The goal of this clinical trial is to learn if attention and ways of thinking impact decision-making and brain processes related to decision-making in people with schizophrenia or schizoaffective disorder relative to people without either condition. It will also learn how brain functioning during decision-making relates to real-world decisions made during daily life. The main questions it aims to answer are: * Does paying attention to specific information impact decision-making and brain processes? * Does thinking in a certain way according to specific 'thinking strategies' improve brain processes related to decision-making? * Does brain functioning during decision-making relate to real-world choices to engage in activities? Researchers will compare brain functioning and decision-making on computer tasks of gambling after participants have been trained to use a positive thinking strategy. They will compare what is different in the brain and behavior when participants use this strategy and when they do not. Participants will also answer brief surveys about activities and feelings for a week in their daily lives. Participants will: * Complete several hours of clinical interviewing, cognitive tests, and surveys of about symptoms, experiences, and personality * Complete computer tasks about gambling decisions during MRI brain scanning and while having their visual attention measured using eye-tracking * Complete brief surveys about their activities and feelings 5 times a day for 1 week using a cell phone. Each survey only take several minutes.