Biological Approach (SL) Flashcards
All biological studies to memorise
Study ONE techniques used to understand the brain and behaviour
Draganski et al (2004)
Aim:
To investigate whether learning a new skill (juggling) would result in structural changes in the brain (neuroplasticity).
Participants: 24 volunteers (non-jugglers)
Design: Repeated measures, pre-test/post-test design
Baseline MRI scan before learning to juggle
Participants split into two groups:
Juggler group: Practiced a three-ball cascade juggling routine for 3 months, then stopped for another 3 months
Non-juggler group: Did nothing (control)
MRI scans taken before learning, after 3 months (learning phase), and after 6 months (3 months after stopping practice)
Results:
After 3 months (learning phase): Jugglers had increased grey matter volume in the mid-temporal lobe (V5 area), associated with visual memory and movement perception.
After 6 months (when they stopped practicing): The increased grey matter shrank, showing that the brain adapts to learning but also prunes unused ne ural connections.
Conclusion:
Neuroplasticity exists: Learning a new skill physically changes brain structure.
Use it or lose it: Neural connections strengthen with use but weaken when unused.
Study ONE example of localisation of function
Sperry and Gazzaniga (1967)
Aim:
To investigate the effects of severing the corpus callosum (which connects the two hemispheres) on communication between the left and right hemispheres of the brain.
Background:
The corpus callosum allows communication between the two hemispheres.
Some epilepsy patients undergo split-brain surgery (cutting the corpus callosum) to reduce seizures.
This provided an opportunity to study lateralization of function—how each hemisphere specializes in certain tasks.
Method:
Participants: Split-brain patients (epileptics who had undergone corpus callosotomy).
Procedure: A series of tasks designed to test hemisphere specialization using a tachistoscope (a device that presents stimuli to only one visual field at a time).
Visual tasks:
A word or image was flashed in the right visual field (RVF) (processed by the left hemisphere).
A different word or image was flashed in the left visual field (LVF) (processed by the right hemisphere).
Object tasks:
Objects were placed in one hand (without sight) to test identification.
Participants were asked to name or draw the object.
Results:
Right visual field (processed by left hemisphere) → Patients could verbally identify the word/image.
Left visual field (processed by right hemisphere) → Patients could not say what they saw but could draw or pick up the object with their left hand.
Tactile tasks: If an object was placed in the right hand (left hemisphere), participants could name it. If placed in the left hand (right hemisphere), they could not name it but could identify it by touch.
Overall finding: The two hemispheres function independently in split-brain patients, with the left hemisphere responsible for language and the right for visual-spatial tasks.
Conclusion:
Lateralization of function exists: The left hemisphere is dominant for language, while the right is better at visual and spatial processing.
The corpus callosum is essential for integrating information between hemispheres.
Study ONE example of neuroplasticity.
Also: Neural network and neural pruning
Maguire (2000)
Aim:
To investigate whether extensive navigation experience (as seen in London taxi drivers) is associated with structural changes in the brain, particularly the hippocampus, a region involved in spatial memory and navigation.
Background:
The hippocampus plays a key role in spatial memory and navigation.
London taxi drivers must pass “The Knowledge,” an intense memorization test of London’s 25,000 streets.
This study examines whether their brain structure adapts due to this training.
Method:
Participants: 16 right-handed male London taxi drivers (with at least 1.5 years of experience) vs. 50 right-handed male non-taxi drivers (control group).
Design: Quasi-experiment (naturally occurring variable: being a taxi driver or not).
Procedure:
MRI scans compared the hippocampal volume of taxi drivers and non-taxi drivers.
Voxel-based morphometry (VBM) measured grey matter density.
Pixel counting compared hippocampal size in taxi drivers vs. controls.
Results:
Taxi drivers had a larger posterior hippocampus compared to controls.
Non-taxi drivers had a larger anterior hippocampus than taxi drivers.
The longer the taxi-driving experience, the greater the posterior hippocampal volume (positive correlation).
No significant differences in other brain areas.
