7 SAQ studies for BIo

Draganski (2004)

Aim: Find out whether the human brain can change structure in response to environmental demands.

Procedure: Random sampling design, self-selected sample Randomly allocated a sample of volunteers into 2 groups. One : jugglers. Two : non-jugglers. Made sure that both groups had no experience of juggling before the start of the experiment. First MRI performed. Participants in the juggler group subsequently spent three months learning a classic juggling routine with three balls. Second MRI performed. Participants in the juggler group spent three months where they were instructed not to practice juggling. Third MRI performed.

Findings: Prior to the start of the experiment there was no difference in brain structure. Second scan the juggler had more gray matter in some areas of the cortex mostly the mid-temporal area. Third scan differences decreased but jugglers denser gray matter

Troster and Beatty (1989)

This study investigated the role of acetylcholine in the formation and retrieval of memory. Participants were injected with either a placebo, .5mg of scopolamine or .8mg of scopolamine. They were given a free recall test, new map test, and remote memory test (which was based on retrieval, rather than encoding of memories.) They found that scopolamine inhibited the encoding of new memories, but did not have a significant effect on retrieval of long-term memories.

Maguire (1999)

This study used MRI scans to compare the brains of London taxi drivers to non-taxi drivers. It found that posterior hippocampi of taxi drivers were significantly larger than the control subjects and the anterior hippocampi were significantly smaller. Also, the volume of the right posterior hippocampi correlated with the amount of time spent as a taxi driver.

Newcomer (1999)

Aim - The aim was to determine whether glucocorticoids released from adrenal cortex during stress have adverse effects on cognitive functions such as learning and memory.

Procedure - Field experiments. Participants separated into three groups for the four day experiment

- Group one were give a tablet containing 160 mg of cortisol per day

- Group two were given a tablet containing 40 mg of cortisol per day

- Group three were given placebo tablets, control group

Participants were then asked to recal parts of a prose paragraph testing their verbal declarative memory.

Findings - High levels of cortisol impaired performance in the memory task as participants who received the highest amount of cortisol had the worst performance in verbal declarative memory.

Conclusion - There is a clear link between levels of cortisol and remembering, higher levels of cortisol resulted in memory impairment.

Wedekind (1995)

Aim: To investigate the role of MHC (major histocompatibility) in human attraction, or how pheromones that are indicative of a person's immune system affect human attraction.

Procedure: 49 female participants and 44 male participants were tested to identify their MHC genes. The men were given cotton t-shirts to wear to sleep for two nights. The researchers collected the t-shirts and placed them in boxes with a hole to smell. Seven boxes were presented to the women for them to smell, one control, meaning it had not been slept in, three from men who had similar immune systems to the women, and three were from men who had different immune systems to the women. The women were asked to rate each t-shirt on a scale of 1-10 in terms of its intensity, pleasantness, and sexiness.

Findings: The women all chose the shirts belonging to men with different immune systems as smelling the most appealing. These results were used to validate evolutionary theory, as according to the theory of evolution, the women would choose to mate with the man who had a different immune system so their offspring would have the strongest immune system possible. However, the very small sample size limits the ecological validity supported by the control group and two experimental groups, so the findings cannot be extrapolated to real life.

Caspi et al (2003)

Aim: To investigate relationship between 5-HTT gene and depression. (5-HTT gene is a serotonin-transporter that decreases the transport of serotonin into cells)

Procedure: Had participants (847) give self-reports on depression

Results: People with short allele for this gene correlated with more vulnerability to depression

Conclusion: Certain diseases based on behavior are caused by genes

Evaluation: this was a longitudinal study, instead of cross sectional. This study was done over a long perio of time.

Kendler et al (2006)

Aims: Investigate the heritability of MDD in a large sample, gender difference in heritability of MDD and change in genetic and environmental factors over time

Pps: 15493 twin pairs and 11175 independent twins born between 1886 and 1958

Procedure: Trained interviewers did telephone interviews between 98 and 03. Interviewers assessed pps for lifetime MDD, they also asked about shared environment and any events in the adult life that could cause depression.

Results: Heritability of MDD was 42% in women and 29% in men (average 38%). No correlation with time living together and MDD. No differences of environmental and genetic factors over time.