Guillaume T. Vallet

Act-In: An integrated view of memory mechanisms

The present article proposes a new memory model called Act-In (Activation-Integration). Act-In extends the multiple trace memory models by placing them within the situated cognition perspective. Act-In considers that the activation and integration mechanisms play a key role in memory processes. These mechanisms are involved in both the construction of memory traces and the emergence of knowledge. The model is based on four main assumptions: (1) Memory traces reflect all the components of past experiences and, in particular, their sensory properties, actions performed on the objects in the environment and the emotional states of individuals. Memory traces are therefore distributed across multiple neuronal systems which code the multiple components of the experiences. (2) Knowledge is emergent and is the product of the coupling of the present experience with past experiences. (3) The brain is a categorisation system which develops by accumulating experiences and which, by default, produces categorical knowledge. (4) The emergence of specific knowledge (memories or episodic knowledge) requires very simple mechanisms which occur during learning and/or during retrieval. These assumptions are defended and discussed in the light of the work reported in the literature.

The perceptual nature of audiovisual interactions for semantic knowledge in young and elderly adults.

Audiovisual interactions for familiar objects are at the core of perception. The nature of these interactions depends on the amodal--sensory abstracted--or modal--sensory-dependent--approach of knowledge. According to these approaches, the interactions should be respectively semantic and indirect or perceptual and direct. This issue is therefore a central question to memory and perception, yet the nature of these interactions remains unexplored in young and elderly adults. We used a cross-modal priming paradigm combined with a visual masking procedure of half of the auditory primes. The data demonstrated similar results in the young and elderly adult groups. The mask interfered with the priming effect in the semantically congruent condition, whereas the mask facilitated the processing of the visual target in the semantically incongruent condition. These findings indicate that audiovisual interactions are perceptual, and support the grounded cognition theory.

Normative Data for the Rappel libre/Rappel indicé à 16 items (16-item Free and Cued Recall) in the Elderly Quebec-French Population

Performance on verbal memory tests is generally associated with socio-demographic variables such as age, sex, and education level. Performance also varies between different cultural groups. The present study aimed to establish normative data for the Rappel libre/Rappel indicé à 16 items (16-item Free and Cued Recall; RL/RI-16), a French adaptation of the Free and Cued Selective Reminding Test (Buschke, 1984; Grober, Buschke, Crystal, Bang, & Dresner, 1988). The sample consisted of 566 healthy French-speaking older adults (50–88 years old) from the province of Quebec, Canada. Normative data for the RL/RI-16 were derived from 80% of the total sample (normative sample) and cross-validated using the remaining participants (20%; validation sample). The effects of participants’ age, sex, and education level were assessed on different indices of memory performance. Results indicated that these variables were independently associated with performance. Normative data are presented as regression equations with standard deviations (symmetric distributions) and percentiles (asymmetric distributions).

The disconnection syndrome in the Alzheimer's disease: The cross-modal priming example

Implicit memory is generally supposed to be preserved in Alzheimers disease (AD). Yet, some implicit priming effects are impaired and others are not. The preserved/impaired priming effects are often interpreted according to the perceptual/conceptual or identification/production distinctions. Perceptual-identification priming paradigms shall be preserved and conceptual-production priming paradigms impaired. A third interpretation is yet possible based on the disconnection syndrome hypothesis which states that patients with AD should fail tasks requiring relatively complex brain communications. In this case, patients with AD should not demonstrated a significant perceptual priming effect in an identification task if this one involved complex brain communications. The present study tests this latter hypothesis with two cross-modal priming experiments using a categorization task. A visual meaningless mask presented with half of the auditory primes tested the nature of the cross-modal priming effect. The control group exhibited significant priming effects for unmasked primes. The interference effect of the mask demonstrated that the priming effect was perceptually driven. Patients with AD did not present any priming effect nor mask interference. The present findings therefore showed that perceptual priming using an identification task could be impaired in AD supporting the disconnection syndrome hypothesis.

When seeing a dog activates the bark: multisensory generalization and distinctiveness effects.

The goal of the present study was to find evidence for a multisensory generalization effect (i.e., generalization from one sensory modality to another sensory modality). The authors used an innovative paradigm (adapted from Brunel, Labeye, Lesourd, & Versace, 2009) involving three phases: a learning phase, consisting in the categorization of geometrical shapes, which manipulated the rules of association between shapes and a sound feature, and two test phases. The first of these was designed to examine the priming effect of the geometrical shapes seen in the learning phase on target tones (i.e., priming task), while the aim of the second was to examine the probability of recognizing the previously learned geometrical shapes (i.e., recognition task). When a shape category was mostly presented with a sound during learning, all of the primes (including those not presented with a sound in the learning phase) enhanced target processing compared to a condition in which the primes were mostly seen without a sound during learning. A pattern of results consistent with this initial finding was also observed during recognition, with the participants being unable to pick out the shape seen without a sound during the learning phase. Experiment 1 revealed a multisensory generalization effect across the members of a category when the objects belonging to the same category share the same value on the shape dimension. However, a distinctiveness effect was observed when a salient feature distinguished the objects within the category (Experiment 2a vs. 2b).