Conclusion:
Neuroplasticity exists: The brain can change in response to experience and learning.
Hippocampus adapts to environmental demands: The posterior hippocampus stores spatial memory, which develops with increased navigation experience.
Study ONE neurotransmitter and its effect on behaviour
Caspi (2003)
Aim:
To investigate the role of the 5-HTT gene in depression after stressful life events.
Background:
The 5-HTT gene influences the production of serotonin, a neurotransmitter involved in mood regulation.
There are two variants (alleles) of the gene:
Short (s) – Linked to lower serotonin production.
Long (l) – Linked to higher serotonin production.
Researchers hypothesized that people with the short allele would be more vulnerable to depression after stress.
Method:
Participants: 847 New Zealand adults from the Dunedin Longitudinal Study, assessed from ages 3 to 26.
Procedure:
Participants were divided into three groups based on their 5-HTT genotype:
Two short alleles (s/s)
One short, one long allele (s/l)
Two long alleles (l/l)
They were assessed for stressful life events (e.g., financial problems, health issues, job loss) from ages 21 to 26.
At age 26, they were assessed for symptoms of depression.
Results:
People with two short alleles (s/s) were more likely to develop depression after stressful life events.
People with one short, one long allele (s/l) showed a moderate risk.
People with two long alleles (l/l) were least likely to develop depression.
Simply having the short allele didn’t cause depression—it only increased risk after stress.
Conclusion:
Gene-environment interaction: The 5-HTT gene moderates the effects of stress on depression.
Having a genetic predisposition does not guarantee depression—stress is a key factor in triggering it.
Study ONE hormone and its effect on behaviour
Scheele (2012)
Aim:
To investigate the role of oxytocin in promoting fidelity (faithfulness) in men who are in romantic relationships.
Background:
Oxytocin is a hormone and neurotransmitter that plays a key role in social bonding, trust, and romantic attachment.
Previous research suggests oxytocin is involved in monogamous behavior in animals, but its effect on human romantic relationships was unclear.
Method:
Participants: 86 heterosexual men (some single, some in a relationship).
Double-blind experiment:
Participants received either oxytocin or a placebo via nasal spray.
After administration, they completed two tasks:
Task 1: Approach/Avoidance Task
Participants were asked to move closer to or away from images of attractive women by adjusting a joystick.
Task 2: Stop-Distance Paradigm
A female experimenter approached the participant and stood at a comfortable distance.
Participants were asked to indicate when she was “too close” and they felt uncomfortable.
Results:
Men in relationships (who received oxytocin) kept a greater distance from the female experimenter compared to the placebo group.
Single men showed no effect of oxytocin—they maintained the same distance regardless of the condition.
In the approach/avoidance task, oxytocin reduced the tendency to move closer to attractive women only in men in relationships.
Conclusion:
Oxytocin promotes fidelity in committed relationships by reducing the approach behavior towards attractive women.
The hormone does not affect single men, suggesting its role is specific to maintaining monogamous bonds.
Study ONE pheromone and its effect on behaviour
Lundstrom and Olsson (2005)
Aim:
To investigate the effects of androstadienone (a derivative of testosterone found in male sweat) on a woman’s mood and perception of male attractiveness.
Background:
Androstadienone is a pheromone-like compound found in male sweat and semen.
It is believed to affect mood, attraction, and interpersonal interactions, particularly in women.
The study aimed to see if androstadienone enhances women’s mood in the presence of a male experimenter.
Method:
Participants: 37 heterosexual women, average age ~25.
Procedure:
Women were exposed to either androstadienone or a control substance.
Their mood was assessed before and after exposure.
The experimenter interacting with the participants was either male or female.
Results:
Androstadienone exposure improved women’s mood, but only when a male experimenter was present.
There was no significant effect when a female experimenter was present.
Conclusion:
Androstadienone may act as a social chemical signal (pheromone), enhancing mood and attraction toward men.
The results suggest pheromones can influence human behavior, particularly in interactions with the opposite sex.
