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Effects of Damage to Right-Hemisphere Brain Structures on Spontaneous Emotional and Social Judgments Andrea S. Heberlein Neuroscience Graduate Program, University of Iowa Ralph Adolphs Neuroscience Graduate Program, University of Iowa Department of Neurology, Division of Cognitive Neuroscience, University of Iowa College of Medicine Humanities and Social Sciences, California Institute of Technology James W. Pennebaker Department of Psychology, University of Texas at Austin Daniel Tranel Neuroscience Graduate Program, University of Iowa Department of Neurology, Division of Cognitive Neuroscience, University of Iowa College of Medicine Recent work in cognitive and social neuroscience has focused on the neural substrates of social judgment. The present study explores the effects of damage to the right-hemisphere somatosensory cortices (RSS), a region known for its role in emotion recognition. Seven subjects with RSS damage were shown a short movie depicting objects that move in socially suggestive ways, a stimulus that typically elicits spontaneous social and emotional attri- butions from normal subjects. The spontaneous verbal responses of RSS-damaged subjects to this movie were compared to those of normal subjects as well as brain-damaged control subjects; the data were derived using a word count and categorization computer program. This method measures spontaneous social and emotional judgments rather than the more typical rating and labeling measures used in neuropsychological studies of social judgment. As predicted, relative to brain-damaged and normal controls, subjects with RSS damage reacted to the stimulus movie with fewer words in categories describing emotional Political Psychology, Vol. 24, No. 4, 2003 0162-895X © 2003 International Society of Political Psychology Published by Blackwell Publishing. Inc., 350 Main Street, Malden, MA 02148, USA, and 9600 Garsington Road, Oxford, OX4 2DQ 705

Effects of Damage to Right-Hemisphere Brain Structures on Spontaneous Emotional and Social Judgments

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Page 1: Effects of Damage to Right-Hemisphere Brain Structures on Spontaneous Emotional and Social Judgments

Effects of Damage to Right-Hemisphere Brain Structures on Spontaneous Emotional and Social Judgments

Andrea S. HeberleinNeuroscience Graduate Program, University of Iowa

Ralph AdolphsNeuroscience Graduate Program, University of Iowa

Department of Neurology, Division of Cognitive Neuroscience, University ofIowa College of Medicine

Humanities and Social Sciences, California Institute of Technology

James W. PennebakerDepartment of Psychology, University of Texas at Austin

Daniel TranelNeuroscience Graduate Program, University of Iowa

Department of Neurology, Division of Cognitive Neuroscience, University ofIowa College of Medicine

Recent work in cognitive and social neuroscience has focused on the neural substrates ofsocial judgment. The present study explores the effects of damage to the right-hemispheresomatosensory cortices (RSS), a region known for its role in emotion recognition. Sevensubjects with RSS damage were shown a short movie depicting objects that move in sociallysuggestive ways, a stimulus that typically elicits spontaneous social and emotional attri-butions from normal subjects. The spontaneous verbal responses of RSS-damaged subjectsto this movie were compared to those of normal subjects as well as brain-damaged controlsubjects; the data were derived using a word count and categorization computer program.This method measures spontaneous social and emotional judgments rather than the moretypical rating and labeling measures used in neuropsychological studies of social judgment. As predicted, relative to brain-damaged and normal controls, subjects with RSSdamage reacted to the stimulus movie with fewer words in categories describing emotional

Political Psychology, Vol. 24, No. 4, 2003

0162-895X © 2003 International Society of Political PsychologyPublished by Blackwell Publishing. Inc., 350 Main Street, Malden, MA 02148, USA, and 9600 Garsington Road, Oxford, OX4 2DQ

705

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and social processes, despite using a similar total number of words (and slightly morewords describing movement, a control category). These results provide further evidencefor the role of the RSS in social/emotional processing and identify a role for the RSS inautomatic representation in ourselves of body states of others to foster emotion recogni-tion and social cognition.

KEY WORDS: Emotion, Social Cognition, Right Hemisphere, Animacy, Anthropomorphizing

We use a wealth of visual cues to make social judgments of others, which in turn guide our social decisions and behaviors. A large literature in social, political, and cognitive psychology has explored these cues and how they are usedfor social behavior, but only recently have neuroscientific approaches beenbrought to bear on the topic. In broad terms, the venture is part of what has becomeknown as “social cognitive neuroscience”—the investigation of the neural under-pinnings of the cognitive processes that guide social behaviors (Cacioppo et al.,2002).

Several recent findings from this fledgling field have provided strong supportfor the idea that social judgments can be made relatively automatically, on thebasis of rather specific types of information and by reliance, in part, on neuralsystems that process the emotional value of that information. These findingsprovide a neurobiological account of person perception that meshes with the lit-erature from social psychology on the same topic (Macrae & Bodenhausen, 2000).An overall picture has emerged in which regions of the brain involved in higher-order visual processing are already specialized to detect certain kinds of sociallyrelevant information. In particular, regions of the extrastriate cortex, notably inthe fusiform gyrus and the superior temporal gyrus, have been linked to the pro-cessing of information about other people’s faces (Kanwisher, McDermott, &Chun, 1997) and about facial movements and other biological motion (Allison,Puce, & McCarthy, 2000), respectively. These visual regions of the brain in turnlink with structures that associate the visual information with its emotional andsocial relevance for the individual, including the amygdala, the orbitofrontalcortex, and the right-hemisphere somatosensory cortices. The last region is thetopic of the present study.

