This 2014 French/UK 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.”
There were multiple problems with this study.
1. The researchers excluded emotional content, although the study involved areas of the brain involved in processing emotions:
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.”
2. The term “unconscious” was used 27 times, including in the title, without defining it. The cited studies defined “unconscious” several meaningfully different ways. How could the findings achieve validity when they contained an undefined term?
3. The experiments involved short-term memories and visual perception, and 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, the researchers didn’t show that these experimental results could be extrapolated into findings about long-term unconscious memories.
4. Data manipulation:
- 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.”
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.”
Didn’t the reviewer have something to say about these four problem areas?
It was a letdown to read the details of the study when its title held out such promise for informing us about the unconscious influence of memories. Per the Scientific evidence page, 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.
http://www.pnas.org/content/111/13/E1310.full “Suppressing unwanted memories reduces their unconscious influence via targeted cortical inhibition”