Newcomer et al (1999)

• Aim: 

  To investigate whether high levels of cortisol interfere with verbal declarative memory.
• Procedure:

  1. Employees and students at Washington University Medical Center
  2. Double-blind laboratory experiment
  3. Conditions:

  • High cortisol (160 mg/day)
  • Low cortisol (40 mg/day)
  • Placebo

  1. Listen to and recall prose paragraphs
  2. Baseline, 1 day after, 4 days later, and 6 days later
• Results:

  • High cortisol group showed worst performance in verbal declarative memory
  • No significant difference between low cortisol and placebo groups
  • Effects were not permanent; performance returned to normal after stopping treatment
• Limitations:

  1. Participants were not in the lab full-time, allowing for potential extraneous variables.
  2. Memorizing prose may not fully represent real-life memory tasks.
  3. Generalizability:

  • Sample limited to university employees and students
  • Specific memory type (verbal declarative) may not apply to all memory processes

  1. Despite precautions, administering cortisol to alter cognitive function raises ethical questions.
• Strengths:

  1. Experimental Design: Allows for establishing cause-effect relationship between cortisol levels and memory performance.
  2. Control Measures:

  • Baseline testing to control for individual differences
  • Use of placebo group
  • Counterbalancing of prose texts

  1. Ecological Validity: Cortisol doses mimicked real-life stress levels.
  2. Longitudinal Aspect: Testing over several days allowed observation of both immediate and longer-term effects.
  3. Ethical Considerations: Informed consent obtained, and effects were not permanent.
• Conclusion:

  High levels of cortisol temporarily impair verbal declarative memory. This effect is dose-dependent, with higher cortisol levels causing greater memory impairment. The results demonstrate a clear link between cortisol levels and memory performance, suggesting how stress can directly affect cognitive function.