Good examples of how these salience-marking structures contribute to socialjudgments come from functional neuroimaging studies of normal individuals aswell as from studies of patients with focal brain damage. For instance, implicitracial stereotyping is associated with activation of the amygdala, a brain structureknown to process the emotional value of stimuli and to regulate fear- and aver-sion-related behaviors (Anderson, Spencer, Fulbright, & Phelps, 2000; Hart et al.,2000). Another good example comes from our own work, which has shown thatdamage to the amygdala impairs the ability to judge the (un)trustworthiness ofpeople from their faces (Adolphs, Tranel, & Damasio, 1998). This finding has been corroborated with functional imaging in a study by Winston, Strange,

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O’Doherty, and Dolan (2002), who found a correlation between amygdala acti-vation in normal individuals and the perceived untrustworthiness of the faces theyviewed. Winston et al. showed that some of these brain activations occur auto-matically in response to untrustworthy faces, even when subjects are not makingany overt judgments about the stimuli they see.

Another set of studies examined judgments of facial attractiveness. Again,activation in particular brain structures concerned with processing emotions (theventral striatum, in this case) was found to be associated with perceived attrac-tiveness of faces (Kampe, Frith, Dolan, & Frith, 2001); again, these patterns ofactivation held independently of subjects’ overt judgments, instead reflecting theirimplicit motivations (Aharon et al., 2001). From these and other findings, it isevident that many of the processes behind the social judgments that we make areautomatic and implicit, and that many such processes involve motivational andemotional processing.

Right-Hemisphere Cortices and Social Judgments: Emotion Recognition

Structures in the right hemisphere appear to be important for the normal pro-cessing of emotional and social information from a variety of cues. Normal sub-jects rely more on information from the left side of the face when judging emotionalexpression, as well as attractiveness and age, from chimeric faces (i.e., faces inwhich the left and right halves are derived from different emotional faces, expressedin this case by the same individual; Burt & Perrett, 1997). Also, subjects rely moreextensively on information from the left half of their visual fields (which isprocessed by the right side of their brain) when making fine-grained judgmentsabout negative emotional expressions (Jansari, Tranel, & Adolphs, 2000). Subjectswith damage to the right hemisphere perform significantly worse than left hemi-sphere-damaged subjects and normal controls in recognizing emotion from facesand other cues (Benowitz et al., 1983; Borod, Koff, Lorch, & Nicholas, 1985;Bowers, Bauer, Coslett, & Heilman, 1985). The right hemisphere’s disproportion-ate involvement in emotional processing appears to begin in childhood, as sug-gested by the finding that subjects with right-hemisphere damage, ages 5 to 10years, were more impaired in recognizing facial expressions of emotion than asimilar group with left-hemisphere damage (Voeller, Hanson, & Wendt, 1988).

Recent investigations have begun to address the question of which right-hemisphere structures are most critical for emotional and social processing. Thesomatosensory-related cortices appear to play a key role. In a comparison of thelesion locations of 108 brain-damaged subjects who had been tested with tasksinvolving recognition of six basic emotions from facial expressions, subjects whoperformed poorly were more likely to have lesions that included right-hemispheresomatosensory-related areas (Adolphs, Damasio, Tranel, Cooper, & Damasio,2000). In a similar analysis comparing the lesion locations of 66 subjects withregard to their performance on tasks of emotional prosody recognition, Adolphs,

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Damasio, and Tranel (2002) found that damage to right-hemisphere somatomo-tor and somatosensory areas disproportionately impaired subjects’ performance.1

Adolphs and colleagues have interpreted these findings as evidence for a role ofsimulation processes in emotion recognition: in order to know what anotherperson is feeling, we activate a representation in ourselves of their body state(Adolphs, 2002; Adolphs et al., 2000, 2002). In support of this idea, a close rela-tionship was found between preservation of touch sensation and performance onfacial emotion recognition: subjects with impairments in sensation performedespecially poorly at recognizing emotion from photographs of faces (Adolphs et al., 2000).

Other findings also support a role for sensory processes in emotion recogni-tion. Production of emotional facial expressions (Adelmann & Zajonc, 1989) aswell as other somatovisceral responses (Cacioppo et al., 1992) can lead to changesin emotional experiences and to emotional physiological changes (Levenson,Ekman, & Friesen, 1990). Note, however, that damage to regions of the righthemisphere outside of the somatosensory regions, including both the parietal andposterior-frontal regions, has been linked to deficits in the production of emo-tional language. Many of these studies have focused on deficits in the productionof normal emotional prosody (e.g., Borod et al., 1985; Ross, 1981, 1993), but atleast one study has shown deficits in the production of emotional content words(Bloom, Borod, Obler, & Gerstman, 1992), although subjects in that study wereusing emotion words in a task that also required recognition of emotional content.Thus, it may be difficult to disentangle deficits in emotion recognition and deficitsin emotion word production, especially for subjects with lesions not confined tosomatosensory cortices.

Adolphs (2002) suggested that right-hemisphere somatosensory cortices andsimulation processes may be engaged primarily in the case of recognition tasksinvolving fine-grained discrimination. In virtually all studies completed to date,however, an explicit recognition task was used. It remains unclear, then, whetherthe right-hemisphere somatosensory cortices would be engaged by tasks thatimplicitly require emotion processing (i.e., in the absence of instructions to labelor rate emotional content).

In the present study, we used a task that measures subjects’ use of words todescribe socially relevant psychological states, including emotion, when narrat-ing the events of the Heider and Simmel (1944) movie. This movie depicts themovements of three geometric objects. Despite the inherent absence of humanparticipants, the movie is normally described in terms of the movements of threeanimate characters with intentions, emotions, and personalities (Berry, Misovich,

708 Heberlein et al.

1 Both of these studies also found that the left frontal operculum was important for emotion recogni-tion (from faces and prosody). We are not focusing on that region here; the current study is aimedat exploring the role of the RSS region, and we plan to address other neural sectors in subsequentwork.

