Chromatic-discrimination thresholds have been determined by use of a CRT color monitor that simulates aperture and object observation modes. The results were compared with earlier ones [Appl. Opt. 35, 176 (1996)] that were obtained under the same experimental observation conditions with different devices. The differences found between the results obtained with the CRT monitor and with visual colorimeters are of the order of magnitude of interobserver variability (9%). However, greater differences were found between results for CRT monitors and for illuminated samples, which could be attributed to suboptimal distribution of the samples in color space. The current results support the usefulness of CRT color monitors in new chromatic-discrimination experiments.