Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common disorders diagnosed among children in the United States (Lynch, 2013). Its increasing prevalence in the United States is becoming a major controversy in the field of psychology. The public also seems to have an opinion. Should we treat children with…Background of ADHDThe history of hyperactive and intentional children is very dense. The diagnosis of ADHD has evolved significantly over the years, but the history of ADHD begins in 1798 (Lange et al., 2010). Sir Alexander Crichton was an Edinburgh doctor who became an expert on mental illness. In the second of his books on mental illness, he talks about attention disorders. He described people unable to concentrate or pay attention with the necessary coherence (Lange et al., 2010). The distractibility of these individuals and the fact that the disorder “is born with a person” are two other similarities that its description has with the modern understanding of ADHD (Lange et al., 2010). Sir Alexander Crichton started the conversation that turned into an ADHD diagnosis, but his definition of the disorder has changed greatly throughout history. The next major contributor to the modern diagnosis of ADHD was Heinrich Hoffman and his “Fidgety Phil” stories (Lange et al., 2010). In 1844, Hoffman described a child who regularly misbehaved, would not listen to his father, and could not sit still (Lange et al., 2010). These symptoms are still part of the DSM diagnosis of ADHD today. His work introduced the public to the idea of ​​a child bordering on ADHD who is not inherently a bad child. Sir George Frederic Still (1868-1941), "the father of British paediatrics", is known...... middle of paper ...... and 10.0 mg/kg in sequential order. Behavioral testing only took place after the second methylphenidate injection per day. The lever press data from the last day (how many days?) of each dose will serve as the data point. After the medication phases, abstinence will be introduced and behavioral data will be collected again. Research QuestionWill behavioral tolerance occur with acute and chronic exposure to methylphenidate?HypothesisBehavioral tolerance will occur; the response rate of rats before and during the drug insult will produce more frequent reinforcement (more adaptive behavior) than after the introduction of abstinence. Data Analysis This is a within-subjects repeated measures design where each animal will receive each level of independent variable and serve as its own control. Data will be analyzed with one-way within-subjects analysis.