Under the Interface Hypothesis, bilinguals’ non-nativelike referential choices may be influenced by the increased cognitive demands and less automatic processing of bilingual production. We test this hypothesis by comparing pronoun production in the L2 of nonbalanced Spanish–English bilinguals to that of English monolinguals in two cognitively challenging contexts. In Experiment 1, both monolinguals and bilinguals produced more explicit references when part of the information was unavailable to their addressee (privileged ground) than when all information was shared (common ground), evidencing audience design. In Experiment 2, verbal load led to more unspecified references than visual load and no load (an effect statistically indistinguishable between groups but numerically driven by the monolingual group). While bilinguals produced overall more pronouns than monolinguals in both experiments, there was no indication that bilinguals’ referential choice was disproportionally affected by increased cognitive demand, contrary to the predictions of the Interface Hypothesis.

There is a complex interplay between mobility and cognition in older adults. We have previously shown that a high-DHA multi-nutrient supplement improves habitual walking speed, verbal memory and psychomotor response latency in older women. Exercise also improves mobility and cognition in older adults, and n-3 fatty acids and exercise share a range of overlapping biological effects. This study examined for the first time the effects of the high-DHA multi-nutrient supplement and aerobic exercise on mobility and cognition in older women. Women (mean age 67 (sd 8) years) were assigned to the following groups: multi-nutrient (1 g DHA, 160 mg EPA, 240 mg Ginkgo biloba, 60 mg phosphatidylserine, 20 mg d-α tocopherol, 1 mg folic acid and 20 µg vitamin B12 per d, n 13), multi-nutrient and exercise (spin class twice per week, n 14), exercise and placebo (n 12) or placebo (n 12). The multi-nutrient was given for 24 weeks and exercise for 12 weeks. No treatment effects were observed for the primary outcome, habitual walking speed. Improvements in verbal memory and executive function were seen for all treatments groups v. placebo (all, P < 0·05). Significant improvements in self-reported emotional well-being were seen with multi-nutrient and exercise groups v. placebo (P = 0·03). The results suggest that the high-DHA multi-nutrient supplement produces similar improvements in cognitive function to aerobic exercise, offering the intriguing prospect that supplementation may be able to mitigate some of the effects of low physical activity on cognitive function in the elderly.

In this study we examined how the introduction of a parallel finger-tapping task influences second language (L2) speech encoding mechanisms and monitoring processes, and how the level of proficiency impacts the efficiency and accuracy of L2 performance under single and dual task conditions. The results indicate that imposing dual task demands had a negative effect on the accuracy of lexical selection and the efficiency of error-correction processes. We argue that this can be explained with reference to attentional bottleneck effects on lexical selection processes and on monitoring. The findings also reveal that the level of L2 competence influenced both the speed and the accuracy of speech encoding processes and the efficiency of monitoring.

Previous dual task studies have demonstrated that patients with sporadic Alzheimer's disease (AD) are impaired in their ability to perform two tasks simultaneously compared with healthy controls, despite being able to successfully perform the tasks alone relatively well. Yet, it remains unclear what the earliest clinical manifestation of this dual task coordination deficit is. This study examined dual task abilities in individuals who are at risk of early-onset familial AD due to an E280A presenilin-1 mutation. Thirty-nine carriers of the gene mutation who did not meet the criteria for AD and 29 non-carrier healthy controls were asked to perform digit recall accompanied by a secondary tracking task. Individuals who were carriers of the genetic mutation demonstrated significantly higher dual task costs than healthy non-carriers. Dual task performance was found to be more sensitive to this very early stage of FAD than episodic memory measures. The findings support the notion that a deficit in the coordination mechanism of the central executive may be a pre-clinical marker for the early detection of AD due to the E280A presenilin-1 gene mutation. (JINS, 2012, 18, 234–241)

The ability to switch rapidly and fluidly between tasks is an important component of many everyday activities. In this study, we used a predictable, externally cued task-switching paradigm to investigate executive control processes in individuals with mild cognitive impairment (MCI). Participants were 26 individuals with amnestic MCI and 26 healthy older adult (OA) controls. In the mixed-task trials, participants switched between classifying whether a digit was odd/even or a letter was a consonant/vowel on every fourth trial. In the single-task trials, participants completed only the digit task or letter task throughout the entire block. Task switching costs were decomposed into nonswitch costs, which reflect the dual nature of the task, and switch costs, which reflect set-shifting abilities. The results revealed that the MCI group was not affected more than the healthy OAs by the requirement of keeping two tasks sets active in working memory (nonswitch costs). In contrast, the cost of switching between the two tasks was significantly greater for the MCI group compared with the OA controls (switch costs). Future research is needed to better understand the nature and implications for daily living of the greater switch costs found for individuals with MCI. (JINS, 2009, 15, 103–111.)

Background: Apathy and depression may be strongly associated with executive dysfunction in Alzheimer's disease (AD). The Frontal Assessment Battery (FAB) is an instrument for assessing executive function. The dual task paradigm is also useful for assessing divided attention. However, the association between apathy/depression and these tasks is unclear.

Methods: Both the FAB and the dual task were used to evaluate AD patients. A two-way analysis of variance was then conducted between the FAB and dual task results and the absence versus the presence of depression or the absence versus the presence of apathy.

Results: Of 88 patients with AD, 26 had both apathy and depression, 26 had depression only, 18 had apathy only, and 18 had neither. Total FAB scores and dual task scores differed significantly between the AD patients with depression and those without depression; the scores were also different between those with apathy and those without apathy. Also, a significant interaction between depression and apathy was noted for the total FAB and dual task scores.

Conclusions: The deficits in the total FAB and dual task scores were larger in AD patients with both apathy and depression compared with patients with either apathy or depression alone. AD patients with both symptoms may have greater deficits in frontal lobe function relative to AD patients with either apathy or depression alone.

The effect of attention allocation on smooth pursuit eye movements (SPEM) was investigated. Eye movements were electrooculographically recorded in 27 healthy subjects who tracked a visual target that moved horizontally with constant or unpredictably varying velocity. In some trials, subjects performed additional auditory discrimination tasks varying in difficulty. Pursuit error decreased when attention was divided between both tasks. The pattern of results is incompatible with the assumption made in previous research that attention enhancement improves SPEM accuracy. Rather, ocular smooth pursuit appears to be executed in the automatic mode, although intentional and selective processes must contribute. Moreover, controlled attention directed to the tracking task interfered with smooth pursuit. A reinterpretation of earlier studies in which visual monitoring tasks were used to improve eye tracking is needed.