 Another source of evidence against massive modularity comes from research on individual differences in high-level cognition (Rabaglia, Marcus, &amp; Lane, 2011). Such differences tend to be strongly positively correlated across domains—a phenomenon known as the ‘positive manifold’—suggesting that high-level cognitive abilities are subserved by a domain-general mechanism, rather than by a suite of specialized modules. There is, however, an alternative explanation of the positive manifold. Since post-Fodorian modules are allowed to share parts (Carruthers, 2006), the correlations observed may stem from individual differences in the functioning of components spanning multiple domain-specific mechanisms. 