Chapter 6 offers the first look into the Discussion stage (Stage 3) of the 4D Framework. We focus on what people feel during a political discussion, captured using psychophysiological measurement during two different lab experiments. In the Psychophysiological Anticipation Study, we measure changes in participants' heart rates and skin conductance as they anticipate a political discussion. We find that individuals had a larger psychophysiological response to even the thought of engaging in a political discussion, compared to observing contentious discussions on video. In the Psychophysiological Experience Study, we measure variation in heart rate and skin conductance during real conversations. We find that individuals exhibit physiological signs of discomfort while in these conversations, especially when the conversation is disagreeable.

Chapter 7 continues our examination of the Discussion stage (Stage 3) of the 4D Framework, aiming to better understand what people actually verbally express in political conversations. We use a series of vignette experiments and a lab experiment to examine the extent to which people express their true opinions to the group, or engage in other expressive behaviors like self-censorship, silencing, or conformity. We find lab experimental evidence of conformity in real conversations and our vignette experiments revealed that individuals were less likely to reveal their real opinions when they were in the political minority and when they were less knowledgeable. We also find that individuals who were less knowledgeable were more likely to have affiliation concerns that explained their expression behavior. Finally, we analyzed the transcripts from the conversations in the Psychophysiological Experience Study to examine variation in what and how individuals discussed politics. We found that weak partisans were most likely to "hedge" their language when revealing their opinions and political identities.

We survey the empirical literature on ethical preferences, covering both survey studies and incentivized laboratory experiments. Crucial axioms such as the Pigou-Dalton transfer principle are not accepted by a large fraction of the subjects. Moreover, in formulating their distributive preferences, subjects attach much importance to the sources of income differences. Their preferences behind a veil of ignorance do not coincide with their preferences in the position of a social planner. These results suggest that prioritarian policy proposals will not necessarily be supported by a majority of the population. Although the majority opinion does not necessarily reflect the ethically desirable perspective, the empirical results still raise some interesting normative challenges

Chapter 8 describes the fundamental research questions, empirical approaches and findings of neurolinguistics. It is a highly interdisciplinary linguistic subfield focusing on the relationship between brain and language behaviour. Concentrating on experimental research, methodological issues include considerations on research participants, data types, and techniques of data acquisition and analysis. The chapter ends with recommendations for further reading and a list of short exercises and ideas for small research projects.

Experimental political science has transformed in the last decade. The use of experiments has dramatically increased throughout the discipline, and technological and sociological changes have altered how political scientists use experiments. We chart the transformation of experiments and discuss new challenges that experimentalists face. We then outline how the contributions to this volume will help scholars and practitioners conduct high-quality experiments.