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Kean, & Baron, 1992; Hashimoto, 1966; Heider & Simmel, 1944). We compareddescriptions of this movie given by subjects with right-hemisphere somatosen-sory cortex (RSS) damage to descriptions given by brain-damaged and neuro-logically normal control subjects. We used a commercially available computerprogram known as Linguistic Inquiry and Word Count (LIWC; Pennebaker,Francis, & Booth, 2001). This program counts words in various categories; forthe purposes of the current study, these include categories termed Affect, SocialProcesses, and Motion (or Movement), as explained below.

We hypothesized that subjects with RSS damage would be impaired in therecognition and processing of affective states and of social interactions from theshape and movement cues in the movie. We predicted that this impairment wouldbe reflected by a reduced use of Affect and Social Processes words, relative tobrain-damaged and normal control subjects. We also predicted that this effectwould be specific to measures related to recognizing affective and socially rele-vant states in others; thus, we predicted that the percentage of words used in acategory unrelated to emotion and social processes, Movement, would not bereduced in the subjects with RSS damage (henceforth, RSS subjects).

Given that we are relying here on verbal reports from the subjects, it is pos-sible that a general language deficit could impair performance on the experimen-tal task. This possibility is unlikely to confound our hypotheses, however: RSSdamage almost never produces deficits in propositional language, whereas damageto left-hemisphere cortices (as sustained by some members of the brain-damagedcontrol group) can produce language deficits. Thus, the effect of language impair-ment would operate in the opposite direction to our hypothesis and predictions.

Method

Participants

Brain-damaged subjects. We tested seven subjects with lesions includingRSS. Subjects were considered to have RSS damage if their lesions included atleast part of the postcentral gyrus on the right (see Figure 1 for lesion overlap,Table 1 for demographic and neuropsychological background). To test for non-specific effects of brain damage on the target task, we compared these seven subjects with eight brain-damaged control subjects (BDCs; see Table 1 for demo-graphic and neuropsychological background). The BDCs had damage to areas not hypothesized to be involved in emotional and social processing (e.g., the occipital cortices, right dorsolateral prefrontal cortices, and left dorsolateral temporal cortices). The BDCs were matched to the RSS subjects with regard to age, level of education, and several psychological and neuropsychologicalmeasures (Table 1).

All brain-damaged participants were selected from the Patient Registry of theDivision of Cognitive Neuroscience, University of Iowa College of Medicine, and

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had been fully characterized neuropsychologically (Tranel, 1996) and neu-roanatomically (Damasio, 2000; Frank, Damasio, & Grabowski, 1997). Weexcluded participants who had impaired visual perception. All participants alsoconformed to the inclusion criteria of the Patient Registry: They had focal,chronic, stable, acquired lesions that could be clearly identified on MR or CTscans. All participants had normal attentional abilities and had IQs in the normalrange, none were demented, none were aphasic, and none were severelydepressed. The subjects were studied in the chronic epoch, i.e., more than 3months after lesion onset. All subjects gave informed consent, as approved by theUniversity of Iowa Institutional Review Board.

710 Heberlein et al.

Table 1. Demographic and Neuropsychological Background Data

Subject Group Gender Time Hand Age Educ. WAIS subtestssince (yrs) (yrs)lesion Sim. Info.acq.

0650GR RSS M 16 yr, 3 m +90 58 10 9 60744ES RSS M 15 yr, 7 m +100 85 8 14 160747RH RSS M 27 yr +100 51 14 9 151711KK RSS F 10 yr, 5 m +100 38 13 7 82107WM RSS M 4 yr, 5 m +100 60 18 11 112126JC RSS F 10 yr, 3 m +100 56 14 15 142328JF RSS F 1 yr, 6 m +100 50 18 12 12RSS mean 3F, 4M 57 14 (4) 11.0 11.7(SD) (14) (2.9) (3.7)0297RF BDC M 19 yr, 8 m +100 51 16 11 130858JM BDC M 15 yr, 2 m +100 52 16 11 11999JLK BDC M 3 yr, 5 m +100 44 16 13 131621LL BDC F 9 yr, 3 m +100 67 9 11 71652CG BDC M 9 yr, 4 m +60 45 11 11 101707LS BDC M 10 yr, 0 m +80 59 10 10 111969CC BDC M 4 yr, 3 m +100 60 12 10 122021TK BDC F 2 yr, 11 m +100 72 12 8 8BDC mean 2F, 6M 56 13 (3) 10.6 10.6(SD) (10) (1.4) (2.2)

NC mean 3F, 59 14 (3) 12.4 12.4(SD) 11M (9) (1.6) (2.3)

Note. Shown are the individual data from all brain-damaged subjects in the right-hemispheresomatosensory cortex-damaged (RSS) target group and the brain-damaged control (BDC) group, as well as group means for the RSS, BDC, and normal control (NC) groups. Data include four subtests of the Wechsler Adult Intelligence Scale Revised (WAIS-R) or Wechsler Adult IntelligenceScale Third Edition (WAIS-III): Similarities, Information, Comprehension, and Matrices. These are reported as a scaled score with a mean of 10 and a standard deviation of 3. Benton FacialDiscrimination Task (Faces), adjusted scores; Benton Judgment of Line Orientation Task (Lines),

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Control subjects. The target group of RSS subjects was also compared to agroup of 14 demographically matched, neurologically normal control subjects(NCs; see Table 1). These subjects had been recruited from the surrounding com-munity via advertisements, and they were compensated for their participation. AllNCs gave informed consent before participating.

Stimulus and Task

We used a video of the movie constructed by Heider and Simmel (1944),which is silent, about 90 seconds long, and depicts a large triangle, a small trian-

Right-Hemisphere Damage and Emotional Judgments 711

WAIS subtests Benton Benton BVRT BVRT AVLT AVLT AVLT Depr.Faces Lines Corr. Error Trial 5 Delay Delay Index

Comp. Matr. (adj.) (adj.) Recall Recog.

