Evidence has been put forward that premature termination of data collection and jumping to conclusions behavior (JTC) is associated with delusions. However, few investigations have attempted to track associations between changes in delusions and changes in JTC measures. In the current study individuals with schizophrenia spectrum disorders completed a version of the JTC task (involving fishing from lakes as opposed to drawing beads from a jar) at two timepoints 12 weeks apart. The results revealed significant negative correlations between change in task performance (number of requested pieces of information) and change in delusion scores over time. This evidence is consistent with the contention that the JTC task is sensitive to the cognitive systems underlying delusions in schizophrenia spectrum disorders.