Publications by authors named "Jonathan M Fawcett"

33 Publications

Comorbid obsessive-compulsive disorder in individuals with eating disorders: An epidemiological meta-analysis.

J Psychiatr Res 2021 Jun 19;141:176-191. Epub 2021 Jun 19.

Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.

The present study aimed to provide a precise, meta-analytic estimate of the prevalence of obsessive-compulsive disorder (OCD) amongst those with a current primary eating disorder (ED) diagnosis, and to isolate its predictors. An online search of PubMed and PsycINFO was conducted with a Boolean search phrase incorporating keywords related to OCD, EDs, comorbidity, prevalence, and epidemiology, complemented by references coded from related review articles and contact with experts in the field. Articles were included if they (a) reported an observational study examining current ED diagnoses, (b) used a semi-structured or structured diagnostic interview for OCD and ED diagnosis, (c) applied DSM or ICD criteria, (d) included adolescent or adult samples (age > 12), (e) included patient or community samples, and (f) reported lifetime or current OCD comorbidity. From the 846 articles identified, 35 lifetime and 42 current estimates were calculated. OCD prevalence was extracted from each study for each ED diagnostic category, along with eleven additional potential moderators. Analyses revealed an aggregate lifetime OCD prevalence of 13.9% CI [10.4 to 18.1] and current OCD prevalence of 8.7% CI [5.8 to 11.8] across EDs. Moderator analyses revealed the prevalence of and risk for OCD in EDs to be greatest in anorexia nervosa binge-eating purging type (ANBP). Further, OCD is most prevalent amongst patient samples than samples recruited from the community.
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http://dx.doi.org/10.1016/j.jpsychires.2021.06.035DOI Listing
June 2021

Neural correlates of the production effect: An fMRI study.

Brain Cogn 2021 Jun 12;152:105757. Epub 2021 Jun 12.

Memorial University of Newfoundland, Department of Psychology, St. John's, NL A1B 3X9, Canada. Electronic address:

Recognition memory is improved for items produced at study (e.g., by reading them aloud) relative to a non-produced control condition (e.g., silent reading). This production effect is typically attributed to the extra elements in the production task (e.g., motor activation, auditory perception) enhancing item distinctiveness. To evaluate this claim, the present study examined the neural mechanisms underlying the production effect. Prior to a recognition memory test, different words within a study list were read either aloud, silently, or while saying "check" (as a sensorimotor control condition). Production improved recognition, and aloud words yielded higher rates of both recollection and familiarity judgments than either silent or control words. During encoding, fMRI revealed stronger activation in regions associated with motor, somatosensory, and auditory processing for aloud items than for either silent or control items. These activations were predictive of recollective success for aloud items at test. Together, our findings are compatible with a distinctiveness-based account of the production effect, while also pointing to the possible role of other processing differences during the aloud trials as compared to silent and control.
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http://dx.doi.org/10.1016/j.bandc.2021.105757DOI Listing
June 2021

Emotional memories are (usually) harder to forget: A meta-analysis of the item-method directed forgetting literature.

Psychon Bull Rev 2021 Apr 12. Epub 2021 Apr 12.

Department of Psychology, Memorial University of Newfoundland, St. John's, NL, Canada.

The current meta-analysis explored whether emotional memories are less susceptible to item-method directed forgetting than neutral memories. Basic analyses revealed superior memory for remember (R) than forget (F) items in both the neutral, M = 19.6%, CI [16.1, 23.1], and the emotional, M = 15.1%, CI [12.4, 17.7], conditions. Directed forgetting in either valence condition was larger for (a) words than for other stimuli; (b) recall than recognition tests; (c) studies that used recall prior to recognition testing; (d) shorter lists; and (e) studies that included buffer items. Direct comparison of the magnitude of the directed forgetting effect across neutral and emotional conditions within studies revealed relatively diminished directed forgetting of emotional items compared to neutral items, with an average difference of 4.2%, CI [2.0, 6.4]. However, the nature of this finding varied broadly across studies, meaning that whether - and to what degree - emotional memories are more resilient than neutral memories likely depends on the methodological features of the study in question. Moderator analyses revealed larger differences (a) in studies for which the emotional items were more arousing than the neutral items, and (b) when buffer items were included. Together, these findings suggest that emotional memories are often more resilient to intentional forgetting than neutral memories, although further research is necessary to characterize the circumstances under which these differences emerge.
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http://dx.doi.org/10.3758/s13423-021-01914-zDOI Listing
April 2021

Factors associated with cognitive impairment during the first year of treatment for nonmetastatic breast cancer.

