case studies-bio approach

  • Baumgartner et al. (2008)
    Goal: To see how oxytocin affects trust.
    Method: 49 participants were given oxytocin or a placebo via nasal spray. They then played a "trust game," where one player sends money to another and trusts them to send it back. This was done while participants were in an fMRI scanner to observe brain activity, especially in areas related to trust and fear.
    Results: Oxytocin increased trust, even after betrayal, and reduced activity in brain areas linked to fear.

  • Bos et al. (2010)
    Goal: To see how testosterone affects trust.
    Method: 24 women were given either testosterone or a placebo and asked to rate how trustworthy they found people in a task where they had to make judgments about others' trustworthiness.
    Results: Testosterone reduced trust in highly trusting individuals but did not affect those who were less trusting.

  • Wedekind and Furi (1997)
    Goal: To see if people prefer the scent of those with different immune system genes (MHC).
    Method: 120 participants smelled t-shirts worn by other people for two days and rated the scents based on attractiveness. This was meant to determine if scent preferences were influenced by genetic differences in the MHC.
    Results: People preferred the scent of individuals with different MHC genes, suggesting scent plays a role in mate choice.

  • Thorne et al. (2002)
    Goal: To see if male pheromones make men seem more attractive.
    Method: 32 women were exposed to male pheromones in a controlled environment, then asked to rate the attractiveness of male faces shown to them in photos.
    Results: Pheromones made men appear more attractive, though factors like the women’s menstrual cycle or contraceptive use had no effect.

  • Kaati et al. (2007)
    Goal: To see if famine or plenty in one generation affects the lifespan of future generations.
    Method: Researchers analyzed historical records from a Swedish town, comparing the food availability of grandparents to the lifespans of their grandchildren.
    Results: Food surplus in grandparents led to shorter lifespans for grandchildren, showing the effect of early-life food availability on future generations.

  • Waterland and Jirtle (2003)
    Goal: To see if diet can change gene expression.
    Method: Mice were fed a diet rich in methyl groups, and researchers studied how this diet affected the gene expression of their offspring, particularly looking at genes linked to health and development.
    Results: The diet influenced gene expression, resulting in healthier offspring with normal weight and lifespan.

  • Curtis et al. (2004)
    Goal: To see what makes people feel disgust.
    Method: 40,000 participants from 165 countries rated how disgusting they found various images, such as spoiled food, animals, or dirty environments.
    Results: Disgust was strongest for things that could threaten health, like spoiled food, suggesting disgust evolved to help us avoid disease.

  • Fessler et al. (2005)
    Goal: To see if disgust sensitivity changes during pregnancy.
    Method: 496 pregnant women filled out surveys about their feelings of disgust, particularly towards food, at different stages of their pregnancy.
    Results: Sensitivity to disgust was higher in the first trimester, likely as a protective mechanism to avoid harmful substances during early pregnancy.

  • Olazábal and Young (2006)
    Goal: To see if oxytocin affects maternal behavior.
    Method: Female prairie voles, which are known for strong pair bonds and parental care, were observed to see if those with more oxytocin receptors showed more maternal behaviors toward pups.
    Results: Voles with more oxytocin receptors exhibited more nurturing behaviors, linking oxytocin to maternal care.

  • Weaver et al. (2004)
    Goal: To see if maternal care affects gene expression in offspring.
    Method: Rats were raised by mothers that either provided high or low levels of nurturing. Researchers then analyzed the stress-related genes in the offspring to see if these were affected by the level of maternal care.
    Results: Offspring of low-nurturing mothers had more stress-related genes activated, making them more prone to anxiety.

  • Phillips and LeDoux (1992)
    Goal: To understand how the hippocampus and amygdala are involved in fear.
    Method: Rats with damage to either the hippocampus or amygdala were conditioned to fear a tone paired with a mild shock, and researchers observed their fear response.
    Results: Rats with damaged amygdalae couldn’t learn to fear the tone, while those with damaged hippocampi couldn’t associate the tone with the shock context, showing distinct roles for these brain regions.

  • Scoville and Milner (1957) & Corkin et al. (1997)
    Goal: To understand how brain damage affects memory.
    Method: HM, a man with severe memory loss due to brain surgery, was studied through interviews, tests, and brain scans to assess his memory abilities.
    Results: HM could not form new long-term memories, which demonstrated the importance of the hippocampus in memory formation.

  • Crockett (2010)
    Goal: To see how serotonin affects moral decisions.
    Method: Participants took either serotonin-boosting drugs or placebos, and then answered moral dilemmas or played a game about accepting fair or unfair offers.
    Results: Those with higher serotonin were more likely to avoid harmful actions and accept unfair offers, showing serotonin’s role in moral decision-making.

  • Feinstein et al. (2011)
    Goal: To see how the amygdala is involved in fear.
    Method: SM, a woman with no amygdala, was exposed to frightening situations, including snakes and haunted houses, to determine if she could feel fear.
    Results: SM did not experience fear, even in scary situations, which highlighted the amygdala’s essential role in fear processing.

  • Holzel et al. (2010)
    Goal: To see if mindfulness changes the brain.
    Method: 16 participants completed an 8-week mindfulness meditation program, with brain scans taken before and after the program to measure changes in brain structure.
    Results: Mindfulness meditation increased gray matter in brain areas related to memory and emotions, indicating neuroplasticity.

  • Maguire et al. (2000)
    Goal: To see if London taxi drivers’ brains change due to their job.
    Method: MRI scans of the brains of London taxi drivers were compared to those of non-drivers to see if driving influenced brain structure, especially areas linked to spatial memory.
    Results: Taxi drivers had larger posterior hippocampi, suggesting their brains had adapted due to the demands of their job.

  • Weaver et al. (2004)
    Goal: To see if maternal care affects gene expression in offspring.
    Method: Similar to study #10, rats were raised by mothers with varying levels of nurturing, and their stress-related gene expression was analyzed.
    Results: Rats with less nurturing mothers showed higher activation of stress-related genes, leading to higher anxiety in adulthood.