Metacontrast, target recovery, and the magno- and parvocellular systems: a perspective.

In metacontrast a masking stimulus reduces the visibility of an adjacent target stimulus. This effect has been interpreted in terms of magno-/parvocellular interactions. It has also been found that a second masking stimulus, which precedes the primary mask by about 90 ms reduces the masking effect. This reduction, which is termed "target recovery," has been hypothesized to reflect parvocellular inhibition of the magnocellular system. However, this is problematic because the time course of this effect is much larger than would be expected from magno-/parvocellular interactions. For this and other reasons, it is difficult to understand metacontrast in terms of magno- and parvocellular mechanisms.