolidation of the procedural memory in both groups and there was no significant difference between the groups. Thus, the results do not support the PDH. No significant correlations were found, which indicates that there is no association between procedural memory and reading ability, phonological awareness or rapid automatized naming (RAN).