While making investment decisions, investors use different reference points that change their values dynamically. In this paper we investigate the impact of the deviation of the portfolio value from different reference points on the investment activity of participants of the investment game, as measured by the turnover volume during the day. We consider the following reference points: (1) the portfolio value before the previous transaction, (2) the initial portfolio value (3) the highest portfolio value and (4) the lowest portfolio value noticed during the time of the game, (5) the best result and (6) the worst result in the game during the transaction day, and (7) the value of the Warsaw Stock Exchange Index (WIG20). The strongest effects on the investment decisions appear to be the highest and the lowest portfolio value noticed during the time of participation in the game.