社会互动视角下人际公平形成的脑机制

doi:10.3724/SP.J.1041.2019.01007

摘要/Abstract

摘要：

最后通牒博弈任务被广泛用以探究公平行为, 以往研究大多集中于对博弈中某一方决策行为和神经机制的探讨, 但是人际公平可能是互动双方重复博弈的结果。因此只考察单个大脑活动, 并不足以揭示由互动双方共同完成的社会认知活动的脑机制。因此, 本研究结合修改版的最后通牒博弈任务和基于fNIRS的超扫描技术, 从群体脑水平上考察人际公平形成的脑机制。行为结果显示, 相比无惩罚条件, 惩罚下提议者的分配金额更高, 且惩罚力度越强, 分配越趋近公平分配。fNIRS的结果显示, 惩罚下右侧背外侧前额叶皮层、顶下小叶和颞-顶联合区的脑间活动同步性显著强于无惩罚条件, 而且两条件的分配金额差异越大, 右侧顶下小叶的脑间活动同步性差异也越大。综上, 脑间活动同步性可以作为惩罚下人际公平形成的客观脑指标, 研究为探讨人际公平的内在机制提供了新的视角。

关键词: 人际公平, 惩罚, 脑间活动同步性, 功能近红外光谱技术, 超扫描技术

Abstract:

Interpersonal fairness plays an important role in human life. Punishment is one of the most fundamental factors in the formation of interpersonal fairness. Although many neuroscience studies have used interactive economic games to explore the neural mechanisms that underlie fair norms’ enforcement and compliance, single brain studies cannot make researchers achieve a complete understanding of the intrinsic mechanisms related to dynamic interactions. Hyperscanning techniques can allow researchers to measure the brain activity of two or more persons simultaneously while they complete cognitive tasks under natural conditions. Therefore, we used fNIRS-based hyperscanning to evaluate changes in behavior and interpersonal neural synchronization (INS) during the formation of interpersonal fairness.

The experimental paradigm referred to the adapted ultimatum game (UG). There were two conditions in our study, punishment and voluntary condition. In the punishment condition, the proposer (A) introduced a distribution scheme. When the recipient (B) accepted it, both of them received money according to the distribution scheme. If B thought that this distribution was unfair, he or she could punish A by spending all or part of their money to reduce A’s gains. One RMB invested in punishment led to a reduction in A’s gains by 5 RMB. However, in the voluntary condition, B was obligated to accept the offer no matter how much A allocated to him or her. The task included 50 trials altogether, 25 trials for each condition. The trials of two different conditions were presented in a pseudo-random way. A total of 44 university students participated in this study, including 13 male and 9 female pairs. Before the experiment, pairs of participants drew lots to decide their roles.

Behavioral results showed that compared with the voluntary condition, the average transfer amount was significantly higher in the punishment condition and much closer to the equal split. Moreover, in the face of unfair distribution, more money was transferred to recipients when they punished more the proposers. Consequently, there was no significant difference between proposers’ and recipients’ final gains in the punishment condition. However, in the voluntary condition, proposers gained more. Results from fNIRS revealed that in the punishment condition, the INS of three brain areas was higher than that of the voluntary condition, including the dorsolateral prefrontal cortex (channel 15), inferior parietal lobule (channel 12, 13), and temporo-parietal junction (channel 9). Additionally, the transfer difference (punishment minus control) was positively associated with an increase of INS in the inferior parietal lobule.

These results suggest that punishment can promote the formation of interpersonal fairness, accompanied by enhanced interpersonal neural synchronizations in the brain areas related to strategic decision-making and theory of mind.

Key words: fairness, punishment, interpersonal neural synchronization, fNIRS, hyperscanning

中图分类号:

张如倩, 刘洁琼, 李先春. (2019). 社会互动视角下人际公平形成的脑机制. 心理学报, 51(9), 1007-1017.

ZHANG Ruqian, LIU Jieqiong, LI Xianchun. (2019). Neural mechanisms of fairness formation in the perspective of social interactions. Acta Psychologica Sinica, 51(9), 1007-1017.

