IB PSYCHOLOGY M26: BIOLOGICAL

MAGUIRE (2000) AIM, SAMPLE, DESIGNS

Aim: See whether the brains of London taxi drivers would be different as a result of exceptional knowledge of the city and hours they spend navigating the streets of London.

Sample: 16 right-handed male taxi drivers, who completed “knowledge” test and had a license for 1.5 years.

Designs: Correlational. Single-blind. Quasi-experiment.

MAGUIRE (2000) PROCEDURE + FINDINGS

Procedure: MRIs of taxi drivers were compared to MRIs of 50 right-handed males who didnt drive taxis. MRIs were compared using pixel counting and voxel-based morphometry (VBM). VBM was used to measure grey matter density of the brain, and pixel counting was used to calculate the size of the hippocampus.

Findings: Larger posterior hippocampus, smaller anterior in taxi drivers (pixel counting). Volume of right posterior hippocampi correlated with amount of time as a taxi driver (VBM).

SHAROT ET AL (2007) AIM, SAMPLE, DESIGNS

Aim: Determine the potential role of biological factors on flashbulb memories.

Sample: 24 participants in NYC on 9/11

Designs: Quasi-experiment. Volunteer sampling. Correlational. 

SHAROT ET AL (2007) PROCEDURE + FINDINGS

Procedure: While in fMRI, participants were shown word cues on a screen. In addition, the word "Summer" or "September" was projected along with words to have the participant link words to summer holidays or 9/11. Participants’ brain activity was observed while they recalled the event. The memories of personal events from the summer served as a baseline of brain activity for evaluating the nature of 9/11 memories. After brain scanning session, participants were asked to rate their memories for vividness, detail, confidence in accuracy, and arousal, then asked to write a description of their personal memories. 

Findings: Those closer to the World Trade Centre that day experienced typical “flashbulb memories,” included greater written detail, and displayed greater amygdala activation.

MCGAUGH & CAHILL (1995) AIM, SAMPLE, DESIGNS

Aim: Study the role of emotion in the creation of memories.

Sample: 18 participants.

Designs: Independent measures. Experimental design. Lab experiment. Double-blind (follow-up)

MCGAUGH & CAHILL (1995) PROCEDURE + FINDINGS

Procedure: Participants evenly allocated to 2 groups. Participants viewed 12 identical slides w/ narrated story. Neural condition heard a boring story about a woman and her son visiting a hospital during a disaster drill. Emotional condition heard a dramatic story where the boy is severely injured in a car accident and undergoes surgery. Participants had to rate emotional intensity on a 1-10 scale. After two weeks participants had to do a memory recognition test, consisting of multiple-choice questions about the slides.

The follow-up study (McGaugh & Cahill 1996) consisted of the same procedure, but participants were injected with propranolol (reduces amygdala activation) or a placebo.

Findings: Emotional condition had significantly better recall than neutral condition. Follow-up study showed that those injected with propranolol had reduced recall even when in the emotional condition.

RONAY & VONHIPPEL (2010) AIM, SAMPLE, DESIGNS

Aim: Determine if men would take greater risks in the presence of an attractive female, than in the presence of a male.  In addition, they wanted to see if testosterone played a role in this behavior.

Sample: 96 male Australian skateboarders from ages 20 - 22.

Designs: Natural experiment. Independent measures. Convenience sampling.

RONAY & VONHIPPEL (2010) PROCEDURE + FINDINGS

Procedure: Each participant attempted one easy and one difficult trick ten times. After a break, participants attempted the same two tricks 10 times in front of either 1) a male researcher and 2) attractive female researcher. The attempts of tricks were measured by successful, crash landing, or aborted to measure risk-taking behaviour. Saliva samples were collected after the task, and heart rate was measured before and during the task.

Findings: Participants took more risks in front of female researcher, and showed higher testosterone levels. No difference in heart rate.

WEDEKIND (1995) AIM, SAMPLE, DESIGNS

Aim: Determine whether one's Major Histocompatibility Complex (MHC) would affect mate choice.

Sample: 49 female and 44 male students from the University of Bern, Switzerland. Each participant was “typed” for their MHC, and a wide variance of MHC was included in the sample.

Designs: Convenience sampling. Double-blind experiment. Laboratory experiment. Correlational.

WEDEKIND (1995) PROCEDURE + FINDINGS

Procedure: Men were instructed to wear a provided cotton t-shirt for two consecutive nights. They were instructed to use fragrance free soap/detergent, avoid deodorant, perfume, spicy foods, alcohol, smoking, and physical activity. After two days, the t-shirts were sealed in boxes. Women had to smell 7 t-shirts: 3 from men with similar MHC, 3 from men with dissimilar MHC, and 1 unworn t-shirt.

Findings: Women generally rated the body odors of men with MHC dissimilar to their own as more pleasant and more attractive than those of MHC-similar men. However, this pattern was reversed in women taking oral contraceptives.

NESTADT ET AL (2000) AIM, SAMPLE, DESIGNS

Aim: Investigate familial nature of OCD.

Sample: 80 participants diagnosed with OCD, and 73 control participants from the same community. First-degree relatives (parents and siblings) of both the OCD and control participants were included, giving a total sample of 343 relatives of OCD cases and 300 relatives of controls.

Designs: Convenience sampling. Random sampling.

NESTADT ET AL (2000) PROCEDURE + FINDINGS

Procedure: First-degree relatives were assessed by trained psychiatrists. Clinical interviews were carried out and were used to diagnose OCD and identify obsessions and compulsions. The researchers compared the lifetime prevalence of OCD in relatives of diagnosed participants and relatives of controls.

Findings: The lifetime prevalence of OCD was significantly higher among relatives of individuals with OCD compared to relatives of control participants.

CASPI ET AL (2003) AIM, SAMPLE, DESIGNS

Aim: Determine whether there is evidence for a gene-environment interaction (G x E) for a mutation of the serotonin transporter gene, 5-HTT.

Sample: 847 New Zealand 26-year-olds.

Designs: Correlational. Holistic approach. Independent measures. 

CASPI ET AL (2003) PROCEDURE + FINDINGS

Procedure: Participants were divided into three groups: two short alleles, one short one long, and two long alleles. They were asked to fill in a “stressful life events questionnaire” within the last 5 years. Participants reported stressful life events and were assessed for depression. 

Findings: Those with one or two short alleles showed more depressive symptoms and suicidal thoughts, especially when exposed to high stress. However, having the gene alone did not cause depression—it only increased risk when combined with stressful experiences.