Implicit learning of natural language syntax

The present dissertation focuses on the question of how humans acquire syntactic knowledge without intending to and without awareness of what they have learned. The aim is to apply the theoretical concepts and the methodological framework provided by implicit learning research to the investigation of language acquisition. The results of six experiments are reported. In terms of design, all experiments consisted of (i) a training phase, during which subjects were trained on a miniature linguistic system by means of different exposure conditions, (ii) an unexpected testing phase, during which learning and awareness were assessed, and (iii) a debriefing session. A semi-artificial grammar, which consisted of English words and German syntax, was employed to generate the stimulus material for experiments 1, 2, 3, 5 and 6; in the case of experiment 4, nonsense syllables were used instead of English words. The linguistic focus was on verb placement rules. Native speakers of English with no background in German (or any other V2 language) were recruited to take part in the experiments.Participants in experiments 1-5 were exposed to the semi-artificial system under incidental learning conditions by means of different training tasks. In experiments 1 and 2, an auditory plausibility judgment task was used to expose participants to the stimulus sentences. In experiment 3, elicited imitations were used in addition to the plausibility judgment task. The training phase in experiment 4 consisted solely of elicited imitations, while training in experiment 5 consisted of a classification task which required participants to identify the syntactic structure of each stimulus item, followed by plausibility judgments. Participants in experiment 6, on the other hand, were exposed to the semi-artificial grammar under intentional learning conditions. These participants were told that the word order of the stimulus sentences was governed by a complex rule-system and instructed to discover syntactic rules. After training, participants in all six experiments took part in a testing phase which assessed whether learning took place and to what extent they became aware of the knowledge they had acquired. Grammaticality judgments were used as a measure of learning. Awareness was assessed by means of verbal reports, accuracy estimates, confidence ratings and source attributions. Control participants did not take part in the training phase.The results of the experiments indicate that adult learners are able to acquire syntactic structures of a novel language under both incidental and intentional learning conditions, while processing sentences for meaning, without the benefit of corrective feedback and after short vi exposure periods. That is, the findings demonstrate that the implicit learning of natural language is not restricted to infants and child learners. In addition, the experiments also show that subjects are able to transfer their knowledge to stimuli with the same underlying structure but new surface features. The measures of awareness further suggest that, in experiments 3 to 6 at least, learning resulted in both conscious and unconscious knowledge. While subjects did not become aware of all the information they have acquired, it was clear that higher levels of awareness were associated with improved performance.The findings reported in this dissertation have several implications for our understanding of language acquisition and for future research. Firstly, while the precise form of the knowledge acquired in these experiments is unclear, the findings provided no evidence for rule learning in the vast majority of subjects. It suggests that subjects in these types of experiments (and perhaps in natural language acquisition) do not acquire linguistic rules. The results support Shanks (1995; Johnstone & Shanks, 2001), who argues against the possibility of implicit rule learning. Secondly, while adults can acquire knowledge implicitly, the work reported in this dissertation also demonstrates that adult syntactic learning results predominantly in a conscious (but largely unverbalizable) knowledge base. Finally, from a methodological perspective, the results of the experiments confirm that relying on verbal reports as a measure of awareness is not sufficient. The verbal reports collected at the end of the experiment were helpful in determining what aspects of the semi-artificial grammar subjects had consciously noticed. At the same time, verbal reports were clearly not sensitive enough to assess whether subjects were aware of the knowledge they had acquired. Confidence ratings and source attributions provided a very useful method for capturing low levels of awareness and to observe the conscious status of both structural and judgment knowledge. Future experiments on language acquisition would benefit from the introduction of this relatively simple, but effective way of assessing awareness

Introspective physicalism as an approach to the science of consciousness

Most ‘theories of consciousness’ are based on vague speculations about the properties of conscious experience. We aim to provide a more solid basis for a science of consciousness. We argue that a theory of consciousness should provide an account of the very processes that allow us to acquire and use information about our own mental states – the processes underlying introspection. This can be achieved through the construction of information processing models that can account for ‘Type-C’ processes. Type-C processes can be specified experimentally by identifying paradigms in which awareness of the stimulus is necessary for an intentional action. The Shallice (1988b) framework is put forward as providing an initial account of Type-C processes, which can relate perceptual consciousness to consciously performed actions. Further, we suggest that this framework may be refined through the investigation of the functions of prefrontal cortex. The formulation of our approach requires us to consider fundamental conceptual and methodological issues associated with consciousness. The most significant of these issues concerns the scientific use of introspective evidence. We outline and justify a conservative methodological approach to the use of introspective evidence, with attention to the difficulties historically associated with its use in psychology

A Connectionist Theory of Phenomenal Experience

When cognitive scientists apply computational theory to the problem of phenomenal consciousness, as many of them have been doing recently, there are two fundamentally distinct approaches available. Either consciousness is to be explained in terms of the nature of the representational vehicles the brain deploys; or it is to be explained in terms of the computational processes defined over these vehicles. We call versions of these two approaches vehicle and process theories of consciousness, respectively. However, while there may be space for vehicle theories of consciousness in cognitive science, they are relatively rare. This is because of the influence exerted, on the one hand, by a large body of research which purports to show that the explicit representation of information in the brain and conscious experience are dissociable, and on the other, by the classical computational theory of mind – the theory that takes human cognition to be a species of symbol manipulation. But two recent developments in cognitive science combine to suggest that a reappraisal of this situation is in order. First, a number of theorists have recently been highly critical of the experimental methodologies employed in the dissociation studies – so critical, in fact, it’s no longer reasonable to assume that the dissociability of conscious experience and explicit representation has been adequately demonstrated. Second, classicism, as a theory of human cognition, is no longer as dominant in cognitive science as it once was. It now has a lively competitor in the form of connectionism; and connectionism, unlike classicism, does have the computational resources to support a robust vehicle theory of consciousness. In this paper we develop and defend this connectionist vehicle theory of consciousness. It takes the form of the following simple empirical hypothesis: phenomenal experience consists in the explicit representation of information in neurally realized PDP networks. This hypothesis leads us to re-assess some common wisdom about consciousness, but, we will argue, in fruitful and ultimately plausible ways

Consciousness, introspection, and subjective measures

This chapter discusses the main types of so-called ’subjective measures of consciousness’ used in current-day science of consciousness. After explaining the key worry about such measures, namely the problem of an ever-present response bias, I discuss the question of whether subjective measures of consciousness are introspective. I show that there is no clear answer to this question, as proponents of subjective measures do not employ a worked-out notion of subjective access. In turn, this makes the problem of response bias less tractable than it might otherwise be

Interoceptive inference, emotion, and the embodied self

The concept of the brain as a prediction machine has enjoyed a resurgence in the context of the Bayesian brain and predictive coding approaches within cognitive science. To date, this perspective has been applied primarily to exteroceptive perception (e.g., vision, audition), and action. Here, I describe a predictive, inferential perspective on interoception: ‘interoceptive inference’ conceives of subjective feeling states (emotions) as arising from actively-inferred generative (predictive) models of the causes of interoceptive afferents. The model generalizes ‘appraisal’ theories that view emotions as emerging from cognitive evaluations of physiological changes, and it sheds new light on the neurocognitive mechanisms that underlie the experience of body ownership and conscious selfhood in health and in neuropsychiatric illness