PSYC2010 Psychological Research Methodology II
A researcher was interested in the effect of reinforcement contingencies (reward and/or punishment) on
learning. To test this the researcher designed a task in which participants were required to try to learn
which numbers presented on a computer screen were good numbers and which numbers were bad
numbers. Participants were instructed to press a computer key when they believed a number was good
and to inhibit responding to numbers they believed were bad. Participants were told that the goal of the
task was to try to respond to as many good numbers as possible and to refrain from responding to bad
numbers. Participants were not told which numbers were good nor which numbers were bad and had
to learn the good from the bad numbers by trial and error. The number of correct responses (key
presses) to the good numbers was the index of learning. To test whether being rewarded or punished
influenced learning the researcher randomly allocated participants to one of the following conditions: 1) a
feedback-only control condition, 2) a reward-only condition, 3) a punishment-only condition or 4) a
reward and punishment condition. In the control condition participants were presented with a feedback
statement after each trial informing the participant whether their response (or lack of response) was
correct or not. In the reward-only condition participants won points when they correctly responded to a
good number or inhibited to a bad number. In the punishment-only condition participants started
with a set number of points but lost points when they incorrectly responded to a bad number or
inhibited to a good number. In the reward and punishment condition the participants won points for
correct responses (or correct inhibition) and lost points for incorrect responses (or failure to inhibit). The
researcher derived the following hypotheses:
1. Participants in the reward-only, punishment-only, and reward and punishment conditions will
make more correct responses than those in the control group (i.e., show better learning)
2. Participants in the reward and punishment condition will make more correct responses than
those in either the reward-only or punishment only conditions.
3. Participants in the reward-only condition will make more correct responses than those in the
These are the resulting data for correct responses across the four conditions:
These are their data:
Control Reward Punishment Reward and
3 8 10 10
5 12 8 14
6 13 9 15
2 11 8 13
5 10 11 11
4 10 10 15
2 12 6 16
4 10 7 13
Use these data to answer the questions on the next pageNote. You must retain 3 decimal places for all calculations or else you will get the wrong answer. Type
your answers (do not submit handwritten answers or calculations). Clearly state which question you
are answering. Use tables where appropriate.
1. Specify the statistical hypotheses AND the conceptual hypotheses (H0 and H1) for the omnibus
analysis of variance (4 marks max).
2. State in symbols the statistical hypotheses (non-directional) for the 3 experimental hypotheses, AND
write an appropriate set of contrasts according to the stated hypotheses (by assigning appropriate
coefficients) for each of them (6 marks max).
3. Describe and justify whether these contrasts are orthogonal (Note: You don t need to use a tree
diagram for this. Show the results of all other tests of orthogonality)(6 marks max).
4. In APA format, write up the results of this analysis as it would appear in the results section of a
journal article. You should include the omnibus results (and present them in the appropriate summary
table as well as in text), including the experimental effect size (omega squared), as well as the results
of the tests of the specific experimental hypothesis (use Bonferroni corrected t-tests; state whether the
hypotheses are supported or not) (32 marks max).
5. If you did not correct your alpha level in the above contrasts how (statistically as well as theoretically
“ be as specific as possible with regards to statistics used) would this have affected your conclusions?
(no more than 200 words) (6 marks max).
6. Would a repeated measures design have been a viable option for this experiment? Justify your answer
in relation to potential advantages and disadvantages of using such a design on this specific study (no
more than 200 words; make sure to relate the advantages/disadvantages to this specific study) (6
marks max).Assignment Notes (for students):
You do not need to do any research into the effect of reward and punishment on learning
You do not need references/citations or an abstract
Do not attach/submit any hand calculations.
Question 4 (i.e., the main bulk of the assignment) should be written up as it would appear in a
results section of a journal article that uses APA formatting. This means you need to have
calculated the results of the appropriate analyses and report them here.
You will need to perform hand calculations (like we have shown in lectures and tutorials) to get
the correct answers to put into your report for question 4. You must adhere to the rounding rules
that we have set out at the beginning of this course (i.e., round to 3 decimal points while you are
conducting the calculations and 2 decimal points for Q4) to get the correct answers. As in the real
world of reporting results of psychological experiments your responses will be marked only as
either correct or incorrect from what you provide in the results section of your assignment.
– You do not need to report the exact p values for Q4 (as per the APA manual) since this is not
easily done when calculating by hand; just use < .05 or ns as relevant - Your final assignment needs to be typed and uploaded through TurnItIn. Assignments will not be accepted by tutors or the lecturer as we need an electronic version to mark. - A word of warning “ TurnItIn sometimes makes the formatting of your assignment look strange when you upload it. Never fear, in most cases, we get to see the assignment as you originally formatted it when we are marking, and if we think something s gone wrong, we ll let you know. So please don t email your tutor your assignment (we only have limited email capacity).
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