Implicit Influence of Affective Postures on the Perception of Others: You Can t Show Me How I Feel

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1 Emotion 2011 American Psychological Association 2011, Vol. 11, No. 3, /11/$12.00 DOI: /a Implicit Influence of Affective Postures on the Perception of Others: You Can t Show Me How I Feel Julia L. Wilbarger, Catherine L. Reed, and Daniel N. McIntosh University of Denver This study examined how one s own posture influences the perception of another s posture in a task with implicit affective information. In 2 experiments, participants assumed or viewed a body posture and then compared that posture with a viewed posture. They were not told that postures varied in affective valence: positive, negative, neutral-abstract, or neutral-meaningful. Posture affect influenced both accuracy and response time measures of posture discrimination. Participants were slower and less accurate for targets that matched an assumed posture, but only for affective postures. This pattern did not hold for matching affectively neutral postures (meaningful or not), nonmatching postures, or for purely visual comparisons. These results are consistent with both cognitive embodiment theories postulating that personal body posture influences the perception of other s postures and emotional embodiment theories postulating sensorimotor and emotional simulation processes that create correspondences between one s own and another s emotional postures. Nonetheless, these findings differ from studies finding facilitation for explicit emotional judgments of affective congruence. People use different information depending on task requirements. The assumption of an affective posture may activate simulations of personal emotional experiences that may, in turn, serve to differentiate personal posture perception from ostensibly the same posture in another person. Keywords: emotion, affect, body perception, embodiment Social perception is an essential part of our everyday interactions. We need to know who people are, what they are doing, and how we should respond to their actions. Much of this information is communicated nonverbally through the face, but body postures are another, perhaps more primal, means of display. Although multiple processes support social emotional interactions, the perception of body posture is one mechanism that opens a window to the emotions and intentions of others (e.g., Atkinson, Dittrich, Gemmell, & Young, 2004; de Gelder, Snyder, Greve, Gerard, & Hadjikhani, 2004; Hatfield, Cacioppo, & Rapson, 1994). We often discern information about others internal states from subtle cues, such as the slump of the shoulders or the tilt of a head, whether we are explicitly conscious of this assessment or not. Knowledge of one s own body and the current actions of one s body may assist in this process by providing a cross-modal template on which one can come to understand others (Meltzoff & Moore, 1995; Reed & Farah, 1995; Reed & McGoldrick, 2007). Despite progress documenting that embodiment processes affect social perception, the specific processes underlying the role of body-specific processing Julia L. Wilbarger, Catherine L. Reed, and Daniel N. McIntosh, Department of Psychology, University of Denver. Julia L. Wilbarger is now at the Department of Kinesiology, University of Wisconsin Madison. Catherine L. Reed is now at the Department of Psychology, Claremont McKenna College. Correspondence concerning this article should be addressed to Julia L. Wilbarger, Department of Kinesiology, University of Wisconsin Madison, 3176 Medical Science Center, 1300 University Avenue, Madison, WI jlwilbarger@education.wisc.edu mechanisms on social perception remain underspecified (Reed & McIntosh, 2008; Winkielman, McIntosh, & Oberman, 2009). Examination of the role of body-specific processing across different social tasks and contexts is therefore needed (Reed & McIntosh, 2008; Wilson, 2002). Our bodies help organize information about others and help us perceive our similarities and differences from them (Reed & McIntosh, 2008). Indeed, our cognitive systems appear to have developed efficient multimodal processes attuned to human body structure and biomechanics to determine whether a visual stimulus (i.e., another person) is like me or the extent to which its physical body can be mapped onto one s own (Reed & Farah, 1995; Reed & McGoldrick, 2007; Wilson, 2002; Wilson & Knoblich, 2005). Correspondences, or matches, between what the perceiver s and another s actions tend to affect performance (Jacobs & Shiffrar, 2005). Reed and colleagues (Reed & Farah, 1995; Reed & McGoldrick, 2007; Reed & McIntosh, 2008) demonstrated a link between the cognitive representations of the perceiver s and another s bodies. In a dual-task paradigm, they found that when participants positioned their body parts in a series of nonrepetitive postures, memory was differentially affected for the corresponding body part positions in another person (i.e., arm movement influenced memory for a visual target s arm position relative to leg position and vice versa). This interaction suggests that a common body representation is used to create a correspondence between one s own self and that of others. At a neural level, facilitated performance obtained from self other correspondences has been attributed to the operation of mirror neuron systems that support this mapping (Jackson & Decety, 2004; Rizzolatti, Fadiga, Fogassi, & Gallese, 2002). 481

