Adult humans are capable of remembering prior events by mentally traveling back in time to re-experience those events. In this review, the authors discuss this and other related capabilities, considering evidence from such diverse sources as brain imaging, neuropsychological experiments, clinical observations, and developmental psychology. The evidence supports a preliminary theory of episodic remembering, which holds that the prefrontal cortex plays a critical, supervisory role in empowering healthy adults with autonoetic consciousness-the capacity to mentally represent and become aware of subjective experiences in the past, present, and future. When a rememberer mentally travels back in subjective time to re-experience his or her personal past, the result is an act of retrieval from episodic memory.

Two experiments investigated recall following two study conditions, (1) repeated test: a study trial followed by multiple recall trials, and (2) repeated study: multiple study trials with no tests. At a retention interval of 5 minutes, repeated study produced a higher level of recall than repeated test. When the retention interval was extended, forgetting was much more rapid in the study condition, with the repeated test manipulation leading to higher recall at an interval of 7 days. We conclude that study and test trials have different effects upon memory, with study trials promoting memory acquisition, and test trials enhancing the retrieval process itself, which protects against subsequent forgetting.

In the course of daily affairs. we are frequently asked or required to recollect the same events from memory. This repeated recollection may occur in educational contexts, as when people are tested on material during the course of a semester and later receive a cumulative final exam. Similarly, eyewitnesses to crimes may be queried repeatedly about what they observed by police, by friends, by lawyers, and then eventualIy in court. More commonly, we all repeatedly retell stories of favorite or notable events in our lives. Despite the ubiquity of such experiences, the ftralegy of repeatedly testing memory has not been the dominant method of studying how memories change over time. Rather, researchers have generally employed between-subjects comparisons, in which . Address correspondeliLc: L, ,*iilhor\ at the Department of Psychology. Rice U n i v usity, Houston, TX 77,-7 i i . l X i i 3 independent groups learn some material irnd then are tested at various times after thc original learning to measure the course of forgetting. This design has the advantage of delayed tests being uncontaminated by recollections on previous tests. as would occur if a within-subjects design were used. However. the "contaminating" influences of previous tests can be of central interest in their own right, with the eyewitness testimony situation representing a prime example (Loftus, 1979). Therefore, the repeated testing of memory for the same events (without intervening study opportunities) also represents a valid, if less used, approach to changes in retention over time.Several experimental paradigms and research traditions have been used to examine effects of repeated testing on memory. For present purposes, we confine interest to those cases in which the tests were given without overt cues (free recall). The most famous example of this technique is that of Bartlett (1932), who gave college students the Indian folktale "The War of the Ghosts" and then tested them repeatedly. He presented no aggregate data to support his conclusions, but rather provided sample recall protocols from his subjects. He reported that their performance became increasingly poor over time; they forgot the story but reconstructed plausible accounts that were skewed to the more typical schema of a fairy tale, a style that was presumably more familiar to his students. Despite the fact that Bartlett (1932, pp. 3-4) criticized the pioneering work of Ebbinghaus (1885/1964), his conclusions about the course of forgetting were broadly consistent with Ebbinghaus's prior work. Of course, his theoretical emphasis was markedly different.Curiously. a second tradition of repeated testing research, begun by Ballard ( I9 13). leads to the opposite conclusion from Bartlett's belter publicized work. Ballard gave schoolchildren poetry and Ic.,led their memories both soon after learning and then again at various periods up to I week later. He reported that children frequently recalled lines of poetry on later tests that were not recalled on earlier ones, a phenomenon he termed r...

This article reports the outcome of a meta-analysis of the relation between the frontal lobes and memory as measured by tests of recognition, cued recall, and free recall. We reviewed experiments in which patients with documented, circumscribed frontal pathology were compared with normal control subjects on these three types of tests. Contrary to conventional wisdom, there is strong evidence that frontal damage disrupts performance on all three types of tests, with the greatest impairment in free recall, and the smallest in recognition. (JINS, 1995, 1, 525–536.)

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Novelty discrimination refers to the ability to decide whether information is new or has been previously encountered. Recent functional neuroimaging work has demonstrated that the hippocampus plays an important function in novelty discrimination. In the study described here, we explored the idea that novelty discrimination does not depend on the hippocampus alone but involves large-scale functional neural networks consisting of spatially remote brain regions. We measured blood flow with positron emission tomography (PET) while subjects semantically encoded visually and auditorily presented situationally novel and familiar words. Following each PET scan, subjects' memory was tested with a standard yes/no recognition test. Blood flow data were analyzed with the covariance-based seed partial least squares (PLS) method. Behaviorally, subjects' recognition performance was higher for novel than familiar words. Neurally, two large-scale functional networks involving the same region of the hippocampus were identified which showed coherent activity either during the encoding of situationally novel (but not familiar) items or situationally familiar (but not novel) items. These findings indicate that different neural networks are active in the processing of situationally novel and familiar information. The observation that the hippocampus participates in both networks supports the principle of neural context.