A reverse translational approach to quantify approach-avoidance conflict in humans

Abstract

Animal approach-avoidance conflict paradigms have been used extensively to characterize effects of anxiolytic agents and probe neural circuitry related to anxiety. However, there are few behavioral approaches to measure conflict in human populations, limiting the translation of findings from animal conflict tasks to human clinical research. We developed a novel approach-avoidance conflict (AAC) paradigm involving situations in which the same decision is associated with "reward" (points) and "punishment" (negative affective stimuli). The AAC task was completed by 95 young adults (56 female) with varying levels of self-reported trait anxiety. As expected, conflict-related approach behavior correlated with self-reported motivation to approach reward and avoid punishment and greater reward level increased approach behavior. Additionally, females exhibited less approach behavior than males. Anxiety Sensitivity Index (Physical subscale) scores related negatively to approach behavior for males, while Behavioral Activation Scale (BAS, Fun Seeking subscale) scores related positively to approach behavior for females. Results support the utility of the AAC task as a behavioral test that has strong reverse translational features. Findings indicate that approach drives and anxiety sensitivity may be important in determining conflict behavior for females and males respectively. The approach-avoidance conflict task offers a novel, translational measure to probe neural systems underlying conflict behavior, motivational processes, and anxiety disorders.

Figure 1. Decisional conditions included within the approach-avoidance conflict (AAC) paradigm

Avoidance-only conditions (Part A) involve no point-reward incentives but only the possibility of viewing a negative (indicated by a cloud) or positive (indicated by a sun) affective stimulus. During conflict conditions (Parts B–D), reward points (2, 4, or 6 point levels) are given only for the outcomes associated with a negative affective stimulus while the competing choice includes no points but a positive affective stimulus. The avatar starts out at different locations on the runway, counterbalanced so there were two trials for each position within each of the condition types. The subject is asked to move the avatar (by pressing arrow keys on a keyboard) to a position that accurately reflects their preference between the two potential outcomes. The position in which they move the avatar determines the relative probability of each of the two outcomes occurring (Part E; 10/90%, 20/80%, 30/70%, 40/60%, 50/50% and vice versa probabilities, corresponding to the nine potential avatar positions ranging from −4 to +4). Therefore, if they move their avatar to the middle, there is a 50% chance of each outcome occurring; if they moved all the way to one side, there is a 90% chance of the nearest outcome occurring, but still a 10% chance of the furthest outcome occurring, and so on.

Figure 2. Sequence of screens presented during one trial of the approach-avoidance conflict (AAC) task

A decisional phase is first presented for a maximum of 4 seconds. The affective stimulus phase consists of either a negative or positive affective image (from the International Affective Picture System [IAPS]) [52] and a matched affective sound (from free source websites such as freesound.org and the International Affective Digitized Sounds [IADS]) [53]. The affective stimulus phase lasts a total of 6 seconds. The reward phase consists of a screen displaying points earned on the current trial as well as the total points collected thus far on the task in combination with a reward-related trumpet sound. The reward phase lasts a total of 2 seconds. An intertrial fixation of 1 second is displayed to allow the subject to prepare for the next trial. The AAC task consists of 18 trials of each condition type (displayed in Figure 1), for a total of 72 trials.

Figure 3. Approach behavior during the approach-avoidance conflict (AAC) task

Approach behavior significantly increased with each successive condition (Avoidance-only < 2-point Conflict < 4-point Conflict < 6-point Conflict) for both males (χ²(3)=57.828, p< 0.001) and females (χ²(3)=67.465, p< 0.001). Males exhibited greater levels of approach behavior during conflict than females (Z=2.66, p=0.008).

Figure 4. Scatterplot displaying relationship between approach behavior on the approach avoidance conflict task (AAC) and ratings of how motivated the individual was to obtain reward

Approach behavior during conflict conditions of the AAC task was significantly related to individual’s post-task questionnaire ratings of how motivated they were to seek reward during the task (males: rho=0.70; p<.001*; females: rho=0.74; p<.001).

Figure 5. Scatterplot displaying relationship between approach behavior on the approach avoidance conflict task (AAC) and scores on the Anxiety Sensitivity Index (ASI) Physical subscale

Approach behavior for males was positively related to scores on the Anxiety Sensitivity Index (ASI) Physical subscale during conflict conditions of the approach-avoidance conflict (AAC) task (rho=−.407; p=.010), while this relationship was nonsignificant for females (rho=−.054; p=.692).

Figure 6. Scatterplot displaying relationship between approach behavior on the approach avoidance conflict task (AAC) and scores on the Behavioral Activation Scale (BAS) Fun-Seeking subscale

Approach behavior for females was positively related to scores on the BAS Fun Seeking subscale during conflict conditions of the approach-avoidance conflict (AAC) task (rho=.385; p=.003), while this relationship was nonsignificant for males (rho=−.113; p=.493).