9 7 48 27 9 2 13 12 30 113 11 47 30 7 4 10 10 29 012 10 41 24 9 1 13 13 29 06 7 39 17 7 5 14 13 30 1

11 9 43 24 5 8 9 9 28 010 10 41 24 5 8 11 9 39 013 7 41 30 9 1 14 14 39 210.6 8.7 41.6 25.4 7.3 4.1 12.0 11.4 29.4(2.5) (1.7) (2.0) (4.9) (1.8) (3.0) (2.0) (2.1) (0.8)10 10 49 23 7 5 9 2 24 015 11 41 26 7 3 11 4 29 015 8 45 28 9 1 15 13 30 010 13 50 25 7 4 13 13 30 09 7 43 23 9 2 10 8 29 09 13 48 27 9 1 14 15 30 0

12 8 45 30 5 9 11 9 25 010 7 47 25 4 7 11 8 30 011.3 9.6 46.7 26.0 7.1 4.0 12.3 11.0 29.0(2.5) (2.5) (2.5) (2.9) (1.9) (2.9) (2.0) (3.0) (2.0)12.9 13.4 ND ND ND ND ND ND ND ND(2.1) (4.0)

adjusted scores; Benton Visual Retention Test number correct (BVRT Corr.) and number of errors(BVRT Error); Rey Auditory-Verbal Learning Test, Trial 5 score, Delayed Recall (30 min), andDelayed Recognition (30 min). Hand = Handedness, where -100 is fully left-handed and +100 is fullyright-handed. The Depression Index was derived by a clinical neuropsychologist blind to subjects’performance on the experimental tasks, based on data from the Beck Depression Inventory and theMMPI (or MMPI-2), Scale 2. Ratings are on a four-point scale, ranging from “0” (no depression) to“1” (mild depression), “2” (moderate depression), and “3” (severe depression).

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gle, and a circle moving around the outline of a larger rectangle (Figure 2). Subjects were seated about 1.5 meters from the TV monitor on which they viewedthe stimulus movie.

Before seeing the movie, subjects were told that they would be asked to “tellme what you saw.” Immediately after the movie, the experimenter started a taperecorder and gave the instruction “Tell me what you saw.” After this initialdescription was recorded, subjects were shown the same movie a second time.This second viewing was followed by a questionnaire, including questions suchas “What kind of person was the big triangle?”, “Why did the two triangles fight?”,and “Why did the big triangle break the house?” These questions addressed theextent to which subjects derived specific kinds of content from viewing the video,and were analyzed as part of a separate study not reported here. After answeringall of these questions, which took about 20 minutes, subjects were asked to tellthe story of the movie a second time. Thus, the entire interview process yieldedanswers to specific questions about the characters and events of the movie, as well

712 Heberlein et al.

Figure 1. The extent and location of the seven RSS subjects’ lesion overlaps. Darker areas indicategreater degree of overlap. Slices a through d, taken at the positions shown on the whole brain

image, show the extent of the lesions. For a color version of this figure, seehttp://www.medicine.uiowa.edu/adolphs/links.html.

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as two descriptions of it. Note that the initial description occurred with no cluesfrom the experimenter that the movie should be described in social, anthropo-morphic, or affective terms; we did not ask subjects to tell a story, nor did weprovide any indication that the shapes could be considered as animate characters.The second description was recorded after an extended series of questions thatmay have led subjects to consider the video in social terms, if they had not alreadydone so. Thus, in the opening approach to the data analysis, it was critical toanalyze the initial and final descriptions separately and to compare the two forpotential differences in the pattern of usage of different word types. After tran-scription, the initial and final descriptions were analyzed separately by the wordcount method described below.

Word Count Analysis

All descriptions, initial and final, were analyzed with LIWC 2001 (Pennebaker et al., 2001). The output from this program consists of a spreadsheetshowing the total number of words in each sample, as well as percentages of wordsin each of 74 categories. LIWC 2001 is a well-validated instrument. In the con-struction of the current version of the intrinsic dictionary, broad word lists wereamassed from several sources of emotion or affect rating scales as well as othersources. Categories were defined from these word lists. Three independent judgesrated the suitability of each word’s inclusion in a given scale. A high level ofagreement (ranging from 86% to 100%) was found for all LIWC 2001 categoryand scale lists. After the second pass of judging, the range of agreement was 93%to 100%. A word could appear in multiple categories if the judges agreed that the

Right-Hemisphere Damage and Emotional Judgments 713

Figure 2. A scene from the Heider and Simmel (1944) movie.

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word in question was a suitable member of each category. Note that this judgingwas undertaken for the LIWC software and not specifically for analysis of thevideo descriptions used in our study.

In keeping with the predictions outlined above, we focused on three LIWC2001 categories. Two of these categories—Affective or Emotional Processes andSocial Processes—were used as target categories. The other category, Motion(called “Movement” here to avoid confusion between the words “emotion” and“motion”), was used as a control category. Although these categories are not equalwith respect to base rates of word usage, the Movement category was a suitablecontrol category because a relatively high percentage of Movement words areused in normal descriptions of the Heider and Simmel video (see Figure 3).

The Affect category contains 615 words drawn from two dimensions calledPositive Emotion and Negative Emotion. Positive Emotion includes two sub-categories: Positive Feelings (e.g., “happy,” “joy,” “love”) and Optimism/Energy (e.g., “win,” “excitement”). Negative Emotion includes three sub-categories: Anxiety/Fear (e.g., “nervous”), Anger (e.g., “hate,” “pissed”), and

714 Heberlein et al.

0

2

4

6

8

10

affect pos emotion neg emotion social movement

RSSmean

Percentage of affect, social, and motion wordsSubjects with right somatosensory cortex damage (n = 7) vs. brain damaged

controls (n = 8) and normal controls (n = 14)

Mean of initial and final descriptions of Heider and Simmel movie

BDCmean

NC.mean

Figure 3. Percentage of words in each category. Note that Affect includes the dimensions PositiveEmotion and Negative Emotion. Subjects with RSS damage use fewer Affect words, in particular

fewer Negative Emotion words, than brain-damaged or normal controls. They also use fewer SocialProcesses words. However, they do not use fewer Movement words, and in fact tend to a higher

percentage of words in this category.

