Which of the following is a difficulty commonly encountered in memory retrieval?

Memory retrieval is often fraught with challenges, and one significant difficulty is that memory changes over time. This phenomenon occurs because memories are not static; rather, they are dynamic and can be influenced by various factors such as new information, emotional states, and even discussions with others. As time passes, the details of an event may become less vivid or may be altered to fit a narrative that the individual constructs. This means that what one recalls may not perfectly align with the original event, leading to inaccuracies and distorted memories.

In contrast, perfect recall of events, unbiased recollection, and accurate perception of all past events do not reflect the common experiences of individuals when attempting to retrieve memories. Human memory is inherently fallible, and the notion that someone can perfectly recall all details or unbiasedly recollect all aspects of an event does not align with the complexities of how memory works, making these options less representative of typical memory retrieval challenges.