Every day, people make choices among options they may have
never experienced. Yet, they can make such choices rapidly, even confidently—yet
unwisely. Whether good or bad, the choices are likely to be biased from past
learning conditions,
Research is now clarifying how biased choices are made. All
choices, biased or not, are influenced by the values we place on alternative
choice options. If a past choice led to a good outcome, people are biased to
make that choice again because a positive value has been attached to it.
If in a current situation where there is no past relevant experience,
we can still make a choice easily. To do that, we must be able to assign
positive value to the choice made. But how can that be done in the absence of
past experience? It now appears from recent experiments that such decisions can
guided by past memory associations.
Memories certainly modulate value assignment and thus decision-making.
In one recent study, brain-scan imaging of humans has revealed that giving
people monetary rewards activates a pre-established network of memories that
spread the positive value of reward to non-rewarded items stored in memory.
This creates a bias for later decisions to choose non-rewarded items.
As an aside, the study revealed that a key structure
involved in memory formation, the hippocampus, predicts choice bias. It appears
that activity in the hippocampus, as revealed in brain scans, helps to spread
the reward value among memories of items that had never been rewarded, and thus
bias future choices for these non-rewarded items.
The rationale for the study began with the authors’ realization
of how the hippocampus helps to form memories. It encodes relationships between
items and events to form a remembered association. Later, when an item is
recalled, the hippocampus can automatically reactive the neural representation of
the associated item. Here then might be a way that the hippocampus could
re-allocate reward value when a past situation is recalled.
The choice task had three stages. First, the subjects had to
learn association between paired items. They were shown a series of pairs of
images, first one and then the other. Next was a reward phase, in which half of
the second stimuli were rewarded with money. Thus, subjects unconsciously learned a response to value
those stimuli that were directly rewarded.
The researchers expected that the non-rewarded member of the pair might
pick up some value by virtue of being associated with the rewarded member of
the pair. If so, a bias might have been created for these non-rewarded items in
future choice situations. Indeed, that is what they found in a later test in
which only the first member of each pair was presented and subjects were asked
to pick the preferred items. If no transfer of value had occurred in the prior
learning, the choices would have been evenly divided. But that is not what was
found. Subjects more often than chance preferred the stimuli that had previously
been paired with a rewarded second stimulus.
Why is this important to the issue of blame? This issue was
never considered by the authors. But to extrapolate from the experiment, we
could conclude that sometimes we may blame a bad choice on the wrong cause. The
real cause may have been our own bias for making a bad choice, in which we had
erroneously assigned value on the basis of some past associations with
experiences that were rewarded. That bias may have been created by some past
experiences in which we had inappropriately assigned a high value to certain choice
options that did not deserve such value.
So, for example, we might have had a past experience in
which a good thing happened at the same time as other events which had no
learned value or even negative value. But the value of the good thing spreads
to bias attitudes toward the other events. In the future, in a different
circumstance, we might unwisely choose the previously low-value option.
Here is a common example. Suppose we have a dear friend who
we have found to offer a valuable relationship. We meet the dear friend’s associates,
who may be unseemly characters that would make poor choices for us to value as
friends. Yet, the value we attached to the dear friend spills over to the
others and makes us less likely to be critical of them. Thus, we might start
running with a bad crowd of people that get us into trouble. When we get into trouble,
we likely will place the blame in the wrong place, without realizing it all
started with the bias created in us by the value we had placed in our dear
friend.
You can probably conjure your own examples. This whole
process of learned bias can affect every aspect of our life. It is important
for us to be more aware of our biases and the true value of our choice options.
Source:
Wimmer, G. E. and Shohamy, D. (2012). Preference by
association: how memory mechanisms in the hippocampus bias decisions. Science.
338: 270-273.
