Search

Human control of action in routine situations involves a flexible interplay between (a) task-dependent serial ordering constraints; (b) top-down, or intentional, control processes; and (c) bottom-up, or environmentally triggered, affordances. In addition, the interaction between these influences is modulated by learning mechanisms that, over time, appear to reduce the need for top-down control processes while still allowing those processes to intervene at any point if necessary or if desired. We present a model of the acquisition and control of goal-directed action that goes beyond existing models by operationalizing an interface between two putative systems--a routine and a non-routine system--thereby demonstrating how explicitly represented goals can interact with the emergent task representations that develop through learning in the routine system. The gradual emergence of task representations offers an explanation for the transfer of control with experience from the non-routine goal-based system to the routine system. At the same time it allows action selection to be sensitive both to environmental triggers and to biasing from multiple levels within the goal system.

We present a neural network model of learning and processing the English past tense that is based on the notion that experience-dependent cortical development is a core aspect of cognitive development. During learning the model adds and removes units and connections to develop a task-specific final architecture. The model provides an integrated account of characteristic errors during learning the past tense, adult generalization to pseudoverbs, and dissociations between verbs observed after brain damage in aphasic patients. We put forward a theory of verb inflection in which a functional processing architecture develops through interactions between experience-dependent brain development and the structure of the environment, in this case, the statistical properties of verbs in the language. The outcome of this process is a structured processing system giving rise to graded dissociations between verbs that are easy and verbs that are hard to learn and process. In contrast to dual-mechanism accounts of inflection, we argue that describing dissociations as a dichotomy between regular and irregular verbs is a post hoc abstraction and is not linked to underlying processing mechanisms. We extend current single-mechanism accounts of inflection by highlighting the role of structural adaptation in development and in the formation of the adult processing system. In contrast to some single-mechanism accounts, we argue that the link between irregular inflection and verb semantics is not causal and that existing data can be explained on the basis of phonological representations alone. This work highlights the benefit of taking brain development seriously in theories of cognitive development. (Contains 1 footnote and 12 figures.)

We report two experiments in which errors and interaction latencies were recorded during routinization of hierarchically structured computer-based tasks. Experiment 1 demonstrates that action selection is slowed at subtask transitions, especially when selecting lower frequency actions. This frequency effect is compounded by concurrent performance of a secondary, attentionally demanding, task. Experiment 2 replicates these results in a more complex task and further demonstrates that the effects are reduced by experience. Several other factors were also found to affect latencies, including the availability of an external disambiguation cue and the temporal distance over which task context needs to be internally maintained. The results support a "dual-systems" account of action selection in which a "routine" system, sensitive to frequency, context, and experience, is selectively modulated by an attentionally demanding "nonroutine" system. (Contains 16 figures, 10 tables and 4 footnotes.)

Research on Tip of the Tongue (ToT) states has been used to determine whether access to syntactic information precedes access to phonological information. This paper argues that previous studies have used insufficient analyses when investigating the nature of seriality of access. In the first part of this paper, these complex issues are discussed and suitable analyses proposed. In the second part, new experimental data are presented. In Experiment 1, English speakers were asked to give information about mass/count status and initial phoneme of nouns, when in a ToT state. In Experiment 2, German speakers were asked to report grammatical gender and initial phoneme of nouns, when in a ToT state. Evidence that syntactic and phonological information are accessed independently was obtained for both languages. Implications for models of language production and further methodological issues in ToT research are discussed.

Byline: Gert Westermann; Nicolas Ruh; Kim Plunkett Abstract In the past twenty years the connectionist approach to language development and learning has emerged as an alternative to traditional linguistic theories. This article introduces the connectionist paradigm by describing basic operating principles of neural network models as well as different network architectures. The application of neural network models to explanations for linguistic problems is illustrated by reviewing a number of models for different aspects of language development, from speech sound acquisition to the development of syntax. Two main benefits of the connectionist approach are highlighted: implemented models offer a high degree of specificity for a particular theory, and the explicit integration of a learning process into theory building allows for detailed investigation of the effect of the linguistic environment on a child. Issues regarding learnability or the need to assume innate and domain specific knowledge thus become an empirical question that can be answered by evaluating a model's performance. Article History: Date received: August 25, 2005 Date revision received: November 13, 2007