PSYCH FINALS STUDY

raine aim (1)

to build on previous research:

• damage to PFC → increased impulsivity and immaturity, altered emotionality, loss of self-control, and inability to modify behavior

• combination of behavioral deficits → increased aggressive behavior

raine sample size

• experimental 41

• control 41

raine results:

reduced activity in _____

some areas, notably areas linked to violence control (e.g. PFC)

raine results:

no difference in _____

some areas - associated with mental illness but not violence

raine conclusion

• NGRIs - significantly different glucose metabolisms in multiple brain areas

• reduced activity in prefrontal areas may explain impulsive behavior, loss of self control, evidence of immaturity, altered emotionality, inability to modify behavior → easier to carry out aggressive behavior (less constraints)

• significance: provides empirical evidence that brain abnormalities in certain parts of the brain can make people more prone to impulsive behavior

raine strengths

• very precise → replicable

• ethical - followed CARDUD

• matched participants design → high internal validity

• high predictive validity - high statistical significance and high number of controls → may be used to predict people who are predisposed to violence

graftman aim

to discover how prefrontal cortex injuries influence violent and aggressive behaviors

graftman sample

• 279 vietnam war veterans who suffered head injuries

• 57 healthy controls

graftman results:

participants who suffered damage to _____ had higher levels of violence and aggression compared to participants who suffered damage to other/no parts of the brain

prefrontal cortex

graftman strengths

viewed entire brain (not just PFC) → higher internal validity - can assert that specifically PFC damage causes violence and aggression

dabbs aim:

focus on ___

age

dabbs sample

87 female inmates in a US maximum security prison

dabbs criminal behavior collected from ___

court records

dabbs conclusion:

negative, underhanded behavior may come from ____

lack of power compared to other, more aggressive, high-testosterone people

dabbs conclusion:

testosterone _____

has an important role but other factors must be considered

dabbs strengths:

____ → no demand characteristics

used historical data

dabbs limitations:

• bi directional ambiguity (correlational study) → no cause/effect

• extraneous variables (PFC abnormalities, environment) → not well controlled

• researcher bias - decreased validity of data

• low population validity

goetz aim

to investigate the hypothesis that “testosterone might influence the activity (or reactivity) of the amygdala”

goetz sampling type

self-selection sampling

goetz results:

higher reactivity of ____ when seeing ___ faces

amygdala, angry

goetz conclusion

increasing levels of testosterone within normal physiological range → significant effect on brain circuits involved in threat-processing and human aggression

goetz strengths

• random assignment → high internal validity

• same baseline testosterone → high internal validity

• all participants experienced both condition → lowers participant variability

goetz limitations

• relatively small sample size

• repetition of trials → expects photos → lower reaction (can also cause fatigue)

• only men → lower pop. validity

• heavily controlled → low ecological validity

• high demand characteristics

passamonti aim

to investigate the relationship between serotonin and activity within the PFC, and activity between the PFC and the amygdala

passamonti DV

activity within the PFC and activity/communication between the PFC and the amygdala

passamonti procedure (misc.)

• randomized groups

• double blind

• measured using fMRI → researchers could see activation of specific areas of brain in reaction to faces

passamonti results

low serotonin →

• reduced activity in frontal lobe when viewing angry face

• weaker communication between amygdala and frontal lobe

passamonti conclusion

• reduced serotonin - effect on PFC-amygdala circuits related to aggression

• lack of activity in PFC - may affect ability to regulate stress response as triggered by amygdala’s reactivity towards threat

passamonti strengths

double blind → reduced researcher bias

passamonti limitations

assumed serotonin levels based on tryptophan (serotonin in synthesized from tryptophan)

annemoon aim

to learn about ongoing neurotransmitter activity, with a focus on serotonin, in particular areas during aggressive confrontations in rats

annemoon procedure (confrontations)

rats were confronted twice by a naive male intruder rat to promote aggressive behaviors

annemoon data collection

serotonin levels were collected at 10 minute intervals before, during, and after

annemoon results

• NAC - serotonin levels increased slightly - not deemed significant above baseline levels

