Which of the following statements best describes a forgetting curve?

The statement that defines a forgetting curve as a gradual decline in memory over time accurately portrays how information is retained and forgotten according to research in cognitive psychology. The forgetting curve, first identified by Hermann Ebbinghaus, illustrates that memories fade at an exponential rate after the initial learning. This means that shortly after learning new information, a significant portion of it is lost, and the rate of forgetting decreases over time.

This concept highlights the idea that while we may recall information immediately after learning it, our ability to retain that information diminishes as time passes without reinforcement or review. Thus, the correct answer encapsulates the essence of the forgetting curve, which emphasizes the decline in memory retention as a function of time.