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Lecture

PSY100H1 Lecture Notes - Twin, Twin Study, Miranda Warning


Department
Psychology
Course Code
PSY100H1
Professor
David Nussbaum

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PSYC39 Lecture 3: PY
Date:
1
Best contemporary textbook in forensic psychology for Canadian students
o Past textbook had things on eye-witness testimony and Miranda rights which don’t really apply to forensic
psychologists at all, esp not if in Canada; b/c in Canada, we don’t have Miranda rights
o This text focuses on criminal aspects of within forensic psychology as opposed to the social science and
perceptual stuff (eye-witness testimony)
Researching biological explanations of crimes and it sort of sees them as pseudo-explanations
o They’re not pseudo-explanations at all, but in historical context they were seen by many forensic
psychologists as being erroneous but that’s because of their origins
Text doesn’t go into molecular biology, genetics or neurochemical approaches and part of the reason is b/c relatively
few forensic psychologists have a good handle on this
o Some forensic psychologists are interested in brain behaviour relationships in criminal context but
mainstream are hostile to brain behaviour relationships
150-200 yrs ago = biology in its infancy and there really wasn’t a good understanding of how the brain worked
o Synapse wasn’t discovered until 100 yrs ago
o So ppl who thought that there might be biological basis for criminal beh were working on a ‘pre-scientific’
model b/c they didn’t know about synapse, neurotransmitters, action potentials things very primitive
Phrenologists made pronouncements
So when ppl started looking at things at a more sophisticated way, from biological perspective, they started looking at
twin studies and adoption studies basically, 2 extreme positions that you can take
o Can say the criminal beh develops due to enviro; the other extreme is that some ppl are just born bad and it
doesn’t matter where they’re raised b/c genes
o Problem w/ extremes: you’re only focusing on one small part of what tends to be complex, interactive sub-
problems that combine to make a more complex overall problem
o Can’t come up with optimal solution w/ extreme views b/c restricting scope of what the real problem space is
Ppl started looking at links between genetics and anti-social beh
o Ppl like slidnoff, mednic and their colleagues could be that genes play a role, could be that the enviro plays
a role so let’s think about research designs where both factors at play and let’s see how we can tease this
out it may be that they both play a role and they interact
o Genetics may be responsible for some percentage of criminal beh, enviro may be responsible for some
percentage of criminal beh and if we look at how the 2 of them go together, we’ll have a better idea of
what’s really causing criminal behavior
And then, if we want to intervene to reduce criminal beh, we’ll know what to do with which ppl
Could have ppl who are genetically loaded for environmental influence in the wrong way
and other ppl may have higher thresholds so may not be flipped to criminal behaviour unless
really bad early enviro; many possibilities
o Classical paradigm = twins
# of diff ways to exploit twinship to study genetic influences on behaviour
1) compare identical twins with non-identical twins; identical twins = identical genes; non-identical
twins share 50% of their genes like regular siblings BUT advantage of studying twins (as controls)
instead of siblings is that their environment will typically be the same (same class in school for ex) =
more shared enviro for non-identical twins than for regular siblings
Compare identical and non-identical twins and see concordance rates for anti-social beh
2) compare non-identical twins with siblings where the twins will have more similar enviro even
though both types of siblings share 50% of genes