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Sadness/Depression (e.g., “cry”). Note that several additional words not assignedto the subcategories of Positive Feelings or Optimism/Energy are included in the Positive Emotion dimension (e.g., “pretty”). Similarly, the Negative Emotiondimension includes additional negatively valenced emotion words not assigned tothe subcategories of Anxiety/Fear, Anger, or Sadness/Depression (e.g., “enemy”).We explored both the Positive Emotion and Negative Emotion dimensions ofAffect because there is considerable evidence that the neural correlates of emotionprocessing may be valence-specific; that is, processing of negative emotions maybe dissociated from processing of positive emotions (e.g., Davidson, 2000). Thereis insufficient empirical basis to formulate a specific hypothesis in this regard, butwe wanted to explore the issue in at least a preliminary fashion.

The second target category, Social Processes, is made up of social pronouns(first-person plural, second-person, and third-person pronouns), communicationverbs (“talk,” “share”), and references to family, friends, and other humans.

To address our prediction regarding the specificity of the findings, we ana-lyzed the control non-target category Movement. This category includes wordssuch as “walk,” “move,” and “go,” and it was our prediction that RSS subjectswould not show a reduction in this category.

Statistical Analysis of Word Count Measures

The key comparisons in this study, in regard to our main predictions, arebetween the three different subject groups (RSS, BDC, and NC) on the threedependent measures (word use in the Affect, Social Processes, and Movement cat-egories). Our study is hypothesis-driven. However, in keeping with the prescrip-tions of Schmidt and colleagues (Schmidt, 1996; Schmidt & Hunter, 1997; Shrout,1997), we provide here a description of the results in terms of means, point esti-mates of effect sizes, and confidence intervals. This analysis was applied to theword use percentages of the initial and final descriptions separately, and also tothe averaged percentages (i.e., the mean of the initial and final descriptions).2 Weadded conventional null hypothesis significance testing with a 3 ¥ 3 ¥ 2 repeated-measures analysis of variance, with Group (RSS, BDC, NC) as a between-subjects variable and Word Category (Affect, Social Processes, Movement) andDescription (initial, final) as within-subjects variables.

Background Neuropsychological Measures

Subjects were given background neuropsychological and psychological teststo assess intellectual ability, memory, visual perception, and depression (Table 1).

Right-Hemisphere Damage and Emotional Judgments 715

2 The exception was one RSS subject (2328JF) whose tape was not decipherable after the initialdescription because of microphone failure, and whose initial description data we included both inthe initial description analysis and in the average analysis.

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The intelligence tests were given to all subjects. The neuropsychological tests ofmemory and visual perception were administered only to the brain-damaged sub-jects, because the normal controls were presumed to be normal in these functions.These neuropsychological measures were used to match the target (RSS) subjectsto the BDCs on basic functions of verbal ability, memory, and spatial perception.The depression index was also obtained in the brain-damaged subjects but not inthe normal controls. References for all of the tests can be found in Tranel (1996).

Wechsler Adult Intelligence Scale (WAIS). The subtests Similarities, Information, Comprehension, and Matrices were obtained from the WAIS-R orWAIS-III.

Rey Auditory-Verbal Learning Test (AVLT). This is a 15-word learning test,comprising five learning trials, a 30-minute delayed recall trial, and a 30-minutedelayed recognition trial. The task measures anterograde verbal memory as wellas attention and concentration.

Benton Visual Retention Test (BVRT). This test measures anterograde visualmemory as well as attention, concentration, and visuoconstructional abilities. Subjects are presented geometric figures for a brief period and are then asked toreproduce the figures from memory.

Benton Facial Discrimination Task. This task requires subjects to match thefaces of identical individuals taken under different views and lighting conditions,and provides a sensitive measure of basic visuoperceptual function.

Benton Judgment of Line Orientation Task. This task requires subjects tomatch two lines at a given orientation with two lines from an array of lines atvarious orientations. It provides another sensitive measure of visuoperceptualfunction.

Results

In their initial descriptions of the video, RSS subjects tended to use fewertotal words in their descriptions, especially relative to NCs. The LIWC word cat-egory analyses, however, are based on percentage of total words used by eachparticipant rather than raw counts. In these terms, RSS subjects used a lower rateof Affect words relative to both control groups (Table 2). This effect was carriedalmost entirely by the Negative Emotion dimension of Affect, although this mayhave been due in part to floor effects in NCs’ use of Positive Emotion words. RSSsubjects also tended to use fewer Social Processes words than both control groups.By contrast, the proportion of Movement words used by the RSS subjects wasvery similar to the BDCs, and in fact somewhat higher than the NCs.

