​2017 - 2018  -  Oxford College of Emory University 

​2015 - 2016  -  Agnes Scott College

2012 - 2015  -  Georgia State University

​2008 - 2013  -  Emory University 


14-week, 7-week, and 3-week semesters; 

LMS: Moodle, BlackBoard, Brightspace, Canvas 

Awards and Fellowships: 

  • O.R.D.E.R. Fellow (On Recent Discoveries by Emory Researchers; 2011-2012)

  • Emory University/Howard Hughes Medical Institute Teacher-Scholar Award (2012)


  • The Dynamics of Choice and Preference (ASC, senior seminar)

  • Research Methods (ASC)

  • Introduction to Psychology (ASC, GSU, Oxford)

  • Introduction to Psychobiology (Oxford)

  • Social Psychology (ASC)

  • Theories of Personality (GSU)

  • Abnormal Psychology (GSU)

  • The Evolution of Acquired Behavior (Emory)

  • Complexity and Psychology (Emory; O.R.D.E.R. seminars)

Labs (Emory):

  • Research Methods (2008; Instructor: Nancy Bliwise)

  • Applied Statistics (2007; Instructor: Nancy Bliwise)

Teaching Assistant (Emory):

  •  Introduction to Psychological Science (2011; Instructor: Scott Lillienfeld)

  • Behavior Modification (2009, 2010, 2011; Instructor: Jack McDowell)

Projects contributed by students from my senior seminar (Agnes Scott, The Dynamics of Choice and Preference) to the Spring Annual Research Conference SpARC 2016

The Spring Annual Research Conference (SpARC) ... provides students and faculty with an opportunity to present their work to the campus community ... fosters essential connections across academic disciplines, and encourages an ongoing dialogue between the liberal arts and sciences. https://www.agnesscott.edu/sparc/

Adekunle, O. & Popa, A.  Higher Payoff or More Options?


[poster]  Having multiple options is appealing in our everyday lives, arguably because it allows for a flexible future. Some studies, however, showed that people may be less satisfied when presented with multiple options. This project investigated whether people preferred to keep their options open (so to speak) by arranging an asymmetrical, continuous choice environment. It was hypothesized that people will work to keep their options open even if it limits acquiring the maximum number of points. Seven Agnes Scott students responded on concurrent Random Interval (RI) schedules of reinforcement. The overall rate of reinforcement was constant, but one target class delivered higher-magnitude reinforcers (5 points vs. 1 point). However, the target class with the lower reinforcer magnitude (1 reinforcer = 1 point) shrank in size when not selected for ten or more consecutive seconds. Every ten-second interval would reduce its size by one fourth of its original size and every new response would increase its size by one fourth (or, if at original size, reset the ten-second interval). Results showed preference for the shrinking class (b ~ 0.9), even though reinforcer magnitude on this class was five times smaller. This suggests that participants preferred to keep their options open, even if meant acquiring a lower overall payoff.


O’lisa Yaa Waithe & Popa, A.   The Effects of Imagery on Psychological Discomfort


[talk]  This study examines the effectiveness of art by means of geometric and spatial relations as a means of therapy for anxiety-based disorders. Recent studies on the nature of trypophobia (fear of holes) suggest that specific geometrical arrangements, such as high contrast midrange spatial frequency images, may automatically trigger feelings of discomfort (Cole & Wilkins, 2013). The purpose of this study is twofold: to replicate the findings reported by Cole and Wilkins (2013) and to explore the extent to which the phenomenon can be reversed. Participants will be exposed to similar stimuli as those used by Cole & Wilkins (2013) via a computer program. They will be asked to rate their level of discomfort and provide a short explanation of why. They will then be asked to manipulate the images using (i.e., re-arrange the elements) using the mouse until the level of discomfort decreases. Each resulting image, as well as the stroke paths, will be recorded and analyzed for concurrences of basic geometric shapes and/or arrangements that help reduce anxiety. The overarching goal is to be able to produce personalized visual stimuli that reduce anxiety, thus increasing the level of personalization and effectiveness of therapeutic approaches to anxiety.