图/表 6

参考文献 56

1	Aron A. R., Robbins T. W., & Poldrack R. A . ( 2004). Inhibition and the right inferior frontal cortex. Trends in Cognitive Sciences.8( 4), 170-177. doi: 10.1016/j.tics.2004.02.010
2	Baumgartner T., Knoch D., Hotz P., Eisenegger C., & Fehr E . ( 2011). Dorsolateral and ventromedial prefrontal cortex orchestrate normative choice. Nature Neuroscience.14( 11), 1468-1474.
3	Benjamini Y. &Hochberg Y. , ( 1995). Controlling the false discovery rate: A practical and powerful approach to multiple testing. Journal of the Royal Statistical Society: Series B (Methodological).57( 1), 289-300.
4	Bilek E., Ruf M., Schäfer A., Akdeniz C., Calhoun V. D., Schmahl C., .. Meyer-Lindenberg A . ( 2015). Information flow between interacting human brains: Identification, validation, and relationship to social expertise. Proceedings of the National Academy of Sciences.112( 16), 5207-5212.
5	, , Casartelli L.., &Molteni M. , ( 2014). Where there is a goal, there is a way: What, why and how the parieto-frontal mirror network can mediate imitative behaviours. Neuroscience & Biobehavioral Reviews.47, 177-193.
6	Corbetta M., Patel G., & Shulman G. L . ( 2008). The reorienting system of the human brain: From environment to theory of mind. Neuron.58( 3), 306-324. doi: 10.1016/j.neuron.2008.04.017
7	Cui X., Bryant D. M., & Reiss A. L . ( 2012). NIRS-based hyperscanning reveals increased interpersonal coherence in superior frontal cortex during cooperation. Neuroimage.59( 3), 2430-2437. doi: 10.1016/j.neuroimage.2011.09.003
8	Dai B., Chen C. S., Long Y. H., Zheng L. F., Zhao H., Bai X. L., .. Lu C. M . ( 2018). Neural mechanisms for selectively tuning in to the target speaker in a naturalistic noisy situation. Nature Communications.9( 1), 2405.
9	Dapretto M., Davies M. S., Pfeifer J. H., Scott A. A., Sigman M., Bookheimer S. Y., & Iacoboni M . ( 2006). Understanding emotions in others: Mirror neuron dysfunction in children with autism spectrum disorders. Nature Neuroscience.9( 1), 28-30.
10	Delgado M. R., Locke H. M., Stenger V. A., & Fiez J. A . ( 2003). Dorsal striatum responses to reward and punishment: Effects of valence and magnitude manipulations. Cognitive.Affective, & Behavioral Neuroscience, 3( 1), 27-38.
11	Fehr E. &Gächter S.., ,( 2000). Cooperation and punishment in public goods experiments. American Economic Review.90( 4), 980-994.
12	Fehr E., & Schmidt, K. M . ( 1999). A theory of fairness, competition, and cooperation. The Quarterly Journal of Economics.114( 3), 817-868.
13	Feng C. L., Luo Y. J., & Krueger F . ( 2015). Neural signatures of fairness-related normative decision making in the ultimatum game: A coordinate-based meta-analysis. Human Brain Mapping.36( 2), 591-602.
14	Gabay A. S., Radua J., Kempton M. J., & Mehta M. A . ( 2014). The Ultimatum Game and the brain: A meta-analysis of neuroimaging studies. Neuroscience & Biobehavioral Reviews.47, 549-558.
15	, Gallagher H.L., &Frith C.D . ( 2003). Functional imaging of ‘theory of mind’. Trends in Cognitive Sciences.7( 2), 77-83.
16	Gao X. X., Yu H. B., Sáez I., Blue P. R., Zhu L. S., Hsu M., & Zhou X. L . ( 2018). Distinguishing neural correlates of context-dependent advantageous-and disadvantageous- inequity aversion. Proceedings of the National Academy of Sciences.115( 33), E7680-E7689.
17	Grinsted A., Moore J. C., & Jevrejeva S . ( 2004). Application of the cross wavelet transform and wavelet coherence to geophysical time series. Nonlinear Processes in Geophysics.11( 5/6), 561-566.
18	Güth W., Schmittberger R., & Schwarze B . ( 1982). An experimental analysis of ultimatum bargaining. Journal of Economic Behavior & Organization.3( 4), 367-388.
19	Hasson U., Ghazanfar A. A., Galantucci B., Garrod S., & Keysers C . ( 2012). Brain-to-brain coupling: A mechanism for creating and sharing a social world. Trends in Cognitive Sciences.16( 2), 114-121. doi: 10.1016/j.tics.2011.12.007
20	Henrich J., McElreath R., Barr A., Ensminger J., Barrett C., Bolyanatz A., .. Ziker J . ( 2006). Costly punishment across human societies. Science.312( 5781), 1767-1770.
21	Holper L., Scholkmann F., & Wolf M . ( 2012). Between-brain connectivity during imitation measured by fNIRS. Neuroimage.63( 1), 212-222. doi: 10.1016/j.neuroimage.2012.06.028
22	Hoshi .( 2003). Functional near-infrared optical imaging: Utility and limitations in human brain mapping. Psychophysiology.40( 4), 511-520.
23	Jiang J., Dai B., Peng D., Zhu C. Z., Liu L., & Lu C. M . ( 2012). Neural synchronization during face-to-face communication. Journal of Neuroscience.32( 45), 16064-16069. doi: 10.1523/JNEUROSCI.2926-12.2012
24	Kamran M.A., & Hong K.S, . ( 2014). Reduction of physiological effects in fNIRS waveforms for efficient brain-state decoding. Neuroscience Letters.580, 130-136.
25	Knoch D., Gianotti L. R. R., Baumgartner T., & Fehr E . ( 2010). A neural marker of costly punishment behavior. Psychological Science.21( 3), 337-342.
26	Knoch D., Nitsche M. A., Fischbacher U., Eisenegger C., Pascual-Leone A., & Fehr E . ( 2008). Studying the neurobiology of social interaction with transcranial direct current stimulation—the example of punishing unfairness. Cerebral Cortex.18( 9), 1987-1990.
27	Knoch D., Pascual-Leone A., Meyer K., Treyer V., & Fehr E . ( 2006). Diminishing reciprocal fairness by disrupting the right prefrontal cortex. Science.314( 5800), 829-832.
28	Koster-Hale J., Saxe R., Dungan J., & Young L. L . ( 2013). Decoding moral judgments from neural representations of intentions. Proceedings of the National Academy of Sciences.110( 14), 5648-5653.
