 At this time, Anne Treisman’s research from the 1960s influenced Craik as the concept of levels of perception formed the basis of her theory of attention.Craik felt that memory must incorporate a series of analyses as well that range from shallow to deep, with the varying depths of encoding representing different levels of memory processing.Together, with Robert Lockhart, Craik co-wrote an article on the levels-of-processing that rivaled the previously accepted Atkinson-Shiffrin memory model at the time.