The brain tends to simplify memory storage needs by employing “icons” of images we see. This is what causes confusion when one is confronted with an actual object that hasn’t been seen for many years. The icon and the actual thing can be subtly different. The lamp we are sure is brass with a green shade may be stored in our brain as such — only the real thing may be stainless steel with a blue shade.

The confusion results due to the iconic storage; the icon is a simplified version, with our mind filling in the details as an overlay on top of that icon when we recall it. The catch is that sometimes these details aren’t accurate even when the iconic portions of the memory are. (I suspect this may be how paintings work as well. The broad strokes are similar to the iconic elements in our memories, and our brain is used to “filling in the details” so that paintings often become “more real” than photos to us.)

Normally the iconic storage works well for us, allowing quick recall of memories. Under ideal conditions, it causes little confusion and everything runs smoothly. But the system is subject to glitches and what seems perfectly stored may in truth be less than correct. Thus the confusion that results with eye witnesses in the courtroom. One man’s overlay on an icon may be different from that of the next witness.

Since these glitches must appear with great regularity, it seems likely that at least on the subconscious level, we must tend to overlook the “mistakes” and glitches in iconic overlays. Thus we may very well be blind to our own mental blind spots.

That said, it is possible to trick a person into thinking their iconic overlay memory must be in error and thus cause them to accept something quite different from their memory of it — especially if you’ve got another task (like reading a map) distracting them. Here’s a good demonstration of how even the substitution of a completely different person can go undetected by manipulating this feature of the human memory: Person Swapping Video
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When not pondering his iconic memory overlays, Duncan Long is a freelance book cover illustrator for HarperCollins, PS Publishing, Pocket Books, Solomon Press, Fort Ross, and many other publishers and self-publishing authors. See his cover illustrations at: http://DuncanLong.com/art.html
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