Seven Coulbourn® Habitest (Coulbourn Instruments, Whitehall, PA, USA) rat operant chambers were used for data collection. Chambers were equipped with two levers on the right sidewall panel and were 5 cm above a grid floor with a food alcove centered between the levers. When response requirements were met, and depending on the experimental condition, one or more 45-mg sucrose pellets (95% sucrose, 3.4 kcal/g; TestDiet®, Richmond, IN, USA) or carrot-flavored pellets (3% sucrose, 3.3 kcal/g; TestDiet®, Richmond, IN, USA) were delivered to the alcove. These pellet types were chosen because these same carrot-flavored pellets were less preferred than sucrose pellets in Sprague-Dawley rats and Zucker rats in a previous study (see Buckley & Rasmussen, 2012 (link)). Two 28-V stimulus lights were situated above each lever as well as a 28-V houselight that was 28 cm above the alcove. A 5 cm X 5 cm fan circulated air in the upper left corner of the left sidewall panel and white noise was generated from a speaker in the upper right corner of the left sidewall panel. Each chamber was placed in a sound-attenuating cubicle and Graphic State® software (Coulbourn Instruments, Whitehall, PA, USA) on a Windows-based computer (located in an adjacent room) controlled all data collection within 0.01-s resolution.