Fig 4. The reciprocal BOLD responses due to eye contact.

The (a) is the exogenous responses in which Ω₊ = 1 when (x = 1, y = 0); the (b) is the endogenous responses in which Ω_- = 1 when (ξ = 1, ψ = 0) and (ξ = 0, ψ = 0). Here the (c) and (d) are the three orthogonal sections of the (a) and (b) respectively; the (e) and (f) are the probabilistic atlas label distributions for the exogenous-endogenous dual system, where the exogenous labels are indexed by real number, and the endogenous labels are indexed by imaginary number.