HUMAN SOCIAL INTERACTION RESEARCH PROPOSAL C8CSNR

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1 HUMAN SOCIAL INTERACTION RESEARCH PROPOSAL C8CSNR Applicants Principal Investigator Student ID Collaborators Name(s) Institution(s) Title of project: Neural basis of verbal and non-verbal false and true belief reasoning in children and adults- an fmri investigation Lay Summary (max 200 words): Theory of mind (ToM) is an ability essential in understanding the beliefs and intentions of others. One component of ToM is the ability to understand when someone else has a false belief and predict their actions based on this. Previous research has suggested brain regions which may be involved in this process- the medial prefrontal cortex (mpfc) and the temporo-parietal junction (TPJ). Sommer et al. (2007) claimed that to accurately test which brain regions are involved, studies should compare neural activity during false belief reasoning with true belief reasoning, as studies which compare false belief reasoning with non-tom abilities may highlight areas that are involved in belief reasoning in general, so may not tell us anything about false beliefs specifically. Previous research has investigated neural differences between adults and children when engaged in verbal and non-verbal false belief tasks, but have used non-tom controls which leads to interpretation issues. This study aims to address this by comparing the brain regions active in children and adults during verbal and non-verbal tasks of false belief, compared to true belief tasks using fmri. This will highlight and differences in the way adults and children process information about false belief between cartoons and stories. Scientific Summary (max 200 words): Previous research suggests age and modality specificity of the mpfc and TPJ in understanding false belief, a component of theory of mind. Sommer et al. (2007) proposed a limitation of studies that compare neural activity during false belief tasks and non-tom controls, such as physical causality stories. They claim that they differ in more ways than the decoupling of another s belief from reality, making it difficult to conclude that any active regions are specifically implicated in false belief reasoning and not reasoning about beliefs and ToM generally. No study has yet compared which brain regions are implicated in false belief reasoning between children and adults and with both verbal and non-verbal tasks taking this methodological issue into account, therefore this study aims to do so. Sommer et al. s (2007) false versus true belief paradigm will be used using both cartoons and sentential stories with both adults and children using fmri. Areas which are active only during the false belief trials suggest that they are implicated specifically in the decoupling of beliefs and reality, essential for false belief reasoning. Furthermore, age and modality related differences will be noted to investigate whether adults and children rely on different areas depending on modality. Table of Costs Equipment Participants MRI scanner 1x x adults (students) Free Structural/Functional scan 10x24 MRI compatible equipment x children. 12x Free Equipment Total 540 Participants total 240 Grand Total 780 i

2 PROPOSED RESEARCH PROGRAMME 1. Background of the project 2. Questions to be answered 3. Plan of investigation 4. Details of data analysis 5. Expected outcomes 6. Details of any difficulties that can be foreseen 7. Future purpose and theoretical implications PROPOSED RESEARCH PROGRAMME Page One 1. Background of the project Theory of mind (ToM) is a component of the social brain essential in understanding that another s beliefs, desires, and intentions can differ from our own. Gopnick and Meltzoff (1997) define it as the process of attribution of mental states to another person, and using them to explain and predict their behaviour. Most researchers have concluded that ToM tasks are typically passed from the age of four or five (Wimmer and Perner, 1983), the most widely used test of this being that of false belief (FB). Understanding the FBs of others requires an ability to distinguish between belief and reality (Sommer et al., 2007) and awareness that beliefs are based on knowledge, sometimes inaccurate, and that they influence behaviour. Correct judgements on FB tasks rely on inhibition of what one knows, and taking the perspective of someone whose knowledge does not match reality. Correct judgements about true beliefs, on the other hand, are not an indication of ToM because the person s actions may be predicted based on reality and a distinction between this and their beliefs is not required (Frith and Frith, 2006). The most commonly used test of FB is Wimmer and Perner s (1983) Sally-Anne test in which subjects must inhibit their own knowledge of where an object is and acknowledge that, unlike themselves, Sally did not see Anne move it and therefore incorrectly believes that it is still where she left it. Following research into ToM in normally developing children (Wimmer and Perner, 1983; Gopnik and Astington, 1988), autistic children (Baron-Cohen et al., 1985; Pilowsky et al., 2000), and apes (Premack and Woodruff, 1978; Povinelli et al., 1990; Heyes, 1998), interest has recently turned to the neural basis of this ability to mentalise. Imaging studies have pointed to the medial prefrontal cortex (mpfc) (Brunet et al., 2000; Gallager et al., 2000; Vogeley et al., 2001) and the temporo-parietal junction (TPJ) (Gallager et al., 2000; Saxe and Kanwisher, 2003; Saxe and Wexler, 2005) as being implicated in ToM. The mpfc is involved in reflection upon one