IB Psychology Paper 1 Review - Biological Approach

NEUROTRANSMITTERS

Passamonti et al. (2012)

The study aimed to investigate how serotonin depletion affects brain activity and emotional regulation, particularly focusing on aggressive behavior and impulsive reactions.

The study employed a repeated-measures design, meaning each participant underwent two separate conditions: serotonin depletion and placebo. Participants consumed a drink that either lacked tryptophan (to reduce serotonin levels) or contained normal levels of tryptophan (placebo). Tryptophan is essential for serotonin production. Brain activity was measured using functional MRI (fMRI) scans while participants viewed images of angry, happy, and neutral faces. This provided data on how serotonin depletion affected responses to emotional stimuli.

Under low serotonin conditions, participants showed reduced activity in the PFC when viewing angry faces. Communication between the amygdala and PFC was weaker during serotonin depletion, indicating a diminished ability to regulate emotional responses. Brain activity was measured using functional MRI (fMRI) scans while participants viewed images of angry, happy, and neutral faces. This provided data on how serotonin depletion affected responses to emotional stimuli.

Reduced serotonin levels impaired the brain's ability to manage impulsive and aggressive reactions. The findings underline the importance of serotonin in maintaining emotional control.

TECHNOLOGY

Radke et al. (2015)

The study aimed to investigate how testosterone influences the amygdala's activation when responding to social threats, particularly when participants approached or avoided angry faces.

A double-blind, placebo-controlled design was used to ensure unbiased results. Half of the participants received a dose of testosterone, while the other half received a placebo. Participants underwent functional MRI (fMRI) scans while completing a social approach-avoidance task. They were shown images of angry and happy faces and instructed to either approach (pull a joystick to enlarge the face) or avoid (push the joystick to shrink the face). Importantly, the participants did not choose their actions—they followed instructions. The researchers focused on amygdala activity and its response to approaching or avoiding angry and happy faces. Brain activity was analyzed to determine how testosterone modulated responses to social threats.

Participants who received testosterone exhibited increased amygdala activation when approaching angry faces compared to the placebo group.

LOCALIZATION

Feinstein et al.(2011)

Participants who received testosterone exhibited increased amygdala activation when approaching angry faces compared to the placebo group.

SM, a 44-year-old woman with focal bilateral amygdala lesions, was the sole participant. SM was exposed to various fear-inducing scenarios, such as visiting a haunted house, handling live snakes and spiders, and watching emotionally evocative films. Researchers also conducted interviews and collected self-reports over three months to assess SM's real-life experiences and emotional responses. Observational data and self-reported fear ratings were collected during the fear-inducing scenarios.

SM exhibited little to no fear in situations that would typically provoke strong fear responses, such as handling snakes or navigating a haunted house. The findings support the idea that the amygdala is critical for triggering and experiencing fear. Damage to this region appears to impair the ability to feel fear, even in situations that are objectively threatening.

EVOLUTION

Ahs et al (2009)

The study aimed to investigate the role of the amygdala in specific phobias, focusing on how brain activity correlates with distress when exposed to fear-inducing stimuli.

16 female volunteers with either snake or spider phobias participated in the study. To confirm their phobias, participants completed the Snake Anxiety and Spider Anxiety Questionnaires. Participants were exposed to pictures of snakes and spiders while undergoing PET scans to monitor brain activity. The researchers compared participants' reactions to the animal they feared versus the animal they did not fear. Brain activity in the amygdala was analyzed, particularly in the right hemisphere. Participants rated their distress levels during exposure to the images.

This suggests that the amygdala plays a significant role in processing fear and distress related to specific phobias. There was a strong correlation between amygdala activity in the right hemisphere and participants' distress ratings.

NEUROPLASTICITY

Luby et al. (2013)

The study aimed to investigate how poverty experienced in early childhood affects brain development at school age and to explore the mediating factors, such as caregiving and stressful life events.

145 children were recruited for the study. These children were assessed annually for 3–6 years before undergoing MRI scans. Cognitive, emotional, and social assessments were conducted annually to track development. MRI scans measured brain volumes, including white matter, gray matter, hippocampus, and amygdala. The researchers analyzed how poverty impacted brain structures and examined mediating factors like caregiver support/hostility and stressful life events.

Poverty was associated with reduced white and gray matter volumes, as well as smaller hippocampal and amygdala volumes.

NEUROPLASTICITY

Sapolsky et al. (1990)

The study aimed to investigate the relationship between social rank and stress levels in wild baboons, focusing on how dominance hierarchies influence physiological stress responses.

