Newcomer
Newcomer et al. (1999)
Experiment on cortisol and memory
Aim :
To investigate how levels of cortisol interfere with verbal declarative memory.
Procedure:
A self-selected sample (recruited through advertisement) of 51 normal and healthy people aged 18–30 was used. It was a randomized, controlled, double-blind experiment running for four days. All participants gave informed consent.
There were three experimental conditions:
- A high level of cortisol (tablet of 160 mg per day), equivalent to cortisol levels in the blood as a consequence of a major stressful event.
- A low level of cortisol (tablet of 40 mg per day), equivalent to cortisol levels in the blood as a consequence of a minor stressful event.
- A placebo (tablet of no active ingredient).
Results
The high-level group performed worse on the verbal declarative memory test than the low-level group. They performed below placebo levels after day 1. The low-level group (mild stress) showed no memory decrease.
Evaluation
This was a controlled randomized experiment so it was possible to establish a cause-effect relationship between levels of cortisol and scores on a verbal declarative memory test. Ethical issues were observed with informed consent. The negative effect of taking high dosages of cortisol was reversible so no harm was done.