Which aspect is least likely to affect a learner’s performance during training?

The aspect of practice frequency is least likely to affect a learner’s performance during training compared to the other options presented. While practice frequency can play a role in skill acquisition, it is not as directly influential as the other factors, particularly when considering a learner's immediate performance in a training environment.

Learner's mental fatigue can significantly impair performance because it affects cognitive function and focus, making it difficult to absorb new information or demonstrate skills effectively. Instructor feedback is crucial for learning; constructive feedback helps learners understand their mistakes and reinforce correct behaviors, thus playing a key role in performance enhancement. Personal interest in the subject can also greatly impact motivation and engagement, leading to better performance as learners are more likely to invest effort and attention in areas they find intriguing.

In summary, while practice frequency is important for skill development over time, it does not have the same immediate impact on performance during training sessions as mental state, feedback, or personal interest do.