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Title: Representing and remembering Lindenmayer-grammars
Author: Shirley, Elizabeth Joan
ISNI:       0000 0004 5356 837X
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2014
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This thesis applies methods from cognitive experimental psychology to investigate processing of complex sequences produced from two Lindenmayer grammars (L-grammars). It presents evidence that human adults develop and retain a lasting representation of these structured sequences within an Artificial Grammar Learning (AGL) paradigm. There is an ongoing debate as to the computational power that the human brain must instantiate in order to support hierarchical cognitive systems such as language and music. The common position is that it must encompass recursive processing, equivalent to context-free grammars in the Chomsky hierarchy. A way to test this is to identify the limits of human ability to process novel sequences that are structured at this level of complexity. In these studies, participants were exposed to an auditory version of a sequence generated by a context-free L-grammar. Successful processing and acquisition was demonstrated if they could subsequently identify grammatical sequences that have been generated by the trained grammar. They should also be able to identify similar but nonetheless ungrammatical sequences. Participants were successful for the simplest (Fibonacci) grammar, and to a lesser extent with the alternative (XOR) grammar. The behavioural results were reflected in response-locked ERP results and spectral analyses, which indicated that processing the Fibonacci grammar engaged different mechanisms than the XOR grammar. Subsequent detailed analyses of the experimental materials including n-gram frequency and entropy measures indicated that these sequences seem to require a form of recursive processing to produce the behavioural results, rather than what may be considered lower level or general learning mechanisms. It was concluded that these experimental results support accounts of cognitive processing that include recursive computations. L-grammar outputs are useful structures to be employed in the ongoing investigation of complex sequence acquisition, particularly in the fields of comparative and developmental study.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available