Prefrontal contributions to executive control: fMRI evidence for functional distinctions within lateral Prefrontal cortex.

The prefrontal cortex (PFC) plays a fundamental role in internally guided behavior. Although it is generally accepted that PFC subserves working memory and executive control operations, it remains unclear whether the subregions within lateral PFC support distinct executive control processes. An event-related fMRI study was implemented to test the hypothesis that ventrolateral and dorsolateral PFC are functionally distinct, as well as to assess whether functional specialization exists within ventrolateral PFC. Participants performed two executive control tasks that differed in the types of control processes required. During rote rehearsal, participants covertly rehearsed three words in the order presented, thus requiring phonological access and maintenance. During elaborative rehearsal, participants made semantic comparisons between three words held in working memory, reordering them from least to most desirable. Thus, in addition to maintenance, elaborative rehearsal required goal-relevant coding of items in working memory ("monitoring") and selection from among the items to implement their reordering. Results revealed that left posterior ventrolateral PFC was active during performance of both tasks, whereas right dorsolateral PFC was differentially engaged during elaborative rehearsal. The temporal characteristics of the hemodynamic responses further suggested that dorsolateral activation lagged ventrolateral activation. Finally, differential activation patterns were observed within left ventrolateral PFC, distinguishing between posterior and anterior regions. These data suggest that anatomically separable subregions within lateral PFC may be functionally distinct and are consistent with models that posit a hierarchical relationship between dorsolateral and ventrolateral regions such that the former monitors and selects goal-relevant representations being maintained by the latter.

Metacognition in motor learning.

Research on judgments of verbal learning has demonstrated that participants' judgments are unreliable and often overconfident. The authors studied judgments of perceptual-motor learning. Participants learned 3 keystroke patterns on the number pad of a computer, each requiring that a different sequence of keys be struck in a different total movement time. Practice trials on each pattern were either blocked or randomly interleaved with trials on the other patterns, and each participant was asked, periodically, to predict his or her performance on a 24-hr test. Consistent with earlier findings, blocked practice enhanced acquisition but harmed retention. Participants, though, predicted better performance given blocked practice. These results augment research on judgments of verbal learning and suggest that humans, at their peril, interpret current ease of access to a perceptual-motor skill as a valid index of learning.

When further learning fails: stability and change following repeated presentation of text.

Kay (1955) presented a text passage to participants on a weekly basis and found that most errors and omissions in recall persisted despite repeated re-presentation of the text. Experiment I replicated and extended Kay's original research, demonstrating that after a first recall attempt there was very little evidence of further learning, whether measured in terms of further acquisition or error correction, over three more presentations of the text passages. Varying the schedule of presentations and tests had little effect, although performance was better when intermediate trials included both presentation and test than when only presentations or tests occurred. Experiment 2 explored whether this 'failure of further learning' effect could be overcome by (a) warning participants against basing their recall on their previous recall efforts and specifically directing them to base their recall upon the passages, (b) making each presentation more distinctive, or (c) drawing participants' attention to areas that would benefit from further learning by requiring them to tally their omissions and errors. The effect persisted in all cases. The findings have serious implications for the learning of text material.

Retrieval-induced forgetting: evidence for a recall-specific mechanism.

Previous work has shown that recalling information from long-term memory can impair the long-term retention of related representations--a phenomenon known as retrieval-induced forgetting (Anderson, Bjork, & Bjork, 1994). We report an experiment in which the question of whether retrieval is necessary to induce this form of impairment was examined. All the subjects studied six members from each of eight taxonomic categories (e.g., fruit orange). In the competitive practice condition, the subjects practiced recalling three of the six members, using category-stem cues (e.g., fruit or__). In the noncompetitive practice condition, the subjects were reexposed to these same members for the same number of repetitions but were asked to recall the category name by using the exemplar and a stem as cues (e.g., fr__orange). Despite significant and comparable facilitation of practiced items in both conditions, only the competitive practice subjects were impaired in their ability to recall the nonpracticed members on a delayed cued-recall test. These findings argue that retrieval-induced forgetting is not caused by increased competition arising from the strengthening of practiced items, but by inhibitory processes specific to the situation of recall.

Independence of scientific publishing. Reaffirming the principle.

Historically, the American Psychological Association (APA), as part of its contract with the editors of APA journals, has granted to the editors sole responsibility to accept or reject manuscripts for publication, without such actions being open for review by APA. Such a policy fosters the freedom of inquiry and expression so necessary for a healthy science. It also serves to protect the Association because publication of an article in an APA journal does not represent endorsement by APA itself. The lessons of history are clear: When political or other pressures interfere with the autonomy of science, the societal and scientific consequences are grim. APA should reaffirm the principle that a healthy science of psychology requires an open exchange of ideas and findings.

On the relationship between recognition speed and accuracy for words rehearsed via rote versus elaborative rehearsal.

