Mental and psychological conditions, medical comorbidity and functional limitation: differential associations in older adults with cognitive impairment, depressive symptoms and co-existence of both.

OBJECTIVE: Cognitive impairment and depressive symptoms are common among the geriatric population but the co-occurrence of both is rarely studied. The purpose of this study was to identify and compare the factors associated with three groups of elderly people: those assessed with cognitive impairment alone (COG), depressive symptoms alone (DEP) or co-existence of both (COG-DEP). METHODS: The cross-sectional study included 600 community-dwellers ages 65 and older. All participants underwent a comprehensive evaluation. Global cognition was measured by the Mini-Mental State Examination (MMSE) and depressive symptoms were defined by the Geriatric Depression Scale (GDS). Specific chronic illnesses relevant to the Charlson comorbidity index (CCI) were self-reported. Functional status was evaluated by the Katz' basic (ADL) and Lawton's instrumental (IADL) activities of daily living scales. RESULTS: COG-DEP was explained by IADL dependence (OR: 11.9, 95% CI: 4.59-30.78), ADL dependence (OR: 11.5, 95% CI: 5.59-23.69), cerebrovascular disease (OR: 3.6, 95% CI: 1.48-8.68), congestive heart failure (OR: 3.4, 95% CI: 1.77-6.59) and diabetes (OR: 2.6, 95% CI: 1.30-5.18), but it was best predicted by functional limitations in the adjusted model. Being functionally dependent and medically ill with shorter life expectancy was shown to significantly increase the odds of being DEP. Functional limitation in IADL was without distinction associated to COG, DEP and COG-DEP. CONCLUSION: The present results on COG, DEP and COG-DEP show the particular relevance of certain medical comorbidities and functional limitations to those three distinct groups of elderly people.

Implicit sequence learning and contextual cueing do not compete for central cognitive resources.

Sequence learning and contextual cueing explore different forms of implicit learning, arising from practice with a structured serial task, or with a search task with informative contexts. We assess whether these two learning effects arise simultaneously when both remain implicit. Experiments 1 and 2 confirm that a cueing effect can be observed under a continuous setting and that there is no interference between contextual cueing and sequence learning. Experiments 3a and 3b tested whether an interference arises specifically when the sequence becomes explicit. Results show that the expression of contextual cueing disappeared in those conditions but that context information is still acquired, and it affects performance when the sequence is removed. The results are discussed in relation to the current debates about the automaticity of implicit learning, and about the role of attention in the acquisition and expression of contextual cueing.

Implicit sequence learning in a search task.

This study investigated the effects of selection demands on implicit sequence learning. Participants in a search condition looked for a target among seven distractors and responded on the target identity. The responses followed a deterministic sequence, and sequence learning was compared to that found in two control conditions in which the targets were presented alone, either at a central location or over a series of unpredictable locations. Sequence learning was obtained in all conditions, and it was equivalent for the two variable location conditions, regardless of the perceptual demands. Larger effects of learning were observed in the central location, both on the indirect measures and on the measures taken from a cued-generation task. The expression of learning decreased selectively in this condition when the sequence validity was reduced over a test block. These results are consistent with the claims that implicit and explicit learning are mixed in this central condition and that implicit learning is not affected by selection difficulty.

Visual learning in multiple-object tracking.

BACKGROUND: Tracking moving objects in space is important for the maintenance of spatiotemporal continuity in everyday visual tasks. In the laboratory, this ability is tested using the Multiple Object Tracking (MOT) task, where participants track a subset of moving objects with attention over an extended period of time. The ability to track multiple objects with attention is severely limited. Recent research has shown that this ability may improve with extensive practice (e.g., from action videogame playing). However, whether tracking also improves in a short training session with repeated trajectories has rarely been investigated. In this study we examine the role of visual learning in multiple-object tracking and characterize how varieties of attention interact with visual learning. METHODOLOGY/PRINCIPAL FINDINGS: Participants first conducted attentive tracking on trials with repeated motion trajectories for a short session. In a transfer phase we used the same motion trajectories but changed the role of tracking targets and nontargets. We found that compared with novel trials, tracking was enhanced only when the target subset was the same as that used during training. Learning did not transfer when the previously trained targets and nontargets switched roles or mixed up. However, learning was not specific to the trained temporal order as it transferred to trials where the motion was played backwards. CONCLUSIONS/SIGNIFICANCE: These findings suggest that a demanding task of tracking multiple objects can benefit from learning of repeated motion trajectories. Such learning potentially facilitates tracking in natural vision, although learning is largely confined to the trajectories of attended objects. Furthermore, we showed that learning in attentive tracking relies on relational coding of all target trajectories. Surprisingly, learning was not specific to the trained temporal context, probably because observers have learned motion paths of each trajectory independently of the exact temporal order.

Sequence learning under dual-task conditions: alternatives to a resource-based account.

In two experiments with the serial reaction-time task, participants were presented with deterministic or probabilistic sequences under single- or dual-task conditions. Experiment 1 showed that learning of a probabilistic structure was not impaired over a first session by performing a counting task, but that such an interference arose over a second session, when the knowledge was tested under single-task conditions. In contrast, the effects of the secondary task arose earlier for participants exposed to deterministic sequences. This difference between deterministic and probabilistic sequences disappeared in Experiment 2, where the counting task was performed on tones associated to the locations. Comparisons between sessions indicated that the secondary task affected not only the expression but also the acquisition of sequence learning, and that greater interference was observed in those conditions that yielded more explicit knowledge. These results suggest that the effects of a dual task on the measures of implicit sequence learning may be partly due to the intrusion of explicit knowledge and partly due to the disruption of the sequence produced by the inclusion of random events.