Order constrained modeling and inference in psychology and law

There is much debate, in the field of Psychology and Law, about race effects and racial bias in legal contexts. Many studies report that people display favoritism towards suspects with light skin over suspects with dark skin. Other studies report the opposite effect, where participants give disproportionately favorable judgments and trial outcomes to suspects of color (see Mitchell et al., 2005 for a full meta-analysis). Such conflicting findings provide an ideal opportunity for model competition. We introduce order-constrained modeling to the field of Psychology and Law. Specifically, we model participants’ decisions when put in the role of an interrogator questioning a suspect. We formed a set of 28 mathematical models by taking a series of verbal hypotheses and translating them into order constraints on Binomial parameters. The hypotheses are informed by various research in Psychology and Law regarding how people’s initial guilt judgments about others might affect later decisions (O’Brien, 2009), how tattoos on a suspect could affect observers’ judgments (Brown et al., 2018), and how the race of a suspect might impact the decisions people make about the suspect (Mitchell et al., 2005). Order-constrained modeling allows us to distinguish very specific, nuanced predictions about how these factors might impact people’s decision making. It also allows for combinations of predictions about the impacts of these factors to be tested jointly, in a single statistical test. We also consider novel mixture models that can capture two sub-populations with different race effects. These mixture models provide an opportunity to explore race-related effects in a new light. We pit all competing hypotheses against each other and test them using our lab’s software, QTEST (Regenwetter et al., 2014; Zwilling et al., 2019).