领域：学术论文 · 社会科学

Taking advantage of online data collection and game-based assessment, we characterized comprehensive developmental trajectories of spatial cognition and its malleability in the present study. We found an a synchrony between the development of spatial cognitive performance and that of its malleability, as the learning rate peaked about 10 years earlier than performance on mental rotation. On the other hand, malleability also depended on the maturation of spatial ability, as children under the age of 10 showed particularly low malleability, which likely resulted from their underdeveloped ability of mirror image discrimination. In short, by combining both coarse but massive online data and fine tuned experimental data, our study illustrates the interaction of spatial cognition and its malleability during development, which also sheds light on translational implications for STEM related educational practice. The developmental trajectory of mental rotation performance observed here is consistent with previous reports on development in adulthood of spatial abilities based on laboratory studies (Wilson et al., 1975). Also, the widespread malleability of mental rotation across the life span is in line with the reported malleability of spatial abilities in various developmental stages (Bavelier et al., 2012; Feng et al., 2007; Uttal, Miller, et al.,2013). The convergence with the findings of traditional laboratory studies (Germine et al., 2012; Hartshorne &Germine, 2015) endorses the reliability and validity of the online game based assessment approach in the present study. Importantly, our study extended previous studies in two aspects. First, our results filled the gap between the known developmental trends of spatial abilities in childhood (Frick et al., 2013; Hawes et al.,2015;  Marmor,  1975) and adulthood (Wilson et al., 1975)by providing information on the transition between childhood and adulthood and by depicting a continuous development trajectory across the life span with the same task. 
Second, the present study comprehensively examined the malleability of spatial ability from childhood to adulthood, identifying late adolescence (16–20years old) as a critical period when individuals are most sensitive to training on mental rotation in particular and possibly spatial cognition in general. A particularly intriguing finding of the present study is the a synchrony between the development of performance and its malleability. The asynchronous developmental paces of malleability and performance have been documented in other cognitive domains, such as language acquisition (Snow & Hoefnagel Höhle, 1978),implying a general principle for the development of cognitive functions. For instance, the training effect from daily practice in spatial cognition may accumulate through development and thus lays the foundation for performance change. Supporting this idea, our results showed that in adolescent and adult age groups, individuals with higher performance also showed higher malleability. On the other hand, both the exploratory online test and the confirmatory experiment suggest that mirror image discrimination might be a gate keeping ability that constrained the malleability of young children. This result is consistent with previous findings that children at the age of 7 to 8 or even older cannot reliably perform above chance in mental rotation tasks involving mirror image discrimination (Aaron & Malatesha, 1974;Hawes et al., 2015). The particular difficulty of mirror image discrimination, which persists across the life span(Bornstein et al., 1978; Gibson et al., 1962; Gregory &McCloskey, 2010), suggests that it may involve unique cognitive mechanisms not implicated in the discrimination of rotated stimuli. Indeed, a previous study shows that children at the age of 6 show a steady decrease in error rate in discriminating 3D objects of different orientations, but the rate of mirror image confusion stays high at least until 7 years old (Hawes et al., 2015). 
Various cognitive mechanisms may contribute to the particular difficulty of mirror image discrimination of children. For instance, Paschke et al. (2012) suggest that mirrored images fit less to the top-down expectation; Hamm et al. (2004) propose that mirror image discrimination requires an additional “flip” of the stimuli out oft he picture plane, which requires more complex transformation of mental representation; McCloskey et al.(2006) suggest that mirror image discrimination requires additionally representing polarity correspondence between the object and the extrinsic axes, which likely poses challenges to young children (see also Gregory& McCloskey, 2010). Our study revealed that the ages between 8 and 9 were critical for developing the ability of mirror image discrimination. Therefore, future studies can test these three hypotheses with children at this age by examining whether mirror image discrimination co­exists with the contributing cognitive functions proposed by these hypotheses. Indeed, the present study suggests that mirror image discrimination might hinder mental rotation performance and its malleability in a wider range of the life span. Visual inspection of Figure4c indicates that the high performers across age groups passed the mirror image trials without much difficulty and performance improves continually, resulting in a more linear shaped learning curve compared with the low performers. In contrast, the low performers needed a substantial amount of training to succeed in mirror image trials; therefore, the learning curve was flattened as an asymptotic line at the point of the mirror image trials. The finding that high malleability of spatial cognition occurred in late adolescence is of potentially great translational implication because of the transferability of mental rotation training effects into other spatial skills(Meneghetti et al., 2016; Terlecki & Newcombe, 2005;Uttal, Meadow, et al., 2013) as well as into STEM related performance (Stransky et al., 2010). That is, training on spatial abilities may be most effective for adolescents and young adults, whereas elementary school children may not benefit as much from it. However, the training should be merit based because there were significant individual differences in malleability as revealed in this study. Finally, the training may not be fully effective until the gatekeeping ability is mastered. In addition, the present study replicated gender difference in mental rotation in the literature with a large sample. Although the male advantage in mental rotation has been well established in the literature, the source of this advantage has been a subject of debate, with arguments emphasizing either biological or experience/cultural factors (Miller & Halpern, 2014). The late emergence of gender difference observed in our study (i.e.,its presence in adolescence and early adulthood but not in childhood) implies the influence of experience related and/or environmental factors, consistent with findings of cross national research (e.g., Levine et al.,2005) and studies on gender stereotype threat (e.g.,Schmader, 2010). For instance, males might be encouraged more to participate in spatial related tasks since childhood than females, and sufficient practice leads to performance advantage in adolescence, which might encourage further participation in spatial related tasks and a persistent male advantage in the following developmental stages. However, it is also possible that the gradual unfolding of male advantage could be the result of late on set hormonal influence or sex dependent brain polymorphism, such as those taking place during and after puberty, though evidence of such influence is mixed in the literature (e.g., Herlitz et al., 2013). 
