Previous research indicates that measures of joint attention provide unique insight into team cognition and performance. In this study, we examined the effects of practice and joint attention on team performance improvement using multivariate mixed models, with an emphasis on exploring the correlation structure between the variances in growth trajectories of team performance and joint attention around estimated means. Observed patterns in team performance showed time dependent trends well known in a variety of learning contexts, including non-linear growth, performance retention, and performance retention loss between multiple practice sessions. Joint attention was found to decrease non-linearly over time, starting out comparatively high and decreasing as a function of time on task. Additionally, we found evidence of negative relationships between joint attention and team performance in our task environment, and we established that joint attention was significantly higher than the chance levels that would be expected by task-constraints alone.