Effects of Perceptual Fluency on Reasoning and Pupil Dilation

Research on perceptual disfluency has examined the effects of perceptually demanding stimuli on information processing and reasoning, suggesting that disfluent stimuli elicit slower and more effortful processing. Recent criticism of perceptual disfluency, however, suggests that the effects disfluent stimuli have on processing are marginal, and that they are mediated by individual differences. Participants completed a computerized reasoning task presented in either a fluent (i.e., easy-to-read font) or disfluent format (i.e., hard-toread font) while pupil diameter was measured by an eye-tracker system. Pupillometry is an established reliable measure of mental activity that reflects differences in cognitive load. Results showed no performance differences between the two groups, as well as no difference in pupil dilation between the groups. Similar to the recent critiques of perceptual disfluency, these results call into question if perceptual disfluency is a valid prime of attentive and deeper processing as has been theorized. Thesis Mentor: Dr. Ty W. Boyer Honors Director: Dr. Steven Engel April 2014 Department of Psychology University Honors Program Georgia Southern University Perceptual Fluency, Reasoning, and Pupil Dilation 1 This project would not have been possible without the dedicated guidance of Dr. Ty Boyer and the help of everyone in the Cognition, Learning, and Development Lab. Special thanks to Jimeisha Brooks for assistance with data collection. Perceptual Fluency, Reasoning, and Pupil Dilation 2 Effects of Perceptual Fluency on Reasoning and Pupil Dilation In our everyday lives, we are constantly making decisions. Some decisions are small, like choosing what to wear on a given morning, while some are a big deal, like which presidential candidate to vote for or where to attend graduate school. Regardless of the importance of the choice, people engage in different strategies to make these decisions, by either following their gut feelings or intuition, or by weighting all the pros and cons to formulate a careful and systematic choice. From the dual-process approach of reasoning, Type 1 processing is consider to be fast, intuitive and effortless, while Type 2 processing is consider to be slow, deliberative and effortful (Evans, 2010; Tversky & Kahneman, 1974). Most scholars concur that each mode serves a particular function and that both possess a set of beneficial characteristics and a set of potential flaws (Kahneman, 2011). Still, it is important to understand and know in which situations it would be more beneficial to depend on one specific type of reasoning. It is also important to know what other factors affect the type of reasoning with which we operate in a given situation. Many psychologists agree that the format in which information is presented impacts how we process the information, and subsequently the decisions we make with such information (Kahneman, 2011; Yue, Castel, & Bjork, 2012). A format may be in terms of gains or losses, numerical representations, or it can be something as simple as how easily, or fluently, the information is understood. Fluency has been defined as the subjective ease with which information comes to mind (Alter & Oppenheimer, 2009), while perceptual fluency has more specifically been defined as the subjective ease with which we process perceptual information. By contrast, perceptual disfluency is defined as the level of difficulty with which we process perceptual Perceptual Fluency, Reasoning, and Pupil Dilation 3 information. A few examples of the different levels of fluency include repetition (i.e., the more something it is repeated, the easier it is to remember it), prose (i.e., statements that rhyme are also remembered easier), or font type (i.e., easy-to-read font is read faster). Research on processing disfluency has focused on adjusting the ease with which we process information with the intent of prompting slower, deeper and systematic processing (i.e., Type 2). In particular, perceptual disfluency deals with the ease of processing stimuli on the basis of manipulations to the perceptual quality of such stimuli (Alter & Oppenheimer, 2009). This stream of research suggests that by using perceptually demanding stimuli individuals enter a state of cognitive strain, in which more effortful, attentive, and exhaustive thinking is required to successfully process information (Kahneman, 2011). As a result of this state of cognitive strain, our mind allocates mental resources to properly perceive the low-quality, or disfluent, stimuli, increasing attention and resulting in a slower, deeper processing as a byproduct of the additional mental resources (Alter, Oppenheimer, Epley, & Eyre, 2007; Kahneman 2011). This effect has been observed across several studies and in different fields including reasoning and problem-solving (Alter et al., 2007, Study 1 and 4), sematic illusions (Song & Schwarz, 2008), High School learning (Diedmand-Yauman, Oppenheimer, and Vaughan, 2010) and cognitive biases (Hernandez & Preston, 2013). Song and Schwarz (2009) also showed that perceptual disfluency sensitizes individuals to risk and threats while reducing their self-confidence at the same time. Despite these findings, the fluency hypothesis has been the subject of recent criticism, and some suggest that the effects of disfluent stimuli are marginal, at best, and are mediated by individual differences (Thompson et al., 2012). More importantly, Perceptual Fluency, Reasoning, and Pupil Dilation 4 several failures to replicate the results reported by Alter and colleagues (2007) have initiated a scholarly debate which calls into reconsideration the theoretical basis of disfluency (Thompson et al., 2012, 2013). As a result of this debate, it was proposed that perceptual dislfuency does elicit thorough and analytic thinking, though this does not guarantee greater accuracy on cognitive tasks (Alter, Oppenheimer & Epley, 2013). The current study aims to contribute to the ongoing discussion on perceptual disfluency by examining this claim. Pupillometry and Disfluency It has extensively been noted that changes in pupil diameter, and specifically dilation of the pupil, can serve as a reflection of cognitive load when an individual completes a cognitive task (Hess & Polt, 1960, 1964; Kahneman & Beatty, 1966; Laeng, Sirois, & Gredeback, 2012). Simply stated, when mentally solving a difficult problem (e.g., 13 x 14 = ___), one’s pupils dilate more, relative to when solving an easier problem (e.g., 3 x 4 = ___). This measurement has also proven to be reliable across different subject populations (Piquado, Isaacowitz & Wingfield, 2010). The physiological reason for this phenomenon is not well understood, though evidence suggesting the role of parasympathetic pathways and prefrontal cortex activation are prominent (Granholm & Steinhauer, 2004). Nonetheless, researchers around the world use pupillometry to study cognitive processes across multiple fields of study (Laeng et al., 2012), which include areas of research that have substantial overlap with disfluency research. For example, on average, individuals' pupils tend to increase in diameter when tested on the comprehension of syntactically ambiguous sentences (Engelhardt, Ferreira &Patsenko, 2010). Hyona, Tommola, and Alaja (2007) measured pupil dilations as a reflection of Perceptual Fluency, Reasoning, and Pupil Dilation 5 effortful comprehension of spoken non-native language. These processes seem to access similar cognitive systems as disfluency, however, no one, to our knowledge, has used pupillometry measures to specifically study the effects of perceptual disfluency on cognition.