Lab Poster for IASL Fall 2015

1. Data & Analysis
Threat Perception and Context Sensitivity Relation
D. McDonald, S. Asi, and S. Lynn
We created the graph using the results from each participant. The data collected is averaged
to display the function of the participants' behavioral response to the target face series. The
calculations were determined by calculating the participants’ average portion of times they
said the target face was threatening. The graph displays the participants’ responses to the
altered face (green) and the target face (blue).
Introduction
An individual’s ability to detect a
threat could be altered by the
context surrounding that target. The
idea of “context sensitivity” has
been studied as a key aspect to the
decision making process. Context
sensitivity argues that when there is
a collection of options from which
the decision maker must choose
then the collection compromises a
unique context (Busemeyer, 1993).
In Busemeyer's study, he noticed
this issue when studying economic
decision making. Subjects were
asked to choose between a gamble
and a certain value. Using the
simple scalability hypothesis the
probability of each figure was
supposed to decrease with the
options. However, Busemeyer
knew differently because the
inconsistencies were due to the
pairings of two choices, and the
context affected the decision
making process. Option A was "win
or lose 5 cents with equal
probability, B is the gamble "win or
lose 50 cents with equal probability,
C is a certain loss of 1 cent, and D
is a certain gain of 1 cent. The
probabilities of choosing A over C,
B over C, A over D, and B over D
were found. It was found that the
probability was higher to choose A
over C then B over C. These results
would imply that the probability to
pick A is greater than B. However,
this was not the case, when the
pairing was A over D, which meant
that the participants made the
decision based on the pairings
rather than the option. From
Busemeyer’s findings, we
hypothesized that a person’s
judgment of a face being
threatening would be influenced by
the other faces that one was
judging. The set of faces under
consideration forms a context that
can influence one’s perception of a
targeted face.
We created an aged target face for the target face series to see if an aged version would
stimulate a different response. Initially, we thought the aged face would be seen as less
threatening due to its age (50-60 years old), but the aged face was perceived as more
threatening in comparison to the targeted face. The graph represents the participants’
responses when stimulated with the target face (red) and the aged face (green).
References
Busemeyer, Jerome R., and James
T. Townsend. "Decision Field
Theory: A Dynamic-cognitive
Approach to Decision Making in an
Uncertain Environment."
Psychological Review 100.3 (1993):
432-59. Web. 1 Dec. 2015.
Olivola, C. Y., Funk, F., & Todorov,
A. (2014). Social attributions from
faces bias human
choices. Trends in Cognitive
Sciences, 18(11), 566-570.
doi:10.1016/j.tics.2014.09.007
By comparing both graphs side by side, we were able to conclude that the threat perception
of the target face was context sensitive, which makes the stimulus dependent on the other
stimuli surrounding the targeted face. The graph’s inflection point is the participants’
threshold of behavioral responses to the targeted stimulus. The threshold determines where
the participant’s perception of the faces shifts from non-threatening to threatening. When
comparing the two data sets, the target face’s threshold shifted during Run 2, so participants
found the target face to be less threatening when paired with the aged face than when paired
with the young altered face in Run 1.
Methods
Our study examines the
participant’s ability to effectively
categorize two different faces
during a threat perception task. We
recruited 28 participants from the
Northeastern University student
body population. Participants saw
two different series of faces that
ranged from non-threatening
physiognomy (i.e., shape facial
features) to threatening
physiognomy. According to
previous research certain facial
features create a more threatening
look than others, for example, a
stronger jaw line is more
threatening than a rounded or
weaker one (Olivola, 2014). Faces
were constructed using FaceGen
Modeler software. Each face series
comprised 11 “morphs” of a “base”
face. With each morph facial
features would change very slightly,
to almost unnoticeable distinctions.
For example, the size of the
individual’s nostrils went from very
small to very large. The faces
ranged from 1-11, one being the
most non-threatening and 11 being
most threatening.
In run one of the experiment there
the series were created from two
young base faces. In run two of the
experiment an old base face was
used in place of one of the young
base faces. The two young faces
were approximately 20-30 years of
age while the old face was
approximately 50-60 years of age.
During the perception task,
participants viewed one face at a
time for 500 ms. Participants
earned or lost points by correctly
detecting whether or not the face
was threatening. They were
instructed to earn as many points
as they could over 300 trials. The
point values favored a conservative
bias, which means to perceive
faces as less threatening.
Therefore, participants with a more
conservative bias earned more
points during the study.
Conclusion &
Discussion
The threat physiognomy’s
dependency on a stimulus’
surroundings upholds Busemyer’s
(1993) findings of context sensitivity
because the choices surrounding
each stimuli influence the
participant’s perception and
ultimately his or her decision. While
conducting the threat physiognomy
study, a person’s threat perception
was affected by the options given.
Threat perception experiences this
phenomenon because an individual
is affected by context sensitivity
when analyzing a threat, making
Busemyer’s (1993) findings
applicable. Though successful in
identifying context sensitivity, our
experiment is limited by the
demographics of the participants
(solely Northeastern Students with
an average age of 18-22 years) and
the type of stimuli (only white
males). Future studies would
ideally study faces of both genders
and different races, and the studies
should select a larger variety for the
demographic of
participants. Currently, we are
investigating how adding an
additional stimulus to the face
perception task would intensify or
hinder a person’s threat perception.
Context sensitivity is applicable to a
person’s threat perception and
would need further investigation to
determine if the relation can be
applied to all settings.
Abstract
Social threat perception is the
ability to effectively identify person
as a threat or not. We investigated
whether or not people’s evaluation
of a face as threatening is biased
by other faces they are also
evaluating. Participants had to
judge two faces that were similar in
features and state “yes” or “no”
when asked if it is threatening.
Participants earned and lost points
for correct and incorrect
categorization of the faces, and
were instructed to earn as many
points as they could. With the
points as motivation, a slight bias to
categorize faces as “not
threatening” would maximize
earnings. We hypothesized that the
participants would not judge the
target face, which was present in
both experiments, any differently if
it was paired with another face.
However, according to the results
context sensitivity, meaning people
use everything in the situation to
form judgments, altered how people
perceived the target face, which is
also called face two. Participants
judged the target face to be more
threatening when it was paired with
a young face than when paired with
an old face. These results show
that the participants were judging
the two faces in relation to each
other rather than separately, as in
the idea of context sensitivity.
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ProbabilityofperceivedThreat
Range of faces from non-threatening to threatening
Run 1 and Run 2 Results
Mean Target Face, Run 1
Mean Target Face, Run 2
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ProbabilityofperceivedThreat
Range of faces from non-threatening to threatening
Run 1
Target Face, Run1
Altered Face, Run 1
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ProbabilityofPerceivedthreat
Range of faces from non-threatening to threatening
Run 2
Target Face, Run2
Aged Target Face, Run2