in Kurt Fischer’s neo-Piagetian skill theory, an indication of the degree of hierarchical integration of a cognitive skill. According to the theory, there are four levels of hierarchical integration within each of four broad tiers of development. The levels correspond to single sets, mappings, systems and systems of systems. Each higher level emerges as an integration of lower-level skill components. Individual skills develop through 4 tiers that embody a total of 13 levels of hierarchical integration throughout development.
See Bridging, Emergence, Hierarchy, Levels of analysis, Levels of organization, Neo-Piagetian theories of cognitive development