KJ00004432262.Pdf
Total Page:16
File Type:pdf, Size:1020Kb
Joumal Joumal of Hiroshirna Prefectural College of Health Sciences Hurnanity and Science 5 (1) 21- 30 2005 Organization Organization and Development of the Brain Mechanism for for Understanding Speakers' Reallntentions Satoshi Satoshi IMAIZUMI*1 Midori HOMMA 勺 Y oshiaki OZA W A* 1 Kazuko Y AMASAKI 叶 *1 Hiroshima Prefectural College of Health Sciences ,Japan *2 Hiroshima Prefectural Rehabilitation Center ,Hiroshima ,Japan Abstract Abstract To clarify how the brain understands the speaker' s rnind for verbal acts ,fM RI irnages obtained frorn 24 subjects and behavioral behavioral data obtained frorn 339 subjects were analyzed when they judged the linguistic rneanings or emotional rnanners of of spoken phrases. The target phrases had linguistically positive or negative rneanings and were uttered warrnheartedly or coldheartedly coldheartedly by a wornan speaker. The results of the 品1RI analyses suggest that neural resources responsible for the speakers' speakers' mind reading are distributed over the superior ternporal sulci (STS) ,inferior frontal regions ,rnedial frontal regions and and posterior cerebellum. When cornpared to the female subjects , the rnale subjects showed significantly stronger activation only only in the right frontornedian cortex , which can be hypothesized to infer the speaker' s hidden but true intentions frorn the speaking speaking acts. The correct judgrnent of the speaker's intentions significantly increased with age for the phrases with inconsistent inconsistent linguistic and emotional valences. Female children showed faster developrnent than rnale children. These results suggest suggest that neural processes for language and ernotional prosody significantly interact to rnentalize verbal acts , and sex differences differences exist in this rnind reading system Key words :rnind reading for verbal acts ,brain ,developrnent , speech cornrnunication 円/“噌Bi Journal Journal of Hiroshima Prefectural College of Health Sciences Humanity and Science 5 (1) 21 - 30 2005 surveyed. surveyed. INTRODUCTION Using Using spoken phrases with positive or negative linguistic Phrases Phrases with positive linguistic meanings may convey meanings uttered by a female with two emotions , negative negative meanings when uttered with coldhearted emotion. warmhearted and coldhearted ,we analyzed brain activities For instance ,“It' s wonderful" uttered with evident sarcasm based on a functional MRI measurement when subjects may convey that “It' s not wonderful at all." On the judged linguistic and emotional meanings of the phrases , contrary , phrases with negative linguistic meanings may and discussed possible neural mechanisms for mentalizing convey positive meanings when uttered with warmhearted speaking acts. We also analyzed the development of the emotion. “How stupid you are" may be interpreted as “How mentalizing ability ,testing young people aged 6 to 28 years nice nice you are" when uttered with warmhearted emotion and of age. a friendly feeling. Listeners have to correctly interpret a speaker' speaker' s emotion and integrate it with the linguistic METHOD meaning of the speech act to understand the hidden but true intentions intentions of the speake r. Little is known about how All experiments in this study were conducted in linguistic linguistic and emotional information is integrated in the accordance with the De c1 aration of Human Rights ,Helsinki brain ,and how this brain mechanism develops and when it 1975 and the research ethics regulations in the authors' matures. matures. affiliation. Written informed consent was obtained from Humans strongly and f1 exibly interpret the speaking each subject after explaining the pu 中 ose and the outline of behavior behavior of other people based on an understanding in their the method for this research and the advantages and own minds. The awareness that other people have beliefs disadvantages expected for the subjects. and desires different from our own and that their speaking behavior behavior can be explained by these beliefs and desires can Speech materials be be referred to as the “ theory of mind" 1, 2) or “mentalizing" 3). Two sets of speech samples were prepared: one for Most conventional theory of mind tests based on a false testing young children ,and the other for testing adults. For belief belief estimate that the “mentalizing" ability matures by as testing adults , frequently used 40 phrases with positive early early as age four. linguistic meanings , such as “1 love you ," and 40 phrases Based on the homologs between studies of single-cell with negative linguistic meanings , such as “1 hate you ," activity activity in monkeys and areas implicated in mentalizing were uttered by a female speaker with a Tokyo dialect , with