Cancer Med 2021 02 16;10(4):1191-1200. Epub 2021 Jan 16.

Department of Psychology, Faculty of Science, Memorial University, St. John's, Newfoundland, Canada.

Background: Women with breast cancer are more likely to develop cognitive impairment (CI), insomnia, fatigue, and mood disturbance than individuals with other cancers. The main objectives of this study were to establish the prevalence of CI and examine the relationships between CI, insomnia, fatigue, and mood over the first year of breast cancer treatment.

Methods: Participants were recruited after diagnosis and completed validated measures of insomnia, objective and perceived CI, fatigue, and mood disturbance at four time points during the first year of treatment. A random intercepts cross-lagged panel model assessed relationships among symptoms over time.

Results: The sample included 98 women. Prevalence of objective CI ranged from 3.1% to 8.2% throughout the year, whereas 36.7% demonstrated a clinically meaningful decline in perceived CI from baseline to 4 months, which remained relatively stable. Greater perceived CI was associated with more fatigue (β = -0.78, z = 17.48, p < .01) and symptoms of insomnia (β = -0.58, z = 5.24, p < .01). Short-term fluctuations in perceived CI (p < .05), but not fatigue or insomnia, predicted future perceived CI. Fatigue (p < .001) was a significant predictor of future reported symptoms of fatigue and insomnia.

Conclusion: Subjective CI is more prevalent than objective impairments. Fatigue, insomnia, and perceived CI remain stable and are associated during the first year of treatment. Changes in insomnia and fatigue may have little effect on future perceived cognition. Women with breast cancer likely require targeted intervention for these side effects.
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http://dx.doi.org/10.1002/cam4.3715DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7926005PMC
February 2021

Memory suppression and its deficiency in psychological disorders: A focused meta-analysis.

J Exp Psychol Gen 2021 May 22;150(5):828-850. Epub 2020 Oct 22.

Max Planck Institute for Human Cognitive and Brain Sciences.

It is still debated whether suppressing the retrieval of unwanted memories causes forgetting and whether this constitutes a beneficial mechanism. To shed light on these 2 questions, we scrutinize the evidence for such suppression-induced forgetting (SIF) and examine whether it is deficient in psychological disorders characterized by intrusive thoughts. Specifically, we performed a focused meta-analysis of studies that have used the procedure to test SIF in individuals either affected by psychological disorders or exhibiting high scores on related traits. Overall, across 96 effects from 25 studies, we found that avoiding retrieval leads to significant forgetting in healthy individuals, with a small to moderate effect size (0.28, 95% CI [0.14, 0.43]). Importantly, this effect was indeed larger than for more anxious (-0.21, 95% CI [-0.41, -0.02]) or depressed individuals (0.05, 95% CI [-0.19, 0.29])-though estimates for the healthy may be inflated by publication bias. In contrast, individuals with a stronger repressive coping style showed greater SIF (0.42, 95% CI [0.32, 0.52]). Furthermore, moderator analyses revealed that SIF varied with the exact suppression mechanism that participants were instructed to engage. For healthy individuals, the effect sizes were considerably larger when instructions induced specific mechanisms of direct retrieval suppression or thought substitution than when they were unspecific. These results suggest that intact suppression-induced forgetting is a hallmark of psychological well-being, and that inducing more specific suppression mechanisms fosters voluntary forgetting. (PsycInfo Database Record (c) 2021 APA, all rights reserved).
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http://dx.doi.org/10.1037/xge0000971DOI Listing
May 2021

Women Are at Greater Risk of OCD Than Men: A Meta-Analytic Review of OCD Prevalence Worldwide.

J Clin Psychiatry 2020 06 23;81(4). Epub 2020 Jun 23.

Department of Psychology, Memorial University of Newfoundland, St John's, Newfoundland, Canada.

Objective: To estimate the worldwide prevalence of obsessive-compulsive disorder (OCD), examine whether women are at greater risk than men, and explore other potential moderators of OCD prevalence to explain variability in community-based epidemiologic studies.

Data Sources: An electronic search of PsycINFO and PubMed was conducted until January 2017, without date or language restrictions, using the keywords OCD, epidemiology, and prevalence. The search was supplemented by articles referenced in the obtained sources and relevant reviews.

Study Selection: Studies were included if they reported current, period, and/or lifetime OCD prevalence (diagnosed according to an interview based on DSM or ICD criteria) in representative community samples of adults aged 18 years or older. A total of 4,045 studies were retrieved, with 34 studies ultimately included.

