Results

Threat Perception and Context Sensitivity Relation Dan McDonald, Suhair Asi, and Spencer Lynn

Introduction

An individual’s judgment of how threatening a face looks could be altered by the context surrounding that face. 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 alternative options within the collection compromise 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. Option A was win or lose 5 cents with equal probability. Option B was the win or lose 50 cents with equal probability. Option C was a certain loss of 1 cent. Option D was 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: the probability was higher to choose A over C than B over C. These results would imply that the probability to pick A is always greater than B. However, this was not the case; the pattern was reversed for the A vs. D and B vs. D choices. This meant that the participants made the decision based on the pairings rather than on a preference for a specific 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 also judging. The set of faces under consideration might form a context that can influence one’s perception of a target face.

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.

Olivola, C. Y., Funk, F., & Todorov, A. (2014). Social attributions from faces bias human choices. Trends in Cognitive Sciences, 18(11), 566-570.

Methods

Our study examines participants’ 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., the shape of 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 changed very slightly, in 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 1 of the experiment the face series were created from two young base faces. In run 2 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 a tendency to categorize the faces as not 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 stimulus 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 other options present. 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. Over two runs of the experiment, participants had to judge three faces that were similar in features and state “yes” or “no” when asked if they were 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 runs, any differently when it was paired with another face, which differed on the two runs. However, participants judged the target face to be more threatening when it was paired with a young face (run 1) than when paired with an old face (run 2). These results show that the participants were judging the two faces in relation to each other rather than separately. We conclude that context sensitivity, meaning people use everything in the situation to form judgments, altered how people perceived the target face.

We created the graph using the results from each participant (n=14). 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 the target face (blue) and alternative face (green). A line’s inflection point is the participants’ threshold of threat detection

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Range of faces from non-threatening to threatening

Run 1

Target Face, Run1

Altered Face, Run 1

We created an aged version 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 target face. The graph represents the participants’ responses when stimulated with the target face (red) and the aged alternative face (green) (n=14).

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Range of faces from non-threatening to threatening

Run 2

Target Face, Run2

Aged Target Face, Run2

By comparing both target face 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 target face. 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 location increased during Run 2. Participants found the target face to be significantly less threatening when it was paired with the aged face in Run 2 than when it was paired with the young face in Run 1 (t25=-5.2, P<0.001).

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Range of faces from non-threatening to threatening

Run 1 and Run 2 Results

Mean Target Face, Run 1

Mean Target Face, Run 2