Abstract
Visual perceptual learning (VPL) is defined as a long-term improvement in performance on a visual task. A recent study has shown that VPL of a stimulus feature results from repetitive presentation of the feature paired with reward (Seitz, Kim and Watanabe, 2008, Neuron). This suggests that at least some types of VPL are highly related to the theory of conditioning. An important question is whether VPL involves conditioning. However, there are two types of conditioning, classical conditioning and instrumental conditioning, which are subserved by different neural mechanisms (O'Doherty et al., 2004, Science). Thus, if VPL that is reinforced or formed by reward involves conditioning, the mechanism for VPL that occurs in a classical conditioning procedure should be different from that in an instrumental conditioning procedure. To address these questions, we trained one group with a classical conditioning procedure (Kim, Seitz, Watanabe, 2008, VSS), and the other group with the instrumental conditioning procedure in which subjects performed a go no-go task by choosing between pressing (go) or not pressing (no-go) a button, in response to one of three orientation stimuli. In the “go” condition, the reward was delivered according to a different reward probability (80%, 50%, 20%) of each orientation. In the no-go condition, the reward was delivered with a constant probability of 50%. Whereas VPL induced by goal-directed instrumental conditioning is governed by the rule of contingency (Rescorla, 1968), VPL that occurs in the classical conditioning procedure follows the rule of contiguity, according to which two events are associated if they repeatedly occur together in time. These suggest that the underlying mechanism between classical conditioning induced VPL and goal-directed instrumental conditioning induced VPL are different. These further suggest that there are more than one mechanisms for VPL.
NIH R01 (EY015980, EY019466, AG031941, MH091801), NSF SMA-0835976.