2 482 WILBARGER, REED, AND MCINTOSH The contribution of the body to social perception, however, involves more than recognizing that someone else is like me at an anatomical level. It also involves assessment of another s emotional state whether they feel positively or negatively toward us. It is important to be able to distinguish subtle differences between postural cues for emotional and nonemotional actions. Recognizing whether someone is reaching over his/her head to strike you or to scratch behind an ear could be critical for survival. Discerning these subtle nuances of human action is something that people do well even with degraded information (Atkinson et al., 2004). Researchers have extended the idea of embodied cognition to that of emotional processing to explain how one s own body can play a role in understanding another s emotional experience, whether the emotional information is explicit or not (Damasio, 1994; Gallese, 2003; Jackson & Decety, 2004; Niedenthal, Barsalou, Winkielman, Krauth-Gruber, & Ric, 2005). Automatic mimicry of facial expressions and body postures is theorized to facilitate knowledge of others emotional states via internal feedback that creates a change in a felt emotional experience (e.g., Hatfield et al., 1994; McIntosh, Druckman, & Zajonc, 1994). The assumption of an emotional facial expression or posture can initiate or change the person s emotional state to be congruent with that expression or posture (McIntosh, 1996). Body posture in particular influences subjective experience of emotion (Riskind, 1984; Stepper & Strack, 1993). Individuals induced to assume postures characteristic of certain emotions report feelings that correspond to those postures; those who slumped tended to feel sad, and those who sat more forward with clenched fists tended to feel anger (Dulcos et al., 1989). By assuming the emotional faces or postures of another, an individual may catch the emotions of that other person (Hatfield et al., 1994; McIntosh, 2006; McIntosh et al., 1994). Sharing an emotional expression or posture and thus an emotional state with another presumably leads to greater knowledge of the other person s feelings, empathy for his/her emotions, and better predictions of his/her subsequent actions. More specifically, understanding of the emotions of others may involve a simulation process that incorporates current bodily input and previous emotional experiences in the modality-specific systems in which they were originally experienced (Niedenthal, 2007). Congruency between the perceiver s mood and the viewed person s emotion may lead to facilitated emotional perception via a simulation process in which shared representational systems are used to represent both the mood and the target (Niedenthal et al., 2005; Wallbott, 1991). Because the simulation of the target relies on the same representational systems as the perceiver s emotion, there can be an interaction between the two. Evidence for embodied simulation in emotion perception comes from a variety of behavioral and neuroscience studies (Adolphs, 2006; Goldman & Sripada, 2005; Winkielman et al., 2009) and supports a link between emotional face and body expressions and the initiation and modulation of a felt emotional experience. For example, when participants categorized photographs of emotional facial expressions, videotaped data showed that they matched the expressions of the faces they were categorizing and that the extent of this mimicry was positively correlated with emotional classification accuracy (Wallbott, 1991). Moreover, Niedenthal, Halberstadt, and Innes-Ker (1999) showed that the ability to engage in facial mimicry (reproducing the observed stimulus using one s own muscles) influenced people s perceptions of facial emotion. Participants were shown a series of images depicting facial expressions that morphed from happy to sad and vice versa. Participants who were inhibited from spontaneously moving their own face muscles indicated that facial expressions changed later than participants who were allowed to engage in facial mimicry and somatic feedback. These findings support the idea that one s own body is used to recognize the emotional expressions of others. However, given that the context of an action influences perceptual processing (Moore, 2006), the influence of body-specific processing may differ depending on the relevance of emotional processing to that task. A number of studies have found that body posture influences explicit judgments of emotional content in visual stimuli (Niedenthal et al., 2005; Strack, Martin, & Stepper, 1988). However, less is known about the role of embodiment when emotion is an implicit part of the task, rather than explicitly part of the task and judgment response. Most emotional judgments in everyday social life are implicit. Thus, examination of the body s influence on processing when people are not explicitly asked to categorize other s emotions is critical for understanding embodiment processes. In this study, we addressed whether emotional body postures implicitly influence processing on a nonemotional, cognitive task. Current Study Although body state contributes to social perception, it is unclear the extent to which emotional processing is distinct from other body-specific dimensions of social perception. The bodyrelated aspects of social perception require that we determine whether someone else has a body similar to our own; indeed, the establishment of self other correspondences influences cognitive performance (e.g., Reed & McGoldrick, 2007). However, the studies cited above argue that it is not just the body posture per se, but also the emotional content of the observer s expression that influences emotional judgments of others (Niedenthal et al., 2005). The questions addressed in this study were whether emotional information is treated differently from body-specific information by our perceptual systems, and whether the two types of information interact. In this study, we used a body perception task that had no a priori or explicit demand for emotion processing to investigate whether implicit, nonintentional emotional information from the perceiver s own body influences performance on a visual posture discrimination task. Postures varied implicitly in affective valence (positive, negative, or neutral). Unlike other studies of embodied emotion, our participants did not identify or judge the posture s emotion only whether two postures were the same or different. We distinguished between two basic hypotheses. The general embodiment hypothesis emphasizes body-specific aspects of social perception and proposes that a perceiver s body posture influences the perception of another s posture with no additional influence of emotional content. Accordingly, preferential performance should be observed for trials in which the perceiver s and target postures matched over nonmatched trails regardless of the emotional valence (Niedenthal et al., 1999; Rizzolatti & Craighero, 2004; Williams et al., 2006). Alternatively, the emotion-specific embodiment hypothesis proposes that the affective content of a posture interacts with the perception of body postures. It suggests that emotions have differential processing because information

