This study served as a pilot study of cingulate gyrus surface areas and their relation to intelligence in individuals with hydrocephalus. Surface areas of the corpus callosum and cingulate gyrus regions were compared between individuals with early hydrocephalus (n = 9) and controls (n = 7). Subsequently, the surface areas were correlated with full-scale intelligence scores and the verbal and nonverbal discrepancy scores. Corpus collosum surface areas were significantly smaller in participants with hydrocephalus. These areas also robustly correlated with full-scale intelligence scores. Although the cingulate gyrus did not differ significantly between the groups, the cingulate gyrus regions were increasingly divergent the more posterior the region. Additionally, the caudal anterior and the posterior cingulate gyrus regions had only moderate positive correlations with full-scale intelligence scores. Although the participants with hydrocephalus had a significantly lower mean performance IQ compared to verbal IQ, the discrepancy scores did not correlate significantly with any of the regions of interest.

This study examined correlations between assessed intelligence and two major categories of reading comprehension: literal-explicit and inferential-implicit. In addition, efficiency of prediction for criterion variables was investigated by utilizing two regression models which incorporated intelligence scores squared and the square root of intelligence scores. Since it is generally accepted that the higher the assessed intelligence of an individual, the higher will be his achievement in all areas of reading comprehension, the present study sought to discover whether there was a curvilinear relationship between intelligence and the two categories of reading comprehension with the factor of intelligence statistically controlled. It was felt that the hypothesized curvilinear relationship would result in significantly better performance by brighter students on inferential questions and significantly better performance by less-bright students on literal questions. Although no cause and effect has been established, based on the data presented in this study and within the. limitations of this study, the following conclusions seem tenable. 1. Since reading comprehension may be viewed as a thinking process, it is important to note that a relationship exists between the assessed intelligence of an individual and his performance on both literal and inferential tests of that process. 2. This study has demonstrated the curvilinear nature of the relationships hypothesized. The higher the assessed intelligence of an individual, the increasingly higher will be his performance on inferential questions. Brighter students tend to make more inferences, but they lose some detail in the process. The less bright students, on the other hand, do very well with detail questions but experience less success in making inferences concerning what is read.