Most of these same patterns were evident in the final descriptions. Becausethe general patterns of effects were quite similar across the initial and final descrip-tions, we averaged the data from the two descriptions. These averaged data, pre-sented in the lower part of Table 2 and in Figure 3, yield several important findings.The overall number of words used did not differ substantially between the groups;

716 Heberlein et al.

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Right-H

emisphere D

amage and E

motional Judgm

ents717

Table 2. Comparison of RSS, BDC, and NC Groups on LIWC Measures

LIWC category RSS mean (SD) BDC mean (SD) RSS vs. BDC, effect size (CI) NC mean (SD) RSS vs. NC, effect size (CI)

Initial descriptionTotal no. words 98.86 (51.6) 121.63 (67.6) -0.38 (-1.40, 0.65) 147.9 (60.3) -0.87 (-1.8, 0.05)Affect 0.91 (1.0) 1.79 (2.0) -0.56 (-1.59, 0.48) 1.77 (1.4) -0.71 (-1.62, 0.20)

Pos. Emotion 0.34 (0.6) 0.60 (0.9) -0.34 (-1.36, 0.68) 0.31 (0.5) 0.06 (-0.83, 0.95)Neg. Emotion 0.57 (1.0) 1.19 (1.5) -0.48 (-1.51, 0.55) 1.46 (1.3) -0.76 (-1.68, 0.15)

Social Processes 1.77 (1.1) 3.05 (1.5) -0.95 (-2.02, 0.12) 3.86 (4.2) -0.69 (-1.60, 0.22)Movement 3.28 (2.0) 2.91 (1.9) 0.19 (-0.82, 1.21) 1.89 (1.5) 0.78 (-0.14, 1.69)

Final descriptionTotal no. words 61.00 (31.6) 62.88 (51.3) -0.04 (-1.06, 0.97) 68.93 (27.6) -0.27 (-1.16, 0.62)Affect 1.91 (2.4) 4.27 (4.2) -0.69 (-1.73, 0.36) 4.86 (3.9) -0.92 (-1.84, 0.01)

Pos. Emotion 0.89 (1.4) 2.11 (2.5) -0.60 (-1.63, 0.44) 1.89 (2.4) -0.50 (-1.84, 0.01)Neg. Emotion 0.84 (1.0) 2.16 (2.5) -0.70 (-1.75, 0.34) 2.89 (2.4) -1.11 (-2.05, -0.17)

Social Processes 4.58 (5.1) 7.70 (5.9) -0.56 (-1.60, 0.47) 7.99 (6.2) -0.60 (-1.50, 0.31)Movement 2.50 (3.3) 1.19 (2.0) 0.48 (-0.55, 1.51) 1.66 (1.5) 0.33 (-0.57, 1.22)

Mean of initial and final descriptionsTotal no. words 88.64 (50.4) 92.25 (38.0) -0.08 (-1.10, 0.93) 108.36 (33.5) -0.46 (-1.36, 0.44)Affect 1.28 (1.3) 3.03 (2.9) -0.78 (-1.83, 0.27) 3.31 (2.4) -1.06 (-2.00, -0.12)

Pos. Emotion 0.55 (0.8) 1.36 (1.4) -0.71 (-1.75, 0.34) 1.10 (1.3) -0.52 (-1.42, 0.38)Neg. Emotion 0.65 (0.7) 1.67 (1.9) -0.72 (-1.77, 0.32) 2.17 (1.6) -1.21 (-2.17, -0.26)

Social Processes 2.89 (2.8) 5.38 (2.9) -0.87 (-1.93, 0.19) 5.93 (4.5) -0.82 (-1.74, 0.10)Movement 2.95 (2.3) 2.05 (1.6) 0.46 (-0.57, 1.49) 1.77 (1.1) 0.65 (-0.25, 1.56)

Note. Data shown for each group are mean percentages of the total number of words (except the data for total numbers of words). CI, 95% confidence interval.

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in fact, the RSS and BDC groups are nearly identical on this measure, and the NCgroup is only modestly higher. In both target word categories (Affect and SocialProcesses), the RSS group is well below the BDC and NC groups. This effect isstrong, ranging from -.78 to -1.06. In both dimensions of Affect (Positive Emotionand Negative Emotion), the findings are similar, with the RSS group well belowthe two control groups; this effect appears especially pronounced for NegativeEmotion. By contrast, in the control category (Movement), the RSS group was notimpaired relative to the control groups; if anything, the RSS subjects tended to useMovement words slightly more than did the control subjects.

Unsurprisingly, given the small sample sizes, we did not obtain overall sta-tistical significance in the conventional parametric analysis contrasts of interest.In particular, there was no main effect of Group, and the primary predictedeffect—a Group ¥ Category interaction (i.e., RSS subjects would use fewer wordsin Affect and Social Processes but not in Movement)—was not significant. Thepower estimates were significantly lower for the Description ¥ Group and Cate-gory ¥ Group interactions than for the other contrasts. There were a few signifi-cant effects, including main effects of Description (p < .005) and of Category (p < .05), and a significant Description ¥ Category interaction (p < .05). In otherwords, subjects used a higher percentage of words in at least some of the cate-gories in the final description relative to the initial; they used more words in thetwo target categories than in the Movement category, and it was principally inthese two target categories that subjects used more words in the final, relative tothe initial, description. This suggests that the questioning process may haveprompted subjects to focus more on affective and social aspects of the video, butinterestingly, this effect operated disproportionately in the subject groups, as evi-denced by the fact that the RSS group remained well below the control groups interms of their use of Affect and Social Processes words in the final description(Table 2).

Although we did not obtain between-group differences with conventional sta-tistical tests, this does not imply that the findings we report here are “unreliable”or that the validity of the between-group comparisons is questionable. Indeed theflaws of these types of criticisms have been extensively documented (Schmidt,1996; Wilkinson & Task Force on Statistical Inference, 1999). We do have smallsample sizes, and the power of our between-group comparisons is modest, but itis precisely for these reasons that the reporting of point estimates, effect sizes,and confidence intervals (as we have done in Table 2) is an appropriate strategyin this study, one that has been strongly endorsed in the APA publication manual(American Psychological Association, 2001). Some of our effect size confidenceintervals include zero, but some do not (especially the contrasts between the RSSsubjects and the NCs). Moreover, it is only through the publication of studies suchas ours, with small Ns, that meta-analysis approaches can eventually providedefinitive answers to the questions we have addressed here (see Hunter &Schmidt, 1990).

