Representational dynamics of memories for real-life events

peer reviewedThe continuous flow of experience that characterizes real-life events is not recorded as such in episodic memory but is condensed as a succession of event segments separated by temporal discontinuities. To unravel the neural basis of this representational structure, we recorded real-life events using wearable camera technology and used fMRI to investigate brain activity during their temporal unfolding in memory. We found that, compared to the representation of static scenes in memory, dynamically unfolding memory representations were associated with greater activation of the posterior medial episodic network. Strikingly, by analyzing the autocorrelation of brain activity patterns at successive time points throughout the retrieval period, we found that this network showed higher temporal dynamics when recalling events that included a higher density of event segments. These results reveal the key role of the posterior medial network in representing the dynamic unfolding of the event segments that constitute real-world memories

The Design and Evaluation of a Temporal-aural-visual Representation to Support Middle School Students' Conceptualization of the Range of Imperceptible Sizes.

Supporting students in conceptualizing the range of imperceptibly small sizes (e.g., sizes of atoms or molecules) has been a challenging topic in science education. Commonly used macroscopic visual representations of imperceptible sizes have been unsuccessful, mainly because they perceptually contradict the definition of “imperceptibly small”. Research indicates that learners may benefit from a novel representation that incorporates a non-visual modality for conveying imperceptibly small sizes. To address this issue, an animated temporal-aural-visual representation (TAVR), which accumulates imperceptible objects across the diameter of a pinhead, was designed. In TAVR, the size of an imperceptible object is represented through its total accumulation duration (time necessary to span the pinhead), and the range of imperceptible sizes is conveyed by the range of the accumulation durations of different objects. Prior studies showed that seventh grade middle school students could understand what a TAVR represents and that they constructed more refined mental models of the range of imperceptible sizes after TAVR interactions. However, the roles and the influences of particular TAVR features, which aimed to augment learners’ temporal experiences, in students’ interpretations of the range of imperceptible sizes were unidentified. In this context, this dissertation investigated the TAVR features in three different aspects: the effects of (1) different combinations of aural and visual modalities, (2) different accumulation intervals (ten objects/sec vs. one object/sec), and (3) perception of the passage of time (kinesthetic fast-forwarding vs. natural passage of time), with two hundred thirty-one 7th grade students. Multiple measures including surveys, pre- and post-instructional card-sorting tasks, students’ self-reported reflections, and focus group interviews were examined. The results indicated that the students who interacted with TAVRs with the features that helped them more intensively perceive the durations of the different accumulation progressions (i.e., visual representation, slower accumulation interval, or natural perception of the passage of time) experienced vast range of temporal durations and, hence, generated the most refined mental models of the range of imperceptible sizes. Based on these findings, detailed discussions on the roles of each of the augmenting features in TAVR, possible scenarios for using temporal representations for learning, and future research topics are presented.PHDEducational StudiesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/99991/1/mysong_1.pd