Further, the experience related and/or environmental factors may interact with biological factors (Eagly & Wood,2013), as gender dependent educational experience and cultural expectation might facilitate the expression of phenotypes prescribed by biological factors. In sum, by combining both a coarse online test and a finetuned experiment, we depicted comprehensive developmental trajectories of spatial cognition and its malleability, which invites research on the development of other cognitive domains. However, our results should be interpreted with caution given several limitations with online studies. First, the participants were self-selected, and the sample composition was certainly biased by that of the user population of the host app. Also, the present study did not verify the accuracy of age reports made by the participants because we were unable to devise an effective safeguard/check for largescale online game-based data collection without making participants uncomfortable about their privacy. Therefore, some age reports might be inaccurate. However, this was unlikely to have distorted the pattern of the reported developmental trajectory because, given the large sample size of the present study, the noise caused by potential inaccurate age reports would have affected our estimation of all the age groups unselectively. Admittedly, the potential presence of inaccurate age reports may have led to an underestimation of developmental difference between age groups, and follow up small scale laboratory-based experiments are necessary to verify findings from the online experiment. Second, in the game-based assessment, participants reported their age information by selecting one of the age bins with the resolution of 5 years old (except theunder10 age group). 
Though this is a common practice in online game applications, it admittedly prevented us from depicting the developmental trajectory with finer resolution. This is particularly regrettable for the under10 age group and the 11–15 age group, in which rapid cognitive development in spatial cognition takes place. To some extent, the pen and paper test provided the missing piece by allowing us to analyze mental rotation ability between the ages of 6 and 13 to depict the change in mirror image discrimination ability during this period. More dedicated investigations are desirable to depict the developmental trajectory at this age range with finer resolution. Third, the online game-based assessment allowed us no control over the time span between participations or between participation activities. This might have led to additional noise in estimating the malleability of each age group. However, the variation in time span was unlikely to affect the relation between behavioral performance and its malleability of each age group differently. Fourth, online studies provide only cross sectional data. Therefore, follow-up longitudinal studies on the critical developmental periods identified by online studies are also necessary to rule out confounding factors such as the cohort effect. Fifth, in the present study, the malleability of spatial cognition was measured by the learning rate among multiple plays on mental rotation; therefore, malleability at the behavioral level may not fully capture plasticity in the neural substrates of mental rotation that may additionally reflect contributions from many factors other than training, such as lesion and sociocultural context. Future neuroimaging studies on the development of neural plasticity will likely provide an interesting comparison with the malleability solely from behavioral training. Finally, the findings of an asynchrony between performance and malleability and that of the coincidence between mirror image discrimination failure and low malleability of spatial cognition did not present causal links, and future work is needed to examine the causality among these factors.


翻译考点：
考点1： “ mirror image trials ” 推荐译为 “ 镜像实验”在本文语境中,可以发现trials实际上指代的是实验.
考点2： “ game-based assessment ” 推荐译为 “ 基于游戏的测评 ”
考点3： “ noise” 推荐译为 “ 随机误差 ”需确保“随机性”限定词不能省略
考点4 ： “ general principle ” 在本文语境中推荐译为 推荐译为 “ 一般规律 ”
考点5： “ the reported ” 在本文语境中推荐译为 “ 报告 ”