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One other way of comparing the RSS and BDC groups is to compare the pro-portion of each group that falls above versus below some threshold value. Wecompared the numbers of subjects in each group falling above and below the NCmean for the averaged score for each of the major categories (Affect, SocialProcesses, and Movement). All seven RSS subjects were below the NC mean inAffect word use, versus only five of the eight BDCs (c2 test, p = .07). The dif-ference is less striking for Social Processes words (6/7 RSS vs. 4/8 BDC). Asexpected, there is no difference for Movement words (4/7 RSS vs. 4/8 BDC).

Here are two examples of initial descriptions of the Heider and Simmel(1944) movie, the first from an RSS subject, the second from a BDC:

2107WM: I saw two triangles, one big one and one small one, and acircle. I also saw not a square but uh, I will call it a sandbox. One thathad up on the left-hand corner up there they had a part of wood that wason hinges that opened and shut. I saw at first two triangles escape fromthe box or left the box, and started pushing each other around just a littlebit. Nudging each other, let’s say, and finally a circle also came out ofthe box, and finally the small rectangle went back into the box in thelater part of the movie. And then the big rectangle went in and also the circle went in the box. And they started moving around and bustingthe box up. They busted the top and one side of it.

999JLK: It started out there was a rectangle that a triangle was insideand then a smaller triangle and a circle came onto the scene. The largertriangle let itself out of the rectangle and started chasing the small tri-angle around and was aggressive with the small triangle. And the circleduring that time got inside the rectangle, and the larger triangle kept pur-suing and striking the small triangle and then went inside, back insidethe rectangle with the circle. And the circle seemed scared of the largertriangle and cowered in one of the corners, moved around and then wasable to get out the door, looked like maybe with the help of the smallertriangle. And then they closed it. The larger triangle then pursued themaround and then they went off the screen, the smaller triangle and thecircle. Then the larger triangle seemed to get angry and kind of brokeapart the rectangle.

Discussion

Relative to demographically matched brain-damaged or normal control sub-jects, the RSS subjects described the Heider and Simmel (1944) movie with alower percentage of words describing affect (especially words describing nega-tive emotion) and fewer words describing social processes. The presence of thesepatterns in comparisons with demographically matched brain-damaged controlsis consistent with the notion that at least some part of the difference in word use

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is specifically due to damage in the neural region of interest. The same RSS sub-jects tended to use more words to describe movements, which implies that thepatterns of impoverished word use are specific to words describing affect andsocial processes. These differences are also unlikely to be due to neuropsycho-logical differences between the groups: The RSS and brain-damaged controlgroups were well-matched on a wide range of demographic and neuropsycholog-ical measures.

The patterns of differences in word use were similar for the initial descrip-tion of the video (which subjects gave after minimal direction on the part of theexperimenter) and for the final description (which subjects gave after an interviewthat may have had the effect of encouraging them to interpret the events of themovie in social terms). RSS subjects used a higher percentage of words describ-ing affect and social processes in their final descriptions than in their initialdescriptions; nonetheless, they continued to use far fewer of these types of wordsthan did either of the control groups. This finding implies that RSS subjects’ lessfrequent use of these types of words is stable and not readily altered by discus-sion of the video’s events.

Both of the control groups used many more negative emotion words than pos-itive emotion words. This difference may well be due to the stimulus movie, whichfeatures salient fighting and destruction events (which are described by nearly allsubjects) but only one celebration event (which is often neglected in subjects’descriptions).3 Thus, although RSS subjects are most different from the twocontrol groups in the category of negative emotion, we cannot conclude that RSSsubjects are specifically impaired in recognizing negative emotions from this stimulus, because of possible floor effects in the use of positive emotion wordsby the control subjects.

This discussion brings up a further point: Our results do not tell us why RSSsubjects use fewer affect words in their descriptions of the stimulus video. Dothey not recognize emotional events as such? Are these events simply not salientfor them, and thus forgotten or neglected in their descriptions? Or do RSS sub-jects use fewer affect words in any speech sample because of deficits generatingsuch words? There is considerable evidence for deficits in emotional languageconsequent to right-hemisphere damage. The right hemisphere appears to beinvolved in both production and reception of emotional prosody (Adolphs et al.,2002; Ross, 1993; Ross, Thompson, & Yenkosky, 1997), processing of emotionalwords (Borod, Andelman, Obler, Tweedy, & Welkowitz, 1992), and productionof emotional content in descriptions produced during a picture story task (Bloomet al., 1992). Even in this latter study, however, it is not clear whether subjectsare failing to recognize emotionally salient components of the pictures, or whether

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3 Unpublished data; Heberlein, Adolphs, & Tranel.

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they are not accessing the emotional words to describe normally perceived stimulus features. Subjects with right-hemisphere damage also show disturbancesin discourse, including deficits interpreting nonliteral statements (Kaplan,Brownell, Jacobs, & Gardner, 1990), and in distinguishing lies from jokes(Winner, Brownell, Happe, Blum, & Pincus, 1998). Both of these groups ofauthors suggested that deficits in recognizing speakers’ intent may underlie righthemisphere–damaged subjects’ discourse comprehension deficits, and this con-jecture is supported by Winner et al.’s (1998) finding that their subjects were alsoimpaired on second-order theory-of-mind tasks. Other authors have reporteddeficits in mental state attribution consequent to right-hemisphere damage (Happé,Brownell, & Winner, 1999; Surian & Siegal, 2001).

As noted above, the use of fewer affect words by RSS subjects may be duenot to deficits in implicit emotion recognition processes (i.e., in recognizing emo-tions without specific instructions to rate or label emotions), but rather to emo-tional word production deficits. That these same subjects use fewer words todescribe social processes, however, provides some clues as to the interpretationof their lower rates of use of affect words. The LIWC category of Social Processesincludes social pronouns, communication verbs, and references to people. Thus,the use of fewer such words may indicate that these subjects saw the movementsof the objects in the Heider and Simmel movie in less person-like terms than didthe control subjects.

