Abstract
Watanabe, Náñez, and Sasaki (2001) introduced a phenomenon they named “task-irrelevant perceptual learning” in which near-visual-threshold stimuli that are not essential to a given task can be associatively learned when concurrently paired with the focal task. How the timing of this pairing affects plasticity has been largely unexplored. More precisely, does the non-essential, near-threshold stimulus need to be presented at exactly the moment of focal concentration, or does some level of neural flexibility exist that would allow for pairing to be temporally close, but not simultaneous to the concentration? The present study explores the relation between the timing of the pairing of a dim motion stimulus with a recognition target. Near-threshold motion stimuli were presented concurrently with presentation of focal stimuli and offset from the same by ±350ms. The concurrent and the 350ms after groups performed significantly better than those who were exposed to the dim motion stimuli 350ms before the focal target. These data are consistent with a model of neuro-modulator induced cortical plasticity. Specifically, for the 350ms after condition, neuro-modulators were likely still present when neurons began responding to the dim motion, and, in the 350ms before condition, it is likely that neurons responding to dim motion were still partially active when the participant recognized the target, eliciting the slight improvements that were observed. This finding supports the notion that concentration-induced neuro-modulator release subserves cortical-plasticity.