3 IMPLICIT INFLUENCE OF AFFECTIVE POSTURES 483 from the body provides feedback that induces or modulates an emotional experience via somatic feedback despite the nature of the task (Hatfield et al., 1994; McIntosh, 1996, 2006; Niedenthal et al., 2005). The emotion-specific embodiment hypothesis predicts that affective (positive or negative) postures are processed differently from neutral postures. Experiment 1 Experiment 1 investigated whether implicit emotion information influences body posture discrimination. Unlike most previous studies of embodied emotion, the task used in Experiment 1 was purely a perceptual discrimination task and did not require a judgment of emotional category, valence, or intensity. This task was selected because it should evoke body-specific processing. Differential body-specific processing has been observed when two postures match or one person imitates another (Rizzolatti & Craighero, 2004; Williams et al., 2006). Similar findings have been found when one person imitates the emotional expression of another (Niedenthal et al., 2005). However, different theories have alternative predictions for how posture matching affects performance. Imitation theory (e.g., Williams et al., 2006) predicts faster and more accurate performance when postures match. Emotional contagion theory (Hatfield et al., 1994) predicts that matching an affective posture (compared with neutral postures) will produce faster, more accurate perception of another person s posture when the two postures match. However, common-code theories (Prinz, 1997; Rothschild, 2006) might predict perceptual interference for both postures and emotions because they activate common representations at the same time. Experiment 1 also investigated whether proprioceptive inputs from one s own body affect body posture discrimination differently from purely visual body posture comparison. Prinz (1997) and Reed and colleagues (2007) have found body-specific processing when comparing proprioceptive posture inputs from the observer with visual posture inputs. In a no-posture condition, participants engaged in a simple visual discrimination task: A visual body posture image was presented, followed by a blank interstimulus interval (ISI), and then a second visual body posture image was presented and compared with the first image. In the posture condition, participants actively assumed a posture for a short time, followed by an ISI, and then compared their own previously assumed posture with a visual body posture image. If personal postural inputs influence performance differently from purely visual postural inputs, it suggests that the same body representation is being used for both proprioceptive inputs from the self and visual inputs from another (Prinz, 1997; Reed & McGoldrick, 2007). To explore whether implicit affective information influences performance, we varied body postures along three affective dimensions: negative, positive, and neutral-abstract. Participants were never told that the postures varied in affect or meaning. Thus, if the affective qualities of the postures were processed automatically, then posture discrimination performance should be different for affective (positive, negative) postures compared with neutralabstract postures. This finding would support the emotion-specific embodiment hypotheses predicting that the emotion of a posture differentially affects the perception of others emotional postures. Furthermore, because positive and negative affective stimuli may also be processed differently (Cacioppo & Berntson, 1994; Hess, Philippot, & Blairy, 1998), both positive and negative dimensions were considered separately in analyses. However, if the processing of body postures is independent of emotional processing as predicted by a general embodiment hypothesis, then the affective valence of the postures should not affect posture discrimination performance. Finally, body posture processing may interact with emotional processing because body representations are also used to interpret emotional or affective information (Niedenthal et al., 2005). Simulations of personal emotional experiences are said to be created when observers assume emotional postures as well as when they see others in emotional postures or expressions (Niedenthal, 2007). If this is the case, we predicted an interaction among postural condition, affective valence, and postural match. Method Participants. Forty-nine undergraduate students (mean age 19.8 years) received extra credit toward psychology courses for their participation in this study. Data from 14 participants were eliminated because more than 20% of their vocal responses were lost due to equipment error. As a result, data from 35 participants (11 men) were analyzed. These participants were assigned randomly to one of two postural conditions: a no-posture condition (n 18) and a posture condition (n 17). Stimuli. Visual posture stimuli were images of a human body created using Poser 2 software (Curious Labs, Inc., Santa Cruz, CA). Each image was approximately 17.5 cm tall and depicted a male human form in a particular posture. All images had a common, neutral facial expression. The images were significantly life-like to represent the human form and evoke body-specific processes (Heptulla-Chatterjee, Freyd, & Shiffrar, 1996). Seven images were created for each of three affective categories (see Figure 1): affectively negative postures (i.e., fear, mad, anguish), affectively positive postures (i.e., joy, nurture, hug), and affectively neutral-abstract postures (e.g., cannot provide a verbal label for the posture). Each posture was equated for the number of body parts involved. Following the experiment, a subset (n 24) of the participants rated the emotionality of each body posture on a scale from 5 to 5. Pretesting confirmed the affective valence of the stimuli. The mean ratings for the negative (M 2.05, SD 0.98), neutral (M 0.29, SD 0.90), and positive (M 1.99, Figure 1. Examples of visual affective posture stimuli: negative, neutral, and positive.

