Chapter 2 Flashcards
multi-dimensional integrative approach
Biological dimensions include causal factors from the fields of genetics and neuroscience. Psychological dimensions include causal factors from behavioral
and cognitive processes, including learned helplessness,
social learning, prepared learning, and even unconscious
processes. Emotional influences contribute in a variety of
ways to psychopathology, as do social and interpersonal influences. Finally, developmental influences figure in any
discussion of causes of psychological disorders.
do phobias have genetic links?
Do you ever feel queasy at the sight
of blood? If so, chances are your mother, your father, or
someone else in your immediate family has the same reaction. In one study, 61% of the family members of individuals with this phobia had a similar condition
what plays a substantial role in the development of many disorders
emotions
developmental critical period
s. Thus, at certain times we may
enter a developmental critical period when we are more or
less reactive to a given situation or influence than at other
times.
As you can see, finding the causes of abnormal behavior
is a
complex process. Focusing on biological or behavioral
factors would not have given us a full picture of the causes
of Judy’s disorder; we had to consider a variety of other influences and how they might interact. We now examine the
research underlying the many biological, psychological,
and social influences that must be considered as causes of
any psychological disorder
genes
Genes are long molecules of deoxyribonucleic acid
(DNA) at various locations on chromosomes within the cell
nucleus. Physical characteristics are determined—or at least
strongly influenced—by our genetic endowment
. Other factors in the environment influence our physical appearance,
however
To some extent, our weight and even our height are
affected by nutritional, social, and cultural factors. Consequently, our genes seldom determine our physical development in any absolute way. They do provide some boundaries
to our development. Exactly where we go within these
boundaries depends on environmental influences.
but some characteristics are determined strongly by genes like
hair and eye color. also some rare diseases like huntington’s disease
dominant and recessive genes and when does gene dominance occur?
A dominant gene is one of a pair of genes that strongly
influences a particular trait, and we need only one of them
to determine, for example, our eye or hair color. A recessive gene, by contrast, must be paired with another (recessive) gene to determine a trait. Gene dominance occurs
when one member of a gene pair is consistently expressed
over the other (for example, a browneyed gene is dominant over a blueeyed gene). When we have a dominant
gene, we can predict fairly accurately how many offspring
will develop a certain trait, characteristic, or disorder,
depending on whether one or both of the parents carry
that dominant gene.
quantitative genetics and molecular genetics
Quantitative genetics basically sums up all the tiny effects across many genes without necessarily telling us which genes are responsible for
which effects. Molecular genetics focuses on examining the
actual structure of genes with advanced technologies such
as DNA microarrays; these technologies allow scientists to
analyze thousands of genes at once and identify broad
networks of genes that may be contributing to a particular
trait (Kendler, 2011; Plomin & Davis, 2009). Such studies
have indicated that hundreds of genes can contribute to
the heritability of a single trait
It has also become clear that adverse life events such as
a “chaotic” childhood can overwhelm the influence of genes
(Turkheimer, Haley, Waldron, D’Onofrio, & Gottesman,
2003). For example
one member of a set of twins in the
Lyons et al. (2009) study showed marked change in cognitive abilities if his or her environment changed dramatically
from the other twin’s because of some stressful event such
as death of a loved one
For psychological disorders, the evidence indicates
that genetic factors make some contribution to all disorders but account for less than half of the explanation
If one of a pair of identical twins has schizophrenia, there
is a lessthan50% likelihood that the other twin will
also (Gottesman, 1991). Similar or lower rates exist for
other psychological disorders
linkage study
In linkage studies, scientists study individuals who have
the same disorder, such as bipolar disorder, and also
share other features, such as eye color; because the location of the gene for eye color is known, this allows scientists to attempt to “link” known gene locations with the
possible location of a gene contributing to the disorder
diathesis-stress model
For years, scientists have assumed a specific method of interaction between genes and environment. According to this
diathesis–stress model, individuals inherit tendencies to express certain traits or behaviors, which may then be activated
under conditions of stress (see l Figure 2.2). Each inherited
tendency is a diathesis, a condition that makes someone susceptible to developing a disorder. When the right kind of life
event, such as a certain type of stressor, comes along, the disorder develop
explain the diathesis-stress model in regards to judy’s situation
s. For example, according to the diathesis–stress
model, Judy inherited a tendency to faint at the sight of blood.
This tendency is the diathesis, or vulnerability. It would not
become prominent until certain environmental events occurred. For Judy, this event was the sight of an animal being
dissected when she was in a situation in which escape was not
acceptable. The stress of seeing the dissection under these
conditions activated her genetic tendency to faint. Together,
these factors led to her developing a disorder. If she had not
taken biology, she might have gone through life without ever
knowing she had the tendency, at least to such an extreme,
although she might have felt queasy about minor cuts. You can
see that the diathesis is genetically based and the stress is environmental but that they must interact to produce a disorder
We might also take the case of someone who inherits a vulnerability to alcoholism.
During college, both this person and
a friend who lack the tendency engage in extended drinking
bouts, but only the individual with the socalled addictive
genes begins the downward spiral into alcoholism. Having a
particular vulnerability doesn’t mean you will develop the
associated disorder.
the smaller the vulnerability,
the greater the the life stress required to produce the disorder; conversely,
with greater vulnerability, less life stress is required.
chemical transporter
The
investigators also identified the genetic makeup of the individuals and, in particular, a gene that produces a substance
called a chemical transporter that affects the transmission of
serotonin in the brain. Serotonin, a neurotransmitter, is particularly implicated in depression and related disorders.
caspi longitudinal study- pg 66
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gene-environment correlation model
This is the gene–environment correlation model or reciprocal gene–environment model (Jaffee, 2011; Kendler,
2011) (see l Figure 2.4). Some evidence indicates that it applies to the development of depression, because some people
may tend to seek out difficult relationships or other circumstances that lead to depression
McGue and Lykken
(1992) have even applied the gene–environment correlation
model to some fascinating data on the influence of genes on
the divorce rate. F
For example, if you and your spouse each
have an identical twin, and both identical twins have been
divorced, the chance that you will also divorce increases
greatly. Furthermore, if your identical twin and your parents
and your spouse’s parents have been divorced, the chance
that you will divorce is 77.5%. Conversely, if none of your
family members on either side has been divorced, the probability that you will divorce is only 5.3%.