Abstract
Our prior findings (Tapia & Breitmeyer2011) showed that the contrast-dependent effects of primes on reaction time to subsequent probes were determined primarily by activity in the magnocellular (M) pathway when unmasked, visible primes were used and by activity in the parvocellular (P) pathway when masked, invisible primes were used. Contrary to some current theories of conscious and nonconscious visual processing, this indicates an important role of the M and P pathways in conscious and nonconscious vision respectively. Here we followed up on these putative respective roles of the M and P pathways by presenting contrast-varying primes and a probe of high fixed contrast either on a red background or else on an equiluminant green background. Replicating the main finding reported by Tapia and Breitmeyer, results showed that the contrast-dependent priming effects were best described by the contrast-response function characterizing M neurons when primes were visible and by the contrast-response function characterizing P neurons when primes were invisible. Moreover, since the M pathway is known to be suppressed by diffuse red light, we predicted and found that a red background relative to a green one significantly reduced priming effects when visible primes were used but not when invisible ones were used. Both findings constitute additional evidence confirming the contributions of the M and P pathway to conscious and nonconscious vision respectively. Tapia, E., & Breitmeyer, B. G. (2011). Visual consciousness revisited: magno- and parvocellular contributions to conscious and nonconscious vision. Psychological Science, 22, 934-942.)
Meeting abstract presented at VSS 2012