Forbes, V., & Popa, A. Human Choice Behaviors Before and After Extinction


[poster]  One way to eliminate behaviors form an organism’s repertoire is to identify and remove the reinforcing contingencies that maintain them. This procedure is referred to as extinction. Extinction is known to be accompanied by a short increase in behavior frequency, intensity, and variability. In this project, we examined various properties of choice behavior before and after extinction was implemented. Preliminary results showed that the frequency of both target and extraneous (non-target) responses increased during the extinction phase. The effect was more pronounced for extraneous responses, possibly for their exploratory potential. Future analysis will focus on various measures of variability before and after reinforcement is withdrawn.


Shen, R. & Popa, A.   Is Competition Sufficient to Increase the Motivation to “Do Well” ?

[talk]  In concurrent schedule procedures, humans exhibit lower sensitivity to reinforcement than non-humans (McDowell, 2013), possibly because points may not be as reinforcing for humans as food is for non- humans. We hypothesized that an environment that creates the impression of competition may increase the reinforcing value of points. Two groups of participants (competition vs. non-competition) responded for 18 minutes in a continuous-choice procedure that arranged concurrent, independent Random Interval (RI) schedule; the target classes were invisible to both groups. Preliminary analyses showed that sensitivity to reinforcement, contrary to our hypothesis, was not noticeably higher in the competition condition. These results showed that competition by itself may not be sufficient to increase motivation. Several potential explanations are discussed, including the perceived relevance (or lack thereof) of the activity.


Tang, X., & Popa, A.   Choice Behavior in Low Discriminability Conditions: Effects of the Operant Class Size


[poster]  The purpose of the study was to explore basic properties of choice behavior when the target classes varied in size, in low-discriminability conditions (invisible target classes). 24 Agnes Scott students responded in environments that arranged symmetrical, concurrent, Random Interval (RI) schedules of reinforcement. The target regions (or classes) were hidden. In one condition (N = 12) the target classes were small (about 4% of the experimental area). In the second condition the target classes occupied approximately 20% of the experimental area. Sensitivity to reinforcement was larger when the classes were small (a ~ 0.70) than when they were large (a ~ 0.19). The same was true for spatial variability, but not for temporal variability, which was larger when the target classes were small.


Booher, C. & Popa, A.   Choice Behavior With and Without Immediate Feedback


[poster]  The purpose of this study was to explore properties of choice behavior when the target classes that have the potential for reinforcement were hidden. Twenty-four Agnes Scott students were randomly assigned to two experimental conditions. In one condition an unpleasant sound was made contingent on each response that occurred outside a target region. In the second condition, extraneous responses were not signaled. In both conditions, reinforced responses resulted in one point and a pleasant sound. Target responses that were not reinforced were never signaled. We hypothesized that the condition with feedback 1) will elicit higher accuracy in locating the target classes and 2) will produce lower levels of behavioral variability. Preliminary results appear to confirm the hypotheses.


Grissom, MK., & Popa, A.    Negative Reinforcement, Superstition, and Apathy

 [talk]  The purpose of this study was to explore the effects of negative reinforcement on the frequency and variability of continuous choice behavior. The concurrent-schedule procedure was implemented via a computer program developed by the second author. Participants began the experiment with a fixed number of points (e.g., 1,000). As time passed, the number of points decreases at a rate of 4 points per second. Responses (mouse clicks) on two target regions stopped the loss of points for a small amount of time (e.g., 4 seconds). The first specific aim was to verify if escape behavior (stop the loss of points) become avoidance behavior (prevent loss of points). The second was to observe if avoidance behavior continued when it was no longer necessary. The third specific aim was to verify to what extent responding continued when it was no longer adaptive (i.e., when loss of points could not be avoided). The fourth specific aim was to observe if responding resurged once its adaptive function - preventing loss of points - was restored. The fifth aim was to explore possible relations between specific, low-level properties of choice behavior (e.g., bout frequency, variability in inter-response intervals) and personality traits (e.g., conscientiousness).