Trials to criterion refer to the number of study and test trials needed to recall material perfectly.

Trials to criterion is a term used in psychology to describe the number of attempts or trials it takes for an individual to reach a specific performance level or criterion. This concept is often used in learning and memory research to measure how quickly a person can learn a new task or behavior.

For example, if a participant in a study is given a series of memory tasks and must correctly recall a certain number of items in each task, the number of trials it takes for the participant to reach the criterion level would be recorded. This information could then be used to compare the learning rates of different individuals or groups.

Another example of trials to criterion could be in a motor learning task, such as throwing a ball into a basket. The number of attempts it takes for the participant to successfully throw the ball into the basket a certain number of times could be recorded as trials to criterion.

Overall, trials to criterion is a useful tool in psychology research to quantify learning and performance, and to compare individuals or groups based on their ability to learn and improve over time.