Bloa Studies

Front 1

Sperry 1968

Back 1

Natural Experiment

To investigage the effect of hemisphere disconnection of the brain of the psychological performances of epileptic patients treating using severing of the corpus callosum.

To prove: Each hemisphere has different functions, each possesses an independent stream of conscious awareness, each has its own set of memories.

11 participants (patients) who had advanced epilepsy that could not be controlled by medication were chosen.

IV: Different parts of the brain being disconnected

DV: Task that the participant had to take part in.

Procedure: Testing visual and tactile information to see which part of the brain works. For example: If looking at something with right eye, left brain works.

Results: Objects shown in right go to left and can be verbally named and written down. Objects shown in left and go to right cannot be verbally named but can be pointed out.

-Shows that the two hemispheres have different ability and functions.
-One side of the brain does not know what the other side has seen or felt.

Conclusion: Left brain- language and writing
Right Brain- drawing, dace recognition

Evaluation:
-Ecological validity
-Helped patients with brain damage
-Explore each part of the brain in more detail
-Patients had different mental abilities before operation
-Cannot be generalized, small sample size
-Cause-effect of brain unable to be established.

Front 2

Kendler et al 1991

Back 2

Aim: whether genetics had an effect on bulimia nervosa in families

Method: gather data of 2000 female twins

Results: rate of 23% in MZ (identical) twins and 9% in DZ (fraternal) twins. In all studies, higher rate in MZ than DZ, varies from 23% to 83%

Conclusion: genetics may have an effect on people getting bulimia.

Evaluation:
-unreliable people may be secretive about bulimia
-No IV is manipulated
-no cause and effect determined
-same genetic material, cannot be generalized
-ONLY FEMALES (gender imbalance)

Front 3

Rosenzweig and Bennett 1972

Back 3

Aim: Whether enriched environment has an effect on the brains development of neurons in the cerebral cortex.

Method: Place a group of rats in 1 enriched environment with interesting toys and another group in 1 deprived environment (no toys) for 30-60 days. Afterwards they were sacrificed.

IV: Enriched env.

DV: Deprived env.

Result: As a result of the enriched env. the rats thickness increased in the cortex. (better memory, learning)

Conclusion: Thickness increased as a result of enriched experience.

Evaluation:
-Animal research may not be generalized
-gives idea on how humans may behave
-unethical: animals get harmed and only used as a last resort

Front 4

Lindstroem et al 1999

Back 4

lab studies

Aim: whether schizophrenic patients had differences in dopamine levels

Method: PET scan of 10 patients with schizophrenia and 10 healthy controls. Inject patients with I-DOPA, which is used in production of dopamine

Results: I-DOPA was taken up more quickly in patients with schizophrenia, suggesting that more dopamine was used for production

Conclusion: more dopamine was used for production with patients with schizophrenia.

Evaluation:
-Artificial environment
-Act under demand characteristics
-Useful, looking at brain activity, how the brain activity works (looking at their levels of hormones and neurotransmitters)
-Ethical findings on abnormalities in the brain - must have consent beforehand
-Expensive, and needs an expert
-Doesn't harm the subject
-However its not easy to find out levels of neurotransmitters in the brain, therefore researchers are open to interpretation of the brain scans, UNRELIABLE

Front 5

Marucha 1997

Back 5

lab studies

Aim: where there is a link between stress and time taken for recovery

Method: 11 dental students had their palates punctured (minor pain) during summer, and 3 days before an examination period (stressful period)

DV: same participants

IV: time that they puncture their palates

Result: wounds took 8 days to heal during summer, but 11 days to heal during examination period

40% increase in healing time during non-stress

Interleukin (substance to aid wound healing, as it facilitates regrowth of skin

Subjects interleukin levels declined 68% during exams

Conclusion: cortisol (stress hormone) lowers interleukin levels, meaning that the body will have a weaker immune system, as the body has lower resistance