Normative data for phonemic and semantic verbal fluency test in the adult French–Quebec population and validation study in Alzheimer’s disease and depression

Abstract Objective: Verbal fluency tasks are principally used to assess lexical access and have shown usefulness for differential diagnosis. The purpose of Study 1 was to provide normative data in the adult French–Quebec population (Canada) for semantic verbal fluency (animals), for two sets of phonemic verbal fluency (TNP and PFL), and for letter P alone (60 seconds per category/letter). The objectives of Study 2 were to establish the diagnostic and predictive validity of the present tasks and normative data in Alzheimer’s disease (AD) and major depressive episode (MDE). Method: The normative sample consisted of 932 participants aged 19–91 years. Based on multiple linear regressions, equations to calculate Z-scores were provided. To assess validity, performance of 62 healthy participants was compared to 62 participants with AD and 41 with MDE aged over 50. Results: Age and education, but not gender, predicted performance on each verbal fluency task. Healthy adults aged 50 and younger had a better performance on semantic than phonemic verbal fluency. In comparison to MDE, AD participants had lower performance on animals and TNP, but not on letter P. Ninety percent of people with a Z-score ≤ −1.50 on semantic verbal fluency had AD and the global accuracy was 76.6%. Test–retest reliability over one year was high for both animals (r = .711) and TNP (r = .790) in healthy older participants, but dropped for animals in people with AD (r = .493). Conclusions: These data will strengthen accurate detection of verbal fluency deficits in French–Quebec adults.

Getting a tool gives wings: overestimation of tool-related benefits in a motor imagery task and a decision task

Two experiments examine whether people overestimate the benefits provided by tool use in motor tasks. Participants had to move different quantities of objects by hand (two at a time) or with a tool (four at a time). The tool was not within reach so participants had to get it before moving the objects. In Experiment 1, the task was performed in a real and an imagined situation. In Experiment 2, participants had to decide for each quantity, whether they preferred moving the objects by hand or with the tool. Our findings indicated that people perceive tool actions as less costly in terms of movement time than they actually are (Experiment 1) and decide to use a tool even when it objectively provides less time-based benefits than using the hands (Experiment 2). Taken together, the data suggest that people overestimate the benefits provided by tool use.

Sensory-Dependent Knowledge in Young and Elderly Adults: Argument from the Cross-Modal Priming Effect

The nature of knowledge, i.e. sensory-dependent or abstract, is controversial. Growing evidence supports the existence of sensory-dependent knowledge in young individuals, but this question remains unexplored in elderly individuals. Thus the first objective of this study was to assess sensory-dependent knowledge in normal aging using a cross-modal priming paradigm. The cross-modal priming is a way to verify the nature of knowledge. However, contradictory results are reported about the existence of a cross-modal priming effect in normal aging. One possible explanation for the controversial findings is the priming task difficulty that would require too much executive resources in elderly participants and would prevent them to obtain a priming effect. Therefore, the second objective was to assess the executive involvement in the priming task. The method was based on a cross-modal priming paradigm with familiar bimodal items. First, all the sound primes were presented. For half of them, a visual abstract mask was presented simultaneously. Then, all the visual targets were processed. A battery of neuropsychological tests was administered to assess the involvement of executive functions in the priming paradigm. The results demonstrated a priming effect in the young and elderly participants, but only for the primes presented without the visual mask. The mask interference demonstrated the perceptual nature of the priming effect which supports the sensory-dependent theory of knowledge. The executive functions were correlated with the priming task only in the elderly participants. These results therefore support the task difficulty hypothesis.

Embodied cognition of aging.

Embodiment is revolutionizing the way we consider cognition by incorporating the influence of our body and of the current context within cognitive processing. A growing number of studies which support this view of cognition in young adults stands in stark contrast with the lack of evidence in favor of this view in the field of normal aging and neurocognitive disorders. Nonetheless, the validation of embodiment assumptions on the whole spectrum of cognition is a mandatory step in order for embodied cognition theories to become theories of human cognition. More pragmatically, aging populations represent a perfect target to test embodied cognition theories due to concomitant changes in sensory, motor and cognitive functioning that occur in aging, since these theories predict direct interactions between them. Finally, the new perspectives on cognition provided by these theories might also open new research avenues and new clinical applications in the field of aging. The present article aims at showing the value and interest to explore embodiment in normal and abnormal aging as well as introducing some potential theoretical and clinical applications.

A Qualitative Impairment in Face Perception in Alzheimer’s Disease: Evidence from a Reduced Face Inversion Effect

Prevalent face recognition difficulties in Alzheimers disease (AD) have typically been attributed to the underlying episodic and semantic memory impairment. The aim of the current study was to determine if AD patients are also impaired at the perceptual level for faces, more specifically at extracting a visual representation of an individual face. To address this question, we investigated the matching of simultaneously presented individual faces and of other nonface familiar shapes (cars), at both upright and inverted orientation, in a group of mild AD patients and in a group of healthy older controls matched for age and education. AD patients showed a reduced inversion effect (i.e., larger performance for upright than inverted stimuli) for faces, but not for cars, both in terms of error rates and response times. While healthy participants showed a much larger decrease in performance for faces than for cars with inversion, the inversion effect did not differ significantly for faces and cars in AD. This abnormal inversion effect for faces was observed in a large subset of individual patients with AD. These results suggest that AD patients have deficits in higher-level visual processes, more specifically at perceiving individual faces, a function that relies on holistic representations specific to upright face stimuli. These deficits, combined with their memory impairment, may contribute to the difficulties in recognizing familiar people that are often reported in patients suffering from the disease and by their caregivers.