TITLE: Student Learning as Confronting Risk
AUTHOR: Eugene Wallingford
DATE: May 10, 2007 11:28 AM
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Last time,
I wrote about how some ideas on human psychology, from
Bruce Schneier's
The Psychology of Security
paper. Part way through, Schneier jokes:
(If you read enough of these studies, you'll quickly
notice two things. One, college students are the most
common test subject. And two, any necessary props are
most commonly purchased from a college bookstore.)
University psychology researchers are as lazy as university
computer scientists, I guess.
Schneier doesn't mention a question that seems obvious to me:
Does this common test audience create a bias in the results
produced? If college students are not representative, then
the results from these studies may not tell us much about
other kinds of peoples' behaviors! In many ways, college
students are not representative of the rest of the world.
They are at a nexus in development, different from teenagers
at home but typically not yet living under the same set of
constraints as people in the working world.
But I'm not too worried. Enough other studies on risk and
probabilistic reasoning have been done with adult subjects,
and they give similar results. That isn't too surprising,
because what we are testing here doesn't involve reflective
choices that are conditioned by development or culture, but
rather reactions to conditions. These reactions are largely
reflexive, under the control of the amygdala, "a very primitive
part of the brain that ... sits right above the brainstem....
[It] is responsible for processing base emotions that come
from sensory inputs, like anger, avoidance, defensiveness,
and fear."
But overthinking Schneier's joke got me to thinking something
else: how do these ideas apply to students in their own world,
where they
score points
for grades in a course, make choices about what they need to
know, and incur the costs of studying something now or later?
Prospect theory tells us that people prefer sure gains to
potential gains, and potential losses to sure losses. I often
observe students exhibit two behaviors consistent with these
biases:
- When the choice is between using a concept, technique, or
language construct that is already understand and using a
new idea that will require some work but which offers
potential long-term benefits, most students opt for the
sure gain.
- Like the refactoring example from last time, when the
choice is between taking the hit now to clean up a
design or program or taking the chance on the current
version, with a potentially bigger loss, most students
opt for the potential loss.
There may be simpler emotional explanations for these behaviors,
but I am thinking about them in a way way in light of Schneier's
article.
Like software developers in general, students certainly fall
victim to optimism bias. I've always figured that, when
students gamble on getting more work done than they reasonably
can in a short period, they were reacting to a world of scarce
resources, especially time. But now I see that whatever
conscious choice they make in this regard is reinforced or
even precipitated by a primitive bias toward optimism. Their
world of scarce resources is in many ways much like the
conditions under which this bias evolved. Further, this bias
is probably reinforced by the fact that college CS students
are just the sort who have been successful at playing
the game this way for many years, and who have avoided the
train wrecks that plagued lesser students in high school or
in less challenging majors. It must be a shock to have a
well-trained optimism bias and then run into something like
call/cc.
Suddenly, the glass isn't half full after all.
A few posts back. I wrote about
reliance on external references.
For students, I think that this turns out to be dangerous
for another reason, related to another tendency that Schneier
documents: the availability heuristic. This
refers to the tendency that humans have to "assess the frequency
of a class or the probability of an event by the ease with
which instances ... can be brought to mind". People are overly
influenced by vivid, memorable instances. When they have
encountered only a few instances in the first place, I think
they are also overly influenced by the instances in that small
set. An instructor can go to great lengths to expose students
to representative exemplars, but that small set will also have
the potential to mislead when relied on too heavily.
Relying on external references to recall syntax is one thing;
it will usually work out just fine, even if its is unacceptably
slow, especially in the context of an exam. But relying on
triggers for more general problem solving can create problems
all its own... The most vivid, most memorable, or only instances
you've seen will bias your results. I am a strong proponent of
reasonable from examples, a lá
case-based reasoning,
but this requires a disciplined use of a reliable "similarity
metric". Students often don't have a reliable enough similarity
metric in hand, and they often haven't learned yet to use it
in a disciplined way. They tend to select the past example that
they remember -- or understand!! -- the best, regardless of how
well it applies in the current context. The result is often a
not-so-good solution and a disillusioned student.
Thinking these thoughts will help me teach better.
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