A researcher was interested in whether the construct of helplessness (as shown by low persistence on tasks, negative affect or emotional state, and negative self-evaluations) is similar in toddlers, preschoolers, and older children.

The researcher recruited a group of 2-year-olds and a group of 4-year-olds and brought them into a playroom setting. The children were videotaped playing with impossible puzzles (tasks that have been shown to induce failure experiences/helplessness) and "helpless" behaviors were measured.

The children were brought back two years later (the first group of children were then 4 and the second group was 6 years of age) and were given another set of impossible puzzles. Helpless behaviors were again measured.

Is the study described above correlational or experimental? Why?