AN ANALYSIS OF INTELLECTUAL STRUCTURES OF THE BRAIN-INJURIES II

ON THE RELATIONSHIP BETWEEN LOCALIZATION OF FUNCTION IN THE BRAIN AND FACTORS OF INTELLIGENCE

Abstract

The present study was designed to examine the relationship between localization of function in the brain and representation of the basic factors of intelligence and to investigate the effect of the occasion of brain lesions on change of intellectual structures.
The quantitative findings reported in this study were based upon the test results from a battery of seventeen intelligencepsychological indicators applied individually to twenty-eight subjects, including patients with various types of brain damage, and to eighty normal control individuals.
The experimental subjects were divided by age into the Low Group (7:6-10:0), the Middle Group (13:6-17:10), the High Group (20:4-28:6), the Frontal Group, the Temporal Group, the Occipital Group on lobe lesions, and the Left Group and the Right Group on hemisphere lesions.
The centroid method of factor analysis and orthogonal rotation of axes were applied to the original correlation matrix based on those seventeen variables, and two factors were extracted in three age groups.
The nature of these factors might be summarized as the basic capacity of reasoning (Factor I) and the ability of reproducing knowledge in a practical situation (Factor II).
When applied to subjects of each age group, the test showed no differences between early and late brain injury, but when applied to patients with left- and right-hemisphere lesions, it was found that those whose left hemisphere had damage made poor records in variables positively loaded with Factor I and Factor II. And subjects with frontal lobe damage had losses in variables positively loaded with Factor I.
From these facts the inferences are drawn that the left hemisphere is relevant to the verbal abilities and frontal lobe lesions are associated with losses of the basic capacity of reasoning.