IB Psych

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Aim

To determine how much of an influence genetics have on determining an individual’s personal psychological qualities.

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Procedure

Participants were monozygotic twins who were separated early in life and apart for most of their lives, and reunited as adults. These participants were given about 50 hours of testing on their individuality, including four personality trait scaled, three aptitude and occupational interest inventories, and two intelligence tests. They also filled out checklists of household belongings to assess their family’s resources, and a family environment scale that measured how they felt about the parenting received by their adoptive parents. They were also given a life history interview, a psychiatric interview, and a sexual history interview. These were carried out individually to avoid the twins’ answers influencing each other.

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Results

The data showed that monozygotic twins who were raised in separate and (often) very different settings grew into adults who were very similar psychologically and in terms of personality. This indicates that genetics has a stronger influence than environment over psychological and personality traits.

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Methods

This research was conducted by performing an experiment and a series of interviews.

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Applications

This study has been built on to further investigate the influence of genetics on personality characteristics and behaviors. It has also led to reevaluation of previous studies that attributed the majority of personality and behavior characteristics to environment. It also led to further investigation of genetic linkage to likelihood of divorce, eating disorders, age at the time of death, job satisfaction, and extroversion vs. introversion. Finally, this study also contributed to the discussion of human cloning, in that it suggested that if it were to be done that there was potential for the clone’s personality to be the same as/similar to the original person.

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Gender

Both men and women were participants in this study, and there isn’t a difference (that is noted) between these groups.

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Ethics

One ethical consideration partially addressed is that eugenicism has always been a very large problem, and this was especially the case in the early 1900s (1920s-1930s), shortly before this study likely began to be formed–assuming it took about 10 years or more to complete as it was described to be a lengthy process to gather participants–this study would have occurred only 50 years after the eugenicist movement was at its peak (Nazi Germany). This is not to say that the researchers had eugenicist intentions (as it does not seem that they did), however, it is necessary to acknowledge the potential for this influence, not only on the research itself, but also how it could be manipulated. This is especially true when attempting to measure a genetic linkage to intelligence, as this has been especially harmful and weaponized in the past (ex: social darwinism). Another ethical consideration discussed is how this research may be used in the conversation of human cloning, and suggests that though the person may still be somewhat similar to the clone due to genetic similarities, there is still ethical concern with this idea because of the reason behind wanting to produce these clones.

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Culture

Some cultural considerations addressed include underlying factors (such as socioeconomic factors, family setting, toxic substances, etc.) may also influence IQ (a trait examined in the study) aside from genetics, being raised in the same environment may affect the reliability of the results, and that one can be influenced by the answers of another to the same question if both participants are present in the same room at the time of interview. Some not addressed include the differentiating treatment of identical twins and fraternal twins, as well as differences between levels of similarity based on the genders of the twins due to cultural influences (such as gender roles).

T. Bouchard, D. Lykken, M. McGue, N. Segal, and A. Tellegen Criticisms

Some critics say that the researchers are not publishing their data as fully and completely as they should, so, their findings cannot be independently evaluated. These critics also claim that many articles are reporting on case studies that indicate strong environmental influences on twins that the researchers did not consider. Another criticism of this study is more so related to twin studies in general: just because twins are raised together does not necessarily mean that they grew up in identical environments; namely that identical twins are often treated rather differently than fraternal twins.

Cerebellum

Physical coordination

What’s the best advice for parents dealing with their teenage children?

Provide structure, organize the teenager’s time, and guide them through difficult decisions (even if there’s resistance), and give them grace and love.

Why do some argue that teens should not be tried as adults and should be spared the death penalty?

Because of the lack of a fully developed brain when still a juvenile, explaining that this means that teens have increased difficulty making mature decisions and understanding the consequences of their actions.

What does the pineal gland have to do with teen behavior?

It takes longer for melatonin (what the pineal gland produces) levels to rise in teenagers than younger kids or adults, regardless of light exposure or stimulating activities. This may be an explanation behind why it is difficult to have a teenager go to bed and get up on a normal schedule.

Why should parents motivate teens with more immediate rewards than long term rewards? (What specific part of the brain is not fully developed, yet?)

The nucleus accumbens are not fully developed yet, which means that the teenagers may be more prone to behaviors that have a rather high excitement factor or a very low effort factor (or both), so suggesting immediate payoffs when proposing a teen do an action is most effective.

What role might dopamine play in a teen’s tendency towards activities with drugs / alcohol?

The rapid changes in dopamine rich areas of the brain during teenage years may be an additional factor in making them vulnerable to drugs and alcohol, as dopamine is the brain chemical involved in motivation and reinforcing behavior. This chemical is especially abundant and active during teen years.

What did the “yellow light” experiment demonstrate about teens and bad decision – making?

Age differences in decision making and judgement may appear under conditions that are emotionally stimulating or have high social impact. Further, most teen crimes are committed by kids in packs.

What is the relationship between the hormone – induced thrill seeking behaviors in teens and their ability to make good judgments in terms of brain development?

Because the sex hormones are especially active in the limbic system, adolescents seek out situations that create intense feelings, namely strong sensations, excitement, and thrills. This thrill seeking may have evolved to promote exploration, independence, and the seeking of one’s own path and partner. However, this may also increase the risk of a teenager ending up in dangerous situations. This is especially true because the parts of the brain responsible for making judgements are still developing during adolescence. This creates a time gap between when teenagers are more likely to engage in risky behaviors and when the structures that allow people to think before they act become active.

What role does hormone activity play in explaining teen behaviors?

Puberty adrenal sex hormones are extremely active in the brain, attaching to receptors everywhere and having a direct influence on serotonin and other neurochemicals that regulate mood and excitability.

What does brain research suggest about teenage bad decisions?

