Problematic research on suppressing unwanted memories

This 2014 human study found:

“Motivated forgetting mechanisms, known to disrupt conscious retention, also reduce unconscious expressions of memory, pointing to a neurobiological model of this process.”

I had multiple problems with this study. The first was that the researchers excluded emotional content, although the study involved areas of the limbic system.

How could the study’s findings apply to:

“The distressing intrusions that accompany posttraumatic stress disorder”

when emotional memories were excluded? It was an unsupported assertion for one of the researchers to state:

“The better understanding of the neural mechanisms underlying this process arising from this study may help to better explain differences in how well people adapt to intrusive memories after a trauma.”

Second, the researchers used the term “unconscious” 27 times, including in the title, without defining it. The studies they referenced defined “unconscious” several meaningfully different ways. How could the findings achieve validity when they contained an undefined term?

Third, the experiments involved short-term memories and visual perception. Sure, the subjects took longer to visually perceive objects that they had been directed to suppress than those that they had been directed to think about. However, I didn’t see where these experimental results could be extrapolated into findings about unconscious memories.

Fourth:

  • The researchers noted:

    “We did not observe less hippocampal activation during no-think than think trials.”

  • This data didn’t fit what they wanted to find, so they:

    “Restricted the search volume to anatomically defined regions of interest.”

  • They still couldn’t make their predetermined finding, so they discarded:

    “An outlier which compromised the significance of this effect.”

It seemed to me that the above process didn’t support the statement that immediately followed:

“Thus, suppression robustly engaged the brain regions associated with memory control, and this was accompanied by reduced activation in the hippocampus.”

I wonder if the reviewer had a problem with these four areas.

It was a letdown for me to read the details of the study when its title held out such promise for informing us about the unconscious influence of memories. Per my Scientific evidence page, I feel it would really help a person as a first step to become somewhat aware of their unconscious memories and feelings, especially when these are expressed through behavior in the physical world.

http://www.pnas.org/content/111/13/E1310.full “Suppressing unwanted memories reduces their unconscious influence via targeted cortical inhibition”

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