sentences:  When fMRI was developed one of its major limitations was the inability to randomize trials, but the event related fMRI fixed this problem.Cognitive subtraction was also an issue, which tried to correlate cognitive-behavioral differences between tasks with brain activity by pairing two tasks that are assumed to be matched perfectly for every sensory, motor, and cognitive process except the one of interest.Next, a push for the improvement of temporal resolution of fMRI studies led to the development of event-related designs, which according to Peterson, was inherited from ERP research in electrophysiology, but it was discovered that this averaging did not apply very well to the hemodynamic response because the response from trials could overlap.