We had participants in each condition generate cues for episodic thinking during delay discounting and ad libitum eating, using an adapted version of a task for assessing the anticipation of future events in depressed individuals (MacLeod, Pankhania, Lee, & Mitchell, 1997 (link)). Episodic-future-thinking participants listed possible positive future events (D'Argembeau & Van der Linden, 2004 (link)) occurring at time periods corresponding to time periods specified in the delay-discounting task. The control- episodic-thinking group based episodic cues on vivid events described in entries of the travel blog of a female writer (
Discounting of hypothetical monetary rewards (of $10 and $100) were assessed at delays of 1 day, 2 days, 1 week, 2 weeks, 1 month, 6 months, and 2 years. Participants chose either the larger reward, available at a delay, or the smaller reward, available immediately, adjusted in 26 steps (26 choices between different combinations of immediate and delayed rewards, based on a standardized procedure commonly used in studies on delay discounting; Rollins, Dearing, & Epstein, 2010 (link)). Prior to each delay-discounting trial, episodic-future-thinking participants were instructed to think about future events corresponding to the delayed time period (Peters & Büchel, 2010 (link)), whereas control- episodic-thinking participants were instructed to think about events described in the travel blog. Indifference points (delays at which participants were equally likely to choose either immediate or delayed rewards) were calculated (Dixon, Marley, & Jacobs, 2003 (link)) to compute area-under-the-indifference-curve values (Myerson, Green, & Warusawitharana, 2001 (link)).
The ad libitum eating task simulated a food-related situation that could trigger impulsive eating, with sessions scheduled at least 90 min after lunch but before dinner. To increase food craving and temptation to eat (Fedoroff, Polivy, & Herman, 2003 (link)), we first had participants rate the sensory appeal of meatballs, fries, sausages, garlic bread, cookies, and dips without tasting them. Unlimited access to the foods was provided for 15 min afterward, and participants provided ratings of the foods’ taste quality and texture. The timing of the task and the sensory pre-exposure to the foods provided a prototypical situation that could lead participants to engage in consumption for immediate gratification instead of delaying gratification for future health. To cue episodic thinking during the taste test, we played the audio recordings of participants’ reports of high-imagery events throughout the eating task.