Immunization against social fear learning
Armita Golkar & Andreas Olsson
Supplemental Materials
Immunization Against Social Fear Learning
by A. Golkar & A. Olsson, 2016, JEP: General
http://dx.doi.org/10.1037/xge0000173
Supplementary Methods
Stimuli. Two pictures depicting angry male faces from the Karolinska Directed Emotional Faces database (Lundqvist, 1998) served as CSs (Items AM02ANS and AM06ANS) and one male individual served as demonstrator. Three different sets of video clips, two for observational pre-exposure and one for observational conditioning, were created using the video editing software Lightworks (version 11.4). All videos showed a computer screen on which the CSs were presented.
Questionnaires
After completing the experimental task, participants answered a post-experimental interview that assessed their awareness of the contingency between the CS and the US during and rated on a 9-point scale (not all – very much) how much they could identify themselves with the person and how much empathy they felt for the person. Additionally, to ensure that the demonstrators were comparable in terms of transmitting emotional information, participants rated (on a 9-point scale, not at all – very much) how much discomfort they thought that the person in the video experienced in response to the shocks, how expressive he was when receiving the shocks, and how natural they experienced his reactions to be. (See Supplementary results)
Participant instructions. Before starting the experiment, participants were attached to the skin conductance and shock electrodes and were informed that the electrical shocks could be experienced as uncomfortable. Following this, participants in the observational pre-exposure group received the following written instructions: “During the first stage, you will watch a movie clip in which another person is watching a presentation of two different faces. Remember to attend to the picture presentation.” Participants in the direct pre-exposure group received identical instructions except that the information about the demonstrator was excluded: “During the first stage, you will watch a movie clip involving a presentation of two different faces. Remember to attend to the picture presentation”. During the subsequent pre-exposure stage, participants in the observational pre-exposure group watched a video clip in which the demonstrator, attached to the same equipment as themselves, was watching a presentation of the CSs. Participants in the direct pre-exposure group watched an identical video clip but in which the demonstrator was absent.
After this stage, all participants watched the observational conditioning video that was preceded by the following written instructions: During this stage, you will watch a movie in which another person is undergoing a similar experiment to the one that you will participate in. The person in the movie is attached to the same equipment as you and the person in the movie can receive an electrical shock when one of two images are shown on the screen. It’s important that you attend to and remember what happens to the person in the movie”.
In experiment 3, the third experimental stage was preceded by the following instructions:
“During this stage, you will be presented with the same stimuli. It’s important that you attend to the presentation.
Data reduction and analysis
CS-elicited responses were assessed as the peak-to-peak amplitude difference in skin conductance to the largest response (in microsiemens, µS) in the .5 to 4.5 second window following stimulus onset. Responses below .02 µS were scored as zero and the raw SCR scores were z-transformed. Analyses were based on the mean SCR to the CS+ and CS- separately for each stage and analyzed using separate mixed analysis of variance for repeated measures (ANOVA) with CS (CS+, CS) as a within-subject factor and Group (Observational pre-exposure; Direct pre-exposure) as a between-subject factor. Significant interactions were followed-up with separate paired-samples t-tests within groups. We adopted a significance level of .05, reporting only effects not qualified by a significant higher-order interaction. We report partial η2 as the estimate of effect size and Greenhouse – Geisser adjustments of degrees of freedom were used when appropriate. Finally, to ensure that the groups did not differ on subjective ratings, questionnaire data were analyzed with separate independent t-tests.
Supplementary results
Experiment 2
Questionnaires. There were no significant between-groups differences (all t’s < 2) in rated identification or empathy with the demonstrator, or in how participants experienced the reaction of the demonstrator in response to receiving the electrical shocks (all t’s < 2).
Experiment 3
Questionnaires. There were no significant between-groups differences (all t’s < 2) in rated identification or empathy with the demonstrator, or in how participants experienced the reaction of the demonstrator in response to receiving the electrical shocks (all t’s < 2).
Supplementary Figure 1. Forest Plot of the effect sizes and confidence intervals of the individual studies and overall estimate.
Note: The effect sizes in the forest plot are presented with masses reflecting the relative weight of that particular experiment in the meta-analysis (experiment weight is determined by the standard error of the observed mean difference). A positive effect size indicates less CS+/CS- differentiation in the Same-demonstrator group (i.e. favors the immunization effect).