A group of University of Iowa scientists is looking for marijuana smokers to help gain insight into the drug's effects and they plan to pay subjects as much as $600 to smoke their pot.

The study will examine how marijuana affects brain function and cognition, with particular attention to the duration of use and the age of first use. The measure is brain imaging studies and achievement tests, such as for math and verbal skills.

Robert Block, associate professor in the school's Department of Anesthesia and the lead investigator on the project, says the group is looking for pot users and control subjects who also consume alcohol and tobacco to participate in the study.

Subjects receive $20 for an initial screening session. Those that participate fully pocket $600. Call (319) 356-3868 for more information.

Block says depending on the results, the study might ultimately be used to support political positions on marijuana. Those could include whether there should be harsher criminal penalties, whether it should be decriminalized or whether it should be allowed for medicinal purposes.