"Attentional focus on one coherent scene does not in itself explain how a complex sequence can be recalled. To understand that, one must take into account that the focus of attention can shift from one level of analysis to another. Cowan: The magical number 4 BEHAVIORAL AND BRAIN SCIENCES (2001) 24:1 93 McLean and Gregg (1967, p. 459) described a hierarchical organization of memory in a serial recall task with long lists of consonants: “At the top level of the hierarchy are those cueing features that allow S to get from one chunk to another. At a lower level, within chunks, additional cues enable S to produce the integrated strings that become his overt verbal responses.”"