Letter Processing in Children with Naming Speed Deficits

Abstract

<p>Research has clearly established that naming speed on a rapid automatized naming (RAN) task is related to reading. However, the nature of this relationship is unclear. Debate continues as to the underlying process or processes that are indexed by the RAN task. The present thesis addressed this issue by exploring the nature of the deficit(s) exhibited by children with slow naming speed on the RAN task. Both orthographic and letter processing skills were examined. The first three experiments used a probe task to examine the letter processing abilities of children with slow naming speed. Levels of orthographic knowledge were also measured. All three experiments indicated that children with slow naming speed on the RAN task are characterized by deficits in orthographic knowledge and in processing individual letters in a sequence. Results suggest that these two deficits may be independent, as difficulties in processing individual letters in a sequence were observed whether or not orthographic structure was present (Experiment 1 and 2). In addition, children with naming speed deficits were able to use the orthographic structure present in a string to aid processing (Experiments 2 and 3b). The processing difficulties exhibited by children with naming speed deficits were not a result of inadequate processing time alone (Experiment 3a and 3b). Providing longer time for these children to encode a letter string did not alleviate the problem. A more fundamental problem in representing individual letters may result in poor or slow processing of letter strings. It is this underlying problem that needs to be corrected in order for letter processing speed to improve. A training study (Experiment 4) illustrated the importance of orthographic pattern recognition training for children with naming speed deficits. Training children to recognize orthographic units within a word facilitated learning of these words, and enabled them to read new words that shared the same orthographic units. Orthographic training also had an impact on the speed with which children identified individual letters in a sequence. Training to increase the speed ofletter identification was successful only when it was preceded by training in orthographic pattern recognition. Training children to recognize larger orthographic units within words may foster an awareness that orthographic consistencies exist within words. When searching for these consistencies within a letter string, children may process the internal elements more efficiently, resulting in an increase in the speed of letter identification when letters are presented in a sequence. Therefore, orthographic training may be beneficial not only in its own right, by addressing the orthographic deficits of children with slow RAN performance, but orthographic pattern recognition training may also be the route through which we can improve processing of individual letters.</p>