Data Extraction: OCD prevalence was extracted from each study alongside 9 moderators: gender, year, response rate, region, economic status, diagnostic criteria, diagnostic interview, interviewer, and age.

Results: The overall aggregate current, period, and lifetime OCD prevalence estimates were 1.1%, 0.8%, and 1.3%, respectively. In a typical sample, women were 1.6 times more likely to experience OCD compared to men, with lifetime prevalence rates of 1.5% in women and 1.0% in men. There was also a trend toward younger adults' being more likely to experience OCD in their lifetime than older adults. All findings demonstrated moderate heterogeneity.

Conclusions: Women are typically at greater risk of experiencing OCD in their lifetime than men.
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http://dx.doi.org/10.4088/JCP.19r13085DOI Listing
June 2020

Refining our understanding of depressive states and state transitions in response to cognitive behavioural therapy using latent Markov modelling.

Psychol Med 2020 Jun 29:1-10. Epub 2020 Jun 29.

Digital Futures Lab, Ieso Digital Health, The Jeffrey's Building, Cowley Road, Cambridge, CB4 0DS, UK.

Background: It is increasingly recognized that existing diagnostic approaches do not capture the underlying heterogeneity and complexity of psychiatric disorders such as depression. This study uses a data-driven approach to define fluid depressive states and explore how patients transition between these states in response to cognitive behavioural therapy (CBT).

Methods: Item-level Patient Health Questionnaire (PHQ-9) data were collected from 9891 patients with a diagnosis of depression, at each CBT treatment session. Latent Markov modelling was used on these data to define depressive states and explore transition probabilities between states. Clinical outcomes and patient demographics were compared between patients starting at different depressive states.

Results: A model with seven depressive states emerged as the best compromise between optimal fit and interpretability. States loading preferentially on cognitive/affective v. somatic symptoms of depression were identified. Analysis of transition probabilities revealed that patients in cognitive/affective states do not typically transition towards somatic states and vice-versa. Post-hoc analyses also showed that patients who start in a somatic depressive state are less likely to engage with or improve with therapy. These patients are also more likely to be female, suffer from a comorbid long-term physical condition and be taking psychotropic medication.

Conclusions: This study presents a novel approach for depression sub-typing, defining fluid depressive states and exploring transitions between states in response to CBT. Understanding how different symptom profiles respond to therapy will inform the development and delivery of stratified treatment protocols, improving clinical outcomes and cost-effectiveness of psychological therapies for patients with depression.
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http://dx.doi.org/10.1017/S0033291720002032DOI Listing
June 2020

Distinctive encodings and the production effect: failure to retrieve distinctive encodings decreases recollection of silent items.

Memory 2020 02 20;28(2):237-260. Epub 2020 Jan 20.

Department of Psychology, Memorial University, Saint John's, Canada.

Studies have shown that when aloud and silent items are studied together, silent items are remembered more poorly than when they are studied independently. We hypothesise that this cost to silent items emerges because, at test, participants search for memories of having said items aloud and when those memory searches fail, participants become uncertain about whether silent items were studied. This effect should be exaggerated if other unique distinctive encoding conditions are also included at study (e.g., mumbling, writing, typing, etc.). To test this prediction, we examined the impact of introducing mumbled, "important" (i.e., words that participants are told are the most important to remember), and mouthed words to a study list of aloud and silent words. Introducing mumbled and "important" words further impaired the recollection of silent items. Introducing mouthed items did not further impair the memorability of silent items because mouthing and speaking aloud are so similar and hence, are not fully unique from each other. The memorability of aloud items was unaffected in all conditions. These results suggest that participants search for distinctive encoding information at test, and only for items that fail those searches (i.e., silent items) do they lose confidence.
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http://dx.doi.org/10.1080/09658211.2019.1711128DOI Listing
February 2020

The Prevalence of Anxiety Disorders During Pregnancy and the Postpartum Period: A Multivariate Bayesian Meta-Analysis.

J Clin Psychiatry 2019 07 23;80(4). Epub 2019 Jul 23.

Department of Psychology, Memorial University of Newfoundland, St John's, Newfoundland, Canada.

Objective: To estimate the prevalence of anxiety disorders in pregnant and postpartum women and identify predictors accounting for variability across estimates.

Data Sources: An electronic search of PsycINFO and PubMed was conducted from inception until July 2016, without date or language restrictions, and supplemented by articles referenced in the obtained sources. A Boolean search phrase utilized a combination of keywords related to pregnancy, postpartum, prevalence, and specific anxiety disorders.