from brain imaging studies , Frith & Frith (1999)3) positive and negative emotions , that is , warmhearted and suggested suggested that the components of the mentalizing system coldhearted emotions (Table 1). The warmhearted include include the (i) superior temporal sulci (STS) , for the utterances were made showing strong pleasure , while the detection detection of the behavior of agents and analysis of the goals coldhearted ones were made showing strong hatred. These and outcomes of this behavior; (ii) inferior frontal regions , utterances were c1 assified into four types: “praise" as the for for the representations of actions and goals; and (i ii) linguistically and emotionally positive phrases ,“ irony" as anterior anterior cingulate cortex / frontomedian regions , for the the linguistically positive and emotionally negative phrases , representations representations of mental states of the self. An implication “ banter" as the linguistically negative and emotionally of of their proposal is that the analysis of another agen t' s positive phrases ,and “blame" as the linguistically and behavior behavior in co 吋unction with the representation of our own emotionally negative phrases. These utterances were mental mental states allows us to make inferences about the digitized and analyzed to extract prosodic characteristics intentions intentions of that agen t. Although such a mentalizing such as FO contour and utterance length ,and then used for system system might contribute to the interpretation of speaking listening tests during functional brain imaging. acts ,no systematic study has been carried out as far as we For testing young children ,frequently used 20 phrases Table 1. Speech materials used for the experiments. ¥Lin¥EjuZ 川m町oMMoneaal nMi 白官ar¥m¥ er Warmhearted (+) Coldhearted ←) Total Positive Positive (+) 40 (praise) 40 (irony) 80 Negative Negative (ー) 40 (banter) 40 (blame) 80 Total Total 80 80 160 -22- Joumal Joumal of Hiroshirna Prefectural College of Health Sciences Hurnanity and Science 5 (1) 21 - 30 2005 J Y o J y o f 400 400 、 :--d b !j !j 300 医主 、 Z ~ 200j 位4 ヨ ーー----一一回 d c 100 100 0.0 1. 0 Time (s) Figure Figure 1. FO contour of two utterances of /iiyo/ (rneaning “ okay") with warrnhearted ernotion (l eft) and and with coldhearted ernotion (right). a: initial FO ,b: rnaximum FO ,c: minimum FO ,d: final FO , FO range= b-c ,length=time difference between d and a. with with positive linguistic rneanings , such as “How nice you whether the pitch of a tone rises or falls. are!" are!" and 20 phrases with negative linguistic rneanings , With the subject in the fM RI systern (Siernens , Magnetic such such as “How bad you are!" were uttered by a female Symphony 1.5T) ,one of the listening tasks and the control speaker speaker with a Tokyo dialect with positive and negative task were altemately perforrned at 30 ・second intervals ,4 ernotions. ernotions. These utterances were digitized and analyzed to tirnes each , and this block design ,which took 4 rninutes to extract extract prosodic characteristics , and then used for listening cornplete ,was perforrned for the 2 listening tasks. The tests. tests. speech and tone stirnuli were presented at the rnost comfortable comfortable level for the individual subjects , once per 3 Acoustic Acoustic analyses seconds. Pressing two buttons with the right index and As shown in Figure 1, fundamental frequency at various rniddle fingers , the judgment and the 陀 sponse tirne were characteristic characteristic timing points and total length of utterances rneasured. were measured and analyzed by ANOV A with two factors The scanning conditions were: the interscan interval consisting consisting of ernotional Manner (Warrnhearted vs. (TR) ,6 seconds; acquisition tirne (TA) ,4 .4 seconds; flip 0 Coldhearted) Coldhearted) as a within-phrase rneasure and linguistic angle ,90 • The irnage data obtained were analyzed using a Meaning (Positive vs. Negative) as a between-phrase statistical pararnetric mapping (SPM2 , the Wellcorne measure. measure. Department of Imaging Neuroscience ,http://www.fi l. ion. uc l. ac.u k/ sp m/ spm2.htrnl) 4). Li stening tasks for MRI measurement The listening subjects for the brain imaging were 24 Developmental analyses right 置 handed healthy adults (1 2 males and 12 fernales; In order to develop a screening test for the early average average age 24.7 years). Two listening tasks were detection of communication problems in children , the irnposed , the language task and the emotion tas k. For the rnind-reading ability from speech was rneasured for 339 language language task , the listening subjects were instructed to listening subjects (1 73 male and 166 female) using spoken judge judge quickly whether the linguistic rneaning of a presented phrases directed to children based on