One of the primary intellectual themes of modern skepticism is that we need to understand the brain as a tool for gathering, processing, and storing information. The brain is a powerful, but extremely flawed, instrument subject to numerous cognitive biases, selective and distorted perception, and malleable memory.

Often I see people amused and entertained by demonstrations of the brain’s true nature, such as optical illusions or attentional blindness – but not everyone truly absorbs these lessons and understands their broad implication. The illusion that we perceive and store information in an objective an accurate way is compelling – but that too is just another construct of the brain.

Every time someone says, “I know what I saw” or “I have a clear memory” they are being profoundly naive. Modern neuroscience has taught us that there is practically no limit to the extent to which we can be fooled, especially by ourselves.

Memory is just one aspect of this picture – memories are living evolving things, not static recordings. We all experience and can understand memory fade – the older a memory, the more faded the details tend to be. We intuitively get that just from our own experience. But that is not the extent of the problems with human memory. Each time we remember something, we reinvent the memory – it changes, updates to account for our current knowledge, details can be added or altered, two or more memories can fuse, and false memories can be fabricated out of whole cloth.

That last bit is the part that most people have a hard time accepting – that a clear and confident memory can be a complete fabrication – a false memory. We tend to equate vividness and details with high confidence in the accuracy of a memory. Yet, high confidence is not a predictor of accuracy.

When you think about it, though, it makes sense. When we imagine something or remember an experience, the same pattern of brain activation occurs as when we actively experience the same thing. A memory is a memory – there is (apparently) no tag that lets us know which memories are of events we actually experienced, and which are things we imagined. All memories feel the same to us, regardless of how accurate or real they are.

A recent study highlights this fact. Researchers exposed subjects to a fake commercial for a fake new popcorn product. In one group the ad images were very vivid. In another group they were not. In yet another group subject were actually given popcorn to taste, and were told it was the new fake brand.

One week later the subjects were quizzed on whether or not they had every tried various products, including the fake one, how confident they were in their memory, and what their attitudes were toward the product. The high imagery group had the same rate of reporting that they actually tried the popcorn as the group that was given the popcorn to eat. They also reported an equally high confidence in their memory. The low-imagery group did not show this effect.

Further, the attitude of the high-imagery group toward the fake product was more positive than the low imagery group.

What this study suggests is that vivid imagery can create a false memory of actual experience. This is in line with other false memory research. Further (and this is why the study was published in the Journal of Consumer Research) this “false experience” effect can be used to increase attitudes towards a brand (even one that doesn’t exist).

The implications of this and other research is clear – false memories can be manufactured. This is precisely why when subjects, sometimes under hypnosis, are invited by a therapist or investigator to imagine themselves experiencing a standard alien abduction scenario, or an episode of childhood physical abuse, or a past life – the experience is not revealing hidden memories, it’s manufacturing false memories.

This is also why, in more everyday examples, it is important to be skeptical of your own memories, no matter how vivid they are or confident you are in their accuracy.