Reported is a study to investigate possible relationships between certain schemes of formal operational thought and the extent to which a cognitive system is open or closed; and to study the logical thought processes of subjects in the transitional phase between adolescence and adulthood using formal operational tasks. Rokeach's (1960) Dogmatism Scale, Form E, was used to select 30 high dogmatics (closed dogmatic system) and 30 low dogmatics (open system) from a group of 188 students. Each group had 15 males and 15 females. Each subject received an individual interview consisting of four Piaget-type formal operational tasks: floating bodies, conservation of displacement volume, flexibility of rods, and correlations. Data were also obtained from Iowa Tests of Educational Development Achievement measures: Background in Natural Science, Interpreting Natural Science, and Composite. Percentages of subjects performing at the formal operational level on each task, respectively, were 17 percent, 43 percent, 42 percent, and 57 percent. Analysis revealed that low dogmatics (formal operational subjects) outperformed on the flexibility of rods task. Differences on the other three tasks were not significant. Male and female dogmatism scores were not significantly different, but low dogmatics had significantly higher achievement percentile rankings on all measurements. (Author/EB)