Using a mixed method, quasi-experimental pre-test-post-test non-equivalent group design, this study inquired into the possibilities of enhancing learners' cognitive abilities, with problem-based learning (PBL; -experimental) and lecture method (control) as predictor variables. Aided by the random scorecards, a group of 51 students was assigned to the experimental (26) and control (25) streams, where their cognitive performance was compared on both the lower and higher-order learning attributes for 15 weeks. Whereas there was a slight difference in the mean scores of the two groups on the three lower-order learning parameters measured at the pre-test, the difference (X[subscript c] = 55.32 < X[subscript e] = 55.8; t-statistic 0.176 < critical t- 2.01) was not statistically significant. However, at the immediate-post-test, the mean scores of the two groups on the three higher-order learning parameters statistically differed (X[subsript c] = 66.81 > X[subscript e] = 59.21) in favor of the control group (t = 2.967 > 2.01; p = 0.005 < 0.05). Although a reduction in weekly learning hours from 3 to 2 was accompanied by a significant improvement in students' cognitive development on the three higher-order learning attributes at the delayed post-test for the experimental group, that of the control group, improved marginally (X[subsript c] = 76.36 < X[subsript e] = 86.31). Even though the generalization of these findings may be limited due to the examination of a single learning discipline, the qualitative and quantitative analyses suggest that PBL is a true stimulant of students' cognitive development over time.