Jonathan M. Fawcett

Forgetting is effortful: evidence from reaction time probes in an item-method directed forgetting task.

Reaction time (RT) was measured in response to visual detection probes embedded within an item-method directed forgetting paradigm. In Experiment 1, study words were presented individually followed by an instruction to remember (R) or forget (F). Probes were presented at stimulus onset asynchronies (SOAs) of 1,400, 1,800, or 2,600 msec in relation to the study word or memory instruction. After the study trials, a yes-no recognition task measured retention of R and F words. Experiment 2 added a no-word control condition and no-probe catch trials. In both experiments, post-F probe RTs were longer than post-R probe RTs at early SOAs. Confirming that participants attended to the memory instructions, there was a significant directed forgetting effect, with greater recognition of R than of F words. These findings contradict the view that directed forgetting in the item-method paradigm is due to the passive decay of nonrehearsed F items; instead, they are consistent with the view that intentional forgetting in an item-method paradigm occurs via the operation of an active, potentially inhibitory, cognitive process.

Risk of Obsessive-Compulsive Disorder in Pregnant and Postpartum Women: A Meta-Analysis

OBJECTIVE Although pregnant and postpartum women are presumed to be at greater risk of obsessive-compulsive disorder (OCD) than the general population, the evidence has been inconclusive. This meta-analysis provides an estimate of OCD prevalence in pregnant and postpartum women and synthesizes the evidence that pregnant and postpartum women are at greater risk of OCD compared to the general population. DATA SOURCES An electronic search of Google Scholar, PsycINFO, PsychARTICLES, and PubMed was performed by using the search terms OCD, obsessive-compulsive disorder, pregnancy, postpartum, prevalence, and epidemiology. We supplemented our search with articles referenced in the obtained sources. The search was conducted until August 2012 without date restrictions. STUDY SELECTION We included English-language studies reporting OCD prevalence (diagnosed according to DSM-III-R, DSM-IV, or ICD-10 criteria) in pregnant (12 studies) or postpartum (up to 12 months; 7 studies) women using structured diagnostic interviews. We also included a sample of regionally matched control studies (10 studies) estimating 12-month prevalence in the general female population for comparison. The control studies were limited to those conducted during the same time frame as the pregnant and postpartum studies. DATA EXTRACTION We extracted author name, year of publication, diagnostic measure, sample size, diagnostic criteria, country, assessment time, subject population, and the point prevalence of OCD. RESULTS Mixed- and random-effects models revealed an increase in OCD prevalence across pregnancy and the postpartum period with the lowest prevalence in the general population (mean = 1.08%) followed by pregnant (mean = 2.07%) and postpartum women (mean = 2.43%). An exploratory analysis of regionally matched risk-ratios revealed both pregnant (mean = 1.45) and postpartum (mean = 2.38) women to be at greater risk of experiencing OCD compared to the general female population, with an aggregate risk ratio of 1.79. CONCLUSIONS Pregnant and postpartum women are more likely to experience OCD compared to the general population.

Of guns and geese: a meta-analytic review of the 'weapon focus' literature

Abstract Weapon focus is frequently cited as a factor in eyewitness testimony, and is broadly defined as a weapon-related decrease in performance on subsequent tests of memory for those elements of an event or visual scene concurrent to the weapon. This effect has been attributed to either (a) physiological or emotional arousal that narrows the attentional beam (arousal/threat hypothesis), or (b) the cognitive demands inherent in processing an unusual object (e.g. weapon) that is incongruent with the schema representing the visual scene (unusual item hypothesis). Meta-analytical techniques were applied to test these theories as well as to evaluate the prospect of weapon focus in real-world criminal investigations. Our findings indicated an effect of weapon presence overall (g= 0.53) that was significantly influenced by retention interval, exposure duration, and threat but unaffected by whether the event occurred in a laboratory, simulation, or real-world environment.

Directed forgetting shares mechanisms with attentional withdrawal but not with stop-signal inhibition.

To explore the mechanisms underlying the ability to intentionally forget, the present study combined an itemmethod directed forgetting paradigm with tasks that measure stop-signal inhibition (Experiments 1 and 2) and inhibition of return (IOR; Experiment 2). Following each study-phase instruction to remember (R) or forget (F), a target was presented centrally (Experiment 1) or to the left or right in the visual periphery (Experiment 2); the target required a speeded response that was sometimes countermanded by a central stop signal. Although stopsignal reaction times were unaffected by the preceding memory instruction (or relationship with word-target location), F instructions improved stopping and delayed responses. Replicating previous findings in the literature, significant IOR was observed following F instructions but not following R instructions (Experiment 2). These findings suggest that intentional forgetting is an active cognitive process that more likely engages attentional mechanisms related to orienting than those related to stop-signal inhibition.

The production effect benefits performance in between-subject designs: A meta-analysis ☆

Producing (e.g., saying, mouthing) some items and silently reading others has been shown to result in a reliable advantage favoring retention of the produced compared to non-produced items at test. However, evidence has been mixed as to whether the benefits of production are limited to within- as opposed to between-subject designs. It has even been suggested that the within-subjects nature of the production effect may be one of its defining characteristics. Meta-analytic techniques were applied to evaluate this claim. Findings indicated a moderate effect of production on recognition memory when varied between-subjects (g=0.37). This outcome suggests that the production effect is not defined as an exclusively within-subject occurrence.

