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C R Swain

Publications and source records attributed to C R Swain.

5 recordsLinked to original sources
PubMed1999

Electrophysiological, behavioral, and subjective indexes of workload when performing multiple tasks: manipulations of task difficulty and training.

This study examined whether alpha event-related desynchronization (ERD) and theta event-related synchronization (ERS) could successfully measure changes in cognitive workload and training while an operator was engaged in a continuous, interactive, control task(s). Alpha 1 (8-10 Hz) ERD, alpha 2 (10-12 Hz) ERD, and theta (3-7 Hz) ERS were determined for a communications event that occurred during multiple task workload conditions or as a single task. Other measures (alpha and theta EEG power, heart rate, respiration, eye blinks, behavioral performance, and subjective workload ratings) were also evaluated. Results showed that alpha 2 EEG, heart rate, behavioral, and subjective measures were sensitive to changes in workload in the multiple tasks. In addition, eye blink rate and behavioral measures were sensitive to training. Alpha ERD and theta ERS were not sensitive to workload and training in our interactive, multiple task environment. However, they were effective indexes of cognitive/behavioral demands within an interactive single task.

Adult↗
PubMed1999

EEG power changes during a multiple level memory retention task.

EEG changes related to the amount of information held in memory during a 4-s retention period were studied. The predictability of the amount of information held in memory was varied. In the weighted condition, 60% of the trials contained only one item and the remaining 40% of the trials were evenly distributed between trials containing 3, 5, 7, or 8 items. In the random condition, the levels were equally represented and randomly presented. In the blocked condition the levels were equally represented but presented in five blocks containing only items from one of the levels. Initial widespread decreases in alpha band power were followed by increased activity in all three conditions. The more difficult of the five levels produced decreased alpha activity in more localized posterior left hemisphere sites. This suggests two alpha mechanisms, one associated with task engagement and the other related to the cognitive demands regardless of the presentation context. Theta band power increased over frontal scalp, and to a lesser extent over left parietal and temporal areas and bilateral occipital sites, during only the weighted condition. These changes were uniform over the entire retention period. Beta 2 activity was also influenced by the task difficulty and the time course of the retention period in the two conditions. Beta 2 activity resembled both alpha and theta in that in levels 1, 2 and 3 it acted like alpha with increasing power over time at numerous widespread sites while the higher difficulty levels showed higher power at the beginning of the retention period and then decreased.

Adolescent↗
PubMed1998

ERP components elicited in response to warning stimuli: the influence of task difficulty.

A series of experiments were conducted to systematically evaluate the relative contributions of task difficulty and stimulus probability to P300 amplitudes. Scalp event-related potentials (ERPs) were recorded and the topographic distributions were evaluated during a multi-level cognitive task with an antecedent warning. In three separate studies, task difficulty (five levels), probability or expectedness (10-60%), and randomness (random or blocked presentation) were manipulated. Response accuracy, subjective ratings, and reference-free averages of the P300 components elicited by the warning stimuli were evaluated. Statistical analysis indicated that significantly larger P300s were associated with the more difficult task warnings except when memory tasks were presented in a blocked design, suggesting that neither task difficulty nor probability alone can account for variations in the P300 in a multi-level task scenario. Results are discussed with regard to adaptation-level theory.

Adolescent↗
PubMed1996

Psychophysiological responses to changes in workload during simulated air traffic control.

In this investigation, eight Air Force air traffic controllers (ATCs) performed three scenarios on TRACON (Terminal Radar Approach Control), a computer-based air traffic control (ATC) simulation. Two scenarios were used each with three levels of difficulty. One scenario varied traffic volume by manipulating the number of aircraft to be handled and the second scenario varied traffic complexity by manipulating arriving to departing flight ratios, pilot skill and mixture of aircraft types. A third scenario, overload, required subjects to handle a larger number of aircraft in a limited amount of time. The effects of the manipulations on controller workload were assessed using performance, subjective (TLX), and physiological (EEG, eye blink, heart rate, respiration, saccade) measures. Significant main effects of difficulty level were found for TRACON performance, TLX, eye blink, respiration and EEG measures. Only the EEG was associated with main effects for the type of traffic. The results provide support for the differential sensitivity of a variety of workload measures in complex tasks, underscore the importance of traffic complexity in ATC workload, and support the utility of TRACON as a tool for studies of ATC workload.

Adult↗