29	Liu T., Saito H., & Oi M . ( 2015). Role of the right inferior frontal gyrus in turn-based cooperation and competition: A near-infrared spectroscopy study. Brain and Cognition.99, 17-23.
30	Makwana A., Grön G., Fehr E., & Hare T. A . ( 2015). A neural mechanism of strategic social choice under sanction-induced norm compliance. eNeuro.2( 3), ENEURO. 0066-14.
31	Marsh L.E., &Hamilton A. F. D., . ( 2011). Dissociation of mirroring and mentalising systems in autism. Neuroimage.56( 3), 1511-1519. doi: 10.1016/j.neuroimage.2011.02.003
32	Miller E.K., & Cohen J.D . ( 2001). An integrative theory of prefrontal cortex function. Annual Review of Neuroscience.24( 1), 167-202.
33	Montague P. R., Berns G. S., Cohen J. D., McClure S. M., Pagnoni G., Dhamala M., .. Fisher R. E . ( 2002). Hyperscanning: Simultaneous fMRI during linked social interactions. Neuroimage.16( 4), 1159-1164.
34	Nozawa T., Sasaki Y., Sakaki K., Yokoyama R., & Kawashima R . ( 2016). Interpersonal frontopolar neural synchronization in group communication: An exploration toward fNIRS hyperscanning of natural interactions. Neuroimage.133, 484-497.
35	O'Doherty J., Kringelbach M. L., Rolls E. T., Hornak J., & Andrews C . ( 2001). Abstract reward and punishment representations in the human orbitofrontal cortex. Nature Neuroscience.4( 1), 95-102.
36	Osaka N., Minamoto T., Yaoi K., Azuma M., Shimada Y. M., & Osaka M . ( 2015). How two brains make one synchronized mind in the inferior frontal cortex: fNIRS-based hyperscanning during cooperative singing. Frontiers in Psychology.6, 1811.
37	Pan Y. F., Cheng X. J., Zhang Z. X., Li X. C., & Hu Y . ( 2017). Cooperation in lovers: An fNIRS-based hyperscanning study. Human Brain Mapping.38( 2), 831-841.
38	Pan Y. F., Novembre G., Song B., Li X. C., & Hu Y . ( 2018). Interpersonal synchronization of inferior frontal cortices tracks social interactive learning of a song. Neuroimage.183, 280-290.
39	Perner J., Aichhorn M., Kronbichler M., Staffen W., & Ladurner G . ( 2006). Thinking of mental and other representations: The roles of left and right temporo-parietal junction. Social Neuroscience.1( 3-4), 245-258.
40	Pierro M. L., Hallacoglu B., Sassaroli A., Kainerstorfer J. M., & Fantini S . ( 2014). Validation of a novel hemodynamic model for coherent hemodynamics spectroscopy (CHS) and functional brain studies with fNIRS and fMRI. Neuroimage.85( 1), 222-233.
41	Reindl V., Gerloff C., Scharke W., & Konrad K . ( 2018). Brain-to-brain synchrony in parent-child dyads and the relationship with emotion regulation revealed by fNIRS-based hyperscanning. Neuroimage.178, 493-502.
42	Ruff C. C., Ugazio G., & Fehr E . ( 2013). Changing social norm compliance with noninvasive brain stimulation. Science.342( 6157), 482-484. doi: 10.1126/science.1241399
43	Sanfey A. G., Rilling J. K., Aronson J. A., Nystrom L. E., & Cohen J. D . ( 2003). The neural basis of economic decision-making in the ultimatum game. Science.300( 5626), 1755-1758.
44	Scholkmann F., Holper L., Wolf U., & Wolf M . ( 2013). A new methodical approach in neuroscience: Assessing inter- personal brain coupling using functional near-infrared imaging (fNIRI) hyperscanning. Frontiers in Human Neuroscience.7, 813.
45	Seeber M., Cantonas L. M., Hoevels M., Sesia T., Visser-Vandewalle V., & Michel C. M . ( 2019). Subcortical electrophysiological activity is detectable with high-density EEG source imaging. Nature Communications.10( 1), 753.
46	Shaw D. J., Czekóová K., Staněk R., Mareček R., Urbánek T., Špalek J., .. Brázdil M . ( 2018). A dual-fMRI investigation of the iterated Ultimatum Game reveals that reciprocal behaviour is associated with neural alignment. Scientific Reports.8( 1), 10896.
47	Spitzer M., Fischbacher U., Herrnberger B., Grön G., & Fehr E . ( 2007). The neural signature of social norm compliance. Neuron.56( 1), 185-196. doi: 10.1016/j.neuron.2007.09.020
48	Tang H. H., Mai X. Q., Wang S., Zhu C. Z., Krueger F., & Liu C . ( 2016). Interpersonal brain synchronization in the right temporo-parietal junction during face-to-face economic exchange. Social Cognitive and Affective Neuroscience.11( 1), 23-32.
49	Weiland S., Hewig J., Hecht H., Mussel P ., & Miltner , W. H. R. ( 2012). Neural correlates of fair behavior in interpersonal bargaining. Social Neuroscience.7( 5), 537-551.
50	Wu Y., Yu H. B., Shen B., Yu R. J., Zhou Z. H., Zhang G. P., .. Zhou X. L . ( 2014). Neural basis of increased costly norm enforcement under adversity. Social Cognitive and Affective Neuroscience.9( 12), 1862-1871. doi: 10.1093/scan/nst187
51	Wu Y., &Zhou X.L, . ( 2012). The context-dependency of fairness processing: Evidence from ERP study. Acta Psychologica Sinica.44( 6), 797-806. doi:
52	[ 吴燕, 周晓林 . ( 2012). 公平加工的情境依赖性: 来自 ERP 的证据. 心理学报.44( 6), 797-806.] doi:
53	Xia M. R., Wang J. H., & He Y . ( 2013). BrainNet Viewer: A network visualization tool for human brain connectomics. PLoS One.8( 7), e68910.
54	Ye J. C., Tak S., Jang K. E., Jung J., & Jang J . ( 2009). NIRS-SPM: Statistical parametric mapping for near-infrared spectroscopy. Neuroimage.44( 2), 428-447. doi: 10.1016/j.neuroimage.2008.08.036
55	Young L.& Saxe R , ( 2008). The neural basis of belief encoding and integration in moral judgment. Neuroimage.40( 4), 1912-1920. doi: 10.1016/j.neuroimage.2008.01.057
56	Zheng L. F., Chen C. S., Liu W. D., Long Y. H., Zhao H., Bai X. L., .. Lu C. M . ( 2018). Enhancement of teaching outcome through neural prediction of the students' knowledge state. Human Brain Mapping.39( 7), 3046-3057.