Tacit within both lay and cognitive conceptualizations of learning is the notion that those conditions of learning that foster "good" retention do so by increasing both the probability and the speed of access to the relevant information. In 3 experiments, time pressure during recognition is shown to decrease accessibility more for words learned via elaborative rehearsal than for words learned via rote rehearsal, despite the fact that elaborative rehearsal is a more efficacious learning strategy as measured by the probability of access. In Experiment 1, participants learned each word using both types of rehearsal, and the results show that access to the products of elaborative rehearsal is more compromised by time pressure than is access to the products of rote rehearsal. The results of Experiment 2, in which each word was learned via either pure rote or pure elaborative rehearsal, exhibit the same pattern. Experiment 3, in which the authors used the response-signal procedure, provides evidence that this difference in accessibility owes not to differences in the rate of access to the 2 types of traces, but rather to the higher asymptotic level of stored information for words learned via elaborative rehearsal.

Psychological Science in the Public Interest: the case for juried analyses.

The inaugural issue of Psychological Science in the Public Interest (PSPI), a new publishing initiative by the American Psychological Society, accompanies this issue of Psychological Science. The report it contains, "Psychological Science Can Improve Diagnostic Decisions," by John Swets, Robyn Dawes, and John Monahan, represents a careful effort by those authors to summarize the potential of modern psychological science to enhance real-world diagnostic decisions. Such decisions (Is a cancer present? Will this individual commit violence? Will an impending storm strike? Will this applicant succeed?) are prevalent and crucial to the lives of individuals and to the well-being of our society. Subsequent issues of PSPI will address other important topics of public interest in areas where psychological science may have the potential to inform and improve public policy. Each of those reports will also represent the efforts of a distinguished team of scientists to report the available evidence, and the implications of that evidence, fairly and comprehensively. In this article, we describe the goals, procedures, and potential of PSPI.

Predicting the future and reconstructing the past: a Bayesian characterization of the utility of subjective fluency.

The subjective sense of fluency with which an item can be perceived or remembered is proposed to be a vital cue in making decisions about the future memorability and the nature of our past experience with that stimulus. We first outline a number of cases in which such perceptual or retrieval fluency influences judgments both about our own future performance and our likely past experience, and then present a Bayesian analysis of how judgments of recognition--deciding whether or not a currently viewed item was studied at a particular point in the past--may incorporate information about the perceptual fluency of that item. Using a simple mathematical model, we then provide an interpretation of certain enigmatic phenomena in recognition memory.

The mismeasure of memory: when retrieval fluency is misleading as a metamnemonic index.

The experiments address the degree to which retrieval fluency--the case with which information is accessed from long-term memory--guides and occasionally misleads metamnemonic judgments. In each of 3 experiments, participants' predictions of their own future recall performance were examined under conditions in which probability or speed of retrieval at one time or on one task is known to be negatively related to retrieval probability on a later task. Participants' predictions reflected retrieval fluency on the initial task in each case, which led to striking mismatches between their predicted and actual performance on the later tasks. The results suggest that retrieval fluency is a potent but not necessarily reliable source of information for metacognitive judgments. Aspects of the results suggest that a basis on which better and poorer rememberers differ is the degree to which certain memory dynamics are understood, such as the fleeting nature of recency effects and the consequences of an initial retrieval. The results have pedagogical as well as theoretical implications, particularly with respect to the education of subjective assessments of ongoing learning.

Continuing influences of to-be-forgotten information.

In the present paper, we first argue that it is critical for humans to forget; that is, to have some means of preventing out-of-date information from interfering with the recall of current information. We then argue that the primary means of accomplishing such adaptive updating of human memory is retrieval inhibition: Information that is rendered out of date by new learning becomes less retrievable, but remains at essentially full strength in memory as indexed by other measures, such as recognition and word-fragment completion. We conclude with a speculation that certain unconscious influences of prior events may, in fact, be stronger if those events were to be forgotten rather than to be remembered.

Generation effects and the lack thereof: the role of transfer-appropriate processing.

We report two experiments designed to test a multifactor transfer-appropriate processing explanation of generation effects, and the lack thereof, in free recall and cued recall. The basic argument is that the act of generating a target enhances the processing of one or more possible types of information (e.g. target-specific information, cue-target relationships, or target-target relationships) and that subsequent retention tests will reveal an advantage (or disadvantage) of such generation (compared to a "read" control) to the degree that a test is sensitive to the information on which processing was focused during study. Across the two experiments, manipulations of identical stimulus materials forced subjects to process different types of information in order to generate targets, producing a striking reversal in the relative levels of free recall and cued recall for targets that had been generated vs. read, and lending strong support to the transfer-appropriate processing aspect of the proposed framework for explaining generation effects.

Retrieval-induced forgetting in an eyewitness-memory paradigm.

The potential impact of repeated questioning of a witness was examined. Subjects were shown slides depicting the aftermath of a theft and subsequently were asked several times to recall selected details of what they saw. Previous experiments employing simple verbal materials have demonstrated that information addressed by questioning becomes more recallable in the future than it would have been without such retrieval practice, but other information, especially that bearing a categorical similarity to the practiced items, becomes less recallable. Such positive and negative effects appeared in subjects' later recall of crime-scene details in the present experiment. These results have an important implication for legal practice: Repeated interrogation of a witness can modify the witness's memory-enhancing the recall of certain details while inducing the forgetting of other details-even when no misinformation is contained or implied in the questioning.

