Final answer:
To determine which group performed the best during retention in a study manipulating feedback frequency and error estimation, one would need to refer to the specific study results, as retention performance can vary with task and context.
Step-by-step explanation:
When it comes to research involving the manipulation of both relative feedback frequency and error estimation, existing studies in motor learning indicate that different combinations can lead to varying outcomes in skill retention. It is generally suggested that a balance of feedback frequency and error estimation is beneficial for effective learning and retention. However, without specific research results, it is not possible to definitively state which group performed best during retention—that is, whether it was 1) high frequency without error estimation, 2) high frequency with error estimation, 3) low frequency with error estimation, or 4) low frequency without error estimation.
To answer this question correctly, one would need to look at the specific study or experimental results in question, as the performance in retention could depend on various factors including the task, the population, and the context in which the learning occurred.