References of "Willems, Sylvie"
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See detailImplicit/explicit memory dissociation in Alzheimer's disease: the consequence of inappropriate processing?
Willems, Sylvie ULg; Salmon, Eric ULg; Van der Linden, Martial ULg

in Neuropsychology (2008), 22(6), 710-7

Dual-process theories of recognition posit that perceptual fluency contributes to both familiarity-based explicit recognition and perceptual priming. However, the priming-without-recognition dissociation ... [more ▼]

Dual-process theories of recognition posit that perceptual fluency contributes to both familiarity-based explicit recognition and perceptual priming. However, the priming-without-recognition dissociation, as observed through the intact mere exposure effect and impaired recognition in patients with Alzheimer's disease (AD), might indicate that familiarity and perceptual priming are functionally distinct. This study investigated whether the AD patients' processing strategies at testing may explain this priming-without-recognition dissociation. First, we replicated the priming-without-recognition effect in 16 patients who exhibited intact exposure effects despite null recognition. Second, we showed that, under identical conditions, inducing a holistic processing strategy during recognition testing increased AD patients' recognition--performance was similar for AD patients and healthy control participants. Furthermore, prompting analytic processing during both priming and recognition tasks decreased AD patients' performance in both tasks. These findings suggest that the extent to which AD patients use perceptual fluency in priming and recognition tasks is contingent on their processing approach. The choice of processing strategy may depend on how difficult patients perceive the task to be. [less ▲]

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See detailExperimental dissociations between memory measures: Influence of retrieval strategies.
Willems, Sylvie ULg; Van der Linden, Martial

in Consciousness & Cognition (2008)

The objective of this study was to explore the participants' processing strategies on the mere exposure effect, object decision priming and explicit recognition. In Experiments 1, we observed that ... [more ▼]

The objective of this study was to explore the participants' processing strategies on the mere exposure effect, object decision priming and explicit recognition. In Experiments 1, we observed that recognition and the mere exposure effect for unfamiliar three-dimensional objects were not dissociated by plane rotations in the same way as recognition and object decision priming. However, we showed that, under identical conditions, prompting analytic (part-based) processing at testing produced a large plane rotation effect on recognition and the mere exposure effect similar to that observed for object decision priming (Experiment 2). Furthermore, inducing a non-analytic (whole-based) processing strategy at testing produced a reduced plane rotation effect on recognition and object decision (Experiments 3 and 4), similar to that observed for the mere exposure effect. These findings suggest that participants' processing strategies influence performance on the three tasks. [less ▲]

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See detailWhat is the impact of the explicit knowledge of sequence regularities on both deterministic and probabilistic serial reaction time task performance?
Stefaniak, Nicolas ULg; Willems, Sylvie ULg; Adam, Stéphane ULg et al

in Memory & Cognition (2008), 36(7), 1283-98

The aim of this study was to explore the role of prior explicit sequence knowledge by comparing its influence on serial reaction time (SRT) performance with either a deterministic or a probabilistic ... [more ▼]

The aim of this study was to explore the role of prior explicit sequence knowledge by comparing its influence on serial reaction time (SRT) performance with either a deterministic or a probabilistic sequence. The results confirm that, with a deterministic sequence, preliminary explicit learning improves SRT performance. On the other hand, with a probabilistic sequence, the results show no advantage for SRT performance in explicit-learning conditions. In addition, by using the process dissociation procedure (Jacoby, 1991), we show that performance on a subsequent generation task was more sustained by controlled processes for participants in the explicit-learning conditions than for those in the incidental condition. On the whole, these results, showing that the influence of explicit knowledge can be suppressed in certain specific conditions, are consistent with the intervention of both implicit and explicit mechanisms in SRT tasks, and the results also show that their relative influence can be modulated by the particular demands of the task. [less ▲]

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See detailCerebral asymmetries in sleep-dependent processes of memory consolidation
Peigneux, Philippe ULg; Schmitz, Remy; Willems, Sylvie ULg

in Learning & Memory (2007), 14(6), 400-406

Preference for previously seen, unfamiliar objects reflects a memory bias on affective judgment, known as the "mere exposure effect" (MEE). Here, we investigated the effect of time, post-exposure sleep ... [more ▼]