Our approach in this study has been to begin with an ecologically salient stim-ulus, a relatively unconstrained task, and a first characterization of how perform-ance differences might be associated with brain damage in specific regions. Assuch, there is considerable variance in the responses that subjects give. Futureextensions of this work should aim to reduce this variance, by considering the useof a more constrained task (for example, one with a time limit), which may forcesubjects to use a more homogeneous response strategy and may more uniformlyengage certain neural structures. Variance could also be reduced with a moreuniform sample of participants (both in terms of neuroanatomy and in terms ofbackground neuropsychology, demographics, and personality). The findings fromthe present study could be used to guide the development of more specific protocols.

Keeping in mind the qualifications discussed above, a plausible interpreta-tion of our findings is that RSS cortices subserve a function that is shared incommon across several emotion-recognition tasks. On the present task, subjectswith damage to RSS regions were impaired in their ability to make social andemotional attributions to moving displays; in prior studies, subjects with suchdamage have been found to be impaired in their ability to recognize how otherpeople feel, from observing their facial expression or from listening to the prosodyof their voice. We previously proposed that RSS cortices participate in emotionrecognition by constructing a somatic representation of another person’s presumed

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internal state (Adolphs et al., 2000, 2002). This hypothesis is related to the ideathat emotion recognition may proceed, in part, via simulation of the emotionalstate we observe in another person.

We would like to extend this simulation hypothesis to the present findings.When faced with stimuli of the kind we used here, subjects may attempt to mapthe actions performed by the geometric stimuli onto somatic and motor repre-sentations corresponding to an execution of such movements and their subsequentsomatosensory perception. Simulation theory proposes that observers answer thequestion “What is happening on the screen?” by posing a related question to them-selves: “What would I feel if I moved in the same way?”

Our explanation is in line with the role of simulation in explaining otherpeople’s feelings, mental states, and intentions, an idea that has been proposed byphilosophers for some time (for a review, see Blakemore & Decety, 2001). Note,however, that a simulation mechanism could be entirely automatic and involun-tary, operating below the level of conscious awareness. Even though subjects areconscious that the stimulus has certain social attributions, it is likely that they arenot aware of how they are making such attributions.

A final issue concerns the distinction between sensory and motor representa-tions. The simulation idea would lead one to predict the involvement of bothmotor and somatosensory cortices, yet our data point primarily to the importanceof somatosensory regions, not motor cortices. This finding is consistent with ourprior studies of the role of right-hemisphere cortices in recognizing emotions fromfacial expressions, and our explanation is the same. We believe that it is thesomatosensory representations that are ultimately required to enable subjects’recognition of the emotional or social meaning of the stimuli. This process issimilar to that proposed by Barsalou (e.g., 1999) in his perceptual theory of knowl-edge, in which sensory and proprioceptive representations underlie conceptualsystems.

The somatosensory representations can, of course, be constructed via motorcortices: one could actually mimic aspects of the stimulus in one’s own body andperceive that body change via somatosensory cortices. However, it is probablynot necessary to literally mimic aspects of the stimulus, and it would be rathercumbersome to do so. Instead, it should be possible to construct a somatosensoryimage without the intermediary of the motor representation. In the same way thatwe can imagine visual or auditory representations without actually seeing orhearing a stimulus, we can centrally construct a somatosensory image withoutactually changing anything in our body, a process analogous to what Damasio(1994) has called the “as-if loop.”

We emphasize that no single brain structure, in isolation, implementsprocesses involved in social judgment. In particular, the extrastriate visual cor-tices, amygdala, ventral striatum, orbitofrontal cortex, and right-hemispheresomatosensory cortices all act together as components of a distributed neuralsystem. Clearly, damage in any one component will affect the functioning of the

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other components. Although all components interact extensively, participate inprocessing at multiple overlapping times, and are connected via feedback, we cannonetheless sketch a basic processing architecture that distinguishes to someextent between the contributions that they make. Thus, the portions of extrastri-ate visual cortices specialized for perceptual processing of social information(fusiform gyrus and superior temporal gyrus) would be most critical in the con-struction of a perceptual representation of the visual stimulus. In our case, wewould expect that visual motion cues are initially processed by medial temporaland parietal sectors that can extract structure and shape from motion. Once sucha shape has been visually segmented, the information can be conveyed to visualcortices in the temporal lobe that will provide further processing and categoriza-tion of the stimulus. The amygdala, ventral striatum, and orbitofrontal cortexwould then link such a highly processed perceptual representation to the modu-lation of an emotional body state (via projections to hypothalamic and brainstemnuclei that can trigger psychophysiological responses). Right-hemispheresomatosensory cortices would come into play in the internal representation of thisemotional response, providing knowledge to the perceiver of how he or she feelsin regard to the perceived stimulus. It is this knowledge, we propose, that is(among other pieces of information) used in the attributions and judgments thatwe make about such stimuli. Our findings provide further evidence for such a roleof right-hemisphere somatosensory cortices in the spontaneous recognition ofemotional states and other social information.

ACKNOWLEDGMENTS

This study was based in part on a dissertation project completed by the firstauthor in fulfillment of the Ph.D. requirements in the Neuroscience GraduateProgram, University of Iowa. She is currently at the Center for Cognitive Neuro-science, University of Pennsylvania. We thank Melissa McGivern and KodiScheer for help in transcribing and preparing the video descriptions, DeniseKrutzfeld and Ruth Henson for assistance in recruiting and scheduling subjects,and Josh Greene and an anonymous reviewer for suggestions on the manuscript.Supported by Program Project Grant NINDS NS19632; A.S.H. was supported in part by an Iowa Presidential Fellowship. Correspondence concerning this article should be sent to Andrea Heberlein, Center for Cognitive Neuroscience,University of Pennsylvania, 3815 Walnut St., Philadelphia PA 19104. Email:[email protected].

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