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C D Wickens

Publications and source records attributed to C D Wickens.

18 recordsLinked to original sources
PubMed1992

Tongue oximetry in children with extensive thermal injury: comparison with peripheral oximetry.

We undertook a prospective study of standard peripheral pulse oximetry versus a modified pulse oximeter probe applied to the tongue in order to determine the efficacy of this alternative monitoring site in children with thermal injuries. Ten patients with a mean age (+/- SD) of 7.5 +/- 4.5 yr were studied on 15 occasions. The mean weight (+/- SD) was 31.4 +/- 13.7 kg and percent surface area burn (+/- SD) was 56 +/- 21%. A total of 1,992 min of anaesthesia time was monitored. Both sites functioned simultaneously 47% of the time; the lingual but not the peripheral site functioned 28% of the time and only the peripheral site and not the lingual functioned 22% of the time. Neither site functioned 3% of the time. The tongue oximeter provided 563 min more monitoring time than the peripheral sites. The tongue oximeter also functioned in children with peripheral vasoconstriction when the peripheral sensor failed and was less susceptible to electrocautery interference. The tongue oximeter is a reasonable adjunct but not a substitute for peripheral oximetry since its application is limited to paralyzed, intubated patients.

Adolescent↗
PubMed1992

Visual scanning with or without spatial uncertainty and divided and selective attention.

An experiment was conducted to address the relation between theories of selective attention and theories of divided attention by examining the pattern of task interference between visual scanning as a sequential and selective attention process and other concurrent spatial or verbal processing tasks. A distinction is proposed between visual scanning with or without spatial uncertainty regarding their possible differential effects on interference with other concurrent processes. The experiment required the subjects to perform a primary tracking task, which was concurrently performed with a secondary spatial or verbal decision task. The relevant information that was needed to perform the decision tasks was displayed with or without spatial uncertainty. The results provide evidence that visual scanning as a spatial exploratory activity produces greater task interference with concurrent spatial tasks than with verbal tasks. Furthermore, spatial uncertainty in scanning is identified to be the crucial factor in producing this differential effect.

Adult↗
PubMed1992

Distance and organization in multifunction displays.

One approach to organizing information in a multifunction display (MFD) is to place related screens of information closer to each other. This study identified three metrics that could be used to operationalize the concept of distance in an MFD. The proposed distance metrics-navigational (the number of choice points lying between two screens), organizational (the hierarchical structure of the data base), and the cognitive (the user's perception of relationships among screens)-were empirically examined by using a simulated, hierarchically arranged, menu-driven MFD in an aviation context. Subjects engaged in two tasks that required them to access different target screens from various starting screens in a 290-screen MFD. The tasks differed in the navigational mechanisms subjects were allowed to use to navigate around the MFD and the relationships between the starting and target screens. The results suggest that the three distance metrics are meaningful within the context of a multifunction display.

Adult↗
PubMed1991

Integrated displays and the perception of graphical data.

Three experiments are presented that apply a principle of compatibility of proximity to the perception of graphical data. These experiments demonstrate that the merits and costs of integral displays relative to separable displays depend in part on the task being performed. Experiment 1 employs a data extrapolation task in which information must be integrated. Here an integral display is found to be superior to a separable display. Experiment 2 employed a data perception task that requires focused attention. This reveals superior performance with separable displays. Experiment 3 employed a multiple cue judgement task in which information integration could be manipulated. Data from Experiment 3 were analysed using the Brunswick lens procedures, and indicated that knowledge of the task structure was influenced by the display type. When selective attention was required, knowledge of the task was superior with separable displays. The results are discussed with reference to the principle of compatibility of proximity, and the implications of the results for the perception of scientific data are noted.

Adult↗
PubMed1990

Event-related brain potentials as indices of information extraction and response priming.

Measures of overt response and of the event-related brain potential (ERP) were used to investigate the processing of a priming stimulus varying in its information content. Subjects were shown sequences of 2 letters that served as a priming and an imperative stimulus. In 3 randomly interspersed conditions the imperative stimulus had a 0.80, 0.50, or 0.20 probability of physically matching the priming letter. The different probability conditions were signaled by the position of a dot flanking the priming letter. Reaction time and accuracy data indicated that the subjects primed their responses as a function of the information conveyed by the priming stimulus. The amplitude and latency of the P300 to the priming stimulus were sensitive to the amount of information conveyed by the priming stimulus and the duration of the processing required. The readiness potential in the foreperiod was lateralized as a function of the priming stimulus. Furthermore, the larger the amplitude of the P300 to the priming stimulus, the larger the lateralization of the readiness potential, indicating that information extraction, indexed by the P300, was related to response priming, indexed by the readiness potential. The results indicate that ERP measures make manifest covert aspects of the priming process occurring in the foreperiod.