Remembering can cause forgetting: retrieval dynamics in long-term memory.

Three studies show that the retrieval process itself causes long-lasting forgetting. Ss studied 8 categories (e.g., Fruit). Half the members of half the categories were then repeatedly practiced through retrieval tests (e.g., Fruit Or_____). Category-cued recall of unpracticed members of practiced categories was impaired on a delayed test. Experiments 2 and 3 identified 2 significant features of this retrieval-induced forgetting: The impairment remains when output interference is controlled, suggesting a retrieval-based suppression that endures for 20 min or more, and the impairment appears restricted to high-frequency members. Low-frequency members show little impairment, even in the presence of strong, practiced competitors that might be expected to block access to those items. These findings suggest a critical role for suppression in models of retrieval inhibition and implicate the retrieval process itself in everyday forgetting.

Intention and awareness in perceptual identification priming.

We show that inferences can be made about differences in retrieval intentionality between direct and indirect tests, even when those tests involve different physical cues. When the presence of old items was not mentioned (indirect test condition), we observed a crossed double dissociation between perceptual identification priming and recognition memory as a function of a manipulation of data-driven versus conceptually driven processing at encoding. When subjects were instructed to use their memory to help them identify test items (intentional retrieval condition), priming could be expressed as a monotonically increasing function of recognition memory performance. This reversed association (Dunn & Kirsner, 1988) between priming and recognition memory cannot be accommodated by a model that views intentional retrieval as common to the tests and attributes the crossed double dissociation to an intertest difference in physical cues and associated processes. A posttest questionnaire measure indicated that awareness of the presence of previously encountered items was ubiquitous among indirect test subjects. Crossed double dissociations between direct and indirect measures can therefore be ascribed to differences in retrieval intentionality but not necessarily to differences in subjective awareness of the past.

Composite models never (well, hardly ever) compromise: reply to Schooler and Tanaka (1991)

With respect to the influence of postevent information, Schooler and Tanaka (1991) made a useful distinction between composite recollections--in which subjects retrieve "items from both the original and the postevent sources" (p.97)--and compromise recollections--in which subjects retrieve" at least one feature that cannot be exclusively associated with either the original or the postevent sources, but which reflects some compromise between [the] two" (p.97). Schooler and Tanaka argued that only the latter constitutes good evidence for blend-memory representations of the CHARM-type. As it turns out, Schooler and Tanaka's intuitions (and Metcalfe & Bjork's, initially) are faulty. Compromise recall--defined as a preference for an intervening alternative over either of the actually presented alternatives--is not normally a prediction of CHARM and may not be a prediction of composite-trace models in general. Only under specialized conditions--a systematic displacement of the test alternatives or a systematic shift attributable to assimilation to prior semantic knowledge--will computer simulations of CHARM produce unimodal compromise recollection. Equally surprising is the fact that separate-trace models, under a different set of conditions, can predict compromise recollection.

Disrupted retrieval in directed forgetting: a link with posthypnotic amnesia.

Certain reliable findings from research on directed forgetting seem difficult to accommodate in terms of the theoretical processes, such as selective rehearsal or storage differentiation, that have been put forward to account for directed-forgetting phenomena. Some kind of "missing mechanism" appears to be involved. In order to circumvent the methodological constraints that have limited the conclusions investigators could draw from past experiments, a new paradigm is introduced herein that includes a mixture of intentional and incidental learning. With this paradigm, a midlist instruction to forget the first half of a list was found to reduce later recall of the items learned incidentally as well as those learned intentionally. This result suggests that a cue to forget can lead to a disruption of retrieval processes as well as to the alteration of encoding processes postulated in prior theories. The results also provide a link between intentional forgetting and the literature on posthypnotic amnesia, in which disrupted retrieval has been implicated. With each of these procedures, the information that can be remembered is typically recalled out of order and often with limited recollection for when the information had been presented. It therefore was concluded here that retrieval inhibition plays a significant role in nonhypnotic as well as in hypnotic instances of directed forgetting. The usefulness of retrieval inhibition as a mechanism for memory updating was also discussed.

The relative roles of input and output mechanisms in directed forgetting.

When Ss are presented a first set of items (Set A) followed by a second set (Set B), a postinput cue to recall only Set B results in better recall of Set B than does a cue to recall Set B then Set A; to a lesser extent, the same result holds for Set A. Such "Only" effects (Epstein, 1970) have typically been attributed to selective search processes at the time of recall. In the free-recall experiment reported here, cues to remember all, only two, or none of the items in each of eight successive four-word blocks were presented either before or after a 3-sec rehearsal period. Even though the search set at output was constant (16 to-be-recalled words), there was an Only effect for blocks followed by selective (postcue) rehearsal, whereas nonselective (precue) rehearsal produced no such effect. More striking than that result was the incredible ability of Ss, whatever the condition, to differentiate to-be-remembered and to-be-forgotten items. Set differentiation during input appears much more important as a mechanism of directed forgetting than either selective search or selective rehearsal.