 The experimental methods available have also changed over time. Surveys have been the dominant method of experimental philosophy for the past few decades, but technology may change this: advances in virtual and augmented reality mean that philosophers can now immerse people in moral dilemmas such as Thompson’s (1971) violinist thought experiment and different versions of the trolley problem (e.g., Navarrete et al 2012). Philosophers interested in the neural correlates of moral judgment can use transcranial magnetic stimulation (TMS) to investigate the effects of enhancing or lessening activity in certain areas of the brain. Even survey methods have seen advances thanks to technology; the ubiquity of smartphones allows researchers to ping people in real time, asking for reports on mood (see section 3.2 below for a discussion of surveys relating to happiness and mood).