Participants had to score below 5 on the initial administration of the SOGS to participate. Scores of 5 or more on the SOGS suggest the possible presence of pathology.

It is the most widely used screen for the potential presence of pathological gambling (Petry). The SOGS is a 20-item self-report questionnaire designed to measure participants' gambling history. This information was requested because each is related to a known risk factor for pathological gambling ( Petry, 2005). The demographic questionnaire asked participants' sex, age, marital status, race or ethnicity, and annual income. They completed the SOGS again following the final gambling session to assess potential negative effects of the procedure. Participants provided informed consent and then completed the SOGS, a demographic questionnaire, and the Gambling Functional Assessment (GFA Dixon & Johnson, 2007) prior to gambling. The primary focus was not whether players could ever display such sensitivity, but rather if they would do so under conditions that mimicked those faced in actual casinos. The present study attempted to determine whether individuals given multiple opportunities to play concurrently available slot machines in a simulated casino environment would demonstrate sensitivity to reinforcement by choosing to play the higher paying machine. These studies assessed sensitivity across conditions or sessions rather than when the options were presented concurrently, which may have hindered discrimination (e.g., Shah, Bradshaw, & Szabadi, 1989). However, several studies from our laboratory have failed to find such sensitivity when participants gamble ( Gillis, McDonald, & Weatherly, 2008 Weatherly & Brandt, 2004). Basic research shows that organisms are generally (e.g., Herrnstein, 1961), but not perfectly (e.g., Baum, 1974), sensitive to relative rates of reinforcement. The literature on gambling is vast, but little of it is experimental or behavior analytic (see Weatherly & Phelps, 2006), which is unfortunate given the potential contributions of behavior analysis to the study of gambling ( Dixon & Holton, 2009 Weatherly & Dixon, 2007). Gambling is both a serious societal problem and a popular pastime (see Petry, 2005).

How slots machines are programmed