The combinations of different ivs & the levels of those ivs create cells. The cells rep the diff conditions in experiment. Multiple the # of levels for each iv = # of conditions in study. Expresses the influence of one iv on the dv. Holds the effects of any other ivs constant. The effect of one iv depends on the level of another iv. Can see if the ivs interact with one another to influence the dv. Provides a more complete pic of what is going on. Graph data in order to determine whether there is an interaction with the dv. Each cell of a factorial design reps a condition. 3 main ways to assign participants to conditions: Different participants randomly assigned to each condition. Participant groups experience all levels of one iv. Single case, quasi, & developmental designs (p. 216-220, 222-235) - Determine whether an experimental manipulation (iv) had an effect on a. Participant"s behavior measured before manipulation single participant.