The study observed a group of monkeys over a 12-year period. Researchers collected blood samples from the baboons to measure cortisol levels, a hormone associated with stress. The study examined how cortisol levels varied with social rank and personality traits.

Subordinate baboons exhibited higher cortisol levels compared to dominant individuals, indicating greater stress. Dominant baboons experienced lower stress levels, likely due to their control over resources and social interactions.

NEUROTRANSMITTERS

Pucilowski et al (1985)

The study aimed to investigate the effects of serotonin on aggression, specifically focusing on how serotonin levels in the amygdala influence aggressive behavior in rats.

Rats were divided into two groups:

• One group received a serotonin injection directly into the amygdala.

• The other group did not receive any injection.

The "resident-intruder test" was conducted, where a stranger rat (the intruder) was introduced into the cage of the resident rat. Researchers measured the time it took for the resident rat to attack the intruder. Attack latency (time taken to attack) was recorded as a measure of aggression.

Attack latency (time taken to attack) was recorded as a measure of aggression. This suggests that higher serotonin levels in the amygdala reduce aggression.

HORMONES AND BEHAVIOR

Albert et al (1986)

The study aimed to investigate the relationship between testosterone levels and aggression, specifically focusing on how changes in testosterone influence dominance behavior in male rats.

Male rats were used due to their tendency to display aggressive and dominance behavior. Rats were divided into groups:

• One group underwent castration to reduce testosterone levels.

• Another group received testosterone implants after castration.

• A control group underwent a "sham" procedure without altering testosterone levels.

The rats were placed in cages together to observe changes in dominance behavior. Researchers measured aggressive and dominance behaviors, such as fighting and establishing alpha status.

Castrated rats showed reduced aggression and were less likely to maintain alpha status. Testosterone replacement restored aggressive behavior and dominance.

PHEROMONES AND BEHAVIOR

Cornwell et al (2004)

The study aimed to investigate the role of pheromones, specifically androstadienone, in influencing attraction and mate preferences.

Female Participants were asked to rate different male faces based on their preferences for short-term or long-term relationships. They were exposed to five different vials containing:

• Androstadienone (a male pheromone),

• Androstenone,

• A female pheromone,

• Control oil (clove oil),

• Another control oil (oil of cade).

The researchers analyzed the correlation between the participants' preferences for male characteristics and their responses to the pheromones.

A positive correlation was observed between the participants' preferences for certain male characteristics and their preference for androstadienone.

PHEROMONES AND BEHAVIOR

Saxton et al (2008)

The study aimed to investigate the effects of androstadienone, a male pheromone, on women's perceptions of men's attractiveness in a real-world social setting.

Female participants were recruited for a speed-dating event. Participants were divided into three conditions:

• Exposure to androstadienone mixed with 1% clove oil.

• Exposure to 1% clove oil only (control).

• Exposure to water (control).

Cotton wool infused with the respective substance was placed under the participants' noses during the speed-dating interactions. Participants rated the attractiveness of the men they interacted with. Attractiveness ratings were collected.

Women exposed to androstadienone rated men as more attractive compared to the control conditions in two out of three studies. This suggests that androstadienone may act as a chemical messenger, enhancing attraction in social contexts.

GENES AND BEHAVIOR

Meyer-Lindenberg (2008)

To see how differences in MAOA gene (high expression vs. low expression) affects brain activity when exposed to threat. The MAOA gene is responsible for the breakdown of important neurotransmitters like serotonin or dopamine.

142 participants. Two separate conditions were investigated:

• High variant gene (MAOA-H)

• Low variant gene (MAOA-L)

fMRIs were used to measure the activity in the amygdala while participants viewed angry or fearful faces.

When exposed to emotional stimuli (fearful face), activity in the amygdala was significantly higher in the MAOA-L participants. The MAOA-L gene may correlate with aggression and impulsive behavior/emotional reactions.

GENETIC SIMILARITIES

Baker et al (2007)

The study aimed to investigate the genetic and environmental influences on antisocial behavior in children, focusing on the heritability of such behaviors.

The study involved 1,210 twins (both identical and fraternal) from California, USA, aged 9-10 years. Data was collected using questionnaires completed by the children, their teachers, and their caregivers. These questionnaires assessed personality traits, behaviors, and social skills related to antisocial tendencies. The researchers conducted statistical analyses to compare the similarities in antisocial behavior between identical and fraternal twins.

The heritability of antisocial behavior was estimated to be around 50%, indicating that genetics and environmental factors each contributed equally to these behaviors. Antisocial behavior in children is influenced by both genetic and environmental factors, with genetics accounting for approximately half of the variance.