Preference for previously seen, unfamiliar objects reflects a memory bias on affective judgment, known as the "mere exposure effect" (MEE). Here, we investigated the effect of time, post-exposure sleep, and the brain hemisphere solicited on preference generalization toward objects viewed in different perspectives. When presented in the right visual field (RVF), which promotes preferential processing in the left hemisphere, same and mirrored exemplars were preferred immediately after exposure. MEE generalized to much dissimilar views after three nights of sleep. Conversely, object presentation in the left visual field (LVF), promoting right hemisphere processing, elicited a MEE for same views immediately after exposure, then for mirror views after sleep. Most importantly, sleep deprivation during the first post-exposure night, although followed by two recovery nights, extinguished MEE for all views in the LVF but not in the RVF. Besides demonstrating that post-exposure time and sleep facilitate the generalization process by which we integrate various representations of an object, our results suggest that mostly in the right hemisphere, sleep may be mandatory to consolidate the memory bias underlying affective preference. These interhemispheric differences tentatively call for a reappraisal of the role of cerebral asymmetries in wake- and sleep-dependent processes of memory consolidation. [less ▲]

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See detailThe contribution of processing fluency to preference : a comparison with familiarity-based recognition
Willems, Sylvie ULg; Van der Linden, Martial ULg; Bastin, Christine ULg

in European Journal of Cognitive Psychology (2007), 19(1), 119-140

There is a great deal of evidence supporting the idea that, when a stimulus is processed fluently, it is more likely to be judged as pleasant. However, this influence of fluency on preference judgement ... [more ▼]

There is a great deal of evidence supporting the idea that, when a stimulus is processed fluently, it is more likely to be judged as pleasant. However, this influence of fluency on preference judgement seems to depend on several experimental conditions. So we tried to better understand these conditions via a comparison with recognition and by manipulating some aspects of the procedure (test format) and material (similarity and figure-ground contrast of the stimuli). Two experiments showed that some conditions maximally induce the use of processing fluency in a preference judgement, as in a recognition task. We discuss the implications of these findings for the well-documented discrepancy-attribution hypothesis (Whittlesea [less ▲]

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See detailMere exposure effect : a consequence of direct and indirect fluency-preference links
Willems, Sylvie ULg; Van der Linden, Martial ULg

in Consciousness & Cognition (2006), 15(2), 323-341

In three experiments, picture quality between test items was manipulated to examine whether subjects' expectations about the fluency normally associated with these different stimuli might influence the ... [more ▼]

In three experiments, picture quality between test items was manipulated to examine whether subjects' expectations about the fluency normally associated with these different stimuli might influence the effects of fluency on preference or familiarity-basea recognition responses. The results showed that fluency due to pre-exposure influenced responses less when objects were presented with high picture quality, suggesting that attributions of fluency to preference and familiarity are adjusted according to expectations about the different test pictures. However, this expectations influence depended on subjects' awareness of these different quality levels. Indeed, imperceptible differences seemed not to induce expectations about the test item fluency. In this context, fluency due to both picture quality and pre-exposure influenced direct responses. Conversely, obvious, and noticed, differences in test picture quality did no affect responses, suggesting that expectations moderated attributions of fluency only when fluency normally associated with these different stimuli was perceptible but difficult to assess. (c) 2005 Elsevier Inc. All rights reserved. [less ▲]

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See detailImplicit memory during isoflurane anesthesia
Iselin-Chaves, Irène; Willems, Sylvie ULg

in Anesthesiology (2006), 105

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See detailA French adaptation of the UPPS Impulsive Behavior Scale: Confirmatory factor analysis in a sample of undergraduate students
Van der Linden, Martial ULg; d'Acremont, M.; Zermatten, A. et al

in European Journal of Psychological Assessment (2006), 22(1), 38-42

Impulsivity is an important and multifaceted psychological construct. Recently, Whiteside and Lynam (2001) have developed the UPPS Impulsive Behavior Scale that distinguishes four dimensions of ... [more ▼]

Impulsivity is an important and multifaceted psychological construct. Recently, Whiteside and Lynam (2001) have developed the UPPS Impulsive Behavior Scale that distinguishes four dimensions of impulsivity: Urgency, lack of Premeditation, lack of Perseverance, and Sensation seeking. In the present study, we investigated the psychometric properties of a French adaptation of the UPPS Impulsive Behavior Scale. Two hundred and thirty-four undergraduate students completed the UPPS Scale. Exploratory and confirmatory analyses revealed a four factors solution similar to that found in the original study. Also, the results indicated that there was good to very good internal reliability for the four subscales. [less ▲]

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See detailImplicit memory during isoflurane anesthesia - Reply
Iselin-Chaves, Irène A.; Willems, Sylvie ULg

in Anesthesiology (2006), 105(2), 430-430

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See detailL'effet de simple exposition : approche cognitive et neuropsychologique
Willems, Sylvie ULg

Doctoral thesis (2005)

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See detailInvestigation of automatic memory during general anesthesia for elective surgery using the process dissociation procedure
Willems, Sylvie ULg; Iselin-Chaves, Irène A.; Jermann, Françoise J. et al

in Anesthesiology (2005), 103

Background: This prospective study evaluated memory function during general anesthesia for elective surgery and its relation to depth of hypnotic state. The authors also compared memory function in ... [more ▼]

