The nature of the operations that support learning should be evident in the form or shape of the learning curve. For example, models that describe learning as an iterative error-correction process expect that the amount learned on each trial follows a decelerating (negatively inflected) function. That prediction is broadly consistent with the shape of the acquisition and extinction curves derived from mean measures of response strength. However, such evidence can be flawed because group means may not accurately portray the response curves of individual subjects in a conditioning experiment. Moreover, such evidence relies on strong assumptions about the way that what has been learned is expressed in responding. The current work presents a new analytical approach to reveal the rate of change in responding across the course of conditioning in individual animals. When applied to the conditioning and extinction data from a large sample of rats, this analysis confirms that responses are acquired and extinguish gradually and, in both cases, follow a decelerating learning curve. That is, changes in responding are largest at the start of conditioning or extinction and get progressively smaller as responding approaches an asymptote. However, rather than conforming to the specific shape predicted by an error-correction process, the results suggest that the amount learned increases according to a logarithmic function such that responding during conditioning and extinction is proportional to the log of the number of trials. The implications of these findings for models of associative learning are discussed. (PsycInfo Database Record (c) 2022 APA, all rights reserved).