Differential cerebral involvement in the cognitive functioning of bilinguals

The cognitive processing strategies of two groups of French-English bilinguals were studied by means of an auditory Stroop test designed to evaluate cerebral hemispheric involvement. An “early bilingual” group were bilingual before the age of 5, and a “late bilingual” group were bilingual after the age of 10. Stimuli were words uttered in pitches that were related to word meanings either congruently (as in the word “high” uttered in a high pitch) or incongruently (the word “haute” uttered in a low pitch). In one condition, subjects were to differentiate low from high pitches, disregarding meaning, while in a second condition, they were to disregard pitch and respond to word meanings. Measures of field independence were also taken. Results of data analyses suggest that male early bilinguals—the most field independent subgroup—process meaning efficiently in both cerebral hemispheres, but process pitch better in the right hemisphere. However, male late bilinguals and female bilinguals, both early and late, process meaning more rapidly in the right cerebral hemisphere and pitch equally rapidly in both hemispheres. The findings are interpreted as reflecting hemisphere-based strategy and sex differences in information-processing by the two bilingual groups.     

Examining age differences in performance of a complex information search and retrieval task.

This study examined age differences in performance of a complex information search and retrieval task by using a simulated real-world task typical of those performed by customer service representatives. The study also investigated the influence of task experience and the relationships between cognitive abilities and task performance. One hundred seventeen participants from 3 age groups, younger (20-39 years). middle-aged (40-59 years), and older (60-75 years), performed the task for 3 days. Significant age differences were found for all measures of task performance with the exception of navigational efficiency and number of problems correctly navigated per attempt. There were also effects of task experience. The findings also indicated significant direct and indirect relations between component cognitive abilities and task performance.     

Concurrent-schedule performance in dairy cows: persistent undermatching.

Performance of dairy cows responding under concurrent variable-interval variable-interval schedules of food delivery was examined, with results analyzed in terms of the generalized matching equation. In Experiment 1, bias measures indicated that crushed barley was preferred over meatmeal when these foods were available under the alternative schedules. For whole-session data, substantial undermatching of response and time-allocation ratios to obtained reinforcement ratios was evident. Postreinforcement pause time ratios approximately matched obtained reinforcement rates. Subtracting these times from total time-allocation values yielded net time-allocation ratios that undermatched obtained reinforcement ratios to a greater degree than did whole-session time-allocation ratios. In Experiment 2, substantial undermatching was evident when the same foods (hay for 2 cows, crushed barley for 2 others) were available under the alternative schedules. Food-related activities and other defined behavior not related to food were quantified by direct observation, and were found to occupy a substantial proportion (roughly 40% to 80%) of experimental sessions. Subtracting the time spent in these activities from the time allocated to each component schedule did not reduce the degree of undermatching obtained. Across all conditions in both experiments, slopes of regression lines relating behavioral outputs to environmental inputs characteristically were below 0.6, which agrees with prior findings and suggests that, contrary to suggestions in the literature, undermatching in dairy cows is not the result of using different foods under alternative schedules or differential pausing under those schedules.