Short-term memory study. Research published in the American Journal of Psychiatry (July 19...

Short-term memory study. Research published in the American Journal of Psychiatry (July 1995) attempted to establish a link between hippocampal (brain) volume and short-term verbal memory of patients with combat-related post-traumatic stress disorder (PTSD). A sample of 21 Vietnam veterans with a history of combat-related PTSD participated in the study. Magnetic resonance imaging was used to measure the volume of the right hippocampus (in cubic millimeters) of each subject. Verbal memory retention of each subject was measured by the percent retention subscale of the Wechsler Memory Scale. The data for the 21 patients are plotted in the accompanying scattergram. The researchers “hypothesized that smaller hippocampal volume would be associated with deficits in short-term verbal memory in patients with PTSD.” Does the scattergram provide visual evidence to support this theory?