通道	MNI坐标			AAL分区		布鲁德曼分区
通道	x	y	z	脑区	概率	脑区	概率
1	59.49	21.37	20.43	右侧三角部额下回	0.67	44-岛盖部, 布洛卡区部分	0.53
2	66.87	-7.18	29.10	右侧中央后回	1.00	43-中央下区	1.00
3	67.53	-33.40	34.90	右侧缘上回	1.00	40-缘上回, 威尔尼克区部分	0.72
4	59.42	-59.03	33.70	右侧角回	1.00	39-角回, 威尔尼克区部分	0.97
5	50.69	36.73	27.05	右侧额中回	0.52	45-布洛卡区三角区	1.00
6	58.80	7.96	36.56	右侧中央前回	0.97	6-前运动皮层和辅助运动皮层	0.78
7	63.88	-20.28	43.97	右侧缘上回	0.76	1-初级躯体感觉皮质	0.83
8	60.37	-45.14	46.84	右侧顶下小叶	0.60	40-缘上回, 威尔尼克区部分	1.00
9	48.36	-68.79	43.83	右侧角回	1.00	39-角回, 威尔尼克区部分	1.00
10	47.43	24.55	43.41	右侧额中回	0.99	44-岛盖部, 布洛卡区部分	0.51
11	54.49	-4.25	50.69	右侧中央前回	0.55	6-前运动皮层和辅助运动皮层	0.97
12	56.89	-31.30	54.81	右侧顶下小叶	0.72	1-初级躯体感觉皮质	0.68
13	49.68	-55.49	55.37	右侧顶下小叶	0.84	40-缘上回, 威尔尼克区部分	0.81
14	33.83	37.74	46.08	右侧额中回	0.98	9-背外侧前额叶皮层	1.00
15	42.48	13.34	56.74	右侧额中回	1.00	9-背外侧前额叶皮层	0.79
16	47.64	-17.53	62.57	右侧中央前回	0.52	4-初级运动皮层	0.65
17	43.34	-42.84	63.31	右侧顶上小叶	0.55	2-初级躯体感觉皮质	0.52
18	32.38	-63.83	61.62	右侧顶上小叶	0.99	7-躯体感觉联合皮层	1.00
19	27.55	24.62	58.16	右侧额上回	0.78	8-前额眼动区	0.99
20	34.22	-1.43	65.56	右侧额上回	0.66	6-前运动皮层和辅助运动皮层	1.00
21	35.98	-29.29	70.73	右侧中央后回	0.64	4-初级运动皮层	0.84
22	28.73	-53.67	70.81	右侧顶上小叶	1.00	7-躯体感觉联合皮层	1.00