Study ONE gene and its link to behaviour
Caspi et al (2003)
Aim:
To investigate the role of the 5-HTT gene in depression after stressful life events.
Background:
The 5-HTT gene influences the production of serotonin, a neurotransmitter involved in mood regulation.
There are two variants (alleles) of the gene:
Short (s) – Linked to lower serotonin production.
Long (l) – Linked to higher serotonin production.
Researchers hypothesized that people with the short allele would be more vulnerable to depression after stress.
Method:
Participants: 847 New Zealand adults from the Dunedin Longitudinal Study, assessed from ages 3 to 26.
Procedure:
Participants were divided into three groups based on their 5-HTT genotype:
Two short alleles (s/s)
One short, one long allele (s/l)
Two long alleles (l/l)
They were assessed for stressful life events (e.g., financial problems, health issues, job loss) from ages 21 to 26.
At age 26, they were assessed for symptoms of depression.
Results:
People with two short alleles (s/s) were more likely to develop depression after stressful life events.
People with one short, one long allele (s/l) showed a moderate risk.
People with two long alleles (l/l) were least likely to develop depression.
Simply having the short allele didn’t cause depression—it only increased risk after stress.
Conclusion:
Gene-environment interaction: The 5-HTT gene moderates the effects of stress on depression.
Having a genetic predisposition does not guarantee depression—stress is a key factor in triggering it.
Study genetic similarity (twins, siblings, parents, adopted children) for one behaviour.
Kendler (2015)
Aim:
To investigate the relative contributions of genetic and environmental factors on drug abuse, alcohol use disorders, and criminal behavior using a new triparental design.
Method:
Participants: The study used data from Swedish national registries that included individuals with detailed records of both biological and adoptive parents.
Design: This study introduced a triparental design, comparing individuals raised by:
Biological mother and father
Adoptive mother and father
Both biological and adoptive parents
The goal was to assess the effects of genetic relatedness (biological parents) and environmental upbringing (adoptive parents) on behavior.
Results:
Genetic Factors: There was a significant contribution of genetic factors to the risk of drug abuse, alcohol use disorders, and criminal behavior. Individuals who were genetically related to individuals with these behaviors were more likely to exhibit similar behaviors.
Environmental Factors: Environmental influences, particularly the characteristics of the adoptive family, were also significant in shaping these behaviors.
Gene-Environment Interaction: The study found evidence of gene-environment interactions, meaning that genetic predispositions could be moderated or influenced by the environmental context.
Conclusion:
Genetic and Environmental Contributions: The study concluded that both genetics and environmental factors play substantial roles in behaviors related to substance abuse and criminal activity.
Implications for Intervention: The findings highlight the importance of considering both genetic vulnerabilities and environmental contexts when addressing risk factors for these behaviors.
Study ONE example of an evolutionary explanation for behaviour.
Fessler (2005)
Aim:
To investigate whether disgust sensitivity is elevated during the first trimester of pregnancy, particularly regarding food-related disgust, as an evolutionary protective mechanism against foodborne pathogens.
Method:
Participants: 691 pregnant women (mean age: 28.1 years) recruited through pregnancy-related websites.
Procedure: Participants completed a web-based survey assessing:
Nausea levels using a 16-point scale.
Disgust sensitivity across eight domains: food, animals, body products, dead animals, hygiene, toilets, sex, and body envelope violations.
Results:
Overall Disgust Sensitivity: Women in the first trimester showed higher disgust sensitivity compared to those in later trimesters.
Food Disgust: Disgust sensitivity related to food was significantly elevated in the first trimester, supporting the hypothesis that increased food-related disgust functions as a protective mechanism against pathogens.
Nausea Correlation: Increased nausea was strongly associated with higher levels of disgust sensitivity, particularly in food-related disgust.
Conclusion:
The study suggests that elevated disgust sensitivity, especially toward food, during the first trimester of pregnancy may serve as an evolutionary adaptation to reduce the risk of foodborne illnesses, protecting both the mother and fetus during a vulnerable period of fetal development.
