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The purpose of this study was to compare two conflicting theoretical perspectives on the relationship between intelligence and sustained attention. The cognitive resources theory assumes that lower IQ subjects are required to allocate greater amounts of their limited attentional resources during information-processing tasks than higher IQ subjects. The arousal theory assumes that there is an optimal level of arousal associated with task performance, and that an increase or decrease in arousal produces impairment in performance. Additionally the arousal theory predicts that increased time on task leads to a decrement in arousal as a function of IQ levels. Signal detection theory applications were used to operationalize and compare the two theories. Specifically, the signal detection parameters of sensory acuity ( d’), the decision criterion (a), correct detections, and false alarms were used to determine subject performance across three time periods ( 2, 4, and 6 mm.) on a visual continuous performance task. Twenty-nine teacher-nominated at-risk for learning difficulties and twenty-nine normally achieving kindergarten students were adminstered the Stanford-Binet:Fourth Edition (SB:FE) and the Wechsler Preschool and Primary Scale of Intelligence-Revised (WPPSI.R), as well as the Gordon Diagnostic System (GDS) Vigilance Task. The GDS is a standardized behaviour-based measure of sustained attention. The results of this study were interpreted as suggesting that ability group differences reflect attentional capacity. Two findings were important in this interpretation. First, regardless of IQ, the groups varied on the signal detection discrimination index. Second, these measures did not vary over time in either group. Thus, the arousal theory was not supported. IQ and attention intercorrelation patterns were higher for the at-risk group compared to the normally achieving group. Exploratory maximum-likelihood factor analyses indicated that intelligence plays a greater role in relation to vigilance for the at-risk for learning difficulties group than the normal achieving group.

1. <i>Cis</i> unsaturated fatty acids were shown to inhibit porcine platelet aggregation in response to both collagen and thrombin. Fatty acids with a <i>trans</i> double bond had an anti-aggregatory effect on collagen-induced aggregation but this was significantly less than that observed with the <i>cis</i> equivalent and was diminished as the dose of agonist increased. Thrombin-induced platelet aggregation was unchanged or slightly potentiated by <i>trans</i> isomers. 2. Both the <i>cis</i> and <i>trans</i> isomeric acids inhibited collagen-induced TXB₂ production. The <i>trans</i> unsaturated fatty acids also inhibited TXB₂ production in response to thrombin, even though they did not inhibit thrombin induced platelet aggregation. 3. Unlike arachidonic acid, the <i>cis</i> and <i>trans</i> mono-unsaturated fatty acids were not rapidly incorporated into membrane phospholipids but modified platelet aggregation whilst in the free acid form. 4. Pre-incubation of platelets with either <i>cis</i> or <i>trans</i> delta 13, 18:1, selectivity inhibited the incorporation of radio-labelled arachidonic acid into membrane PS. 5. <i>Cis</i> and <i>trans</i> unsaturated delta 13, 18:1, inhibited the initial turnover of membrane PI in response to thrombin possibly by an inhibitory effect on PI-specific phospholipase C. After 5 minutes, however, the level of arachidonic acid released from both PI and PE was increased in the presence of the isomeric fatty acids. This may have been via a potentiation of the action of phospholipase A₂. 6. An increased release of arachidonic acid could result in the inhibition of aggregation if metabolised via the 12-lipoxygenase pathway, as the end products of this sytem have direct anti-aggregatory activity and inhibit the cyclo-oxygenase enzymes thus reducing TXA₂ synthesis. 7. <i>Cis</i> unsaturated fatty acids, which produce a greater level of membrane disruption than the <i>trans</i>, may lead to more efficient channelling of the released arachidonic acid in the direction of the lipoxygenase pathway, and thereby produce a greater inhibition of aggregation. The possibility remains that the <i>cis</i> isomers have another, as yet unidentified mechanism by which they inhibit platelet aggregation.

The purpose of this study was to indicate norms for most comfortable loudness levels (MCLs) and to investigate the relationships among MCL and related measures. In addition MCL values for males and MCL values for females were separated to see if any differences existed between sexes.A pure tone average (PTA) and a spondee threshold (ST) were obtained for each of 54 subjects (23 males, 31 females) to assure normal hearing. The following measures were then obtained on all subjects: 1.) The MCL was obtained using a bracketing method. 2.) A Bekesy audiometer was used to determine MCL using both a 2.5 dB/second and a 5 dB/second attenuation rate. 3.) The lower limit of the most comfortable loudness range (LLMCR) was determined using a nonBekesy procedure. 4.) The upper limit of the most comfortable loudness range (MCR). Again, both 2.5 dB/second and 5 dB/second attenuation rates were used. The Bekesy MCR tracings also provided the ULMCR and the LLMCR values for Bekesy obtained MCRs. Four analyses of variance (ANOVA) were computed for various MCL and MCR measures to investigate the relationships among these measures. It was concluded that no significant differences occurred between males and females in all MCL and related measures.Averages were presented for each individual MCL procedure which ranged from 51.29 dB to 56.77 dB HL. Average MCRs (actual ranges) were 30.54 to 42.78 dB. Some significant differences were found among specific procedures which are discussed in the text, however, these differences may not be significant from a clinical standpoint. In general, non-Bekesy procedures were recommended for use clinically because they produced the least variability in subjects and they require the least amount of time in administration.

This study was conducted to consider the overlap of intelligence and memory as measured by the Wechsler Intelligence Scale for Children-Revised (WISC-R) and the Wide Range Assessment of Memory and Learning (WRAML). Archival data were analyzed with canonical correlation to determine the overlap of the two instruments. Results indicated that the WRAML seems to yield similar information as that obtained through administration of the WISC-R. This overlap appears due to the short-term memory components of Digit Span and Arithmetic. Therefore, the assumption that the WRAML provides unique information concerning short-term memory seems questionable. Implications concerning the possible clinical utility of the WRAML are discussed. / Department of Educational Psychology

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Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 183-192). Also available via the Internet.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1951. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.E.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 133-135). Also available via the World Wide Web.