That it’s partially due to hormonal changes, but also because the part of the brain that makes teenagers more responsible is not finished maturing yet during those years.

Why does development occur from the back of the brain to the front?

Because structures in the back of the brain mediate direct contact with the environment by controlling sensory functions such as vision, hearing, touch, and spacial processing. After that are areas that coordinate those functions. Lastly is the prefrontal cortex, which is responsible for executive functioning: planning, setting priorities, organizing thoughts, suppressing impulses, and weighing the consequences of one’s actions. In this way, it makes sense that the brain would develop in this sequence, as it appears to develop in order of sophistication of function.

What is the purpose of pruning

It is too soon to know, Giedd says. But, based on what the article says, it appears to be associated with development and eliminating unnecessary synapses (those that are not used as often as others). Also to get faster connections in the brain (though fewer).

Summarize what is meant by the “pruning” process that occurs during adolescence.

This process affects some of our highest mental functions. These neural changes do not alter the number of nerve cells but the number of synapses between them. Between ages 6-12, the neurons grow bushier, each making dozens of connections to other neurons and creating new pathways for nerve signals. Then, the thickening of this gray matter peaks when girls are about 11 and boys 12.5. During this period a lot of pruning is occurring. Gray matter is thinned out at a rate of about .7% each year, tapering off in the early 20s. Simultaneously, white matter thickens. Essentially: ““You get fewer but faster connections in the brain””. It’s more efficient, but it is likely losing some of its raw potential for learning and its ability to recover from trauma.

Why is it important that twins are studied?

Because although most brain development seems to follow a set plan based on genetics, other, subtler changes in gray matter reflect experiences within one’s environment. So, by following twins, who start out with either identical or similar programming but then diverge as life gives them different paths, Dr. Jay Giedd hoped to further delineate the influences of nature and nurture on behavior.

Why in the study do they want to follow people until they are about 25 years old?

Because both gray and white matter continue extensive structural changes until that point.

To determine how the brain develops from childhood into adolescence and on into early adulthood.

What was the goal of the study that began in 1991?

Use it or lose it principle

The more an area of the brain is exercised, the stronger it becomes

The body and the body act as a

Unified system

Everything psychological is ultimately biological meaning

Every thought, every action, is the result of something happening in the brain

The brain is the ___ and ___ center for all human activity

command, control

What is a neural network

Neurons connecting and firing

How many neurons and how much info do they compute per second

100 billion, 10-27 bits of info per second

What happens when neurotransmitters in the brain are interfered with, enhanced, or mimicked

Changes in mood and behavior

All addictions are the product of

Self administered drugs that produce biologically rewarding effects

What is a seizure

Electric malfunction of the brain that spreads

What are split brain surgeries used for

To relieve violent seizures

Sperry and Gazzaniga’s results

When the right hemisphere of the brain is active, but the left is not, participants could not name the object given

Why is damage to the left hemisphere worse

Because it is responsible for complex thought, language, logic, and speech

Hypothalamus

Ventral part of forebrain above pituitary gland and below thalamus. Does homeostasis, emotions, thirst, hunger, circadian rhythms, and sexual behavior, influences motivation and reward seeking behavior

Levay

Homosexuals have smaller nuclei in anterior hypothalamus

Maguire

Taxi study

Eugene Pauly

Amygdala + hippocampus destroyed, only muscle/procedural memory remained

Frontal lobe

Executive decisions: planning, decision making, speech

Occipital lobe

Visuals

Parietal lobe

Perception of stimuli

Temporal lobe

Auditory processing and memory

Amygdala

Emotional memory and fear responses

Basal ganglia

Habit forming and procedural memory

Hippocampus

Short term memory to long term memory

Nucleus accumbens

Addiction and motivation

Porges

GABA goes down with age, as does cognition, link there, interesting for dementia patients

Wilhelm

Genetic testing for depression, more positive feelings than negative, more distressed if you had the gene, sample was bad because they were old,42% had depression at some point and others were unlikely to develop it because they were old, highly educated, and agreed to testing.

Phineas Gage

Was a foreman of a railroad construction company, blasting accident propelled iron rod through his left cheek and front of head, after was profane and impatient, unable to make plans for the future. Researcher used CT Scanner to see bottom of left and up through top of frontal lobe damaged meaning his reasoning, planning, decisions, and ability to stop primitive behaviors was damaged.

Ian (paralyzed man) story

Dived into wave, hit his head, everything went numb, broke spinal cord, could more arms but not individual fingers, he tried experimental medicine: stimulation sleeve shocks muscles to make them contact and move. Basic 3 components of this: 1) chip in brain and ability to record that data, 2) Computer takes those signals and decodes the intent and recodes them to deliver them to the 3) stimulation system that evokes the muscle motions. Risks of surgery that was unneeded: pneumonia, blindness/deafness, death. After he did it he was able to open and close his hand, play guitar video game, drive, swipe card, pour glass, lift weighted bottle, and lift a small dumbbell.

Diathesis stress model

Genetic predisposition + enviro = mental illness

Caspi

5HTT gene: increased risk of depressive symptoms and increased risk of depression diagnosis, 43% of people have this short allele but will only develop depression given stressful life events (enviro)

Interactionist approach

Uses different approaches (biological, sociocultural, cognitive)

Reductionist approach

Studies simplest, most basic mechanisms believed to be responsible for behavior

Adoption studies

If behavior consistent in adoptive family: enviro

If behavior consistent in bio family: bio

Limited in that adoptive families can be similar to bio families, making nature vs. nurture distinction difficult

Monozygotic vs. dizygotic

Mono: identical 100% same genes

Di: fraternal, 50% genes same

Enviro same for both

Purpose of twin studies

Isolate and determine nature vs. enviro