The objective of this research is to　investigate the influences of sentiment, personal characteristics, and information sequence on investors’ stock investment decisions. That is, when processing information for investment decisions, whether economic forecasts, personal characteristics, and information sequence affect investors’ decision-making and cause significant discrepancies on investors’ belief adjustment process. Non-professional investors were tested and ANOVA and T-tests were applied for empirical test and analysis. The empirical result suggests that, on the sentiment front, investment decisions are affected by economic and stock-market forecasts, and that investors tend to over-react to both positive and negative information, thus resulting in over or under-valuation in stock prices. On the personal characteristics front, the result merely suggests that optimistic investors tend to over-react to positive information, and whether pessimistic investors over-react to negative information remains unverified. Also, taking into consideration investors’ sentiment and the optimism and pessimism they show, the result indicates that overreaction is jointly affected by economic forecasts and personal characteristics, especially when investors are exposed to positive information. On the information sequence front, the result suggests that investment decisions are affected by information sequence and indicates recency effect. To sum up, this research suggests that, when information is presented in different forms, sentiment and personal characteristics cause significant discrepancies on investors’ stock investment decisions.