Study Selection: Articles reporting the prevalence of 1 or more of 8 common anxiety disorders in pregnant or postpartum women were included. A total of 2,613 records were retrieved, with 26 studies ultimately included.

Data Extraction: Anxiety disorder prevalence and potential predictor variables (eg, parity) were extracted from each study. A Bayesian multivariate modeling approach estimated the prevalence and between-study heterogeneity of each disorder and the prevalence of having 1 or more anxiety disorder.

Results: Individual disorder prevalence estimates ranged from 1.1% for posttraumatic stress disorder to 4.8% for specific phobia, with the prevalence of having at least 1 or more anxiety disorder estimated to be 20.7% (95% highest density interval [16.7% to 25.4%]). Substantial between-study heterogeneity was observed, suggesting that "true" prevalence varies broadly across samples. There was evidence of a small (3.1%) tendency for pregnant women to be more susceptible to anxiety disorders than postpartum women.

Conclusions: Peripartum anxiety disorders are more prevalent than previously thought, with 1 in 5 women in a typical sample meeting diagnostic criteria for at least 1 disorder. These findings highlight the need for anxiety screening, education, and referral in obstetrics and gynecology settings.
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http://dx.doi.org/10.4088/JCP.18r12527DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6839961PMC
July 2019

A Bayesian multivariate approach to estimating the prevalence of a superordinate category of disorders.

Int J Methods Psychiatr Res 2018 12 14;27(4):e1742. Epub 2018 Sep 14.

MRC Clinical Trials Unit, University College London, London, UK.

Objective: Epidemiological research plays an important role in public health, facilitated by the meta-analytic aggregation of epidemiological trials into a single, more powerful estimate. This form of aggregation is complicated when estimating the prevalence of a superordinate category of disorders (e.g., "any anxiety disorder," "any cardiac disorder") because epidemiological studies rarely include all of the disorders selected to define the superordinate category. In this paper, we suggest that estimating the prevalence of a superordinate category based on studies with differing operationalization of that category (in the form of different disorders measured) is both common and ill-advised. Our objective is to provide a better approach.

Methods: We propose a multivariate method using individual disorder prevalences to produce a fully Bayesian estimate of the probability of having one or more of those disorders. We validate this approach using a recent case study and parameter recovery simulations.

Results: Our approach produced less biased and more reliable estimates than other common approaches, which were at times highly biased.

Conclusion: Although our approach entails additional effort (e.g., contacting authors for individual participant data), the improved accuracy of the prevalence estimates obtained is significant and therefore recommended.
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http://dx.doi.org/10.1002/mpr.1742DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6383646PMC
December 2018

Inducing preference reversals in aesthetic choices for paintings: Introducing the contrast paradigm.

PLoS One 2018 19;13(4):e0196246. Epub 2018 Apr 19.

Department of Psychology, Memorial University of Newfoundland, St. John's, Newfoundland, Canada.

Understanding what leads people to reverse their choices is important in many domains. We introduce a contrast paradigm for studying reversals in choices-here between pairs of abstract paintings-implemented in both within-subject (Experiment 1; N = 320) and between-subject (Experiment 2; N = 384) designs. On each trial, participants chose between a pair of paintings. A critical pair of average-beauty paintings was presented before and after either a reversal or control block. In the reversal block, we made efforts to bias preference away from the chosen average-beauty painting (by pairing it with more-beautiful paintings) and toward the non-chosen average-beauty painting (by pairing it with less-beautiful paintings). Meta-analysis revealed more reversals after reversal blocks than after control blocks, though only when the biasing manipulations succeeded. A second meta-analysis revealed that reversals were generally more likely for participants who later misidentified their initial choice, demonstrating that memory for initial choices influences later choices. Thus, the contrast paradigm has utility both for inducing choice reversals and identifying their causes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0196246PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5908093PMC
August 2018

Familiarity, but not recollection, supports the between-subject production effect in recognition memory.

Can J Exp Psychol 2016 Jun;70(2):99-115

Rotman Research Institute.

