Human-Computer Interaction 3e Dix, Finlay, Abowd, Beale
exercises - 1. the human
EXERCISE 1.1
Devise experiments to test the properties
of (i) short-term memory (ii) long term memory, using
the experiments described in this chapter to help
you. Try out your experiments on your friends. Are
your results consistent with the properties described
in this chapter?
answer
The aim of this exercise is to get the
student to think about experimental design. The experiments
devised can effectively be repeats of the originals.
Chapter 9 can be used for reference on experimental
design.
(i) Short term memory (STM)
The student should first choose an aspect
to investigate: for example, digit span, recency effect,
decay.
Example solution: STM decay
- Subjects
- ideally selected to represent population,
more probably undergraduate students (try to get
a range of academic subjects).
Sample size: 10+
- Experiment
-
- split subjects into two groups. Each subject
studies list of 15-20 words (could try with
both nonsense words and actual words to see
any difference). Subject has to recall list
either (a) immediately or (b) after 20 second
delay. Measure the number (or percentage) of
the words remembered correctly.
- A within-groups design can be used to avoid
individual bias or group variation (as long
as different lists are used for each attempt).
- independent variable -- delay in recall
dependent variable -- number correctly recalled.
- Group (b) should be given a task to do during
the delay period in order to avoid rehearsal.
If possible this task should occupy a different
channel to minimise interference, e.g. a visual
recognition task.
- Hypothesis
- Those in (b) will perform worse than
those in (a) since STM will decay.
- Analysis
- graphs to see decay.
T test
(ii) Long term memory (LTM)
The student should first choose an aspect
to investigate: for example, the total time hypothesis
or the distribution of practice effect.
Example solution: distribution
of practice effect
- Subjects
- as above. Should have no prior experience
of the skill to be learned.
- Experiment
-
- split subjects into 3 groups. Each subject
must learn a skill (for example shorthand or
typing -- must be measurable). Group A learns
for 1 hour a week for 6 weeks. Group B learns
for 2 hours a week for 3 weeks. Group C learns
for 3 hours a week for 2 weeks.
- After each group's training is complete the
subjects are tested and the number of mistakes
made are noted.
- Between-groups design.
- independent variable - style of learning
dependent variable - accuracy
- Hypothesis
- Group A will be best (due to the distribution
of practice effect)
- Analysis
- ANOVA
(N.B. This one is not easy to run but
could be done with cooperation from friends)
Other exercises in this chapter
ex.1.1 (ans), ex.1.2 (ans), ex.1.3 (ans), ex.1.4 (tut), ex.1.5 (tut), ex.1.6 (open), ex.1.7 (open)
all exercises for this chapter