Ackermann et al. (2013)

Associations between Basal Cortisol Levels and Memory Retrieval in Healthy Young Individuals.

Background information: Cortisol is known to affect memory processes. High cortisol levels enhance memory consolidation, but have been shown to impair memory retrieval (i.e. recall). However, the effects of individual differences in basal cortisol levels on memory remain largely unknown.

Aim: To investigate whether individual differences in cortisol levels predict picture

encoding (learning) and recall.

Method: 1225 healthy young male and female participants between 18 and 35 years old viewed two different sets of emotional and neutral pictures on two consecutive days.

The pictures comprised two sets (Set 1 and Set 2) of 24 positive, 24 negative, and 24 neutral pictures interleaved with 24 scrambled pictures. Additionally, four pictures showing neutral objects were presented to control for primacy and recency effects (two pictures were shown in the beginning of the presentation, the other two at the end). These pictures were not included in the analysis.

Both sets were recalled after a short delay (10 min). Also, on Day 2, the pictures seen on Day 1 were additionally recalled, resulting in a long-delay (20 hr) recall condition.

Cortisol levels were measured three times on Days 1 and 2 via saliva samples before encoding the memories, between encoding and recall as well as after recall testing.

Results: Stronger decreases in cortisol levels during retrieval testing were associated with better recall of pictures, regardless of emotional value of the pictures or length of the retention interval (i.e., 10 min vs. 20 hr). However, during encoding, individual differences in average cortisol levels as well as changes in cortisol did not predict memory recall.

Conclusion: The results support previous findings indicating that higher cortisol levels during retrieval testing hinders recall of episodic memories and extend this view onto individual changes in basal cortisol levels.

Evaluation:

Strengths of the study: No “normal” level of cortisol was assumed. Instead each person’s increase or decrease in cortisol was measured individually against their basal level. The differences in recall therefore related to a decrease from that person’s norm and not an average across the whole group. This increases the validity of the findings.

Limitations of the study: This was quite a narrow age range and it would be good to compare with older people’s recall related to their own changes in cortisol.

Also, in elderly participants in other studies, chronic elevation of cortisol over several years has been associated with worse episodic memory performance. It would be interesting to check the results with younger people who have chronically raised cortisol levels.

For More Study Notes…

To keep up-to-date with the tutor2u Psychology team, follow us on Twitter @tutor2uPsych, Facebook AQA / OCR / Edexcel / Student or subscribe to the Psychology Daily Digest and get new content delivered to your inbox!