Five experiments explored the basis of the between-subjects production effect in recognition memory as represented by differences in the recollection and familiarity of produced (read aloud) and nonproduced (read silently) words. Using remember-know judgments (Experiment 1b) and a dual-process signal-detection approach applied to confidence ratings (Experiments 2b and 3), we observed that production influences familiarity but not recollection when manipulated between-subjects. This is in contrast to within-subject designs, which reveal a clear effect of production on both recollection and familiarity (Experiments 1a and 2a). Our findings resolve contention concerning apparent design effects: Whereas the within-subject production effect is subserved by separable recollective- and familiarity-based components, the between-subjects production effect is subserved by the familiarity-based component alone. Our findings support a role for the relative distinctiveness of production as a means of guiding recognition judgments (at least when manipulated within-subjects), but we also propose that production influences the strength of produced items, explaining the persistence of the effect in between-subjects designs. (PsycINFO Database Record
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http://dx.doi.org/10.1037/cep0000089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4886847PMC
June 2016

A meta-analysis of the worldwide prevalence of pica during pregnancy and the postpartum period.

Int J Gynaecol Obstet 2016 Jun 3;133(3):277-83. Epub 2016 Feb 3.

Lakehead University, Department of Psychology, Thunder Bay, Ontario, Canada.

Background: Although pica has long been associated with pregnancy, the exact prevalence in this population remains unknown.

Objectives: To estimate the prevalence of pica during pregnancy and the postpartum period, and to explain variations in prevalence estimates by examining potential moderating variables.

Search Strategy: PsycARTICLES, PsycINFO, PubMed, and Google Scholar were searched from inception to February 2014 using the keywords pica, prevalence, and epidemiology.

Selection Criteria: Articles estimating pica prevalence during pregnancy and/or the postpartum period using a self-report questionnaire or interview were included.

Data Collection And Analysis: Study characteristics, pica prevalence, and eight potential moderating variables were recorded (parity, anemia, duration of pregnancy, mean maternal age, education, sampling method employed, region, and publication date). Random-effects models were employed.

Main Results: In total, 70 studies were included, producing an aggregate prevalence estimate of 27.8% (95% confidence interval 22.8-33.3). In light of substantial heterogeneity within the study model, the primary focus was identifying moderator variables. Pica prevalence was higher in Africa compared with elsewhere in the world, increased as the prevalence of anemia increased, and decreased as educational attainment increased.

Conclusions: Geographical region, anemia, and education were found to moderate pica prevalence, partially explaining the heterogeneity in prevalence estimates across the literature.
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http://dx.doi.org/10.1016/j.ijgo.2015.10.012DOI Listing
June 2016

The representational consequences of intentional forgetting: Impairments to both the probability and fidelity of long-term memory.

J Exp Psychol Gen 2016 Jan;145(1):56-81

Department of Psychology and Neuroscience, Dalhousie University.

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.
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http://dx.doi.org/10.1037/xge0000128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4694085PMC
January 2016

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

J Behav Ther Exp Psychiatry 2015 Jun 7;47:1-8. Epub 2014 Nov 7.

MRC Cognition and Brain Sciences Unit, Cambridge, UK.

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.
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http://dx.doi.org/10.1016/j.jbtep.2014.10.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4324850PMC
June 2015

Effects of distinctive encoding on correct and false memory: a meta-analytic review of costs and benefits and their origins in the DRM paradigm.

Psychon Bull Rev 2015 Apr;22(2):349-65

Department of Psychology, Washington University in St. Louis, St. Louis, MO, 63130, USA,

We review and meta-analyze how distinctive encoding alters encoding and retrieval processes and, thus, affects correct and false recognition in the Deese-Roediger-McDermott (DRM) paradigm. Reductions in false recognition following distinctive encoding (e.g., generation), relative to a nondistinctive read-only control condition, reflected both impoverished relational encoding and use of a retrieval-based distinctiveness heuristic. Additional analyses evaluated the costs and benefits of distinctive encoding in within-subjects designs relative to between-group designs. Correct recognition was design independent, but in a within design, distinctive encoding was less effective at reducing false recognition for distinctively encoded lists but more effective for nondistinctively encoded lists. Thus, distinctive encoding is not entirely "cost free" in a within design. In addition to delineating the conditions that modulate the effects of distinctive encoding on recognition accuracy, we discuss the utility of using signal detection indices of memory information and memory monitoring at test to separate encoding and retrieval processes.
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http://dx.doi.org/10.3758/s13423-014-0648-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4305508PMC
April 2015

Electrophysiological markers of biological motion and human form recognition.

Neuroimage 2014 Jan 21;84:854-67. Epub 2013 Sep 21.

Department of Psychology and Neuroscience, Life Sciences Centre, Dalhousie University, Halifax, NS B3H 4R2, Canada.