4 484 WILBARGER, REED, AND MCINTOSH SD 0.73) postures were significantly different from each other (p.05). Directions for assuming body postures consisted of a several, simple verbal instructions to move individual body parts. Directions ranged from three to five steps. Each direction was for the participant to move a specific body part. These instructions were presented on a computer screen in a 36-point font (see Table 1). Most participants reported that poses were easy to assume correctly, and only four participants required verbal prompts to assume the poses correctly. Two types of trials were constructed. In match trials, the initial posture matched the target posture. In the no-match condition, the initial posture was different from the target posture. To create no-match trials, each initial stimulus was paired with one target stimulus from each affective category. Half the trials were match and half of the trials were no match. Each posture was presented 6 times randomly throughout the experiment for a total of 126 trials. Apparatus. The experiments were run on a Power Mac7100/ 66. The stimuli were presented on a 15-in. color monitor with pixel resolution. The stimulus presentation and responses were coordinated using PsyScope (Pittsburgh, PA) software and a button box. A microphone connected to the button box recorded voice responses and response time (RT). Procedure. Participants were randomly assigned to either the no-posture or the posture condition. In the no-posture condition (see Figure 2), participants sat and were asked to direct their attention to the computer screen positioned 36 in. away at eye level. We required participants to sit to reduce the natural tendency to imitate body posture stimuli and minimize bodily correspondences between the perceiver and the visual posture stimuli. In each trial, participants were presented a body posture stimulus for 250 ms followed by a 2.5-s ISI and a 250-ms presentation of a target body posture stimulus. The target was rotated 45 to the left so that the participants had to make use of an internal representation of the posture rather than simply matching a visual image. As fast and as accurately as possible, the participant responded verbally whether the initial and target postures were the same or different. In the posture condition (see Figure 2), the participant stood in front of a computer monitor located 36 in. away at eye level. They started in a neutral posture: standing, facing forward, arms down at their sides, and feet parallel about 8 in. apart. The initial stimulus was a set of written directions that instructed the participant to assume a specific posture. Once in the posture, the instructions were cleared from the screen. The posture was held 1.5 s and participants returned to the starting posture when RELAX appeared. After a 2.5-s ISI, the target appeared and participants responded verbally whether the assumed and target postures were the same or different. For both conditions, response accuracy and RT were recorded. Participants were videotaped to ensure that the postures were assumed correctly. Results Videotape analysis by an independent rater confirmed that all participants accurately assumed the postures in the posture condition. Proportion error and mean RT were calculated for each condition. For all analyses, alpha was set at.05. Table 1 Examples of Labels and Directions for Assuming Postures in Experiment 1 Negative affect Positive affect Neutral affect Anguish Fear Joy Play Put your left hand behind your back. Put both arms out to the sides. Put one foot on the yellow dot to your right. Put both arms out to the sides with palms up. Put your right foot on the green dot behind you. Put your right hand on your forehead. Bend your wrists up. Put your right hand on your right thigh. Raise your arms up more. Raise your right arm above your head. Raise your right hand palm out in front of your forehead. Tip your head forward and down a little. Raise your left arm away from your side a little. Drop your shoulders. Raise your left hand palm out in front of your chest. Lean back.

5 IMPLICIT INFLUENCE OF AFFECTIVE POSTURES 485 a Proportion of Error No Posture Negative Positive Neutral- Abstract Affect Condition Non-match b Proportion of Error Posture Negative Positive Neutral- Abstract Affect Condiiton Non-match Figure 2. Experimental paradigm: Body posture discrimination task. In the no-posture condition, participants compared two, sequentially presented visual posture stimuli. In the posture condition, participants followed written directions to physically assume a posture and compared their own posture with a visual posture stimulus. Posture conditions. To determine whether posture conditions influenced discrimination performance overall, an F test for posture condition (no posture vs. posture) indicated that the noposture condition had fewer errors, F(1, 33) 6.02, p.02, and faster RTs, F(1, 33) 12.65, p.001, than the posture condition. Overall, physically assuming an emotional posture decreased the speed and accuracy of posture discrimination. Error data. To determine whether the affective valence of the perceived postures and the congruency between two postures influenced the accuracy of posture perception, we conducted a 3 (affect: negative, positive, neutral) 2 (match: match, no match) repeated measures analysis of variance (ANOVA) for each of the posture conditions (no-posture and posture) using error data. For the no-posture condition, there were no significant main effects or interactions. Only the main effect of match, F(1, 68) 3.58, p.076, and the interaction for affect by match, F(2, 68) 2.77, p.077, approached significance. There was a trend for match trials to be more difficult than no-match trials, but only for the negative and positive postures (see Figure 3). For the posture condition, there were significant main effects for affect, F(2, 32) 6.71, p.01, and match, F(1, 32) 11.87, p.01. Post hoc analyses revealed that negative postures were more difficult to distinguish than either neutral postures, t(16) 3.92, p.001, or positive postures, t(16) 2.1, p.05. Positive and neutral postures were not significantly different from each other, t(16) 1.37, p.19. trials were more difficult to distinguish than no-match trials. However, the interaction between affect and match, F(2, 32) 10.00, p.001, clarifies these effects (see Figure 3), indicating that affect influences error rate for match trials only (i.e., participant posture matched the target posture). Post hoc analyses revealed greater error rates for match than no-match trials but only for negative and positive postures Figure 3. Experiment 1: Affect by match interactions for error data in (a) no-posture and (b) posture conditions. Error bars indicate standard error. negative, t(16) 3.36, p.004; positive, t(16) 4.5, p.001 but not for neutral postures t(16) 1.75, p.09. RT data. RT data produced similar patterns as the accuracy data and confirmed the affect by match interaction (see Figure 4). A 3 (affect: negative, positive, neutral) 2 (match: match, no match) repeated measures ANOVA was conducted for each of the posture conditions. For the no-posture condition, there were no significant main effects or interactions. In contrast, for the posture condition, there were significant main effects of affect, F(2, 32) 6.38, p.01, and match, F(1, 32) 9.53, p.01. Post hoc a Response Times (ms) b Response Times (ms) No Posture Negative Positive Neutral- Abstract Affect Condition Posture Negative Positive Neutral- Abstract Affect Condition Non-match Non-match Figure 4. Experiment 1: Affect by match interactions for response time (RT) data in (a) no-posture and (b) posture conditions. Error bars indicate standard error.