The control of working memory resources in intentional forgetting: Evidence from incidental probe word recognition ☆

We combined an item-method directed forgetting paradigm with a secondary task requiring a response to discriminate the color of probe words presented 1400 ms, 1800 ms or 2600 ms following each study phase memory instruction. The speed to make the color discrimination was used to assess the cognitive demands associated with instantiating Remember (R) and Forget (F) instructions; incidental memory for probe words was used to assess whether instantiating an F instruction also affects items presented in close temporal proximity. Discrimination responses were slower following F than R instructions at the two longest intervals. Critically, at the 1800 ms interval, incidental probe word recognition was worse following F than R instructions, particularly when the study word was successfully forgotten (as opposed to unintentionally remembered). We suggest that intentional forgetting is an active cognitive process associated with establishing control over the contents of working memory.

The origins of repetitive thought in rumination: Separating cognitive style from deficits in inhibitory control over memory

Background and objectives Rumination is a major contributor to the maintenance of affective disorders and has been linked to memory control deficits. However, ruminators often report intentionally engaging in repetitive thought due to its perceived benefits. Deliberate re-processing may lead to the appearance of a memory control deficit that is better explained as a difference in cognitive style. Methods Ninety-six undergraduate students volunteered to take part in a direct-suppression variant of the Think/No-Think paradigm after which they completed self-report measures of rumination and the degree to which they deliberately re-processed the to-be-suppressed items. Results We demonstrate a relation between rumination and impaired suppression-induced forgetting. This relation is robust even when controlling for deliberate re-processing of the to-be-suppressed items, a behavior itself related to both rumination and suppression. Therefore, whereas conscious fixation on to-be-suppressed items reduced memory suppression, it did not fully account for the relation between rumination and memory suppression. Limitations The current experiment employed a retrospective measure of deliberate re-processing in the context of an unscreened university sample; future research might therefore generalize our findings using an online measure of deliberate re-processing or within a clinical population. Conclusions We provide evidence that deliberate re-processing accounts for some – but not all – of the relation between rumination and suppression-induced forgetting. The present findings, observed in a paradigm known to engage top-down inhibitory modulation of mnemonic processing, provide the most theoretically focused evidence to date for the existence of a memory control deficit in rumination.

Directed Forgetting: Comparing Pictures and Words

The authors investigated directed forgetting as a function of the stimulus type (picture, word) presented at study and test. In an item-method directed forgetting task, study items were presented 1 at a time, each followed with equal probability by an instruction to remember or forget. Participants exhibited greater yes-no recognition of remember than forget items for each of the 4 study-test conditions (picture-picture, picture-word, word-word, word-picture). However, this difference was significantly smaller when pictures were studied than when words were studied. This finding demonstrates that the magnitude of the directed forgetting effect can be reduced by high item memorability, such as when the picture superiority effect is operating. This suggests caution in using pictures at study when the goal of an experiment is to examine potential group differences in the magnitude of the directed forgetting effect.

Assessing the costs and benefits of production in recognition

The production effect is a memory advantage for items studied aloud over items studied silently. Although it typically is found within subjects, here we also obtained it between subjects in a recognition task—providing new evidence that production can be an effective study strategy. Our experiment, and a set of meta-analyses, also evaluated whether the within effect reflects costs to silent items and/or benefits to aloud items. Contrary to a strong distinctiveness account, we found little evidence that aloud items show an additional within-subjects benefit. Instead, silent items suffered an additional within-subjects cost. Blocking silent and aloud items eliminated this cost, suggesting that the cost was due to mixing silent and aloud items. Our discussion focuses on implications for distinctiveness and strength accounts of the production effect and on how to implement production as an encoding strategy depending on the learner’s goals.

The Representational Consequences of Intentional Forgetting: Impairments to Both the Probability and Fidelity of Long-Term Memory

We investigated whether intentional forgetting impacts only the likelihood of later retrieval from long-term memory or whether it also impacts the fidelity of those representations that are successfully retrieved. We accomplished this by combining an item-method directed forgetting task with a testing procedure and modeling approach inspired by the delayed-estimation paradigm used in the study of visual short-term memory (STM). Abstract or concrete colored images were each followed by a remember (R) or forget (F) instruction and sometimes by a visual probe requiring a speeded detection response (E1–E3). Memory was tested using an old–new (E1–E2) or remember-know-no (E3) recognition task followed by a continuous color judgment task (E2–E3); a final experiment included only the color judgment task (E4). Replicating the existing literature, more “old” or “remember” responses were made to R than F items and RTs to postinstruction visual probes were longer following F than R instructions. Color judgments were more accurate for successfully recognized or recollected R than F items (E2–E3); a mixture model confirmed a decrease to both the probability of retrieving the F items as well as the fidelity of the representation of those F items that were retrieved (E4). We conclude that intentional forgetting is an effortful process that not only reduces the likelihood of successfully encoding an item for later retrieval, but also produces an impoverished memory trace even when those items are retrieved; these findings draw a parallel between the control of memory representations within working and long-term memory.