<p>Abrupt, large changes in symptom severity (sudden gains or sudden losses) can have a lasting impact on the outcome of psychological treatment. Sudden gains and losses have also been shown to occur in non-clinical samples. While it has been assumed that similar processes lead to sudden shifts in clinical and non-clinical settings, it is still unclear how sudden changes in both kinds of contexts relate to another. Recent theories suggest that for a lasting effect to happen, the sudden gain must be perceived and processed by those who experience them. While there is evidence that processed sudden gains are more stable than unprocessed sudden gains, much about the perception of a sudden shift by those who experience them remains unclear. In a first attempt to close this gap, we conducted a daily diary study with a non-clinical sample consisting of 138 participants. The participants were asked to rate their self-esteem, personality, and affect, as well as to indicate whether they perceived any changes in these variables since the previous day or week. Our results replicated previous findings that sudden gains and sudden losses also occur in non-clinical samples, but are unstable and not associated with depressive symptoms in such samples. Furthermore, although we found that participants’ perceptions of change were associated with their actual experiences, more fine-grained analyses showed that this association was mainly due to participants reporting correctly that they experienced <i>no</i> change. That is, participants had difficulty identifying sudden shifts in their experience. Altogether this suggests that non-clinical sudden gains and sudden losses are different from clinically relevant sudden changes because they are followed by different processes. We discuss limitations of our study and also point to questions for future research.</p>