Sophie Germain

Inhibitory control of memory in normal ageing: Dissociation between impaired intentional and preserved unintentional processes

The aim of this study was to compare the performance of elderly and young participants on a series of memory tasks involving either intentional or unintentional inhibitory control of memory content. Intentional inhibition processes in working and episodic memory were explored with directed forgetting tasks and in semantic memory with the Hayling task. Unintentional inhibitory processes in working memory, long-term memory, and semantic memory were explored with an interference resolution task, the retrieval practice paradigm, and the flanker task, respectively. The results indicate that elderly participants’ performance on the two directed forgetting tasks and the Hayling task is lower than that of young ones, and that this impairment is not related to their initial memory capacity. This suggests that there is a specific dysfunction affecting intentional inhibitory control of memory contents in normal ageing.

Dissociation of perceptual and motor inhibitory processes in young and elderly participants using the Simon task.

Deficits in inhibitory abilities are frequently observed in normal aging. However, few studies have explored the generality of these deficits in a single group of participants. Here, we used an adaptation of the Simon task to differentially assess perceptual and motor inhibition using the same stimuli and task design and to determine whether these processes use separate or shared cognitive resources. We were interested in determining whether (1) normal aging is associated with the use of separate (as previously evidenced in young participants) or similar cognitive resources to perform perceptual and motor inhibition tasks; (2) older participants present a specific impairment in one of these two processes. Analyses of reaction times indicated that motor and perceptual inhibitory processes share some cognitive resources and both are impaired in normal aging. These results can be interpreted by considering that a dedifferentiation process is responsible for the inhibitory deficits presented by older participants.

Patients with Alzheimer's disease use metamemory to attenuate the Jacoby-Whitehouse illusion.

Patients with Alzheimers disease (AD) relying predominantly on familiarity for recognition, research has suggested that they may be particularly susceptible to memory illusions driven by conceptual fluency. Using the Jacoby and Whitehouse [Jacoby, L.L., & Whitehouse, K. (1989). An illusion of memory: False recognition influenced by unconscious perception. Journal of Experimental Psychology: General, 118, 126-135] illusion paradigm, we extended these findings and found that AD patients were also sensitive to perceptually driven false recognition. However, AD patients were equally able to disregard perceptual fluency when there was a shift in the sensory modality of the study and test stages. Overall, these findings support the notion that patients with AD can be susceptible to fluency-based memory illusions but these patients can strategically control the fluency attribution following their metamemory expectation in exactly the same way as elderly adults and young adults.

Exploration of perceptual and motor inhibition in children with traumatic brain injury

Perceptual and motor inhibition were examined using conflict resolution tasks for 12 children with traumatic brain injury and 24 matched controls. Direct comparisons of inhibition performances between the two groups showed a specific and disproportionate impairment of motor inhibition (compared with perceptual inhibition) for the children with traumatic brain injury, which suggests that inhibition processes might be differentially impaired in children after traumatic brain injury.