There is a well-defined biological response to stress, said Daniel Reisberg, a professor of psychology and perception at Reed College in Portland, Ore. The body prioritizes resources and sharpens your focus to help you cope with stress.
The body activates a stress response mechanism, or the hypothalamic-pituitary-adrenal, or H.P.A., axis. This is a chemical sequence that starts with the hypothalamus in the forebrain, sending chemical signals to the pituitary, which then secretes the stress hormone ACTH, which then causes the adrenal glands to produce cortisol, experts said.
This is where memory comes into play.
The stress hormone cortisol causes a person to have tunnel vision in the extreme or a really narrow snapshot of what happened, Professor Reisberg said. “When you’re under high stress, not only does it have an impact on how things are recorded in your brain but also how you can report on the memory,” he said.
The second a person walks away from an event, the memory of it starts to fade. This is when a memory can be contaminated by talking to the authorities, a lawyer, friends or bystanders, Professor Reisberg said.
People fill in gaps in their memory with context and references from their own experiences, Jeff Evan Saerys-Foy, an assistant professor of psychology at Quinnipiac University in Hamden, Conn., said.
“People will sort of incorporate things,” he said. “Even with these very vivid events, the inaccuracy keeps going on with time. There is a possibility for change.”
Memories formed during a traumatic event become an amalgamation of a person’s understanding of the world, the people around them and the snippets they were able to encode into their brain.
“Our working memory has a limited capacity,” Professor McNally said. “You cannot encode everything at once, especially when it is happening very quickly. Our minds are just not that powerful.”