Lecture 2: What if the memory is not credible?

We have talked much about different forms of memory and how to help patients learn better from dentists.

But this session would not be complete have I not told you the very nature of our memory: our memory is what we reconstructed from the fact, rather than the fact itself. Just like our perception, what we feel about is not really the things in their objective status. Vision does not mean video-taking because what we see consists of our subjective interpretation. So is memory. What we recall consists of our subjective interpretation. That’s why psychologists would use the verb ‘reconstruct’ to describe memory processing. And therefore, we should not feel surprised that there is always some ‘errors’ or ‘distortions’ in our memory, compared to the fact. Psychologist Daniel Schacter made seven sub-categories of the ‘wrong memories’.

For example, we may forget something that we are so familiar with, and the information is just ‘blocked’ when we want to use it. Sometimes we forget something merely because we did not focus on processing the information. These are the problems about omission, i.e., we fail to do something correctly with our memory.

More interestingly, sometimes we think we have remembered something, but what we recall is the memory distorted by some factors.

For example, patients may recall two things: they have received dental scaling by Dr Wang and extraction by Dr Smith. But in fact, it is Dr Wang for extraction and Dr Smith for dental scaling. The patients just misattribute the wrong dentists to wrong treatment. Patients’ memory may also be shaped by some bias, such as a stereotypic idea. For example, they may relate a toothache to dentine hypersensitivity, which is very common and the first thing that comes to their mind. These are the problems of commission of memory, which means people did recall, rather than forget, something. The problem is what is recalled is somehow distorted.

And finally, we need to pay attention to some personal factors, especially the effect of ageing and neurodegenerative diseases in older people. I will not focus too much on these issues here in this course because these issues are more relevant to geriatric healthcare. But I think there is one thing very crucial that all dental professionals should pay attention to. It is very often that we find older patients forget something, we thought that there is some memory deficit, perhaps cognitive impairment or even dementia, with the older patient. Nevertheless, we need to be aware that such ‘poor memory’ may derive from more fundamental problems. Remember the general framework of memory?

The poor memory may reflect not just a problem of storage and retrieval but also a problem about encoding, i.e., how older people collect information. For example, some patients with severe dementia may fail to respond to your question, it’s not because of poor memory but poor attention. They have more serious problems in orienting themselves to others. For patients with delirium, they could even get confused about when and where they are. Finally, sometimes patients may be less responsive to dentists because of a lack of motivation, which can be seen in patients with depressive disorders. They ‘know’ things but they are not willing to give a response. Memory is just part of the cognitive-affective function of human beings.

I think the problem of misattribution is very important to dental treatment nowadays. Because today we have too many sources of information. We should not blame the patients for wrongly connecting this and that, because things are too complicated. They may pick up something from their friends and pick up something from the Internet, and put everything in a new story which they believe in. I think misattribution is a good example of the reconstructive nature of memory. In clinical settings, we are aware of the situation when patients forget something. However, we should also be aware of the situation when patients ‘remember’ something, which still needs to be validated, for example, by medical history.

Memory is not equal to hard evidence – it is the product reconstructed by our brain.