其他摘要 |
Visual working memory (VWM) refers to the limited-energy memory system which encodes and manipulates instant information. Complex cognitive abilities, such as reasoning, problem-solving and fluid intelligence are related closely to VWM. Slot model assumes that memory representation is stored individually in memory slots, and the number of slots could be considered as visual working memory capacity. In that view, working memory span should be expected to constrain working memory precision’s development. In contrast,qualitative model assumes that VWM is a limited-resource memory system, and its limitation cannot be presented in slots number. It also assumes that working memory precision, which would decrease by the increasing number of stimulus,should correlate with working memory span in a degree, not completely. Yet recent research deploying young adults as participants yield incongruent results.The analysis of previous results suggests that cognitive differences because of individual development and individual differences in intelligence may confuse the results.
In order to investigate relationship between working memory precision and span, here we used original and mirror delayed response task to measure children’s working memory precision and span in different age and intellectual levels. And irrelevant stimulus were used during encoding or insolidating phase of revised delayed response task to investigate inhibition’s influence on VWM’s development and individual differences.
Study1 comprised Experiment1 and Experiment2, which investigated how children’s VWM precision and span developed cross-sectionally and longitudinally. Exp1 found that VWM span reached adult level around age 12-13,and precision would not stop increase at least around 14-15 years’ old. The precision under high-load condition would develop into adolescence, and this pattern still exist even controlling for intelligence. It demonstrated that VWM precision developed independently from span and it took more time to become mature. Exp2 further tracked the participants from Exp1 for 1year and found the similar results longitudinally. VWM precision still developed even after span stopped which also demonstrated that precision was a more sensitive indicator for cognitive development in late-childhood. Study1 showed that VWM precision did grow influenced by the inhibition rather than span.
Study2 compared VWM precision and span among different intellectual
level children. Exp3 taking the same tasks from Study1 found that intellectually gifted children’s span did not significantly differ from peers with good intelligence, yet precision was much higher. In high-load conditions, gifted children’s precision was even similar to adults’ level. This suggested that VWM span was more easily failed to detect the difference of cognitive individualdifferences for high-intelligence group of children. VWM precision, however, is a validated cognitive indicator without the limitation of span.
On the basis of Study1 and 2, Study3 further examined how inhibition would influence children’s VWM precision and span. Exp4 changed the time phase where distractor appeared, appearing at the encoding or insolidating phase of the new revised task to see how VWM precision and span of individuals with different age and intellectual levels would change. Results showed that distractors did not affect children’s or adults’ span, but it damged precision, especially in insolidating phase. Additionally, children’s ability to prevent from encoding distracting stimulus was similar with adults, yet the ability to retrieve with distracting representation was much worse. This demonstrated that development of inhibition in insolidating phase was probably the main reason for VWM’s development and individual differences during late childhood.
In general, this study finds that VWM precision is not dependent on span which makes slot model’s hypothesis not reasonable to explain the results. Hence,the results here support the qualitative models. Moreover, precision turns out to be a more sensitive and validated cognitive indicator than span for late-childhood and high-intelligence children. Traditional view of VWM capacity only taking span as indicator should be reconsidered. Additionally, this study helps better understanding the possible storage mechanism of VWM and results could provide valuable suggestions for future VWM evaluation and training. |
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