Publication Date


Document Type


First Advisor

Lankford, James E.

Degree Name

M.A. (Master of Arts)

Legacy Department

Department of Communication Disorders




The primary purpose of the present investigation was to determine the nature of subject strategy in response to closed set synthetic sentences through the exploration of subject reaction time. The experiment was based on a previous study of subject strategy by Speaks, Jerger and Jerger (20). Initially, performance-intensity functions were established for two message sets; one set of ten dissimilar first order approximation sentences (Set 1), and another set of ten randomizations of a single first order sentence (Set 2). Subject reaction times were then determined for the two message sets in quiet and in the presence of an ipsilateral competing message. Performance-intensity functions were defined for both Sets 1 and 2 for five normal hearing subjects and cumulative functions were established by computing the mean identification scores across subjects. The identification thresholds for these cumulative P-I functions were compared to those of the Speaks, Jerger and Jerger (20) investigation. Reaction time values were then determined for each of ten normal hearing subjects in response to five replications of the four listening conditions, Sets 1 and 2 in quiet and in the presence of a competing message. From the reaction time values, three facets of subject response were explored: 1) total sentence duration versus subject reaction time, 2) subject reaction time for Set 1 versus reaction time for Set 2 and 3) the effect of the competing message. The P-I functions which were defined for this study compared well with those of the Speaks, Jerger and Jerger (20) investigation with the exception of relative subject performance for the two sets. While the previous study indicated improved performance for Set 2, a reversal of this finding was witnessed in the present investigation with improved performance for Set 1. With regard to the reaction time values, a significant difference was indicated for each of the three facets which were explored. First, subject reaction time was found to be significantly shorter than sentence duration. Secondly, the comparison of reaction time in response to the two message sets indicated that longer exposure was required for Set 2 to insure correct identification. Finally, the competing message was shown to significantly effect the subject's response. Subject reaction time was appreciably increased when the items were presented in the presence of a competing message. For the P-I functions, it was concluded that the identification threshold determined for each set actually had little to do with the subject's recognition tactic. It was suggested that the very small differences found between sets for this study and for the previous study were more likely attributable to a factor other than the particular strategy utilized by the subject for identification. For the reaction time experiment, it was concluded that the subjects had sufficient information to correctly identify each of the sentence items prior to hearing the sentence in its entirety. While the increased similarity of the items for Set 2 and the addition of a competing message both significantly lengthened the subject's reaction time, attention to the completed sentence was never reflected in the reaction time values. The subject was always able to correctly identify the sentence items on the basis of initial sentence information. It was concluded that in the identification of closed set synthetic sentences, the subject attends primarily to that information in each sentence which distinguishes it from the remaining alternatives.


Includes bibliographical references.||Includes illustrations.


vi, 60 pages




Northern Illinois University

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