1,720,963 research outputs found
CAN NEUROPSYCHOLOGICAL EVIDENCE INFORM CONNECTIONIST MODELING - ANALYSES OF SPELLING
No full textThe symbolic information-processing paradigm in cognitive psychology has seen a growing challenge from neural network models over the past decade or so. While neuropsychological evidence has been of great utility in informing information-processing modelling, the emergence of less rigidly modular connectionist models raises the possibility that constraints from the behaviour of a damaged system may give relatively little information about these more complex structures. We believe that this will not prove to be the case, however, and discuss connectionist models of two sub-components of the spelling process which, internally, blur modular boundaries, and which explain, rather than describe, the relevant neuropsychological evidence. The models operate serially, and thus fall within a domain which has been a stronghold of symbolic modelling. The strong neuropsychological support which emerges for such models is therefore of particular interest
Spelling and serial recall: Insights from a Competitive Queueing model
No full textACKGROUND: Issues in Spelling Research: An Overview; Spelling Routes (or Roots or Rutes); Writing and Spelling: The View from Linguistics; SPELLING DEVELOPMENT: Sources of Information used by Beginning Spellers; The Role of Phonological and Orthographic Processes in Learning to Spell; Towards a Model of Spelling Acquisition: The Development of Some Component Skills; ABNORMAL SPELLING: Spelling Processes of the Reading Disabled; On the Development of Lexical and Non-Lexical Spelling Procedures of French-Speaking, Normal and Disabled Children; The Modularity of Reading and Spelling: Evidence from Hyperlexia; COMPUTATIONAL MODELS: Computational Approaches to Normal and Dyslexic Spelling; Representation and Connectionist Models: The NETspell Experience; REMEDIATION: Teaching Spelling: Bridging Theory and Practice; Organizing Sound and Letter Patterns for Spelling
Neuropsychologically plausible models of sequence generation
No full textWe investigate the possibility of incorporating the sequential dynamics of a 'Competitive Queuing' system in a multi-layer perceptron (MLP) architecture. The approach is applied to a model of output processes in spelling, and we show that it provides an explanation for so-called 'Graphemic Buffer Disorder'. We describe a patient with an apparently novel dysgraphia affecting the start of words, and show that this can also be explained in terms of a simple manipulation to the model
Interactions between knowledge sources in a dual-route connectionist model of spelling
No full textIt is now standard in the psychological literature to assume that the functional architecture for the system involved in spelling a word from memory uses two routes, a phonological route and a lexically based route. We describe a modular connectionist model based on this dual route architecture. Both routes in the model, tested in isolation, are able to simulate important aspects of the relevant psychological data. Some progress has been made towards combining the two routes into a single system. In attempting a coherent connectionist account, however, we are forced to address from first principles the difficult problem of the synchronisation and integration of information from each route into an output which combines the capabilities of both.
We believe that the interactions between cognitive modules may be more difficult to model than the modules themselves, and that connectionist approaches, by forcing these interactions to be addressed at a basic level, may help to focus attention on difficult problems of psychological modelling which might otherwise not be addressed
Towards a unified process model for graphemic buffer disorder and deep dysgraphia
No full textModels based on the competitive queuing (CQ) approach can explain many of the effects on
dysgraphic patients’ spelling attributed to disruption of the “graphemic output buffer”. Situating
such a model in the wider spelling system, however, raises the question of what happens when
input to the buffer (e.g., from a semantic system) is degraded while the buffer remains intact. We
present a preliminary exploration of predictions following from the CQ approach. We show that
the CQ account of the graphemic buffer predicts and explains the finding that deep dysgraphic
patients generally show features of graphemic buffer disorder, as disrupted input from a damaged
semantic system has an inevitable effect upon the functioning of the buffer. The approach also explains
the most salient differences between the two syndromes, which are seen as consequences of the differ-
ence between an intact sequence generation system operating on degraded input versus a damaged
sequencing system operating on intact input
A localist implementation of the Primacy model of immediate serial recall
No full textWe present a localist, connectionist implementation of the Primacy model of immediate serial recall. We demonstrate a connectionist ordering mechanism which is localist and activation-based rather than based on association and illustrate the parallels between the Primacy model and current connectionist models of speech production. This enables us to give an integrated explanation both of phonological errors in short-term memory and of errors in speech production
Objective functions for topography: A comparison of optimal maps
No full textTopographic mappings are important in several contexts, including data visualization, connectionist representation, and cortical structure. Many different ways of quantifying the degree of topography of a mapping have been proposed. In order to investigate the consequences of the varying assumptions that these different approaches embody, we have optimized the mapping with respect to a number of different measures for a very simple problem-the mapping from a square to a line. The principal results are that (1) different objective functions can produce very different maps, (2) only a small number of these functions produce mappings which match common intuitions as to what a topographic mapping "should" actually look like for this problem, (3) the objective functions can be put into certain broad categories based on the overall form of the maps, and (4) certain categories of objective functions may be more appropriate for particular types of problem than other categories
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Modelling serial order in behaviour: studies of spelling
Full text linkSerial order in behaviour remains an interesting problem for computational modelling in
psychology, especially for connectionist approaches. The 'Competitive Queuing' (CQ)
approach to sequence generation has the advantage of accounting for a number of
common features apparent in several different types of serial behaviour. This thesis
addresses the general account which the CQ approach can give for constraints on serial
errors within sequences by developing models of an acquired disorder of spelling,
'graphemic buffer disorder' (GBD). Two approaches to the development of a simple
initial model of GBD into more complex models are demonstrated, and are related to
the general problem of accounting for serial category constraints in sequencing.
The initial CQ model of GBD is based on an existing model of speech production with
minimal spelling-specific changes. A number of shortcomings are identified in the
I performance of this model, in particular the inability to distinguish consonant and vowel
letters, which prevents a striking feature of GBD errors - the preservation of
consonant/vowel status - from being modelled. An analysis of the general problem of
adding domain-specific constraints to CQ models suggests two approaches to
improving the initial model. Two alternative extended models are thus advanced. The
first is a development of the initial model incorporating an external template to specify
consonant/vowel information. Simulations with this model demonstrate a much improved fit to :the data. The second model" develops a novel architecture, generalising
the CQ approach to multi-layer networks. The model is less detailed but demonstrates
the correct general features of the GBD error pattern. The relationship between the
models is discussed and possible future research directions are identified
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