Previous studies have shown that people with mild intellectual disabilities have difficulty in "weighing-up" information, defined as integrating information from two different sources for the purpose of reaching a decision. This was demonstrated in two very different procedures, temporal discounting and a scenario-based financial decision-making task. In the present study, both tasks were presented to 24 participants who attended day services for people with learning disabilities (mean Full-Scale IQ = 59.8), half of whom were trained to use a visual aid to support decision-making. Performance of control participants did not change over repeated testing, but use of the visual aid substantially improved the quality of decision-making on both tasks: temporal discounting performance became more orderly, and participants were able to provide more information to justify their decisions in the financial decision-making task. The visual aid also substantially improved participants' ability to justify decisions they made about their own lives. We suggest that, while the visual aid was designed and evaluated as a means of increasing the quality of reasoning that supports a decision, it may also have potential as an aid to therapeutic interventions aimed at encouraging wiser decision-making. (Contains 1 table and 4 figures.)