The purpose of this study was to test the comparability of several psychological instruments commonly used in Information Systems (IS) cognitive style research. The objective was to determine the limitations of: existing instruments in IS cognitive style research. The motivation for this research was the inconclusive findings reported in IS human information processing research. The study used a repeated measures design. Each individual completed the following cognitive style and personality instruments; the Myers-Briggs Type Indicator, the Group Embedded-figures Test, the Learning Style Inventory, the Human Information Processing Survey, and the Torrance Tests of Creative Thinking (Figural Form A). The individual also completed a dichotic listening and tachistoscope task. Data was collected from business administration, BCIS, liberal arts majors, and IS professionals. The results of this study indicate IS researchers need to consider several factors in the use of these instruments. A direct relationship exists between cognitive ability and results on the GEFT. Cognitive ability should be considered a moderating variable in interpreting the results of the GEFT. Also, the hypothesis that the GEFT is a surrogate for analytical and low-analytical abilities is not supported by this study. Other reported results include the inappropriateness of using the TTCT with adult populations. Also, the MBTI appears to be an appropriate instrument for measuring cognitive styles in IS research. This study reported that gender is a moderating factor on the classification of MBTI types in that gender is not evenly divided among feeling and thinking types. This study reported no relationships between the cognitive style and personality instruments with the physiological measurements. The validity of the physiological measurements could be the underlying factor for not reporting any significant relationships. IS researchers will benefit from this study through an improved understanding of the appropriateness and applicability of these instruments. This benefits research through the strengthening of instrument selection.