Background: This prospective study evaluated memory function during general anesthesia for elective surgery and its relation to depth of hypnotic state. The authors also compared memory function in anesthetized and nonanesthetized subjects. Methods: Words were played for 70 min via headphones to 48 patients (aged 18–70 yr) after induction of general anesthesia for elective surgery. Patients were unpremedicated, and the anesthetic regimen was free. The Bispectral Index (BIS) was recorded throughout the study. Within 36 h after the word presentation, memory was assessed using an auditory word stem completion test with inclusion and exclusion instructions. Memory performance and the contribution of explicit and implicit memory were calculated using the process dissociation procedure. The authors applied the same memory task to a control group of nonanesthetized subjects. Results: Forty-seven patients received isoflurane, and one patient received propofol for anesthesia. The mean ( SD) BIS was 49 9. There was evidence of memory for words presented during light (BIS 61–80) and adequate anesthesia (BIS 41–60) but not during deep anesthesia (BIS 21–40). The process dissociation procedure showed a significant implicit memory contribution but not reliable explicit memory contribution (mean explicit memory scores 0.05 0.14, 0.04 0.09, and 0.05 0.14; mean automatic influence scores 0.14 0.12, 0.17 0.17, and 0.18 0.21 at BIS 21–40, 41–60, and 61–80, respectively). Compared with anesthetized patients, the memory performance of nonanesthetized subjects was better, with a higher contribution by explicit memory and a comparable contribution by implicit memory. Conclusion: During general anesthesia for elective surgery, implicit memory persists even in adequate hypnotic states, to a comparable degree as in nonanesthetized subjects. [less ▲]

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See detailL'effet de simple exposition : un simple amorçage?
Willems, Sylvie ULg

Scientific conference (2004, May)

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See detailDifférences interindividuelles dans la propension aux faux souvenirs
Willems, Sylvie ULg; Van der Linden, Martial ULg

in Brédart, Serge (Ed.) Souvenirs récupérés, souvenirs oubliés et faux souvenirs (2004)

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See detailSensation-seeking and impulsivity in young and older adults' decision making
Willems, Sylvie ULg; Van der Linden, Martial ULg; Marczewski, Philippe

in Brain & Cognition (2003), 51(2), 237-239

The somatic marker hypothesis asserts that decision-making processes involve emotion. Using a gambling task that models real-life decisions, studies showed that old adults perform less efficiently than ... [more ▼]

The somatic marker hypothesis asserts that decision-making processes involve emotion. Using a gambling task that models real-life decisions, studies showed that old adults perform less efficiently than younger adults, by adopting a strategy that is disadvantageous on the long term. This study aimed at re-examining the age effect on decisionmaking with the same paradigm, and to explore whether differences are related to sensation-seeking and impulsivity traits of personality. Young and older adults were compared on the gambling task (Bechara, Damasio, & Damasio, 2000a), and on questionnaires of sensationseeking and impulsivity. Results confirmed an age effect on the gambling task performance. Moreover, performance in both young and older adults on this task was correlated to scores on the sensation-seeking scale, but not to the rating of impulsivity [less ▲]

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See detailL'effet de simple exposition : un simple amorçage?
Willems, Sylvie ULg

Scientific conference (2003)

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See detailNormal mere exposure effect with impaired recognition in Alzheimer's disease
Willems, Sylvie ULg; Adam, Stéphane ULg; Van der Linden, Martial ULg

in Cortex : A Journal Devoted to the Study of the Nervous System & Behavior (2002), 38(1), 77-86

We investigated the mere exposure effect and the explicit memory in Alzheimer's disease (AD) patients and elderly control subjects, using unfamiliar faces. During the exposure phase, the subjects ... [more ▼]

We investigated the mere exposure effect and the explicit memory in Alzheimer's disease (AD) patients and elderly control subjects, using unfamiliar faces. During the exposure phase, the subjects estimated the age of briefly flashed faces. The mere exposure effect was examined by presenting pairs of faces (old and new) and asking participants to select the face they liked. The participants were then presented with a forced-choice explicit recognition task. Controls subjects exhibited above-chance preference and recognition scores for old faces. The AD patients also showed the mere exposure effect but no explicit recognition. These results suggest that the processes involved in the mere exposure effect are preserved in AD patients despite their impaired explicit recognition. The results are discussed in terms of Seamon et al.'s (1995) proposal that processes involved in the mere exposure effect are equivalent to those subserving perceptual priming. These processes would depend on extrastriate areas which are relatively preserved in AD patients. [less ▲]

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See detailEffet de Simple exposition et reconnaissance pour des objets tridimensionnels chez des enfants âgés de 5 à 12 ans et des jeunes adultes
Catale, Corinne ULg; Willems, Sylvie ULg; Van der Linden, Martial ULg