Current models suggest that human form and motion information are initially processed through separate pathways, then integrated in action perception. Testing such a sequential model requires techniques with high temporal resolution. Prior work demonstrated sensitivity of a posterior temporal event-related potential (ERP) effect - the N2 - to biological motion, but did not test whether the N2 indexes biological motion perception specifically, or human form/action perception more generally. We recorded ERPs while participants viewed stimuli across 3 blocks: (1) static (non-moving) point-light displays of humans performing actions; (2) static stick figures with clear forms; and (3) point-light biological motion. A similar sequence of ERP components was elicited by human forms in all blocks (stationary and moving), and reliably discriminated between human and scrambled forms. The N2 showed similar scalp distribution and sensitivity to stimulus manipulations for both stick figures and biological motion, suggesting that it indexes integration of form and motion information, rather than biological motion perception exclusively - and that form and motion information are therefore integrated by approximately 200ms. We identified a component subsequent to the N2, which we label the medial parietal positivity/ventral-anterior negativity (MPP/VAN), that was also sensitive to both human form and motion information. We propose that the MPP/VAN reflects higher-order human action recognition that occurs subsequent to the integration of form and motion information reflected by the N2.
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http://dx.doi.org/10.1016/j.neuroimage.2013.09.026DOI Listing
January 2014

Event-method directed forgetting: forgetting a video segment is more effortful than remembering it.

Acta Psychol (Amst) 2013 Oct 7;144(2):332-43. Epub 2013 Aug 7.

Dalhousie University, Halifax, Nova Scotia, Canada. Electronic address:

Videos were presented depicting events such as baking cookies or cleaning a fish tank. Periodically, the video paused and an instruction to Remember (R) or Forget (F) the preceding video segment was presented; the video then resumed. Participants later responded more accurately to cued-recall questions (E1) and to true/false statements (E2-5) regarding R segments than F segments. This difference was larger for specific information (the woman added 3 cups of flour) than for general information (the woman added flour). Participants were also slower to detect visual probes presented following F instructions compared to those presented following R instructions. These findings suggest that intentional forgetting is an effortful process that can be performed even on segments of otherwise continuous events and that the result is a relatively impoverished representation of the unwanted information in memory.
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http://dx.doi.org/10.1016/j.actpsy.2013.07.005DOI Listing
October 2013

Assessing the costs and benefits of production in recognition.

Psychon Bull Rev 2014 Feb;21(1):149-54

Department of Psychology, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada,

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.
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http://dx.doi.org/10.3758/s13423-013-0485-1DOI Listing
February 2014

Risk of obsessive-compulsive disorder in pregnant and postpartum women: a meta-analysis.

J Clin Psychiatry 2013 Apr;74(4):377-85

Lakehead University, Department of Psychology, 955 Oliver Rd, Thunder Bay, ON, P7B 5E1 Canada.

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.
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http://dx.doi.org/10.4088/JCP.12r07917DOI Listing
April 2013

Intentional forgetting diminishes memory for continuous events.

Memory 2013 10;21(6):675-94. Epub 2013 Jan 10.

Department of Psychology, Dalhousie University, Halifax, Nova Scotia, Canada.

In a novel event method directed forgetting task, instructions to Remember (R) or Forget (F) were integrated throughout the presentation of four videos depicting common events (e.g., baking cookies). Participants responded more accurately to cued recall questions (E1) and true/false statements (E2-4) regarding R segments than F segments. This was true even when forced to attend to F segments by virtue of having to perform concurrent discrimination (E2) or conceptual segmentation (E3) tasks. The final experiment (E5) demonstrated a larger R >F difference for specific true/false statements (the woman added three cups of flour) than for general true/false statements (the woman added flour) suggesting that participants likely encoded and retained at least a general representation of the events they had intended to forget, even though this representation was not as specific as the representation of events they had intended to remember.
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http://dx.doi.org/10.1080/09658211.2012.748078DOI Listing
February 2014

The production effect benefits performance in between-subject designs: a meta-analysis.

Acta Psychol (Amst) 2013 Jan 9;142(1):1-5. Epub 2012 Nov 9.

Dalhousie University, Department of Psychology, Halifax, NS, Canada B3H 4J1.

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.
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http://dx.doi.org/10.1016/j.actpsy.2012.10.001DOI Listing
January 2013

Communicative and noncommunicative point-light actions featuring high-resolution representation of the hands and fingers.

Behav Res Methods 2013 Jun;45(2):319-28

Department of Psychology & Neuroscience, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.