通道	MNI坐标			AAL分区		布鲁德曼分区
通道	x	y	z	脑区	概率	脑区	概率
1	59.49	21.37	20.43	右侧三角部额下回	0.67	44-岛盖部, 布洛卡区部分	0.53
2	66.87	-7.18	29.10	右侧中央后回	1.00	43-中央下区	1.00
3	67.53	-33.40	34.90	右侧缘上回	1.00	40-缘上回, 威尔尼克区部分	0.72
4	59.42	-59.03	33.70	右侧角回	1.00	39-角回, 威尔尼克区部分	0.97
5	50.69	36.73	27.05	右侧额中回	0.52	45-布洛卡区三角区	1.00
6	58.80	7.96	36.56	右侧中央前回	0.97	6-前运动皮层和辅助运动皮层	0.78
7	63.88	-20.28	43.97	右侧缘上回	0.76	1-初级躯体感觉皮质	0.83
8	60.37	-45.14	46.84	右侧顶下小叶	0.60	40-缘上回, 威尔尼克区部分	1.00
9	48.36	-68.79	43.83	右侧角回	1.00	39-角回, 威尔尼克区部分	1.00
10	47.43	24.55	43.41	右侧额中回	0.99	44-岛盖部, 布洛卡区部分	0.51
11	54.49	-4.25	50.69	右侧中央前回	0.55	6-前运动皮层和辅助运动皮层	0.97
12	56.89	-31.30	54.81	右侧顶下小叶	0.72	1-初级躯体感觉皮质	0.68
13	49.68	-55.49	55.37	右侧顶下小叶	0.84	40-缘上回, 威尔尼克区部分	0.81
14	33.83	37.74	46.08	右侧额中回	0.98	9-背外侧前额叶皮层	1.00
15	42.48	13.34	56.74	右侧额中回	1.00	9-背外侧前额叶皮层	0.79
16	47.64	-17.53	62.57	右侧中央前回	0.52	4-初级运动皮层	0.65
17	43.34	-42.84	63.31	右侧顶上小叶	0.55	2-初级躯体感觉皮质	0.52
18	32.38	-63.83	61.62	右侧顶上小叶	0.99	7-躯体感觉联合皮层	1.00
19	27.55	24.62	58.16	右侧额上回	0.78	8-前额眼动区	0.99
20	34.22	-1.43	65.56	右侧额上回	0.66	6-前运动皮层和辅助运动皮层	1.00
21	35.98	-29.29	70.73	右侧中央后回	0.64	4-初级运动皮层	0.84
22	28.73	-53.67	70.81	右侧顶上小叶	1.00	7-躯体感觉联合皮层	1.00

