Attention Training for Opioid-maintained Cocaine Users

Inclusion Criteria: * Current opioid dependence as evidenced by 1) documentation of prior treatment for opioid dependence or signs of withdrawal, 2) self-reported history of opioid dependence for 12 consecutive months and, 3) a positive urine toxicology screen for opiates. * Diagnosis of opioid dependence and cocaine dependence as well as laboratory confirmation of recent cocaine use in the form of positive urine toxicology during the month prior to study entry. * For those who recently participated in a research study involving medications other than methadone, at least 2 weeks of washout period before enrollment. Those already taking methadone would continue with their current course while participating in this study. * A history of cocaine use, a minimum of 1/2 gram and more than once per week during the preceding 30 days. * Must be seeking treatment for opioid and cocaine use. * For women of childbearing age, a negative pregnancy test at screening with agreement to use adequate contraception to prevent pregnancy and monthly pregnancy tests. * The ability to speak, read, and write in English at an eight-grade literacy level. Exclusion Criteria: * Serious medical illnesses including hypertension, tachycardia, bradycardia, or other arrhythmias and major cardiovascular, cerebrovascular, renal, endocrine, or hepatic disorders; * Serious psychiatric illness, history of psychosis, schizophrenia or bipolar type I disorder. * Current major depression. Subjects with current depressive symptoms not meeting criteria will be included in the study, with the exception of those endorsing suicidal and homicidal thoughts, will be excluded even if full criteria for major depression are not met. * Current diagnosis of alcohol or drug dependence other than opiates, cocaine, nicotine and cannabis. * Current use of over-the-counter or prescription psychoactive drugs (antidepressant, anxiolytics, antipsychotics, mood stabilizers, psychostimulants) or drugs that would be expected to have major interactions with drugs to be tested, e.g., benzodiazepines, codeine, percocet, and other opiate drugs that will interact with methadone. * Liver function tests (ALT or AST) greater than 3 times normal. * Self-reported color blindness or (non-corrected) defective vision