We describe the creation of a set of point-light movies depicting 43 communicative gestures and 43 noncommunicative, pantomimed actions. These actions were recorded using a motion capture system that is worn on the body and provides accurate capture of the positions and movements of individual fingers. The movies created thus include point-lights on the fingers, allowing for representation of actions and gestures that would not be possible with a conventional, line-of-sight-based motion capture system. These videos would be suitable for use in cognitive and cognitive neuroscientific studies of biological motion and gesture perception. Each video is described, along with an H statistic indicating the consistency of the descriptive labels that 20 observers gave to the actions. We also produced a scrambled version of each movie, in which the starting position of each point was randomized but its local motion vector was preserved. These scrambled movies would be suitable for use as control stimuli in experimental studies. As supplementary materials, we provide QuickTime movie files of each action, along with text files specifying the three-dimensional coordinates of each point-light in each frame of each movie.
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http://dx.doi.org/10.3758/s13428-012-0273-2DOI Listing
June 2013

Interplay of the production and picture superiority effects: a signal detection analysis.

Memory 2012 26;20(7):655-66. Epub 2012 Jun 26.

Department of Psychology, Dalhousie University, Halifax, NS, Canada.

Three experiments explored the interaction between the production effect (greater memory for produced compared to non-produced study items) and the picture superiority effect (greater memory for pictures compared to words). Pictures and words were presented in a blocked (E1) or mixed (E2, E3) design, each accompanied by an instruction to silently name (non-produced condition) or quietly mouth (produced condition) the corresponding referent. Memory was then tested for all study items as well as an equal number of foil items using a speeded (E1, E2) or self-paced (E3) yes-no recognition task. Experiments 1, 2, and 3 all revealed a small but reliable production × stimulus interaction. Production was also found to result in a liberal shift in response bias that could result in the overestimation of the production effect when measured using hits instead of sensitivity. Together our findings suggest that the application of multiple distinctive processes at study produces an especially discriminative memory trace at test, more so than the summation of each process individually.
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http://dx.doi.org/10.1080/09658211.2012.693510DOI Listing
February 2013

Intentional forgetting reduces color-naming interference: evidence from item-method directed forgetting.

J Exp Psychol Learn Mem Cogn 2013 Jan 25;39(1):220-36. Epub 2012 Jun 25.

Department of Psychology, National Chung-Cheng University, Chiayi, Taiwan.

In an item-method-directed forgetting task, Chinese words were presented individually, each followed by an instruction to remember or forget. Colored probe items were presented following each memory instruction requiring a speeded color-naming response. Half of the probe items were novel and unrelated to the preceding study item, whereas the remaining half of the probe items were a repetition of the preceding study item. Repeated probe items were either identical to the preceding study item (E1, E2), a phonetic reproduction of the preceding study item (E3), or perceptually matched to the preceding study item (E4). Color-naming interference was calculated by subtracting color-naming reaction times made in response to a string of meaningless symbols from that of the novel and repeated conditions. Across all experiments, participants recalled more to-be-remembered (TBR) than to-be-forgotten (TBF) study words. More importantly, Experiments 1 and 2 found that color-naming interference was reduced for repeated TBF words relative to repeated TBR words. Experiments 3 and 4 further found that this effect occurred at the perceptual rather than semantic level. These findings suggest that participants may bias processing resources away from the perceptual representation of to-be-forgotten information.
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http://dx.doi.org/10.1037/a0028905DOI Listing
January 2013

Does an instruction to forget enhance memory for other presented items?

Conscious Cogn 2012 Sep 9;21(3):1186-97. Epub 2012 Jun 9.

Dalhousie University, Department of Psychology and Neuroscience, 1355 Oxford Street, PO Box 5000, Halifax Nova Scotia, Canada.

In an item-method directed forgetting paradigm, participants were required to attend to one of two colored words presented on opposite sides of a central fixation stimulus; they were instructed to Remember or Forget the attended item. On a subsequent recognition test, the Attended words showed a typical directed forgetting effect with better recognition of Remember words than Forget words. Our interest was in the fate of the Unattended words. When the study display disappeared before the memory instruction, there was no effect of that instruction on unattended words; when the study display remained visible during presentation of the memory instruction, there was a reverse directed forgetting effect with better recognition of unattended words from Forget trials than from Remember trials. Incidental encoding of task-irrelevant stimuli occurs following presentation of a Forget instruction - but only when those task-irrelevant stimuli are still visible in the external environment.
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http://dx.doi.org/10.1016/j.concog.2012.05.002DOI Listing
September 2012

Inhibition of return and schizophrenia: a meta-analysis.