6 486 WILBARGER, REED, AND MCINTOSH analyses revealed that negative postures were slower than both positive, t(16) 3.11, p.007, and neutral postures, t(16) 2.78, p.01, but positive and neutral trials did not differ from each other (p.05). RTs were also slower for match compared with no-match trials, t(16) 3.34, p.004, as well as the affect by match interaction, F(2, 32) 3.78, p.05. The interaction revealed differences between match and no-match trials for affective postures, but not for neutral postures. RTs for negative and positive postures for match trials were significantly slower than the no-match stimuli, t(16) 3.81, p.002, and t(16) 3.90, p.001, respectively, but there were no differences between match and no-match trials for neutral postures, t(16) 1.02, p.30. Discussion In summary, physically assuming an emotional posture decreased the speed and accuracy of posture discrimination relative to comparing two visual postures. However, the affective qualities of the posture one has assumed also affect performance. When personal posture and target postures match, discrimination performance declines (more errors, slower RTs) when the posture has a positive or negative affective valence relative to postures with an affectively neutral valence. Negative postures seem to accentuate the effect. These findings suggest that the observer s body influences visual perception differently from purely visual processing. Discrimination performance was influenced only in the posture condition and for those postures that matched; no effects were found for the no-posture condition. The posture discrimination task appears to evoke body-specific processing. Although this finding supports an embodiment hypothesis, stronger support was found for an emotion-specific embodiment hypothesis because the affective valence of the stimuli influenced performance above and beyond an overall embodiment effect. Differential discrimination performance was found only for matching affective postures in the posture condition. In the posture condition, when the assumed affective posture matched the visual target, responses were slower and less accurate than when the assumed affective posture did not match the target. This pattern of results is the opposite of what has been found in studies that required participants to assume face or body postures and make judgments about the emotional content of a visual stimulus (Hatfield et al., 1994; Niedenthal et al., 1999; Williams et al., 2006). Thus, it was important to replicate our findings in a second experiment and address potential alternative explanations for the affect by match interaction. Experiment 2 In Experiment 2, we modified the methodology of Experiment 1 and addressed two potential alternative explanations for the affect by match interaction. First, the affective stimuli used in Experiment 1 had semantic meaning in contrast to the neutral stimuli. Thus, the interaction may have stemmed from the use of additional semantic mechanisms to process affective but not neutral postures. To address this issue, we added a fourth set of stimuli that could be verbally labeled and that were semantically but not emotionally meaningful. For example, participants viewed and assumed postures such as salute or stop. Examples of the labels and meanings for the sets of emotional and meaningful postures are listed in Table 1. In Experiment 2, we used four sets of stimuli: affectively negative, affectively positive, neutralabstract (i.e., cannot be labeled easily), and neutral-meaningful (i.e., can be labeled easily). Second, the difference between affective and neutral stimuli may be related to physical difficulty. The affective postures may have differed from neutral postures in terms of physical complexity because the sets differed in the number of directions or steps to achieve the postures. To address this potential issue, we equated the number of steps to assume all stimulus postures. In addition, at the end of the experiment, participants viewed an image of each posture and rated it for difficulty in achieving that posture. As in Experiment 1, participants were videotaped and their tapes were analyzed to ensure that the participants assumed the correct positions. Method Participants. Undergraduates from the University of Denver participated for extra credit in their psychology courses. Nineteen participants rated the affective qualities of the new stimulus set prior to Experiment 2. Twenty-four different participants (mean age 19.5 years) took part in Experiment 2. Data from eight participants were eliminated because more than 20% of their vocal responses were lost due to microphone error. As a result, data from 16 participants (eight men) were analyzed. In addition, 13 of the participants from Experiment 2 and 13 additional participants who did not participate in Experiment 2 rated the online difficulty of assuming each of the postures. Stimuli. Four stimulus sets were used: three sets from Experiment 1 (affectively negative, affectively positive, neutralabstract) plus a new neutral-meaningful set. The same procedure was used for creating the neutral-meaningful stimuli as in Experiment 1. There were four stimuli in each set. Stimuli were pretested to establish their affective valence and meaningfulness. Individuals (n 19) who did not take part in the experiment rated the affective qualities of the stimuli on a 9-point scale from 1 (very negative expression) to9(very positive expression). The mean ratings for stimuli in each category were negative 3.1, positive 6.8, neutral-abstract 4.8, and neutral-meaningful 4.6. Neutralabstract and neutral-meaningful categories were not significantly different from each other (p.05), but were significantly different from the negative, t(18) 6.30, p.001, and t(18) 5.40, p.001, respectively, and positive stimuli, t(18) 6.40, p.001, and t(18) 7.80, p.001, respectively. The positive and negative stimuli were also rated as significantly different from each other, t(18) 8.61, p.001. These participants were then asked to describe the stimuli in one or two words. Their descriptions were highly consistent. For example, the neutral-meaningful stimuli were described as (a) salute or military pose, (b) don t know or questioning, (c) halt or stop, and (d) wait or slow down. Apparatus. The same equipment was used as in Experiment 1. Procedure. The procedure was similar to the posture condition in Experiment 1. The instructions for all postures were constructed from a common set of directions for movement of a single body part. Each of the individual body part directions was practiced before the beginning the experiment to ensure that partici-

