The possibility exists that some people might be at a disadvantage in registering their responses to a computerized test if mouse manipulation were complicated. This would be of particular concern if some groups were differentially affected by the complexity of manipulation. This study analyzed data from a pilot test conducted in 1991 for the Computer-Based Academic Skills Assessments of the Praxis Series of professional assessments for beginning teachers. Computerized test items in reading and mathematics that required simple or complex mouse manipulation were administered to 337 (244 females and 93 males) white examinees and 148 minority group examinees (104 females and 44 males). Examinees were asked to describe their own experiences with mouse use. Very little evidence of differential effects was observed for sex or ethnicity. Whatever differential effect may exist is difficult to disentangle from other test behavior differences, but there would seem to be little cause for concern about mouse use. (Contains two figures and two references.) (Author/SLD)