s own and other s mental states, whereas the TPJ is involved in recognising actions and intentions from biological motion (Frith and Frith, 2006). Sommer et al. (2007) found increased activation of the mpfc during true belief attributions in comparison to false, which they explain in terms of a distinction between stimulus-independent and stimulus-orientated processes. FB processing is stimulus-independent, as the person s belief about where the object is is independent from its actual location. True beliefs are stimulus-orientated as they are the same as the actual location of the object- subjects do not need to process the character s mental state and the actual location differently. The mpfc shows greater activation during stimulus-orientated than stimulus-independent processing (Gilbert et al., 2005). Sommer et al. (2007) found increased activation of the right TPJ during false compared to true belief processing. This area had previously been shown to respond more to FB stories than control false photograph scenarios (Saxe and Kanwisher, 2003), leading to the suggestion that it may have a general role in mentalising and belief processing. Sommer et al. s (2007) false versus true belief ii

3 PROPOSED RESEARCH PROGRAMME Page two paradigm demonstrated that this area is only active during FB processing, stressing its role in the decoupling of beliefs and reality. Samson et al. (2007) tested two stroke patients using FB paradigms to investigate the distinction between two component processes of ToM- taking someone else s perspective and inhibiting one s own. They concluded that self perspective-inhibition and other perspective-taking represented two distinct components of ToM with distinct neural networks involving the right prefrontal cortex and left TPJ. Most research has predominantly focused on ToM in adults, although it is widely accepted that ToM is a developmental concept (Wellman et al., 2001; Baron-Cohen et al., 1985). Kobayashi et al. (2007) investigated age and modality related differences in the brain regions active during ToM tasks, testing children and adults on both verbal (stories) and non-verbal (cartoons) FB tasks. ToM components activated the right mpfc and bilateral TPJ and right IPL for all subjects, although children show greater activation in the right superior temporal gyrus (STG) and right ventro-medial PFC than adults. In the bilateral TPJ and left STG, adults showed greater activation during the story ToM condition, whereas children showed greater activation during the cartoon ToM condition. They concluded that adults may use different brain regions to process FBs than children and that this may be modalityspecific. Sommer et al. (2007) claimed that studies comparing ToM scenarios with physical causality controls are problematic as it is possible that the areas identified may be involved in reasoning about beliefs in general and therefore cannot specifically highlight regions involved of the decoupling of belief and reality in FB reasoning. Using non-tom cartoons may involve mentalising to some extent, but they differ from ToM scenarios in more ways than belief attribution, such as attribution of intentions and emotions (Sommer et al., 2007). Therefore comparing FB scenarios with physicality scenarios, as Kobayashi et al. (2007) did, may not highlight brain regions that are specifically involved in the decoupling of belief in reality in FB reasoning. This poses a problem for interpreting their results. This study aims to address this by comparing the neural activation of children and adults during both verbal and non-verbal FB scenarios, using true belief scenarios as a control. This will allow investigation of brain regions that are specifically involved in the decoupling of belief and reality and whether these are age or modality specific. 2. Questions to be answered What are the brain regions involved in FB reasoning? Do these regions vary between children and adults? Do these regions vary between verbal and non-verbal scenarios? Do children and adults show differential patterns of activation between verbal and non-verbal scenarios? 3. Plan of investigation Twenty-four right-handed subjects will take part in a mixed-design fmri experiment using a 3-T GE Signa scanner (General Electric Medical Systems, Milwauki, WI) with a standard head coil. Twelve of these subjects will be adults and twelve will be children, aged between years to allow comparison with Kobayashi et al. s (2007) sample. The subjects will have no history of neurological or psychiatric disease. Testing children in fmri investigations can be problematic as it is important to keep movement to a minimum, therefore any subjects that show excess movement during their time in the scanner (>5mm) will be excluded from the experiment. The design of the experiment will be a 2x2x2 mixed design. There will be three factors, each with two levels: age- child or adult, which is a between-subjects factor; task- verbal or non-verbal, which is within-subjects; and belief- true or false, also within-subjects. The stimuli will be based on the Sally-Anne Scenario. Non-verbal stimuli will replicate Sommer et al. s (2007) cartoons, with permission, whereas verbal stimuli will represent the same information in sentential form. Stimuli will be divided into three sections- story, belief and response, as in Sommer et al. (2007), separated by intervals of between 5.6 and 13.8 seconds, varying randomly. Subjects must use an iii

