"Other theorists (Hummel & Holyoak 1997; Shastri & Ajjanagadde 1993) have applied this neural synchronization principle in a way that is more abstract. It can serve as an alternative compatible with Halford et al.’s (1998) basic notion of a limit on the complexity of relations between concepts, though Halford et al. instead worked with a more symbolically based model in which “the amount of information that can be represented by a single vector is not significantly limited, but the number of vectors that can be bound in one representation of a relation is limited” (p. 821). Shastri and Ajjanagadde (1993) formulated a physiological theory of working memory very similar to Lisman and Idiart (1995), except that the theory was meant to explain “a limited-capacity dynamic working memory that temporarily holds information during an episode of reflexive reasoning” (p. 442), meaning reasoning that can be carried out “rapidly, spontaneously, and without conscious effort” (p. 418). The information was said to be held as concepts or predicates that were in the form of complex chunks; thus, it was cautioned, “note that the activation of an entity together with all its active superconcepts counts as only one entity” (p. 443). It was remarked that the bound on the number of entities in working memory, derived from facts of neural oscillation, falls in the 7 6 2 range; but the argument was not precise enough to distinguish that from the lower estimate offered in the present paper. Hummel and Holyoak (1997) brought up similar concepts in their theory of thinking with analogies. They defined “dynamic binding” (a term that Shastri & Ajjanagadde also relied upon to describe how entities came about) as a situation in which “units representing case roles are temporarily bound to units representing the fillers of those roles” (p. 433). They estimated the limit of dynamic binding links as “between four and six” (p. 434). In both the approaches of Shastri and Ajjanagadde (1993) and Hummel and Holyoak (1997), these small limits were supplemented with data structures in long term memory or “static bindings” that appear to operate in the same manner as the long-term working memory of Ericsson and Kintsch (1995), presumably providing the “active superconcepts” that Shastri and Ajjanagadde mentioned."