The effect of demand characteristics on the facial feedback effect

Previous facial feedback experiments have resulted in mixed outcomes and small effect sizes. Because of this, researchers have suggested that variability in experimental validity may be to blame, namely demand characteristics. To address this, we created an experiment to see how demand characteristics might influence the facial feedback effect. We told participants different hypotheses about the facial feedback effect: that it exists, or that it doesn’t. Then, we had participants smile, scowl, and maintain a neutral expression. We found that demand characteristics influence facial feedback effects. Our results confirm that telling participants that the effect is real increases facial feedback effects and that telling participants that the effect is not real decreases facial feedback effects. Interestingly, we found a small, yet significant, effect even after telling participants that we were trying to prove that the facial feedback hypothesis is false. This finding shows that facial feedback isn’t completely driven by demand characteristics. EFFECT OF DEMAND CHARACTERISTICS ON FACIAL FEEDBACK 3 Introduction Many modern theories of emotion posit that sensorimotor feedback from the peripheral nervous system influences emotion (James, 1884). According to these theories, changes in the peripheral nervous system should lead to changes in emotional experience. One way of investigating this prediction is by manipulating facial expressions of emotion. The facial feedback hypothesis posits that when individuals make a facial expression of an emotion, then that physical change influences their emotional experience towards that emotion (Adelmann & Zajonc, 1989). This hypothesis is derived from broader theories that suggest sensorimotor feedback from the peripheral nervous system creates emotional experience. For example, the simple act of posing a smile can produce happiness; feeling happy can be influenced by them smiling in addition to the person’s happiness influencing them to smile. To date, evidence for the facial feedback hypothesis has been mixed. A seminal study found that the facial feedback effect occurred when participants unknowingly made smiling faces and evaluated humorous material (Strack, Martin, & Stepper, 1988). They directed participants to hold a pen in their mouth in two different ways to create and inhibit a smile. After performing tasks using the pen, they were asked to rate a cartoon on its funniness. They found that the cartoons were rated the funniest when creating a smile with the pen, and least funny when inhibiting a smile. However, recent replications of this study have failed, with some attributing this failure to the effect being either weak or completely false (Wagenmakers et al. 2016; Strack, 2017). This hypothesis has also been tested using other experimental models. Researchers have found that making the facial expression and/or postures of various emotions such as fear, happiness, anger, and disgust resulted in participants rating higher levels of the corresponding emotions (Larsen, Kasmatis, & Frey, 1992; Duclos et al., 1989). However, a facial feedback effect has not been found for surprise (Reisenzein, Studtmann, & Horstmann, 2013). Nevertheless, an examination of the cumulative evidence via meta analysis suggests that facial feedback can have a small effect on emotional experience (Coles, Larsen, & Lench, 2019). Despite this, the evidence remains mixed. EFFECT OF DEMAND CHARACTERISTICS ON FACIAL FEEDBACK 4 Demand Characteristics As explained below, a common explanation is that these effects are not real, but are the result of demand characteristics (Kaiser & Davey, 2017). Demand characteristics are cues in a study that make participants aware of the study’s hypothesis (Orne, 1962). While demand characteristics come in many forms (Sharpe & Whelton, 2016), the most popular has to do with the result of hypothesis awareness and the “good participant” role (Orne, 1962). A participant becomes aware of the hypothesis. Then, as a result of this awareness and wanting to please the researcher, the participant reports what they think the researcher wants to hear, not what they are truly experiencing. Demand characteristics are particularly concerning to facial feedback researchers for multiple reasons. First, many methods used in facial feedback research may alert participants about the experimenter’s interest in studying facial feedback effects. For example, a participant directed to raise their cheeks and show their teeth might guess they are being asked to smile. Second, self-reports are the primary means to measure emotions, which are easily changed by the participant. Emotions are subjective in nature, which necessitates subjectivity within these experiments ​(​Larsen & Fredrickson, 1999)​. ​ Consequently, if participants become aware that the experimenter is testing the effects of posed smiles on happiness, they have the ability to adjust their