7 IMPLICIT INFLUENCE OF AFFECTIVE POSTURES 487 pants knew what the directions meant and could execute the position accurately. For each posture, participants received four sequentially presented instructions to assume the pose (see Table 2). This change in procedure equated the number of instructions across postures and standardized the time postures were held. As in Experiment 1, participants were asked to compare their own posture with the visual target posture. For all trials, participants moved themselves into a particular posture based on instructions presented on the computer monitor and held that posture for 1.5 s. When RELAX appeared on the screen, they returned to the starting position of arm at sides and legs together. After a 2.5-s ISI, a visual target was presented and participants determined whether the two postures were the same or different. There were 128 trials total. Participants were videotaped during the experiment so that the fidelity of their assumed poses to the target could be assessed. At the end of the experiment, participants were asked to provide subjective ratings of the difficulty to assume each posture. Results The data were processed in the same manner as Experiment 1. Analysis of the videotaped postures by an independent rater confirmed that participants accurately assumed the postures. Error data. A 4 ( affect: negative, positive, neutral-abstract, neutral-meaningful) 2 (match: match, no match) repeated measures ANOVA was conducted for proportion error data (see Figure 5a). Significant effects were found for match, F(1, 15) 23.88, p.0001, and for the affect by match interaction, F(1, 15) 3.74, p.039, but not for affect, F(1, 15) 1.68, p.05. Overall, match trials were less accurate than no-match trials, but the interaction demonstrated that this difference varied by affect. The difference between match and no-match trials was greater for negative, t(15) 3.88, p.05, and positive postures, t(15) 4.35, p.05, than for neutral-abstract postures, t(15) 2.20, p.05. There was no difference between match and no-match conditions for neutral-meaningful postures (p.05). These findings suggest that the semantic content of the affective postures did not drive the affect by match interaction found in both Experiment 1 and Experiment 2. RT data. As in Experiment 1, RT data confirm the affect by match interaction (see Figure 5b). A 4 (affect: negative, positive, neutral-abstract, neutral-meaningful) 2 (match: match, no match) ANOVA was conducted for RT data. Main effects were found for affect, F(3, 13) 3.79, p.038; negative , SE 37.24; positive , SE 53.93; neutral-abstract , SE 32.43; neutral-meaningful , SE 38.85; and match, F(1, 15) 10.67, p.005; match , SE 41.34; no-match , SE The significant affect by match interaction, F(3, 13) 4.62, p.02, replicated the results of Experiment 1, indicating a significant difference between affective and neutral stimuli for the match condition. The negative and positive postures were significantly slower for the match than the no-match trials: negative, t(15) 3.50, p.003; positive, t(15) 2.57, p.021, but not for the neutral-abstract, t(15) 1.13, p.05, or neutral-meaningful postures, t(15) 1.63, p.05. Again, semantic content did not appear to drive the affect by match interactions of Experiments 1 and 2. Postural difficulty ratings. To determine whether affective postures were more difficult to assume than neutral postures, a Table 2 Directions for Assuming Postures in Experiment 2 Negative Positive Meaningful Neutral Anguish Touched Salute Neutral 8 Put both feet on the red dots. Put both feet on the red dots. Put both feet on the red dots. Put both feet on the red dots. Put your right hand on your forehead. Put your right hand on your chest. Put your right arm out to the side. Put your right arm out to the side. Drop your shoulders. Relax your right arm. Put your right hand near your eyebrow. Put your right hand behind your back. Tilt your head forward. Tilt your head to the left. Turn your right palm down. Put your left hand on your left thigh. Aggression Come here Wait Neutral 4 Put your left foot on the blue dot. Put both feet on the red dots. Put both feet on the red dots. Put both feet on the red dots. Bend your right elbow fully. Put your arms in a circle in front of you. Bend your right elbow half way. Bend your right elbow half way. Bend your left elbow half way. Move your hands 2 ft apart Bend your left elbow half way. Bend your left elbow half way. Close both hands. Tilt your head to the left. Turn your palms forward. Turn your palms up. Stop Play Halt Neutral 3 Put your left foot on the green dot. Put your right foot on the yellow dot. Put both feet on the red dots. Put both feet on the red dots. Put your right arm straight out in front of you. Put both arms out to the side. Put your right arm straight in front of you. Put both arms out to the side. Bend your left elbow fully. Raise your right arm a little. Relax your left arm. Turn your palms up. Turn your palms forward. Lower your left arm a little. Turn your palm forward. Bend your left elbow so your left hand is pointing up. Attack Joy Don t know Neutral 7 Put your left foot on the blue dot. Put both feet on the red dots. Put both feet on the red dots. Put both feet on the red dots. Raise your arms over your head. Put both arms out to the side. Put both arms out to the side. Put both arms out to the side. Bend your elbows downward. Raise your arms up more. Bend your elbows downward. Bend your wrists up. Close your hands. Turn your palms up. Turn your palms up. Turn your palms out.

