This group consists of strong verbs that do have a change in vowel in present tense and in imperfect, but not in perfect participle. The formula is slightly different:

ge- + present tense stem + suffix (-en)

infinitiv present imperfect perfect participle   sehen => ich sehe, er sieht sah => gesehen (to see => seen)     essen => ich esse, er isst aß => gegessen (to eat => eaten)     laufen => ich laufe, er läuft lief => gelaufen (to run => run)     fahren => ich fahre, du fährst fuhr => gefahren (to drive => driven)