Evaluation:
Artificial
Single experiment lacks ecological validity
Cannot be generalized outside the study conditions
Other studies investigating same topic with same method = similar findings
Ethical- no one is harmed

Front 6

Kasamatsu and Hirai 1999

Back 6

Aim:
To see how sensory deprivation affects the brain
Also to see how the serotonin affects behavior

Methods:
Studied a group of Buddhist monks who went on a 72-hour pilgrimage to a holy mountain in Japan.
Monks did not consume water or food; did not speak and were also exposed to cold weather.
Researchers took a blood sample before monks ascended into the mountain and immediately after they reported having hallucinations

Results:
After about 48 hours, monks began to have hallucinations, seeing ancient ancestors or feeling their presence by their sides.
They found that serotonin levels had increased in the monks? brains thus the higher levels of serotonin activated the hypothalamus and frontal cortex resulting in the hallucinations.

Conclusion:
Researchers concluded that sensory deprivation triggered the release of serotonin, which altered the way that the monks experienced the world, a behavior expressed by humans.

Connection of study to question
-Thus, this study shows that the neurotransmitter serotonin affects the human behavior of increased arousal causing hallucinations (as demonstrated by monks after a spike in serotonin), therefore affecting human behavior in terms of arousal and emotion.

Front 7

Martinez and Kesner 1991

Back 7

Aim:
To determine role of neurotransmitter acetylcholine on memory, specifically memory formation.

Methods:
Rats were trained to go through maze and get to the end where they received food.
After rats were able to do this, he injected:

1st group -scopolamine, which blocks acetylcholine receptor sites.
2nd group - physostigmine, blocks production of cholinesterase (does 'clean-up' of - acetylcholine from synapse and returns neuron to its 'resting state').
3rd group - control (no injections).

Results:
Scopolamine - slower at finding way round maze and made more errors than control/physostigmine group.
Physostigmine - ran faster compared to both groups and made fewer wrong turns.

Conclusion:
Acetylcholine played an important role in creating a memory of the maze.

Evaluation
Strengths:
Design and application
Use of an experimental method with a control group made it possible to establish cause- and-effect relationship between levels of acetylcholine and memory.

Limitations:
Questionable to what extent these findings can be generalized to humans. (Possible to apply research on rats to human beings)
Assumed that memory processes are the same for all animals.

Front 8

Curtis et al 2004

Back 8

Aim: Whether there were patterns in people's disgust responses

Method:
Tested whether there were patterns in disgust responses via an online survey
77 000 participants from 165 countries.
Participants were asked to rank their level of disgust for 20 images.
Within the 20 images were 7 pairs where one was infectious or harmful to the immune system and the other was similar but non-infectious.
For example, one image was a plate of bodily fluid and its pair was a plate of blue viscous liquid.

Results:
The disgust reaction was strongest for images which threatened the immune system.
Disgust also decreased with age and women had higher disgust reactions than men.

Conclusion: people before couldn't be picky, their aim was just to survive
Nowadays humans have choice

Evaluation:

Strengths
Applicable as it is ecologically valid
Can be generalised
Cost effective
Time effective
Some quantitative data

Limitations
No cause and effect
No control over variables
Low range of levels
The study was conducted online
The validity of the results is somewhat unreliable

Front 9

Caspi et al 2003

Back 9

Aim: To study the role of 5-HTT gene in depression after experiences of stressful events.

IV: Participant with a mutated gene (shorted allele).

DV: vulnerability to depression

Study: Gene influences level of serotonin (controlling mood). Gene mapping. Long allele is a bit more frequent (57%).

Findings: Participants with mutated gene who experienced many stressful events were more likely to become depressed.

Conclusion: Gene may indicated vulnerability to depression after stress.

