Perceptual learning without signal.

Perceptual learning is characterized by an improvement in a perceptual task following practice. Several studies have demonstrated that top-down processes, such as attention and task-related expectations, can be necessary components of perceptual learning [Ahissar & Hochstein, 1993, 2000, 2002; Fahle & Morgan, 1996; Seitz, Lefebvre, Watanabe, & Jolicoeur, 2005; Seitz, Nanez, Holloway, Koyama, & Watanabe, 2005; Seitz & Watanabe, 2003; Shiu & Pashler, 1992]. Here, we report an experiment that isolated top-down processes in perceptual learning, using a variant of the Gosselin and Schyns (1992) no-signal procedure. Results indicate that top-down processes can be sufficient to produce substantial, possibly long-lasting and rotation-invariant perceptual learning.