There are at least a couple of different approaches to this topic, as it is a bit subjective. Any general, sweeping claim can be a problem, as it means the person making the claim has the burden to prove it empirically. Or, in this case, it can be situational.
For example, when it comes to forgetting something intentionally — sure, some people consciously choose to forget / refuse to store certain information, depending on what is involved. Did some type of trauma / bad experience occur that makes the person want to forget? Or, as the text readings this week explain, is it that the STM is attempting to process a large amount on information at once. or various information is competing for space in STM, causing a bottleneck that, in turn, causes some forgetfulness (Revlin, 2013)?
Or is it because of other environmental circumstances that affect memory function and choosing what to remember and what to forget. Stressful day at work? A tragedy in the news? Or is the forgetfulness because of certain biases, or a lack of motivation to retain certain information? Or maybe retrieving a higher-priority thought temporarily causes forgetfulness about another thought, depending on the many factors that led up to the decision? Whichever the reason, there can be a wide array of explanations why someone chooses to be forgetful about something.
One glaring issue with blanketing forgetfulness as intentional is that it may not be fully considering that memory inevitably declines with age. Biology wins in the end. If a memory function study were conducted on a 16 year-old versus a 60 year-old, would it be fair to conclude that the 60 year-old was intentionally forgetting information? Or are there other factors involved?
What if a person has lesions in the parietal lobe or prefontal cortex, thereby impeding memory function? Further, there is plenty of evidence to support that central executive function declines with age, And depending on IQ and some degree of genetics, some people may have a stronger central executive function than others. Or does the person have low seratonin, or faulty dopamine function (Revlin, 2013)? In other words, biological factors must always be considered.
In short, determining why a person can be forgetful requires looking at both nature and nurture factors.
Revlin, R. (2013). Cognition theory and practice (1st ed.). New York, NY: Worth Publishers