Key Study: Cortisol and Memory (Buchanan and Lovallo, 2001)

Travis DixonBiological Psychology, Cognitive Psychology, Post-Traumatic Stress Disorder

The effects of cortisol release on memory formation could explain why people who experience traumatic events (like war) have long-lasting and intrusive memories of the trauma.

This study can be found in Chapter 4 of the Student’s Guide.


Studies conducted before this experiment in 2001 showed that cortisol can have a detrimental effect on memory. Animal studies, however, had shown the opposite: stress can improve memory.  This was the first study (at the time) that investigated the influence of cortisol on emotional memory in humans. It’s important to remember that cortisol is released by the adrenal gland during the stress response. So if we’re feeling stressed our amygdala will trigger the HPA axis and cortisol will be released. This experiment tested how that release of cortisol might affect memories of emotional information. While this study looked at memory of both positive and negative emotional material, understanding how stress affects memory could help us understand memory-related symptoms of PTSD, such as intrusive memories.

Methodology and Results

  • 48 participants (24 male/female)
  • Healthy participants (screened for psychiatric and neurological conditions)
  • Double-blind, independent samples design
  • Participants received 20mg of cortisol or a placebo
  • They were then shown a range of images, either pleasant scenes (eg. nice food, mountain scenery), unpleasant (e.g. disfigured people, threatening weapons) scenes or neutral scenes (e.g. a bicycle). The images were shown to participants on a TV.
  • Participants ranked how emotionally arousing they found the images.
  • One week later the participants’ memories of the images were tested (they were not told about the memory test beforehand).
Person Pouring Out Pills On Hand

The cortisol and placebo tablets given to the participants were identical.

The results showed that both groups remembered the emotionally arousing images better than the neutral images. The results also showed that the cortisol group remembered significantly more emotionally arousing images than the control group. The strongest effect was found in cued memory – when participants where given a category title (e.g. injured people, food, sports) and asked to recall the images.


  • How does this study show emotion influences cognition (memory)?
  • How can this study show ethical considerations in research on hormones and/or the effects of emotion on cognition?
  • How can this study show the use of research methods (experiments) to study hormones and/or the effect of emotion on cognition?
  • How can this study provide explanations for intrusive memories of traumatic events (a symptom of PTSD)?
  • How can this study provide evidence for an evolutionary explanation of behaviour (stress enhancing memory consolidation of emotional events)?
African American Mother and Child

When applying this study to explain PTSD we could focus on the effects of stress on memory consolidation. However, it’s important to note that cortisol enhanced the memory of positive AND negative emotionally arousing material.

Critical Thinking Considerations

  • Emotion and cognition: generalizability: what real life conditions might moderate the effects demonstrated in this study?
  • Ethical considerations: what are the potential negative impacts of this research on participants? How could these negative effects be reduced by following ethical guidelines?
  • Research methods: What are the limitations of using an experimental design in this experiment to study the effects of stress hormones on cognition?
  • PTSD: What are the limitations in using this study to explain symptoms of PTSD, such as intrusive memories?


Buchanan, Tony W., and William R. Lovallo. “Enhanced Memory for Emotional Material following Stress-level Cortisol Treatment in Humans.” Psychoneuroendocrinology 26.3 (2001): 307-17.

Link to original article here.