认知与发展心理学研究室知识库

    奖赏能够提高个体的行为动机，使人产生愉快的情绪，并且能够优化个体的注意资源分配。在多种奖赏物中，金钱奖赏和社会奖赏是典型代表。大脑奖赏系统随着个体年龄的增长不断发展、成熟。儿童期和青少年期是个体奖赏系统发展的关键时期。本研究在前人研究的基础上进一步探讨个体奖赏加工随年龄增长的发展特点，个体在不同年龄段对金钱奖赏、社会奖赏的动机差异，以及两类奖赏如何影响个体的冲突控制行为。
    本研究选择8岁左右的儿童、13岁左右的青少年和成人作为被试，人民币和渝快面孔作为金钱奖赏和社会奖赏。三个子研究都采用修订版的MID和SID任务以及主观评定量表来考察儿童、青少年、成人的奖赏加工。两种任务都有无、低、高三种奖赏量。研究一旨在考察儿童、青少年和成人对金钱奖赏和社会奖赏加工的行为特点。在研究一中，达到奖赏标准的被试能够得到巧元人民币和一本荣誉证书分别作为金钱奖赏和社会奖赏。研究二在研究一的基础上采用ERP技术探讨儿童、青少年、成人奖赏加工的认知神经机制。根据被试在相应任务中的行为表现，他们能够分别得到9-4_5元不等的奖金以及一至五等奖的荣誉证书作为金钱奖赏和社会奖赏。研究三在研究一和研究二的研究发现的基础上，采用ERP技术探讨了金钱奖赏和社会奖赏如何影响儿童、青少年和成人的冲突控制行为。被试在目标阶段进行的是经典的Simon任务。三个研究分别得到以下主要结论:
    (1)研究一中，随着奖赏量的增加，在选择反应时任务中，金钱奖赏和社会奖赏都能够提高儿童、青少年和成人的反应速度。在青少年组和成人组，男性被试在高奖赏的条件下反应速度快于低奖赏，但是女性在两种奖赏量条件下反应速度无显著差异。在儿童组，女孩在高奖赏的条件下的反应快于低奖赏。但是，在高低奖赏条件下，儿童组男孩反应的错误率高于女孩，并且，他们在社会奖赏的高奖赏条件反应错误率高于无奖赏。对于主观评定指标，儿童组和青少年组对社会奖赏的主观评定分数高于金钱奖赏。这些结果表明，青少年组和成人组的男性比女性对奖赏更加敏感。而且，对于儿童和青少年，实在的、量化的社会奖赏比金钱奖赏更具激励效应。
    (2)研究二针对线索一P3成分、目标一P2和目标一P3成分来探讨个体在奖赏加工时的动机激发、情绪唤起和注意分配。成人被试在金钱奖赏条件下的线索一P3平均波幅大于社会奖赏。青少年对奖赏的情绪反应，即目标一P2成分的平均波幅大于成人，并且能够被社会奖赏有效地调节。奖赏对于青少年注意分配(目标一P3)的调节比成人更加有效。由于奖赏系统的发育不成熟，儿童的注意分配无法受到不同奖赏量的调节。此研究表明，青少年对奖赏最为敏感，奖赏能够引起他们更强的情绪唤起和更有效的注意资源分配。
    (3)研究三针对线索一P3成分、目标一N2和目标一P3成分来探讨个体在奖赏加工时的动机激发、奖赏对冲突监测的调节和奖赏对冲突解决的影响。个体的冲突控制能力在儿童、青少年阶段持续发展。和金钱奖赏高奖赏条件不同，女性被试在社会奖赏奖赏高奖赏条件下，反应速度慢于男性和金钱奖赏高奖赏条件，但是错误率和无奖赏、低奖赏却没有差异。因此，在主要要求准确率的任务中，可以采用社会奖赏来激励女性。金钱奖赏的高奖赏使得儿童组女孩和青少年组被试对与任务无关的冲突信息进行加工，说明过高的动机会对冲突控制能力尚不成熟的个体的冲突控制行为产生消极的影响。
    综上所述，金钱奖赏和社会奖赏能够有效激励个体的行为。儿童的大脑奖赏系统尚未发育成熟，不能很好地利用奖赏信息调节自己的目标导向行为。在儿童期，女孩对奖赏的敏感性高于男孩。青少年期是对奖赏的高敏感时期。奖赏能够有效调节青少年的注意资源分配、社会奖赏能够有效调节青少年的情绪。但是对于儿童和青少年，过高的行为动机都会对任务相关的注意力集中产生影响。成人期能够利用奖赏信息抑制对于任务无关信息的加工。并且，在青少年和成人阶段，男性被试对奖赏更加敏感。在考虑个体对某种奖赏物的动机时，主客观指标应该综合考虑。