4 PROPOSED RESEARCH PROGRAMME Page three fmri-compatible touch pad to decide whether the character s response was expected or unexpected based on her belief by pressing one of two buttons with their index or middle finger of their right hand. Stimuli will be presented for 1400ms, except the response cartoon or text which will be for 2000ms. The experiment will consist of two runs. In each run, 20 true belief stories- 10 verbal, 10 non-verbal- and 20 FB stories again 10 verbal and 10 non-verbal, will be presented in a random with a second interval between them to allow brain activation to return to baseline. Therefore each subject will see: 10 verbal true belief stories, 10 non-verbal true belief stories, 10 verbal FB stories, and 10 non-verbal FB stories. Each run will last between 27.2 seconds and 51.8 seconds. A scan will be taken at the onset of each stimulus measuring BOLD responses using a T2*-weighted echo-planar imaging sequence to produce a 3D image of the whole brain. The regions of interest (ROI) are the mpfc and the TPJ. Saxe (2006) discussed limitations of focusing exclusively on specific ROIs in fmri experiments, as significant activation in these regions may be misinterpreted due to an unawareness of the activity the rest of the brain, concluding that limiting investigation to ROIs only, without a voxel-based whole brain analysis, obscures the bigger picture. Therefore this experiment will include both whole-brain imaging and analysis of ROIs. An anatomical scan will be conducted on each subject to allow accurate mapping of the anatomical brain structure underlying patterns of activation and highlight any abnormalities. fmri identifies functional activity in areas of the brain that are active during stimuli exposure by detecting increased oxygen. When a brain region is active, neurons require more oxygen. The increased blood flow to that region exceeds the amount required, resulting in a temporary increase in local oxygen level, which affects the magnetic properties of the blood s water, changing the BOLD signal. Increased BOLD signals in a particular area during stimulus exposure indicate that that region is active, implying some involvement in the processing of that stimulus. Functional activity will be compared between true and FB stories and differences between groups and modalities will be observed. 4. Details of data analysis fmri output data consists of a time-varied BOLD signal for each voxel. Fourier transformation converts this raw data into a 3D image form. The data will be analysed using SPM2 software in MATLAB. Post-processing corrections will need to be made as during the subjects time in the scanner, more brain regions will be active than the ones of interest for comparison. For example, slight head movements and movements from pressing the button in the behavioural task will result in activation in the motor cortex. Data will be spatially smoothed using a Gaussian filter. Activation during the story slides will be used as a baseline condition because they will be of similar visual complexity as the belief slides. Four analyses will be computed for each subject- true belief versus story, FB versus story, FB versus true belief, and true belief versus false. fmri analysis will not include data from the response slide, which will only be used for the purpose of the behavioural task. A subtraction technique will be used for the contrasts: verbal true belief minus story, verbal FB minus story, non-verbal true belief minus story, and non-verbal FB minus story. A 2x2x2 mixed ANOVA will then be performed with the previously described factors. This will show whether any differences in activation between true and FB scenarios are significant and whether these are age or modality specific. It will also show whether any of these factors interact. 5. Expected outcomes What are the brain regions involved in FB reasoning? Sommer et al. (2007) found FB activated the right TPJ whereas true belief activated the mpfc. As this study will also encorporate a true belief control, it can be expected that Sommer et al. s (2007) results will be replicated when comparing true versus FB. Do these regions vary between children and adults? During Kobayashi et al. s (2007) ToM stories, children showed greater activation than adults in the right vmpfc and the right STG. There is no previous research suggesting whether this is during ToM tasks in general, or if they use different areas in the iv

5 PROPOSED RESEARCH PROGRAMME Page four process of decoupling beliefs and reality. If children show different activation to adults during FB only, it suggests that the processes used by children in the decoupling of beliefs and reality involve different brain areas to those used by adults. If, however, Kobayashi et al. s (2007) results are replicated indiscriminately for both false and true beliefs, it suggests that the right vmpfc and the right STG are involved reasoning about beliefs in general in children more so than in adults. Do these regions vary between verbal and non-verbal scenarios? ToM stories activate the left STG more, and the mpfc less than ToM cartoons (Kobayashi et al., 2007), suggesting that this area s involvement in ToM is modality specific. If this area is more active during false than true belief stories, it suggests that its involvement may specifically be in the decoupling of beliefs and reality, whereas if it does not significantly differ it suggests that it is involved in beliefs in general. It would also suggest that the neural mechanism by which we reason with FBs is modality specific, which has not been demonstrated before. Do children and adults show differential patterns of activation between verbal and non-verbal scenarios? Kobayashi et al. (2007) found that within the ToM task, the bilateral TPJ and left STG were more active in adults during the story task and in children during the cartoon task. These areas were less active in adults whilst viewing cartoons and children whilst viewing stories. This suggests that children and adults use different brain regions in understanding beliefs in general, and that these may be modality specific. This study will identify whether the same is true for understanding FBs. It is expected that areas of activity will differ between adults and children and between verbal and non-verbal tasks, with both groups utilising different brain areas during both. Additionally, these patterns will differ between false and true belief stories to highlight areas that are involved in reasoning about beliefs in general, and those that are involved in decoupling beliefs and reality. 