Poster (2002)

Introduction Chez l’adulte, il est classiquement observé que l’exposition répétée à des stimuli conduit à un accroissement de la préférence pour ces derniers en comparaison à de nouveaux stimuli (Effet de ... [more ▼]

Introduction Chez l’adulte, il est classiquement observé que l’exposition répétée à des stimuli conduit à un accroissement de la préférence pour ces derniers en comparaison à de nouveaux stimuli (Effet de simple exposition, ESE; [1]). En revanche, un grand nombre d’études [2] montrent chez l’enfant un effet inverse suggérant une préférence pour la nouveauté. Le but de cette étude est d’utiliser le paradigme de simple exposition chez des enfants de différentes tranches d’âge afin de déterminer la période durant laquelle la préférence pour la nouveauté s’inverse et est remplacée par la préférence pour la familiarité. Participant 16 enfants (de 5 à 6 ans et de 7 à 8 ans), 22 enfants (de 9 à 10 ans), et 17 enfants (de 11 à 12 ans) et 16 jeunes adultes (de 18 à 30 ans). Matériel Dans la phase d’encodage, les sujets évaluent l’orientation (droite/gauche) de 12 figures tridimensionnelles présentées 5 fois durant 2,5 secondes. Lors de la phase test, le sujet est soumis à deux tâches de jugement à choix forcés (préférence et reconnaissance) sur 12 paires d’objets tridimensionnels nouveaux-familiers. Les deux jugements se portent sur les mêmes items et leur ordre de passation est contrebalancés entre les sujets. Résultats et Discussion Un effet de préférence différent du hasard est observé chez les adultes (P<.05) dans le sens d’une préférence pour les stimuli préalablement exposés (ESE), mais non chez les enfants (Ps>.1). Pourtant, lorsque l’on examine les relations entre préférence et reconnaissance, on constate que les enfants de 5/6 ans ont tendance à préférer les nouvelles figures et non les figures préalablement exposées et reconnues (Chi-carré= -.15, p=.05). En revanche, cette tendance s’inverse au cours du développement, et ce, dès 11/12 ans où les enfants tendent à préférer les stimuli préalablement exposés et reconnus (Chi-carré=.17, p=.02). Ce choix de préférence pour les stimuli familiers persistent chez les jeunes adultes (p<.05). Notre étude montre que les plus jeunes enfants ont tendance à préférer les nouveaux stimuli alors que les jeunes adultes préfèrent les stimuli familiers quand on compare leurs choix de préférence à leur performance en reconnaissance. A partir de 11-12 ans, les enfants montrent le pattern inverse indiquant un « shifting » de la préférence pour la nouveauté vers la préférence pour la familiarité. Ces données montrent que les scores en reconnaissance influencent différemment la préférence en fonction de l’âge. [less ▲]

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See detailNeural and cognitive bases of upper limb apraxia in corticobasal degeneration
Peigneux, Philippe ULg; Salmon, Eric ULg; Garraux, Gaëtan ULg et al

in Neurology (2001), 57(7), 1259-1268

OBJECTIVE: To investigate the neural and cognitive bases of upper limb apraxia in corticobasal degeneration (CBD). METHODS: Eighteen patients with CBD underwent a cognitive neuropsychological assessment ... [more ▼]

OBJECTIVE: To investigate the neural and cognitive bases of upper limb apraxia in corticobasal degeneration (CBD). METHODS: Eighteen patients with CBD underwent a cognitive neuropsychological assessment of apraxia and resting [(18)F]-fluorodeoxyglucose PET scanning. Two complementary measures of apraxia were computed for each modality of gesture production. First, a performance score measured error frequency during gesture execution. Second, as a more stringent test of the integrity of the praxis system, the correction score measured the patient's ability to correct his or her errors on a second attempt. For each measure type, a cut-off score for the presence of apraxia was defined with regard to healthy controls. Using each cut-off score, the regional cerebral glucose metabolism of patients with CBD with apraxia (i.e., performing below cut-off score) was compared with that of patients with CBD without apraxia. RESULTS: Mean performance scores were below normal values in all modalities. Anterior cingulate hypometabolism predominated in patients with CBD who performed below the cut-off performance score. At variance, mean correction scores were below normal values for gesture imitation only. Hypometabolism in superior parietal lobule and supplementary motor area characterized patients with CBD who were unable to correct their errors at the same rate as control subjects did. CONCLUSIONS: Distinct neural networks underlie distinct aspects of the upper limb apraxic deficits in CBD. Extending previous findings of gesture production deficits in CBD, the use of complementary measures of apraxic behavior discloses a visuoimitative upper limb apraxia in CBD, underlain by a metabolic decrease in a parietofrontal neural network. [less ▲]

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