视觉工作记忆离线态表征的生成机制

Cognitive mechanisms underlying the formation of offline representations in visual working memory

视觉工作记忆在人类理解动态变化的视界过程中发挥着重要作用。根据工作记忆状态模型,视觉工作记忆表征可以被存储在在线态或离线态,并可依据任务需求在这两种存储态之间灵活切换。然而,目前还不清楚离线态记忆表征如何由在线态表征转换生成。本研究将通过实验检验两种可能的转换加工假设:巩固假设和衰减假设。研究通过采用序列呈现提取范式来有效引导记忆表征分别被存储在两个不同的表征状态中,并在此基础上对状态转换过程相关的刺激间隔时间和呈现时间进行调控。结果显示,当与状态转换过程相关的时间不足时,会导致记忆表征状态的转换过程与新刺激的在线加工过程叠加,从而发生资源竞争。这一结果符合记忆表征状态转换的巩固假设,即工作记忆的离线态表征通过记忆项目的在线态表征巩固进入离线态而形成。

Visual working memory(VWM)plays a foundational role in advanced cognitive functions.The state-based models propose a hierarchical organization of functional states,where memory representations with high attentional priority are retained in an online state(i.e.,active state),while those with lower priority are kept in an offline state(i.e.,passive state)for later use.The memory representations can be dynamically transferred between the two states according to the task demands.However,there was rare work to explore how the memory representations transitioned into the offline state from the online,generating the offline representations.Here,we put forward two hypothesis,the consolidation hypothesis and the fade-away hypothesis.To explore this question,participants were instructed to remember two sequential memory arrays,with Memory array 2 being detected before Memory array 1.In this memory task,Memory array 1 was held in the offline state during the active maintenance of Memory array 2.Colored squares served as memory stimuli.30 healthy college students participated in each experiment.We primarily modulated the temporal context related to the state transformation of memory representations:the interval delay between the two memory arrays in Experiment 1 and the presentation time of Memory array 2 in Experiment 2.The load of online memory varied between two and four in each trial.These variables were within-subject factors.Experiment 1 aimed to verify that the shortage of interval delay between memory arrays led to the failure of state transformation in the condition of 0.8s-interval.Experiment 2 attempted to determine which hypothesis,consolidation or fade-away,aligned better with the state transformation process.The exploration of representational state transformation was built on the resources-dissociation account,which proposed that the offline representations are independent of the active processing of online representations.Memory arrays 1 and 2 were used to test the offline and online memory,respectively.The results of Experiment 1 showed that variations in online load did not affect offline memory when extending the interval delay from 0.8s to 1s.This indicated that the state transformation of Memory array 1 continued beyond 0.8s after its disappearance and could complete within a 1s-interval.In Experiment 2,the interval was designed at 0.8s.We observed that the online load variation had no impact on offline memory when extending the presentation time of Memory array 2 from 0.2 s to 0.5 s.This supported the consolidation hypothesis,indicating that the sufficient presentation time of Memory array 2 allowed for the state transformation of Memory array 1 to complete before the subsequent processing of Memory array 2.Thus,we concluded that the state transformation involved a consolidation processing to transfer the online representations to the offline state,rather than natural fade-away of persistent neural activity.In summary,the state transformation acts as a process of consolidating online memory representations into the offline state,thereby forming offline representations.This process can be completed within a sufficiently long retention interval,or continue during the presentation of subsequent stimuli when providing a deficient interval.The current findings provide fresh insights into the mechanisms of representational maintenance in the two distinct states.