6. Details of any foreseen difficulties Investigating social cognitive behaviours in non-natural social environments may be problematic, according to Saxe (2006) as the sources of social information used by subjects are abstracted and impoverished, whereas in the real world social interaction relies on social cues from other people, rather than cartoons or stories. This presents a problem for all neuro-imaging studies of ToM of this nature, therefore does not specifically challenge the results of this particular design. Using children in fmri experiments can also be problematic as excess movement in the scanner should be avoided, and they are more likely than adults to become restless and move. However, excluding subjects who show excess movement (>5mm) should prevent this affecting the results. 7. Future purpose and theoretical implications This experiment aims to add to the evidence base around the brain areas involved in the specific component of ToM of understanding others FBs, and investigate whether the areas that are important for understanding verbal and non-verbal FB scenarios differ between adults and children. Age-related differences in FB reasoning will further existing knowledge on the development of this ability, which may currently be limited to the development of understanding beliefs in general due to previous studies using non-tom controls. Modality-related differences in neural activation will suggest that future studies looking to compare the neural activation of adults and children during FB tasks should consider that the resources used to understand ToM by children and adults may differ depending on modality, so comparing activity in response to one type of stimuli alone across ages may not provide the full picture. v

6 PROPOSED RESEARCH PROGRAMME Page five TO BE USED FOR REFERENCES ONLY Baron-Cohen, S., Leslie, A.M. & Frith, U. (1985), Does the autistic child have a theory of mind? Cognition, vol. 21, pg Brunet, E., Sarfati, Y., Hardy-Baylé, M.-C. & Decety, J. (2000), A PET investigation of the attribution of intentions with a non-verbal task, Neuroimage, vol. 11, pg Frith, C. & Frith, U. (2006), Theory of mind, Current biology, vol. 15, no. 17, pg Gallager, H.L., Happé, F., Frunswick, N., Fletcher, P.C., Frith, U. & Frith, C.D. (2000), Reading the mind in cartoons and stories: an fmri study of theory of mind in verbal and non-verbal tasks, Neuropsychologia, vol. 38, pg Gilbert, S.J., Frith, C.D., & Burgess, H.C. (2005), Involvement of rostral prefrontal cortex in selection between stimulus-oriented and stimulus independent thought, European journal of neuroscience, vol. 21, pg Gopnik, A.,& Astington, J.W., (1988), Children's understanding of representational change and its relation to the understanding of false belief and the appearancereality distinction, Child Development, vol. 59, pg Gopnik, A. & Meltzoff, A.N. (1997). Words, thoughts, and theories. MIT Press, pg Heyes, C.M. (1998), Theory of mind in non-human primates, Behavioural and brain sciences, vol. 21, pg Kobayashi, C., Glover, G.H., & Temple, E. (2007), Childrens and adults neural bases of verbal and nonverbal theory of mind, Neuropsychologia, vol. 45, pg Povinelli, D. J., Nelson, K. E. & Boysen, S. T. (1990), Inferences about guessing and knowing by chimpanzees (Pan troglodytes), Journal of Comparative Psychology, vol. 104, pg Premack, D. & Woodruff, G. (1978), Does the chimpanzee have a theory of mind? Behavioral and Brain Sciences, vol. 1(4), pg Samson, D., Apperly, I.A., & Humphreys, G.W. (2007), Error analyses reveal contrasting deficits in theory of mind : neuropsychological evidence from a 3- option false belief task, Neuropsychologia, vol. 45, pg Saxe, R. (2006), Why and how to study theory of mind with fmri, Brain Research, vol. 1079, pg Saxe, R. & Kanwisger, N. (2003), People thinking about thinking people: the role of the temporo-parietal junction in theory of mind, Neuroimage, vol. 19, pg Saxe, R. & Wexler, A. (2005), Making sense of another mind: the role of the right temporo-parietal junction, Neuropsychologia, vol. 43, pg Pilowsky, T., Yirmiya, N., Arbelle, S. & Mozes, T. (2000), Theory of mind abilities of children with schizophrenia, children with autism, and normally developing children, Schizophrenia research, vol. 42(2), pg Vogeley, K., Bussfield, P., Newen, A., Herrmann, S., Happé, F., Falkai, P. et al. (2001), -Mind reading: neural mechanisms of theory of mind and self-perspective, Neuroimage, vol. 14, pg Wellman, H.M., Cross, D. & Watson, J. (2001), Meta-analysis of theory of mind development: the truth about false belief, Child development, vol. 72(3), pg Wimmer, H. & Perner, J. (1983), Beliefs about beliefs: representation and constraining function of wrong beliefs in young children s understanding, Cognition, vol. 13, pg vi