A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Organizational Studies, University of Regina. xiv, 159 p. Dual-process theories distinguish between more automatic, intuitive cognitive processes and analytical, reflective processes. One of the major contributions of this theoretical perspective is that people vary in the extent to which they are disposed to think in a more analytic and reflective way relative to relying more on their intuitions. Such individual differences have been linked to a large number of other important psychological factors, such as general cognitive ability (Stanovich, 1999), improved detection of fake news (Pennycook & Rand, 2019) and pseudo-profound bullshit (Pennycook, Cheyne, et al., 2015) as well as disbelief in epistemically suspect claims (Pennycook, Fugelsang, et al., 2015a). However, there are more than 20 measures that claim to assess thinking, which raises two distinct possibilities: 1) various researchers have developed measures of seemingly related but distinct types of thinking styles. This suggests that there isn’t a theoretical synthesis to be had; or, 2) many of these thinking style measures are derived from similar underlying theories – dual process theories (even if unstated by the researchers). We addressed this issue by correlating items from 14 thinking styles measures with the Cognitive Reflection Test (CRT; (Frederick, 2005; Toplak et al., 2014)), a behavioral measure of individual differences in analytic thinking (that also is confounded with cognitive ability). We reduced the number of items by selecting the items that had the highest correlation with the CRT. Next, across six studies, we systematically narrowed down the items and tested the underlying factor structure. This revealed that a four-factor correlated structure was best: Actively Open-Minded Thinking about Evidence (AOT-E), Dogmatism (AOT-D), Intuitive Thinking (IT), and Effortful Thinking (ET). Predictive validity for the resulting Comprehensive Thinking Style Questionnaire (CTSQ) was established using a host of variables (e.g., epistemically suspect beliefs, bullshit receptivity, empathy, moral judgments, among others). The CTSQ also correlated with performance on cognitive tasks including the Alice Heim Group Ability Test, CRT, and heuristics and biases. The CTSQ, or the individual subscales, can be used in place of popular thinking style measures, including scales like the Need for Cognition scale, but also behavioral measures like the CRT. Student yes