The amount of political information that voters decide to acquire during an electoral campaign depends, among other things, on prior ideological beliefs about parties and/or candidates. Voters that are ex ante indifferent about the candidates attach little value to information because they perceive that voting itself will have little value. Voters that are ex ante very ideological also attach little value to information because they think that the news will hardly change their opinion. Thus, high incentives to be informed can be found at intermediate levels of ideological strength. Moreover, the impact of increased political knowledge on turnout is asymmetric: New information increase the probability of voting of indifferent voters but decrease that of very ideological voters. These results are derived within a decision theoretical model of information acquisition and turnout that combines the Riker-Ordeshook (1968) approach to voting behaviour with the Becker (1965) approach to 'personal production functions'. These predictions are then tested on survey data from the 1997 British Election Study. Our empirical findings are compatible with all the results of the theoretical exercise.