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PSYC39 Lecture 3: PY
Date:
2
By utilizing the differences in genetic similarity and the extent of the shared enviro have relatively
powerful tools to examine the effects of genes and early enviro in terms of criminal outcomes
There have been studies that look at the effect of early enviro
o Early enviro are seen to be more critical especially by criminologists (=sociologists who look at pop’n studies
involving crimes)
o Criminologists aren’t psychologists in that they don’t look at individuals but rather, they look at large groups
of ppl and they compare
Large samples and they primarily look at (sociological) demographics such as gender, age differences
(young vs. old), diff socioeconomic status
A lot of sociology grew out of Marxist theory and Marx believed that social class determines of many
outcomes and that’s why he didn’t like capitalism (b/c some classes were favoured over others and
things were intrinsically unfair)
One of the problems with Marxist thought (aside from the fact that there’s no real, coherent
psychological theory underlying it) in economies that tried Marxism, it didn’t seem to work – so if
you don’t give ppl incentives to do things, they typically don’t (ppl don’t behave altruistically)
The extreme Marxist position led to a lot of the early sociology and some sociologists decided to
study criminal beh between these diff groups of diff socioeconomic levels
Found: ppl occupying lower socioeconomic classes seem to produce more crime so they
said that it’s valid that due to the strain in the lower class, they become criminals
Of course, not everybody in the lower class becomes criminals many of them rose above
their origins and made success
Again, to just look at one side of this complex system is deemed overly simplistic
On the same token, you see a lot of ppl due to genetic reasons, who you would think would excel at
life, actually mess up
So it’s not just a matter of genes, or just the environment; there’s interaction
How might this interaction play out?
o Cassidy did a # of studies looking at more specific biological markers
o Found that it’s NOT simply a biological marker (for ex: MAO; looked at 2 types; the A type which is one of the
responders to stress and childhood maltreatment)
o Found that it’s not just how reactive ppl are to stress and it’s not simply how much stress they have, but how
these 2 factors go together
o At the end of his studies, the question was: is the level of MAO-A (an enzyme that metabolizes monoamines
such as 5HT, DA, norepi) is there something mechanistic there for further study?
o There have been links btn the hormone testosterone (male sex hormones) and aggression
Responsible for development of male sexual characteristics physically
Post-puberty = huge increase in testosterone in males = responsible for facial, deep voice, more
strength
With the same relationship occurs in women, but women’s testosterone levels are much lower
From personality perspective, one of the things testosterone does is it gives ppl a position in the
social dominance hierarchy
Some ppl w/in any social structure are more dominant and some are less dominant so,
have social hierarchies that appear to be self-organized
But really, they’re not exactly self-organizing
Original research looked at dominance hierarchies in animals specifically, gorillas
o Social Hierarchies in Gorillas:
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PSYC39 Lecture 3: PY
Date:
3
Alpha male = ruled the group of gorillas and as the dictator, he got food first, got most of the
females; if someone challenged him, would beat them up b/c he was the better fighter
Middle males = got the odd female gorilla; got leftovers
Bottom males = at the bottom of the social hierarchy = no females, and scraps from the middle class
Social hierarchy seen in virtually every mammalian species that was ever studied
What determines who’s at the top, bottom or middle? Maybe it’s testosterone b/c the guys at the
top, it would help them if they were more aggressive and if they were stronger/muscular we
know that testosterone is responsible for this characteristic
Took measurements of blood from alpha male, middle and bottom males
Found that alpha males had more testosterone than middle males and the low monkeys had the
lowest levels of testosterone
So they determined that biology determined social status this was a dominant belief for 10 years
But then noticed that as the alpha male starts to age and although he may still be in charge, some of
the younger monkeys get really angry; one day, one of the younger gorillas has a confrontation with
and beats up the alpha male
Now the young gorilla who beat up the alpha male now becomes the alpha male
Then looked at testosterone levels in the gorillas:
The former low-status gorilla who had low levels of testosterone had a jump in his
testosterone level by 300%; after beating up alpha male, testosterone levels went sky-high
and has more testosterone than everyone else
The alpha male’s testosterone fell by 80%; have only 1/5 as much circulating testosterone as
they had when they were ruling
These findings made us realize that it’s not simply biology that determines position; it’s also
behaviour and the outcome of behaviour that determines biology
Not a one-way street; there’s an interaction between the 2
Testosterone CAN CAUSE aggression; but aggression (especially successful aggression) can also
influence testosterone levels
o Not only true of gorillas; have done many studies on humans (very diff paradigms) but they all look at
competition, success and failure
Ex) if you measure testosterone levels b4 hockey game of the two teams, levels will be relatively high
in anticipation of competition
Then go out and play
Then measured testosterone levels after the game, in winners and losers
Winners levels go up even further and losers levels go down; probably one of the reasons
why some teams go on ‘WINNING STREAK’
b/c every time they win, get a little more testosterone which makes them a little more
aggressive/confident/stronger
and teams that lose have reverse reaction
another study: didn’t ask ppl to take part in competition but rather, they asked participants to
imagine themselves losing or winning; accordingly, testosterone levels went up or down
o Question: why do you ever lose a game after winning a game? There may be a lag in time between when you
the game and when you play the next game. Don’t want too much time to intervene b4 they play the next
game. The other thing is that the other team has something to say about it as well they may have won their
last game also, which would’ve increased their levels also. Sometimes, teams go on a LOSING streak, they get
really angry become aggressive and testosterone levels shoot up.
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