[1]	陈沛琪, 张银玲, 胡馨木, 王静, 买晓琴. 10~12岁儿童社会价值取向对第三方利他行为的影响：情绪的作用[J]. 心理学报, 2023, 55(8): 1255-1269.
[2]	付博, 彭坚, 梁潇杰, 陈丽芳, 于桂兰. 下属亲领导非伦理行为的持续与消退：基于领导反应的视角[J]. 心理学报, 2023, 55(5): 844-860.
[3]	徐楚言, 朱麟, 王芸萍, 王瑞冰, 刘聪慧. 外语口语焦虑对言语互动质量的影响：fNIRS超扫描研究[J]. 心理学报, 2023, 55(12): 1949-1965.
[4]	许丽颖, 喻丰, 彭凯平. 算法歧视比人类歧视引起更少道德惩罚欲[J]. 心理学报, 2022, 54(9): 1076-1092.
[5]	杨莎莎, 陈思静. 第三方惩罚中的规范错觉：基于公正世界信念的解释[J]. 心理学报, 2022, 54(3): 281-299.
[6]	陈思静, 杨莎莎, 汪昊, 万丰华. 主观社会阶层正向预测利他性惩罚[J]. 心理学报, 2022, 54(12): 1548-1561.
[7]	陈思静, 邢懿琳, 翁异静, 黎常. 第三方惩罚对合作的溢出效应：基于社会规范的解释[J]. 心理学报, 2021, 53(7): 758-772.
[8]	陈思静, 徐烨超. “仁者”还是“智者”：第三方惩罚对惩罚者声誉的影响[J]. 心理学报, 2020, 52(12): 1436-1451.
[9]	殷西乐, 李建标, 陈思宇, 刘晓丽, 郝洁. 第三方惩罚的神经机制：来自经颅直流电刺激的证据[J]. 心理学报, 2019, 51(5): 571-583.
[10]	张阔, 何立媛, 赵莹, 王敬欣. 奖励和惩罚在注意控制过程中的优化和分离：眼动研究[J]. 心理学报, 2019, 51(11): 1207-1219.
[11]	黎晓丹, 丁道群, 叶浩生. 身体姿势启动的内隐权力感对公平决策的影响[J]. 心理学报, 2019, 51(1): 106-116.
[12]	崔丽莹, 何幸, 罗俊龙, 黄晓娇, 曹玮佳, 陈晓梅. 道德与关系惩罚对初中生公共物品困境中合作行为的影响[J]. 心理学报, 2017, 49(10): 1322-1333.
[13]	刘蕴, 李燕萍, 涂乙冬. 员工为什么乐于助人？多层次的领导–部属交换对帮助行为的影响[J]. 心理学报, 2016, 48(4): 385-397.
[14]	陈思静;何铨;马剑虹. 第三方惩罚对合作行为的影响：基于社会规范激活的解释[J]. 心理学报, 2015, 47(3): 389-405.
[15]	谷莉;白学军;王芹. 奖惩对行为抑制及程序阶段中自主生理反应的影响[J]. 心理学报, 2015, 47(1): 39-49.