8 488 WILBARGER, REED, AND MCINTOSH a Proportion Error b Response Times (ms) Negative Negative Positive Neutral-Abstract Neutral-Meaningful Affect Condition Positive Neutral-Abstract Neutral-Meaningful Affect Condition Non- Non- Figure 5. Experiment 2: Affect by match interactions for (a) error and (b) response time (RT) data in posture conditions. Error bars indicate standard error. subset of the 24 participants (n 13) rated how difficult it was to assume the various postures at the conclusion of the experiment. Affect significantly influenced perceptions of postural difficulty, F(3, 10) 5.61, p.016. Post hoc analyses revealed that negative postures (M 6.71, SD 0.22) were rated as more difficult than all other postures: positive postures (M 6.19, SD 0.19), t(12) 3.87, p.05; neutral postures (M 6.08, SD 0.15), t(12) 2.98, p.05; or meaningful postures (M 5.85, SD 0.23), t(12) 3.72, p.05. However, positive postures were rated equivalently to neutral, t(12) 0.55, p.05, and meaningful postures, t(12) 1.76, p.05. Although negative postures were rated as being more difficult to assume than the other postures, the positive postures were not rated more difficult than the neutral postures. Thus, perceived postural difficulty does not appear to account for the differences between positive postures and the neutral postures that produce the affect by match interaction. Nonetheless, the postural difficulty ratings were conducted at the end of the experiment and may not have been an adequate measure of pose difficulty because of the lag between assuming and viewing the postures and rating them. We addressed this issue by having a new set of 13 participants rate the difficulty of assuming the posture immediately after they physically assumed it, following the same procedure as in Experiment 2. Only a marginal effect of affective category was found, F(3, 10) 2.98, p.083. Post hoc analyses revealed that negative postures (M 5.83, SD 0.15) were more difficult than positive postures (M 5.48, SD 0.12), t(12) 3.21, p.05, but not neutral-abstract (M 5.84 SD 0.17), t(12) 1, p.05, or neutral-meaningful postures (M 5.65, SD 0.14), t(12) 1.19, p.05. Although negative postures were perceived as more difficult to assume than positive postures, affective postures as a category could not be distinguished from neutral postures in terms of their perceived physical difficulty. Discussion The results of Experiment 2 replicate Experiment 1 and rule out several alternative hypotheses. As in Experiment 1, participants were slower and less accurate in discriminating postures when the viewed postures had affective content and matched their own posture. Experiment 2 indicates that the semantic content of the affective postures did not appear to drive this affect by match interaction because this pattern of results was not found for neutral-meaningful postures. In addition, the results could not be attributed to the difficulty in processing the posture instructions between conditions. The participants perceptions of the difficulty did not differ between the affective and neutral conditions. Finally, there appears to be something distinctive about the perception and evaluation of negative postures. In both experiments, compared with positive postures, negative postures produced larger differences between match and no-match trials and were perceived to be more difficult to assume. Two potential mechanisms may contribute to this effect. First, negative postures may be physically more difficult to assume because of the physical effort required to maintain negative postures. Many negative postures require muscle tension and constriction relative to neutral and positive postures. For example, muscles in the neck and arms have to be held contracted and thus use more energy resources than the maintenance of positive or neutral postures. Second, affect may be used as information (Schwarz & Clore, 2003). If negative postures simulate negative emotional experiences, people may use this information and the fact that they do not like to feel negative emotions in their judgments of perceived difficulty. General Discussion Recent work has demonstrated that cognition and perception are embodied, that is, intimately connected with our bodies and how we use them (Barsalou, 1999). The insight that our own body position may influence social emotional processes has led to research on its involvement in social perception, including work on imitation and facial mimicry (Moody & McIntosh, 2006; Niedenthal et al., 2005; Winkielman et al., 2009). This study s novel contribution is that instead of examining how affective body postures influence explicit emotional evaluations of visual stimuli, it investigated the influences of implicit affective postural information on a visual posture discrimination task for which the emotional information was not directly relevant to performance. Thus, the emotional components of the task were completely implicit, as it is in most everyday social situations. In the present study, we investigated whether affective postures would be processed differently from affectively neutral postures when participants compared their own postures with postures of another. Results from Experiments 1 and 2 indicated that implicit affective information in the perceiver s postures influenced performance. When the two postures matched, errors and RTs were greater for affective versus nonaffective postures. Thus, not only did the participant s own body influence the perception of others,

