This article offers a model of collaboration processes in which both parties are sharing the task work load at an equal level of cognitive difficulty. The model poses six collaboration factors as important in the man-machine collaboration. The six factors are cognitive orientation, deep knowledge, intention sharing, control plasticity, adaptivity, and experience or memory. The model predicts that two clusters of settings of the six factors exist: one for novices and one for experts. Four experiments are presented that support this prediction and that offer several new insights into what makes for effective collaborator design. Also many new questions arise.