Overcoming suppression in order to remember: Contributions from anterior cingulate and ventrolateral prefrontal cortex

The ability to remember is often compromised by competition from irrelevant memories. However, acts of selective remembering can alter the competitive relationship between memories; memories that are selected against are weakened, whereas those that are retrieved are strengthened. Whereas the weakening of selectedagainst memories is typically evidenced by subsequently poorer recall of these memories, the present study tested the hypothesis that when previously selected-against memories can subsequently be successfully retrieved, such acts of successful retrieval are associated with engagement of neurobiological mechanisms that serve to detect and overcome competition. Consistent with this hypothesis, fMRI revealed that anterior cingulate cortex and right ventrolateral prefrontal cortex are differentially engaged during successful retrieval of previously selected-against memories, and that their engagement is directly related to the magnitude of weakening that is induced by prior acts of selecting against these memories.     

Telling a story or telling it straight: the effects of entertaining versus accurate retellings on memory

People retell events for different reasons. Sometimes they try to be accurate, other times entertaining. What characterizes retellings from different perspectives? How does retelling perspective affect later recall of events? In the current research, participants retold a story either three times or not at all. By instruction, retellings were either entertaining or accurate. Compared to accurate retellings, entertaining retellings contained more affect, but fewer sensory references. On a subsequent memory test, participants who retold with an accuracy goal recalled the greatest number of story events, and their recall protocols were the most accurate and detailed, and least exaggerated. However, recognition memory did not differ across groups, suggesting that differences in retrieval structures (necessary for recall but not recognition) were key to understanding later differences in memory. Compared to telling it straight, the creative process of telling a story leads to qualitative and quantitative changes in later recall. Copyright © 2004 John Wiley & Sons, Ltd.     

Attention during memory retrieval enhances future remembering

Memory retrieval is a powerful learning event that influences whether an experience will be remembered in the future. Although retrieval can succeed in the presence of distraction, dividing attention during retrieval may reduce the power of remembering as an encoding event. In the present experiments, participants studied pictures of objects under full attention and then engaged in item recognition and source memory retrieval under full or divided attention. Two days later, a second recognition and source recollection test assessed the impact of attention during initial retrieval on long-term retention. On this latter test, performance was superior for items that had been tested initially under full versus divided attention. More importantly, even when items were correctly recognized on the first test, divided attention reduced the likelihood of subsequent recognition on the second test. The same held true for source recollection. Additionally, foils presented during the first test were also less likely to be later recognized if they had been encountered initially under divided attention. These findings demonstrate that attentive retrieval is critical for learning through remembering.     

Diminished testing benefits in young adults with attention-deficit hyperactivity disorder

Memory retrieval has been shown to enhance the long-term retention of tested material; however, recent research suggests that limiting attention during retrieval can decrease the benefits of testing memory. The present study examined whether testing benefits are reduced in young adults with attention-deficit hyperactivity disorder (ADHD). College students with and without ADHD read three short prose passages, each followed by a free recall test, a restudy period or a distractor task. Two days later participants recalled the passages. Although participants without ADHD did not show a significant benefit of testing over restudying, testing did produce recall benefits relative to not taking a test. These testing benefits were diminished in participants with ADHD, who did not show any advantage of testing over either restudying or no test. The absence of testing benefits in the ADHD group is likely due in part to decreased recall on the initial test. These findings have implications for improving educational practices among individuals with ADHD and also speak to the need to examine individual differences in the effectiveness of testing as a learning strategy.     

Remember-Know judgments and retrieval of contextual details

The Remember-Know (R-K) task is commonly used to differentiate between recollection and familiarity-based recognition memory. To further validate this test, we assessed the number of contextual details available to participants after giving R or K responses. We also examined the effect of retention interval on the episodic character of memories by administering the R-K task after both 10-minute and 1-week retention intervals. At 1 week, items receiving R responses were accompanied by a significant number of episodic details, while K responses were not. A large number of items that received R responses at the 10-minute delay received K responses at 1 week, and these items were not accompanied by episodic detail during the later test. Items that were judged familiar at 10-minutes but were labeled as recollected at 1 week were also not accompanied by significant memory of the study episode, suggesting that these items were recollected from the first test session. Overall, the data are consistent with the idea that R responses, unlike K responses, are accompanied by memory for episodic detail, and that the loss of memory for episodic detail over time parallels the conversion of R responses to K responses.