• PFC - serotonin levels decreased below baseline levels during and after confrontation - deemed significant

• acute changes in serotonin levels during and after an aggressive confrontations

annemoon conclusion

serotonin has an inhibitory effect on aggressive behavior - consistent with previous research

annemoon strengths

very controlled - all rates housed with one female rate and were same age, weight, cage, temperature, food, and water

annemoon limitations

• fast changes in behavior (changes could occur due to initiation/termination of aggression or entirely different changes in behavior) → low internal validity

• changes lasted up to 1 hour afterwards - may reflect change in behavioral state that outlasted actual behavior

• animals → low pop. validity

annemoon NAC and PFC roles

NAC - related to reward component of drug addiction and in control of reactive aggression

PFC - important in controlling aggressive behavior and general impulsivity

maguire aim

• to see if the brains of London taxi drivers would differ due to their exceptional knowledge of the city any many hours they spent navigating London

• to see if there is a relationship between the amount of time spend driving taxis and the anatomy of the brain

maguire method

correlational

maguire sample

16 right handed male london taxi drivers - range of ages

maguire control

50 right handed males who did not drive taxis (from MRI database)

maguire strengths

• single blind

• high ecological validity

maguire limitations

• very specific and relatively small sample size → low population validity and hard to generalize

• no cause/effect relationship

perry & pollard aim

to investigate how global neglect and chaotic neglect affect brain growth in children

perry & pollard sample

122 kids, 0-17 years old, all reported to child trauma center

perry & pollard procedure (data source)

many data sources: pre- and perinatal history, physical development

perry & pollard results (stats)

64.7% globally neglected and 11.5% of chaotically neglected had abnormal brain activity (dysfunction)

perry & pollard conclusion

severe neglect (especially global) can change the physical shape of the brain

neglect → less sensory stimulation → lack of connections made in important areas of the brain → neural pruning

perry & pollard strengths

• data triangulation

• high sample size

• looked at prenatal drug exposure → higher internal validity

perry & pollard limitations

• low population validity

• limited control of extraneous variables

global and chaotic neglect definition

global - full deprivation

chaotic - deprived of one thing or sporadic neglect

caspi aim

to investigate whether the variation of the MAOA gene (MAOA-L) would infuence the relationship between childhood abuse and ASB later in life

caspi method

correlational longitudinal study

caspi sample

1037 children in New Zealand, 52% male

caspi 4 ASB outcomes

1. extent of exhibited adolescent conduct disorder

2. whether convicted of violence offense

3. disposition towards violence

4. antisocial personality disorder symptoms

caspi results (1)

suffered from child abuse + had MAOA-L → stronger inclination to ASB

caspi results (2)

association between maltreatment and ASB - conditional (depending on MAOA genotype) - true for all 4 antisocial outcomes

caspi conclusion (1)

may explain why children who suffer from child abuse develop ASB later in life

caspi conclusion (2)

may be because genetic predisposition (different variations of MAOA) and environmental factors (childhood behavior) influence behaviors such as ASB

cases aim

to investigate the genetic origins of aggression by studying the effects of MAOA gene deficiency

cases IV manipulation

mice were genetically modified to lack the gene that regulates the production of MAOA

cases results (qualitative)

• control mice would sniff and engage with other mouse

• transgenic mice adopted a hunched position and engaged in aggressive behavior

cases results (quantitative)

transgenic mice had a small increase in dopamine, 6 to 9 times serotonin increase, and increased norephinephrine

cases conclusion

supports link between MAOA gene, neurotransmitter regulation, and aggressive behavior

no proper breakdown of serotonin/dopamine → neural circuits involved in impulse control and aggression were disrupted → heightened aggressive responses

cases strengths

• high amounts of qualitative data

• findings reflect human behavior

• cause/effect

cases limitations

• low pop validity

• ethics

• low ecological validity