Early experiences have a larger
effect on mood than more recent ones: Study
Washington: New insight on how our experiences during a task or
interaction shape our current mood has been recently reported by an
international team of researchers. Published in the open-access eLife journal,
the study suggests that early experiences may have a larger effect on our mood
than more recent events. These findings hold implications for the timing of
events in experimental or clinical settings and suggest new directions for mood
interventions tailored to individual patients. People routinely report on their
moods during everyday activities and when they interact with clinicians
providing mental health care. It is commonly believed that the most recent
experiences during a task or interaction with someone else may have the
strongest effect on how an individual feels at a given time. But in a series of
experiments, researchers show that early experiences can have a more
significant impact on someone's mood. The research team included first author
and Postdoctoral Research Fellow Hanna Keren and colleagues at the Intramural
Research Program of the National Institute of Mental Health (NIMH), National
Institutes of Health, Bethesda, US.
To address the question of how the timing of an event can impact
our current mood, Keren and colleagues began with a computational modeling
approach. They developed a novel Primacy model, based on the concept that
experiences occurring early in an interaction or game prevail over more recent
ones in affecting our mood. They then pitted this model against a Recency
model, based on the idea that more recent experiences have a stronger effect on
mood. They showed that the Primacy model accounts more for self-reported mood
when compared to the Recency and other computational models. They also examined
their models concerning the moods of people of different ages, as well as
healthy and depressed participants. To do this, they recruited a group of adult
volunteers to participate in an online gambling game with small monetary
rewards based on their success in the game. They invited the volunteers to
report their moods using a sliding scale at several points during the game.
In the second set of experiments, they recruited a group of
adolescent volunteers to play a similar game in the laboratory while measuring
these participants' brain activity using functional magnetic resonance imaging.
They also collected data on whether the participants had depression, as this can
also impact an individual's current mood. The researchers found that early
events during the game had the greatest impact on mood in both the adolescent
and adult groups. This was also true for individuals with and without
depression.
Their imaging data also suggested that earlier experiences in the
game 'switched on' parts of the frontal brain associated with moods, rather
than later events. These results provided evidence for the neural encoding of
the team's Primacy, but not the Recency model. Altogether, the findings raise
some important questions, such as why adverse experiences early in a task or
interaction may have lasting effects on an individual's mood. Future studies
assessing the impact of events on mood over longer time periods might help answer
these questions.
In the meantime, Keren and the team suggest their current work may
have implications for the way clinicians providing mental health care interact
with patients or assess the effectiveness of their treatment, as the timing of
good and bad experiences may affect how patients feel about their
treatment.