Schizophr Res 2012 Mar 4;135(1-3):55-61. Epub 2012 Jan 4.

Department of Psychology, Dalhousie University, Life Sciences Centre, 1355 Oxford Street, Halifax, Nova Scotia, Canada.

Inhibition of return (IOR) is a phenomenon that involves inhibited or delayed orienting to previously cued locations in favor of attending to novel locations. To date, research on IOR in patients with schizophrenia has generated mixed, and seemingly conflicting, results. Some researchers report patients with schizophrenia exhibit blunted or delayed IOR, while other researchers report normal IOR, in terms of time course and magnitude. This meta-analysis summarizes the literature that has employed an IOR task in patients with schizophrenia and with controls while focusing upon a procedural feature, the use of a cue back to fixation, between the cue and target that is known to be important when executive control has been hampered in non-clinical populations. Fifteen experiments were located yielding a total sample of 362 patients with schizophrenia or schizoaffective disorder and 285 controls. Using a meta-analytic approach, results of the present analyses show that patients with schizophrenia demonstrate delayed IOR in the single cue procedure. In the cue back to fixation procedure, the time course of IOR among patients is more consistent with that of controls. Differences in measured IOR between patients with schizophrenia and controls are largely related to a deficit in endogenous disengagement of attention.
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http://dx.doi.org/10.1016/j.schres.2011.11.034DOI Listing
March 2012

The control of working memory resources in intentional forgetting: evidence from incidental probe word recognition.

Acta Psychol (Amst) 2012 Jan 26;139(1):84-90. Epub 2011 Oct 26.

Dalhousie University, Department of Psychology, Halifax, NS, Canada.

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.
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http://dx.doi.org/10.1016/j.actpsy.2011.10.001DOI Listing
January 2012

Tag, you're it: tagging as an alternative to yes/no recognition in item method directed forgetting.

Acta Psychol (Amst) 2011 Sep 16;138(1):171-5. Epub 2011 Jul 16.

Dalhousie University, Canada.

The current study contrasted a standard yes/no recognition task with a tagging recognition task in the context of an item-method directed forgetting paradigm. During the study phase, a series of words was presented one at a time, each followed by an instruction to remember (R) or forget (F). The retention of R and F study words was tested using either a typical yes/no recognition task or a tagging recognition task in which participants labeled each word as "R", "F" or "New". The directed forgetting effect observed in each task was equivalent in magnitude. However, the tagging recognition task afforded an additional analysis of the errors of misattribution that was not possible with the more typical yes/no recognition task. Interestingly, when falsely recognizing a Foil word, participants were more likely to assign an "F" tag than an "R" tag. These errors of misattribution are consistent with existing accounts of directed forgetting that suggest R words are better encoded than F words. We argue for the utility of the tagging procedure, given it does not alter the directed forgetting effect normally seen with yes/no recognition but provides additional information about errors of misattribution.
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http://dx.doi.org/10.1016/j.actpsy.2011.06.001DOI Listing
September 2011

Larger IOR effects following forget than following remember instructions depend on exogenous attentional withdrawal and target localization.

Atten Percept Psychophys 2011 Aug;73(6):1790-814

Department of Psychology, Life Sciences Centre, Dalhousie University, 1355 Oxford Street, Halifax, Nova Scotia, Canada.

When words are onset in the visual periphery, inhibition of return (IOR) for a subsequent target is larger when those words receive an intervening forget instruction than when they receive a remember instruction Taylor (Quarterly Journal of Experimental Psychology, 58A, 613-629, 2005). The present study manipulated the allocation of endogenous and exogenous attention to assess the source of the forget > remember IOR difference. We determined that the forget > remember IOR difference likely arises from the differential withdrawal of exogenous-rather than endogenous-attention. Furthermore, this forget > remember IOR difference occurs only when a spatially compatible localization response is required; it does not occur when a simple detection response or a perceptual discrimination is required. This suggests that the forget > remember difference in the magnitude of IOR is not due to differences in perceptual/attentional processing. Instead, an instruction to remember or forget biases spatial responses in accordance with whether a location has previously contained relevant or irrelevant information. We suggest that directed forgetting in an item-method paradigm is not accomplished by changes in attention; rather, the changes in attention are coincident with changes in memory and may serve to bias later responses away from a source of unreliable information.
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http://dx.doi.org/10.3758/s13414-011-0146-2DOI Listing
August 2011
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