Source Amnesia: What It Is and Why It Happens

You know something but you don't know how, when, or where you acquired this knowledge. In fact, it's known as source amnesia and may be indicative of a problem that requires medical attention.
Source Amnesia: What It Is and Why It Happens
Elena Sanz

Written and verified by the psychologist Elena Sanz.

Last update: 21 December, 2022

Imagine that you’re talking to a friend and you tell them an anecdote or story that you find really interesting. A few days later, you talk to them again and they tell you the same information as if you didn’t know it. They assure you that they got it from a newspaper or the internet. Naturally, you’re surprised, as you thought you were the source of this information. Are they teasing you? As a matter of fact, they may be suffering from source amnesia.

Source amnesia is a common phenomenon that everyone experiences at certain times and that shouldn’t necessarily cause alarm. However, in some cases, it occurs with such frequency that there may be an underlying disorder. Let’s take a closer look.

Source amnesia

Source amnesia is the inability to accurately remember the context in which you obtained certain information. In this case, you’re fully capable of remembering the data itself but are confused as to where the knowledge came from. How, when, and where did you acquire it? You simply don’t know or you have the wrong idea about it.

It involves a dissociation between semantic memory (that of data and facts) and episodic memory (of contexts and lived events). In the case of source amnesia, somehow, when encoding the information, you weren’t able to integrate both aspects. Furthermore, when you do recover it, there are certain deficiencies. In short, you have problems monitoring the source of this particular knowledge.

This is something that’s happened to everyone at some time or another. For example, when you have a piece of information, but you can’t give any details beyond “I saw it somewhere”. This ‘somewhere’ might be a book, a newspaper, a television program, or a conversation with a friend. One of the main problems derived from this phenomenon is that you might give credibility to hoaxes or unfounded news by not remembering if you got your information from a prestigious media outlet or if a neighbor told you about it.

These kinds of situations can often be comical but, at the same time, rather awkward. For instance, you find yourself recommending a movie or a recipe to someone who actually previously gave that same information to you.

Man with fountain amnesia
In source amnesia, there’s a dissociation between semantic memory and episodic memory.

Why does source amnesia occur?

Source amnesia isn’t always indicative of a neurological problem. In many cases, the passage of time is a highly relevant factor. For example, when returning from a trip it’s easy for you to remember that you saw a church on the second day of your trip. However, decades later it’ll be hard for you to remember where you saw that church and you’ll struggle to recall what year it was.

This happens by the same process of coding and storage of memories. Information is initially encoded in episodic memory, but, after a certain threshold of time, the memory is stored in the semantic memory. This means that the data referring to when and where you obtained the information has faded away.

On the other hand, the degree of attention you pay when encoding the information also has a tremendous influence on your memory. If you’re paying attention, it’ll be easier to integrate data from the source context (and retrieve it later) than if you only receive the information in passing while you’re thinking about and doing other things.

Emotions also play a role. Indeed, situations involving emotions are more easily remembered later.

Different causes

Beyond the above contributing factors to source amnesia, there are a few causes that may require medical attention:

  • Age. Older people are more likely to suffer from source forgetfulness. This is presumably due to age-associated neuronal loss in the frontal lobes. They can benefit from training that leads them to pay deliberate attention to the context when encoding information.
  • Alzheimer’s disease. This disorder is associated with frontal lobe dysfunction and causes difficulties for patients in monitoring reality. It can generate source amnesia.
  • Frontal lobe damage. This type of damage causes a disconnect between semantic and episodic memory, causing sufferers to make many more errors in their source memory.
  • Psychological disorders. It’s also common to find this phenomenon in disorders such as depression, schizophrenia, and post-traumatic stress disorder.
woman with dementia
Both aging and Alzheimer’s disease can be causes of source amnesia.

Prevention and treatment

As you can see, not all cases are the same. Many people may experience source amnesia occasionally, due to inattentiveness or advanced age. However, in other cases, there may be important background diseases.

If you suffer from source amnesia on a regular basis or it’s interfering with your daily life, you can benefit from specific memory training carried out by professionals. First of all, you’ll need to have an evaluation to find the cause and take the appropriate measures. Therefore, don’t hesitate to consult your doctor.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Janowsky, J. S., Shimamura, A. P., & Squire, L. R. (1989). Source memory impairment in patients with frontal lobe lesions. Neuropsychologia27(8), 1043-1056.
  • Moore, S. A. (2009). Cognitive abnormalities in posttraumatic stress disorder. Current Opinion in Psychiatry22(1), 19-24.
  • Shimamura, A. P., & Squire, L. R. (1987). A neuropsychological study of fact memory and source amnesia. Journal of Experimental Psychology: Learning, Memory, and Cognition, 13(3), 464–473.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.