Remembering and Forgetting in Traumatized Ugandan Refugees

Gulu, Uganda (vis photography)


Most of us have memories from the past that we'd rather forget. When those memories are of a traumatic nature, they can more difficult to expel from our minds. Unwanted memories can be rejected by means of active inhibitory processes (Anderson & Levy, 2009), but these mechanisms are impaired in individuals with post-traumatic stress disorder, or PTSD (Zwissler et al., 2011):

Essentially, PTSD patients have trouble remembering what they are supposed to remember and forgetting what they would rather not remember. They appear to have impaired memory control.

A group of German investigators conducted a study on memory and forgetting in one of the more unsettling regions of the world: northern Uganda. The Lord's Resistance Army (LRA), a terrorist organization, has waged a long and brutal campaign to overthrow the government of Uganda:

Rape, torture, and murder have become the group's hallmarks in the almost fifteen [twenty or twenty-five] years that they have terrorized the citizens of Northern Uganda. The ranks of the LRA are filled in large part (approximately 80%) by children, who are kidnapped and brainwashed into service with the group. Human rights NGOs place the number of children currently fighting with LRA at around 3,000. LRA members also kidnap children, particularly girls, to serve as sex slaves; some have even been given as "gifts" to arms dealers in Sudan.

Zwissler and colleagues (2011) recruited severely traumatized participants for a study on directed forgetting, a memory task where instructions are given to remember some items but to forget others during the encoding phase. The participants were 51 young people (mean age=20.8 yrs, range 16–30) living in Internally Displaced Persons (IDP) camps near the city of Gulu in Northern Uganda. All were equally exposed to traumatic events such as abduction, but only 26 were diagnosed with PTSD, an anxiety disorder marked by intrusive memories and flashbacks.

The participants had two years of education on average, and many were functionally illiterate. For this reason, pictures were used as the stimuli (instead of words, which are commonly used in this type of study). The pictures were neutral in valence to examine whether memory issues in this population would extend to non-emotional material.

In the experiment, 28 pictures (Set A) were presented during an initial encoding phase. Each picture was followed by a symbol that signaled whether the preceding picture should be remembered or forgotten. During the test phase, all 28 pictures were presented, along with new pictures that served as "lures" that were similar to the initial set (Set B; see below).



Fig. 1 (Zwissler et al., 2011). Illustration of the picture sets showing three representative target-distractor pairs: (a) set A; (b) Set B. (Original photographs were shown in colour.)

For each stimulus, participants were told to indicate whether they had seen it before, regardless of the prior instruction to remember or forget. Overall accuracy in the task is shown in the figure below. The non-PTSD group had better memories for the pictures they were told to remember, compared to those they were told to forget. In contrast, the PTSD group showed no difference in accuracy for the to-be-remembered vs. the to-be-forgotten pictures.

Fig 2 (Zwissler et al., 2011). A comparison of the effect of directed forgetting on discrimination accuracy in the two groups. PTSD, post-traumatic stress disorder. *Indicates significant differences.

One way to view these results is that the participants with PTSD performed worse than controls for items they were supposed to remember, and were unable to invoke inhibitory processes to suppress memory for the to-be-forgotten items ("trouble remembering what they are supposed to remember and forgetting what they would rather not remember"). Breaking down task performance a little further, the PTSD group was more inclined to make "false alarm" errors to the lures related to pictures they were supposed to remember. This suggests that the details of the to-be-remembered pictures weren't encoded as well, and were more easily confused with related pictures they didn't see.

The authors concluded that...

...traumatized individuals with (but not without) PTSD are impaired in their ability to selectively control episodic memory encoding. This impairment may contribute to clinical features of the disorder such as intrusions and flashbacks.

However, "directed forgetting" is usually not a practical strategy when real life events are unfolding. Do these results this imply that the non-PTSD group was better able to dissociate themselves from traumatic events as they were occurring (or shortly thereafter)? Whether such a process can effectively occur at all during horrible tragedies is highly controversial (e.g., Terr vs. Loftus). The phenomenon is more often studied when applied to the retrieval of traumatic or unwanted memories (Anderson & Levy, 2009), not during the encoding phase.

Tragically, there appears to be No End to LRA Killings and Abductions in central Africa, according to Human Rights Watch. These ongoing atrocities should not be ignored.

So watch the video Dear Obama: A Message from Victims of the LRA.


Further Reading on Forgetting:

Forgetting is Key to a Healthy Mind
Letting go of memories supports a sound state of mind, a sharp intellect--and superior recall

Living and Forgetting

I Forget...

I Forgot...

...and it's Memory Week at the Guardian.


References

Anderson MC, Levy BJ. (2009). Suppressing unwanted memories. Curr Dir Psychol Sci. 18:184-194.

Zwissler, B., Hauswald, A., Koessler, S., Ertl, V., Pfeiffer, A., Wöhrmann, C., Winkler, N., & Kissler, J. (2011). Memory control in post-traumatic stress disorder: evidence from item method directed forgetting in civil war victims in Northern Uganda. Psychological Medicine, 1-9 DOI: 10.1017/S0033291711002273

"This was taken at the Guru Guru IDP camp. It was definitely the most uncomfortable place we visited with the most obvious results of 22 years of war and spiritual oppression. Favor of God Ministries is just beginning to work in this camp. They begin with 2 weeks of Trauma Counseling and then offer a 2-month long Portable Bible School. If it’s like any of the other camps we visited, it will be a completely different place afterwards."

vis photography
by Leah Vis