sentences:  One method is a block related design, in which two or more different conditions are alternated in order to determine the differences between the two conditions, or a control may be included in the presentation occurring between the two conditions.By contrast, event related designs are not presented in a set sequence; the presentation is randomized and the time in between stimuli can vary.efMRI attempts to model the change in fMRI signal in response to neural events associated with behavioral trials.