A series of experiments was performed using the free recall of short story-like passages and a variety of analytic techniques to investigate two aspects of the mental representation of text: the nature of the encoding, and the structural relations among information in memory. The verbatim component of recall was the most variable across several factors, declined fastest after a moderate interval but was unresponsive to the recall accuracy demanded by instructions. It seemed to represent the most accurate information rather than any specifically verbatim encoding, Qualitative analysis demonstrated that verbatim recall was strongly determined by lexical and contextual constraints. Substitutions tended to be higher frequency words, supporting semantic decomposition and the loss of finer components of meaning. The mental representation appeared to consist of information on a number of levels of detail and accuracy, with no evidence for discrete propositions. The literature indicates two alternative approaches to structural factors in discourse comprehension. 'Text-led' theories employ structures peculiar to text and stress causal relations as organising factors. 'Knowledge-led' theories base organisation on the structure of corresponding information in semantic memory and predict that thematic relations, whether causal or not, will dominate memory. Evidence from clause recall contingencies and simple cluster analyses supported the 'knowledge-led' position. The differential behaviour of 'narrative' and 'nodal', apparently organised around verbs (activities) and nouns (actors or objects) respectively, was also consistent with knowledge-led processing. The implications of the results for selective processing during comprehension, and for the role of working memory were discussed. An attempt was also made to identify possible semantic memory structures which might be responsible for organising the episodic representation of information derived from text. Though still sketchy, the present framework is consistent with several recent lines of research and provides direction for future investigation.

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Earthquakes are amongst the most destructive of natural phenomena and have been the subject of significant research effort over many decades, to predict the onset of seismic events. Electromagnetic emissions detected prior to earthquakes provide a potential data source for seismic predictions and research suggests that specific pre-seismic electromagnetic activity can be directly related to specific earthquakes although it is still an open issue as to the precise links between these electromagnetic emissions and subsequent earthquakes. In this research, findings of the long memory or the self-organization of several pre-earthquake MHz electromagnetic time-series provide significant outcomes regarding the earthquake prediction. It is also recognised that enhanced radon gas emission has an equally long history as being associated with seismic activity. In general, several anomalous soil radon emissions have been observed prior to earthquakes and this has been recorded all over the world. The abnormal soil radon exhalation from the interior of the earth has been associated with earthquakes and is considered as an important field of research. The research reported in this thesis compared and contrasted the merits of combining electromagnetic emission data and radon exhalation data as precursors of earthquakes with the aim of enhancing earthquake prediction methodology. The findings from the long-memory analysis of radon disturbances in the soil indicated a very significant issue: the radon disturbances in the soil prior to earthquakes exhibit similar behaviour as the MHz RF disturbances of general failure. So, the radon precursors and the MHz electromagnetic correspond to the same pre-earthquake phase. Geological explanations were proposed in view of the asperity model. Persistent and anti-persistent MHz anomalies were due to the micro-cracking of the heterogeneous medium of the earth's crust which may have led the system's evolution towards the global failure. Fractal methods have been used on historical data, to investigate MHz electromagnetic time-series spectra on emissions preceding major earthquakes over the period 2007 to 2014 and the characteristics of enhanced radon emissions have been studied over the period 2008 to 2015 for seismic events occurring in the Aegean Region. It has been found that both the electromagnetic emissions and the radon exhalation data exhibit similar fractal behaviour and are associated with impending seismic activity. Hence both phenomena are relevant to earthquake predictions and should both be employed in any systematic approach to this problem as the varying geological and geographic conditions under which earthquakes can occur, might preclude one or other data from being measurable. According to the several techniques applied in this thesis, all should be employed in sequential steps, albeit the power-law spectral fractal analysis is the most significant to trace long-memory patterns of 1/f processes as those of the processes of earthquakes.