Social Security #:
General Psychology – Honors
EXAM #2 ANSWERS
Brief answers and bulleted responses are acceptable
Answer in space provided; if you use the back, please indicate that.
A researcher conducts a typical twin study to determine the genetic and environmental
influences on the etiology of schizophrenia:
The researcher recruits 500 pairs of MZ twins and 500 pairs of DZ twins, all of
them raised together?
What does MZ and DZ stand for, and what are the
characteristics of these 2 pairs of twins?
MZ – monozygotic, identical (share 100% of genes)
DZ – dyzygotic, fraternal (share ~ 50% of genes)
If the concordance rate for schizophrenia among MZ twins is 75% and the
concordance rate for schizophrenia among DZ twins is 30%, what can the
That genetics influences the onset of schizophrenia, over and above environment.
How does he justify this conclusion?
What is it about twin studies that allow us to
make these conclusions? [2 points]
Since both sets of twins were raised with similar background, the only thing that can
account for differences in the similarities between these twin pairs is the fact that MZ
have same genes—thus genetics is important.
If genetics fully accounted for the development of schizophrenia, what would be
the concordance rate among MZ twins? [1 point]
Name at least ONE criticism of this twin study approach. [1 point]
MZ twins are treated more similarly than DZ twins, thus this would mean that environment can
account for differences in the concordance rates of MZ and DZ twins.
Nonshared environmental effects not as apparent.
For each of the following scenarios, identify the four major elements of classical conditioning.
Specifiy for each:
a) the unconditioned stimulus (US), b) the conditioned stimulus (CS),
the unconditioned response (UR), and d) the conditioned response (CR). [2 points each,
for a total of 8 points]
To discourage coyotes from attacking their sheep, ranchers feed the coyotes
small pieces of mutton tainted with poison that, when ingested, cause the
coyotes to experience extreme dizziness and nausea.
Later, when the coyotes