HOWEVER: people without mutated gene also become depressed; large population carries the mutated gene (difficult to conclude that it is a major contributor). There is no evidence against the idea that it could be the stressful events (environmental factors) that made people depressed- not clear now envr. factors influence genes.

evaluation:
-no cause and effect
-unreliable (people can lie)
-cannot be generalized

Front 10

Fessler 2006

Back 10

Aim:
Fessler hypothesized that disgust helps to compensate for the suppressed immune system.

Method:
He asked 496 healthy pregnant women between ages 18 - 50 to rank 32 potentially disgusting scenarios.
For example, maggots on a piece of meat in an outdoor waste bin.
Before asking the women to rank the level of disgust in the scenarios, Fessler asked questions to determine whether they were experiencing morning sickness.

Results:
Women in their first trimester scored higher in disgust sensitivity than women in the second and third trimesters.
When Fessler controlled the study for morning sickness, the response only applied to scenarios involving food.

Conclusion:
Fessler explained this in terms of the large extent of dangerous diseases, which are food-borne.

Natural selection may have helped human ancestors to be pickier with food to compensate for increased susceptibility to disease.

Being pickier with food would also help humans avoid diseases that could harm unborn offspring, and thus, threaten the species.

Evaluation:

Strengths
large sample (496 women) - generalizability
Wide age range (18-50 years) - generalizability
Although it is restricted to women it could lead to insight on gender differences
Data was ranked by self-report - quantitative thus could use statistical analysis

Limitations
Findings can not be solely based on evolution, as the environment could be an interfering variable
There is cultural and emotional influences on women's disgust
Quasi-experiment meaning that the IV could not be manipulated
Data was ranked by self-report which is often unreliable
Individual differences in terms of food 'likes' and 'dislikes'

Front 11

Wahlstein 1997

Back 11

Aim: He tried to show that higher socio-economic status improves IQ scores.

Findings: They found that well controlled adoption studies conducted in France have found that transferring an infant from a family with a low socio economic status to a home where parents have a high socio economic status improved childhood IQ scores by 12-16 points.

Conclusion: This study shows that the environment plays a key role in determining intelligence and it also can be used to support the idea that the environment can play a key role in determining behavior.

Front 12

Hetherington and Ranson 1942

Back 12

Aim: looking at appetite regulation with different parts of the brain lesioned

Method: lesioning the ventromedial hypothalamus in rats

Results: rats had increase food intake, and often doubled their weight

Conclusion: that the damage had prevented the rat's satiety centre from functioning. Normally when rats feed, the VMH stops the feelings of hunger as it receives messages from the digestive system and they stop eating

Evaluation:
limited because the hypothalamus is such a small part of the brain, it is hard to say that the only part they damaged when lesioning it was the VMH. Other parts of the hypothalamus may have been damaged and they could have had an effect on the rat's eating behaviour.

Front 13

Raine 1997

Back 13

Aim: To directly asses brain functioning in violent individuals- to discover (using PET scans) if murderers who pleaded not guilty by reason of insanity (NGRI) to show evidence of brain abnormalities

IV: Whether participants were controls or prisoners who pleaded not guilty for reasons of insanity (NGRI's)

DV: Brain activity

Method: PET scans were taken (researchers used/took permission to use the data); 41 participants (39 male, 2 female) and matching 41 participants (controls) was selected based on sex, age and matched to a NGRI participant.

Findings: Found reduced glucose metabolism in prefrontal cortex and increased activity in the right amygdala, suggesting the PFC is less active than in normal controls and amygdala may be more active.

Conclusion: asymmetric activity in the amygdala- imbalance causing misunderstanding of fear and consequences.

Evaluation:
STRENGTHS
Largest sample ever imaged (can be generalised to other NGRIs)
PET scanning is very scientific, and can be interpreted by more than one researcher, likely to be reliable
Matched pairs - control group had good matching

WEAKNESSES
Can only be generalised to NGRIs (not to non-violent criminals, all murderers)
Doesn't take into account environmental factors, which can also cause brain differences
Findings don't say violence is biological (nurture/nature debate)
Does not give causes of brain dysfunction