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Biomedical subjects

K Z Li

Publications and source records attributed to K Z Li.

6 recordsLinked to original sources
PubMed2001

Walking while memorizing: age-related differences in compensatory behavior.

This study investigated predictions of the life-span theory of selection, optimization, and compensation, focusing on different patterns of task priority during dual-task performance in younger and older adults. Cognitive (memorizing) and sensorimotor (walking a narrow track) performance were measured singly, concurrently, and when task difficulty was manipulated. Use of external aids was measured to provide another index of task priority. Before dual-task testing, participants received extensive training with each component task and external aid. Age differences in dual-task costs were greater in memory performance than walking, suggesting that older adults prioritized walking over memory. Further, when given a choice of compensatory external aids to use, older adults optimized walking, whereas younger adults optimized memory performance. The results have broad implications for systemic theories of cognitive and sensorimotor aging, and the costs and benefits of assistive devices and environmental support for older populations.

Adult↗
PubMed2000

The role of inhibition in the regulation of sequential action.

We investigated the regulation of sequential action using a new paradigm. Participants learned a sequence of seven stimulus categories and then monitored for them during successive displays. All displays were instances of these categories, presented in pseudorandom order. On each trial, participants monitored for an instance of Category 1, pressed a key on a computer keyboard, then monitored for an instance of Category 2, pressed a key on the keyboard, and so on for all seven categories. Thus, a perfect trial contained exactly seven responses. Intrusion errors were classified as a function of ordinal distance from the current serial position (n). Fewer intrusion errors were made at near serial positions than at far ones, suggesting a gradient of lateral inhibition. In addition, more intrusions were made on n + 1 categories than n - 1 categories, suggesting greater availability of intended than completed goals. In accord with current models of sequential action, the results indicate lateral and self-inhibition as important mechanisms in regulation of sequential action.

Adult↗
PubMed1998

Distractibility, circadian arousal, and aging: a boundary condition?

Two studies assessed the presence of a synchrony effect between peak circadian arousal and time of testing for both older and younger adults. Participants performed a reading aloud task that included distracting words that were either present or absent and, if present, were either thematically related or unrelated to the target text. As well, the distracting material was presented in either spatially predictable or unpredictable locations. In each experiment, older and younger adults were tested at optimal versus nonoptimal times. Both experiments showed age differences in susceptibility to distraction, replicating earlier findings (e.g., M. C. Carlson, L. Hasher, R. T. Zacks, & S. L. Connelly, 1995). Neither showed differences due to time of testing, suggesting a boundary condition for cognitive disruptions associated with circadian arousal patterns.

Adolescent↗
PubMed1994

Age differences in the interpretation of misaligned "You-Are-Here" maps.

"You-Are-Here" (YAH) maps, common in shopping malls and office buildings, are difficult to interpret if not aligned with their surroundings. Younger and older adults made direction decisions after viewing simple maps representing a university campus. YAH arrows were either upright and coordinated with viewer position or contra-aligned 180 degrees. Contra-alignment caused subjects, especially older adults, to take more time and be less accurate. Women were slower on contra-aligned maps, although no less accurate, than men. The need to mentally realign such incongruent maps in order to make correct direction decisions can cause serious difficulty for older adults trying to navigate through large, complex environments.

Adult↗