9 IMPLICIT INFLUENCE OF AFFECTIVE POSTURES 489 but also the implicit emotional content of a posture influenced performance in this nonemotional task. This pattern of results indicates more than just body-specific perception the effects are specific to the emotional content of the postures. These results have implications for refining theories of embodied emotion. One implication of our findings is that the body discrimination task evoked body-specific processing. Our results support the general embodiment hypothesis. Overall, the active assumption of postures changed the way observers viewed other people when the two postures matched. Merely comparing two visual posture stimuli did not affect perception to the degree that actively assuming and matching a posture did. Discrimination was slowed and more error prone in posture compared with no-posture conditions. This reduction in performance is consistent with two complementary mechanisms. First, body position information from proprioceptive inputs is less reliable compared with visual inputs (van Beers, Sittig, & van der Gon Denier, 1996) so that cross-modal matching conditions would be impaired compared with purely visual matching conditions. Second, it is consistent with common-code theory that interprets this interference as arising from a common body representation being accessed during concurrent personal posture and visual target posture comparisons (e.g., Prinz, 1997). The visual posture input competes with the proprioceptive posture input for access to a common body representation, resulting in slower, more error-prone performance. The decline in performance for matched postures is also consistent with previous findings by Reed and McGoldrick (2007) because of the timing parameters of the task; multimodal body posture comparison intervals of 2.5 s lead to performance interference, but longer intervals lead to performance facilitation presumably because the initial competition for a common body representation can be resolved over time. However, none of these explanations provide mechanisms to explain why implicit emotional processing will interact with body information processing. A second implication of our results is stronger support for the emotion-specific embodiment hypothesis. Results from both experiments indicate that the affective valence of the posture influenced performance beyond an overall embodiment effect. Posture affect influenced performance even though it was implicit to the task and irrelevant for task performance: Differential discrimination performance (for both errors and RT) was found only for matching affective postures in the posture condition. When the assumed affective posture matched the visual target, responses were slower and less accurate than when the assumed affective posture did not match the target. The assumption of affectively neutral postures did not produce this pattern of performance. In addition, this interaction between affective valence and posture match could not be explained by additional semantic processing or physical difficulty of assuming affective postures (Experiment 2). On first consideration, these results appear to be in conflict with previous studies on imitation, emotional contagion, and rapid facial responses (Hatfield et al., 1994; Moody & McIntosh, 2006; Williams et al., 2006). In these emotion identification or classification studies, correspondences in the affective postures of the self and others (or matches) enhance emotion judgments (cf. Niedenthal et al., 2005). In the present experiments, we found that self other matches actually interfered with affective posture discrimination performance. However, this apparent conflict can be resolved when one considers the functional utility of emotional contagion in conjunction with task requirements. Theories of emotional contagion and mirror neuron systems (Hatfield et al., 1994; Niedenthal et al., 1999; Rizzolatti & Craighero, 2004; Williams et al., 2006) suggest that matching can help us simulate the emotions of others to understand what they feel. When people match another s affective posture, their prior experiences are reproduced in the originally implicated neural systems as if the individual were there in the very situation (Gallese, 2003) and that information can be used to evaluate the corresponding emotional state of another. Sensorimotor and affective states are theorized to be stored in modality-specific association areas. When those experiences are remembered, the original patterns of sensorimotor and affective states are reactivated (Niedenthal et al., 2005). It has been postulated that the as-if loops that represent embodied states can be rapidly and flexibly implemented in the neural system by linking the ventromedial prefrontal cortex, the limbic system, somatosensory, and motor cortex (Damasio, 1994). For example, remembering fear could involve simulating the experience of fear, including activating specific trunk and arm muscles that have pushed or leaned away in prior fear experiences or of facial muscles that have opened the eyes and mouth wide. With this type of mechanism, there are clear perceptual benefits to matching another s posture when the task is to evaluate his or her emotion. Thus, when emotion is relevant to the task (i.e., understanding another s emotion), facilitated processing occurs when self and other match because the activated personal emotion information can be used directly to evaluate the other person s emotional state. However, the present study provides evidence that the above mechanism does not always lead to performance facilitation and that task requirements can affect the outcome of the emotion simulation process. When the task does not require the explicit use of that affective information for emotion evaluation, contagion and mirror systems may actually accentuate distinctions between people, especially when the task is to directly compare someone else to oneself. Instead, unlike previous studies that asked, What is the emotion? our task asked, Is that person like me? The activation of personal emotion representations, in combination with the body representations, differentiates personal affective postures from visual inputs of another s affective posture when comparing the two. It may also change decision criteria. If assuming an affective posture reinstates one s own, individually experienced emotional state, then it may shift the standard by which one judges like me or not like me to a more stringent criterion. In other words, personal experience creates a more refined emotional representation than what one perceives from others. Because the two representations are close, it takes time to compare them. Because information from one s own body is prioritized, there is an emotion-specific cost of discriminating matching postures. Thus, the same emotion simulation mechanisms may be operating in both cases, but the outcomes differ because the information is used for different purposes. Emotion simulation can facilitate the identification of an emotional state in another person, but it can also distinguish one s own experiences of that emotion from another s when directly comparing them. This interpretation is consistent with what has been proposed by Decety and colleagues (Decety & Chaminade, 2003.) They suggest that when empathizing with others, people rely on