self-reports accordingly. Third, if references to popular media are any indication (Spector, 2017), people believe that smiling influences happiness. As such, participants do not need formal education on the facial feedback hypothesis to deduce that the experimenter is interested in the effects of smiling on happiness. To summarize, facial feedback experiments are particularly vulnerable to demand characteristics because it is easy for participants to guess that the experiment is interested in emotions, participants can easily change their self-reports of emotions, and many participants are familiar with the idea of facial feedback. To address these concerns, facial feedback researchers have Kaiser & Davey (2017) found that when controlling for participant’s awareness of the hypothesis, the facial feedback effect was only found in participants that were aware of the study’s interest in emotion. In this study, participants were told to change eyebrow and cheek muscles to create a smile, a frown, and a neutral expression while reading statements that were clearly positive, clearly negative, and ambiguous. Then, participants completed a EFFECT OF DEMAND CHARACTERISTICS ON FACIAL FEEDBACK 5 two part debrief to determine awareness of the study’s hypothesis; participants that mentioned emotional expressions in an open-response portion were deemed aware, participants that selected relevant hypotheses from a checklist of possibilities were deemed to have prompted awareness, and those that did neither were completely unaware. This study only found a facial feedback effect in participants that were completely aware, not in those who had prompted awareness or were unaware. Specifically, while all groups had a main effect for statement type, the aware group was the only one who had a main effect of pose on their ratings of the ambiguous statement. This study corroborates previous beliefs that facial feedback effects may be driven by demand characteristics. Addressing Demand Characteristics in Facial Feedback Experiments To date, facial feedback researchers have used two broad approaches to addressing demand characteristics. First, some researchers measure and control for the degree to which participants are aware of the purpose of the experiment, often through a digital survey or in-person interview. If there is any indication that the participant believed that the experiment had to do with emotions, then their data is analyzed, and either controlled or excluded as statistically appropriate (Duclos et al., 1989; Reisenzein & Studtmann, 2007). However, there are a few limitations of this method. First, these interviews do not occur until the end of the experiment, so it is often unclear if participants were aware of the purpose of the study during vs. after the study. Furthermore, participants who are already trying to be good participants might also intentionally deny awareness of the experiment's purpose (Orne, 1962). A second approach that facial feedback researchers use to address concerns about demand characteristics is to deceive the participant about the true nature of the study. For example, Strack, Martin, & Stepper (1988) influenced participants to smile or pout by directing them to hold a pen in their mouth in different ways. However, deception requires more complicated directions that may be unclear to the participant. Consequently, participants may be unable to follow these directions correctly and may create expressions that do not resemble a genuine expression of emotion (Soussignan, 2002). Another flaw is that after this, an interview must be conducted to determine the experimenter’s success in deceiving the participant. Because of this, the experiment then involves previously mentioned issues of EFFECT OF DEMAND CHARACTERISTICS ON FACIAL FEEDBACK 6 trusting the participant’s word and our own assumptions on the relationship between participant awareness and demand characteristics. Our experiment seeks to examine the effects of demand characteristics using a third approach: manipulating ​ demand characteristics. To do this, we will present participants with explicit hypotheses and examine how each hypothesis changes as a result. In our study, we either told participants that we believe that the facial feedback effect exists, told them that the facial feedback effect does not exist, or kept the participants unaware of our interest in the facial feedback effect. While eliminating demand characteristics may be a simpler experimental model, manipulating them provides a more rigorous test. If the facial feedback effect is false and is driven solely by demand characteristics, then there should be no effect found when participants are told that the effect is false. However, finding the effect in this condition would be strong evidence that the facial feedback effect exists. We hypothesize that participants are told that the facial feedback effect exists, then demand characteristics will cause them to report more intense emotions than if we tell them