    Reward can enhance behavioral motivation, elicit positive emotion and optimize the allocation of attention resources for people. Among multiple reward stimuli, monetary  and  social  rewards  are typical representative.  The  development  and maturation of brain reward system begins at birth and continues throughout an individual's  life.  The  childhood  and  adolescence  are  critical  periods  for  the development of brain reward system. According to previous research, the current study further investigated the  developmental changes  in  reward  processes,  the incentive differences between monetary and social rewards and how the two kinds of rewards impact the response inhibition behavior for children, adolescents and adults.
    In the current study, 8-year-old children and adolescents around 13 years old as well as adults were recruited as experimental participants, Chinese Yuan and smiling faces were regarded as monetary and social rewards. Adapted incentive-delay tasks and self-report questionnaires were adopted to investigate the monetary and social reward processing. Both tasks had three levels of reward magnitudes (no, low and high). In study 1，qualified participants received 15 Chinese Yuan and an honor certificate as monetary and social rewards, respectively. According to the results of studyl，study 2 adopted the technique of ERP to investigate the neural basis of reward processes for children, adolescents and adults. According to the final score of the participants, 9-4_5 Chinese Yuan and honor certificates of five grades were awarded to the participants as monetary and social rewards. Study 3 aimed to investigate the effects  of  monetary  and  social  rewards  on  response  inhibition  behavior.  The participants should conduct the classical Simon task at the target responsing stage.The 3 studies drew the following conclusions respectively:
    (1)In study 1，the results indicated that both monetary and social reward effectively speeded up responses for all three age groups as reward magnitude increased in the choice reaction time task. Among adolescents and adults, males exhibited faster responses in high reward than low reward condition, while females responded equally fast in both conditions. For children, girls responded faster to high reward than low reward condition. However, boys committed more errors than girls in low and high reward conditions, and they had more errors in high reward than that in no reward condition for social reward. Regarding the subjective ratings, both children and adolescents exhibited higher motivation for social reward than monetary reward.These findings indicated that males in adolescent and adult groups were more sensitive to reward than females, tangible and quantitative social rewards had stronger incentive power than monetary rewards among children and adolescents.   

    (2) In study2, for the ERP data, cue-P3, target-P2 and target-P3 were investigated to identify the reward motivation, emotional arousal and attention allocation during reward responses. Adults showed larger cue-P3 responses for monetary than social rewards.  Adolescents'  emotional responses to reward,  which were reflected in target-P2, were stronger than those of adults and were effectively regulated by different magnitudes of social reward. Attention allocation (target-P3) was regulated by reward magnitudes more effectively for adolescents than adults, and limited by an immature reward system, attention allocation of children was insensitive to reward magnitudes. The current study revealed that adolescents had heightened sensitivity to reward  with inducing  stronger  emotional  arousal  and  more  effective  attention allocation during reward processes.   
    (3) In study 3, cue-P3, target-N2 and target-P3 were investigated to identify the motivation elicition, the regulation effect of monetary and social rewards on conflict monitoring and  conflict  resolution.The  ability  of  conflict  control  is  ongoing developing during childhood and adolescence. For high reward of social reward female participants responded to the targets slower than male participants and high reward of monetary reward. Different from that of monetary reward, there were no differences on error rate among no, low and high rewards under social reward for female participants. Thereofore, in the tasks which require high accuracy, social reward could be selected to motivate female. Under high reward of monetary reward, incongruent trials elicited more positive frontal-central target-P3 component than congruent trials for adolescents group and girls in the children group. The results indicated that too high behavioral motivation could have negative influence on conflict control behavior.  
    Above all, monetary and social rewards could motivate individual's behavior effectively. Because of the immature brain reward system, children could not make good use of the reward information to regulate their goal-directed behavior. During childhood, girls are more sensitive to reward than boys. Adolscents are hypersensitive to rewards. Reward could regulate the attention allocation of adolescents effectively. In addition, social reward could regulate adolescents' emotional arousal effectively.For children and adolescents, too high motivation could have negative effect on task-related attention concentration. During adolescence and adulthood, males are more sensitive to reward than female. When measuring an individual's motivation for a reward, objective performance and subjective ratings should be simultaneously considered.