First-year psych students love spouting off about that dusty old Jungian theory concerning mankind's penchant for duality. (You know, that whole thing about our supposed yin-yang nature or potential for both good and evil.) Well, they'd probably have an effin' field day analyzing some of the disparate flicks featured every year at the International Horror and Sci-Fi Film Festival. Imaginative fables of impossible feats and futuristic stories of hope are mixed with twisted tales of bloodthirsty abominations and terrifying deeds to make up the lineup of feature-length movies and short films of 30 minutes or less that screen at the annual event, which operates in conjunction with the Phoenix Film Festival. Now in its eighth year, it dispenses both cerebral sci-fi thrills and ghastly horror film chills that send your psyche into overdrive.