Double dissociations were long considered a gold standard
for establishing functional modularity. However, Plaut (1995)
demonstrated that double dissociations could result without
underlying modularity. He damaged attractor networks with
separate orthographic and semantic layers (as well as a hid-
den layer with feedback connections from semantics) that were
trained to map orthography to semantics. Damaging con-
nections coming from either the orthographic layer or recur-
rent semantic connections (to and from cleanup units) could
both yield double dissociations, with some models exhibit-
ing greater relative deficits for abstract words, and others for
concrete words. We investigated whether double dissocia-
tions would emerge in a simpler attractor network with 2 sets
of units (orthographic and semantic) and 2 layers of connec-
tions (orthographic-to-semantic and recurrent semantic con-
nections). Random damage to orthographic-semantic con-
nections yielded double dissocations (some damaged mod-
els showed stronger relative deficits for abstract words, while
others showed stronger relative deficits for concrete words).
Semantic-semantic damage led only to concrete deficits. The
presence of double dissociations given different degrees of
damage in each model reconfirm Plaut's (1995) findings in
simpler, “flat” attractor network (O'Connor, Cree, & McRae,
2009), with less potential for modularity. The tendency for
concrete impairments given damage to the semantic attractor
level is at once surprising and revealing; it demonstrates a di-
vision of labor (and partial modularity) that emerges in this
network. We will discuss theoretical implications, as well as
next steps in this research program.