Toward a standard experiment for studying post-treatment return of fear

Fear sometimes returns after successful fear attenuation via in vivo exposure to fear signals. Post-treatment return of fear is of considerable interest both practically and theoretically, but factors associated with return of fear are poorly understood due to conflicting results from procedurally diverse experiments. This paper reports two very similar experiments in which fear of animal specimens was weakened then allowed to return so that factors associated with return of fear could be studied. In each experiment attentional focus versus distraction during exposure served as a between-subjects independent variable. In each case, attempts also were made to predict return of fear via several nonmanipulated variables: initial fear, initial avoidance during voluntary exposure, initial heart rate during voluntary exposure, and speed of fear reduction during repeated exposure trials. With the sample sizes used there was only suggestive evidence that return of fear was associated with distraction during exposure, and with relatively rapid fear decline during exposure. More importantly, the experiments are offered as standard, replicable models for research that will permit procedurally homogeneous investigations of variables with which return of fear is associated.