Adolescent↗
PubMed1990

Proximity compatibility and information display: effects of color, space, and object display on information integration.

We report two experiments in which different features of the display of multiple channels of information are varied in their proximity to one another. The display presents three indicators of aircraft stall danger (airspeed, flaps, and bank). On some trials the stall danger is estimated, requiring information integration. On other trials the value of individual indicators is estimated, requiring focused attention. In Experiment 1 the spatial proximity between indicators and their distinctiveness in color were manipulated. Spatial proximity had little effect on either focused attention or integration, whereas a distinct color code improved focused attention and disrupted integration. In Experiment 2 the three indicators were presented as a bar graph or were combined as features of an object display, either with or without color coding of the separate dimension. Relative to the bar graph display, the object display improved information integration but disrupted focused attention. The presence of color borders restored the focused attention accuracy, with a slight cost to response time.

Aerospace Medicine↗
PubMed1990

The perceptual interaction of graphical attributes: configurality, stimulus homogeneity, and object integration.

Researchers have proposed that graphical efficacy may be determined, in part, by the nature of the perceptual interactions that exist between attributes used to create graphical displays. One extreme type of interaction is integrality, in which two or more physical dimensions are represented as a single psychological dimension in the observer. An alternative type of interaction is configurality, in which a global emergent dimension is available to the observer in addition to the component attributes. Thirteen stimulus sets, each composed of attributes commonly used in the design of graphs, were submitted to the performance-based diagnostics of integrality and configurality. Analyses suggest a continuum of configurality among the present stimulus sets, with little evidence for integral graphical attributes. The configural pattern of results was more common when two identical dimensions were paired (homogeneous stimuli) than when two different dimensions were paired (heterogeneous stimuli). However, there was no evidence that pairs of dimensions belonging to a single object (object integration) were any more configural than dimensions belonging to different objects. Object integration was, however, consistently related to inefficient performance in tasks requiring the filtering of one of two component dimensions.

Adult↗
PubMed1989

Resources, confusions, and compatibility in dual-axis tracking: displays, controls, and dynamics.

Why do people often find that performing two tasks at once is harder than performing one task at a time? Three mechanisms of task interference that might answer that question were investigated: resource competition, confusions, and incompatible task proximity between processing stages. The subjects performed dual-axis compensatory tracking with error displays that were either integrated or separated, with axis controls that either were integrated into one stick or remained separate, and with control dynamics on the two axes that were either the same or different. Tracking error increased and control activity decreased as a function of the combined difficulty of the two control dynamics. Integrated displays and integrated controls both led to increased confusions between tracking axes although error was not reliably affected. Significantly, performance was also affected by whether the integrality of displays matched that of controls. These results suggest that resource competition, confusions, and compatibility of proximity play distinct roles in dual-axis tracking performance.

Acceleration↗
PubMed1987

Age differences in the speed and capacity of information processing: 1. A dual-task approach.

Sixty subjects, spanning the age range from 20 to 65, performed a series of tasks designed to evaluate the effects of aging on the speed and capacity of the human information-processing system. A tracking task was performed alone and concurrently with different versions of a Sternberg memory search task that varied the degree of resource competition with the tracking task. A dichotic-listening task, a tracking-task measure of perceptual-motor speed, and a complex transcription task were also performed. The data revealed a monotonic decrease in processing speed with age but no difference in time-sharing abilities between age groups. The latter conclusion was supported by a factor analysis of the test scores, which revealed that scores on the factor defining time-sharing did not differ with age.

Adult↗
PubMed1987

Adult age differences in the speed and capacity of information processing: 2. An electrophysiological approach.

A total of 60 subjects performed different variants of the Sternberg memory search task in an experiment designed to evaluate aging differences in the speed of the human information-processing system. The present study examined the nature of the age-related slowing using convergent methodologies of Sternberg's additive factors logic, the speed-accuracy trade-off, and the P300 component of the event-related brain potential. These methodologies revealed that a substantial component of slowing was manifest in perceptual encoding, response criterion adjustment, and response execution, with a lesser component related to memory search speed.

Adult↗
PubMed1985

Processing of stimulus properties: evidence for dual-task integrality.

The conditions under which dual-task integrality can be fostered were assessed in a study in which we manipulated four factors likely to influence the integrality between tasks: intertask redundancy, the spatial proximity of primary and secondary task displays, the degree to which primary and secondary task displays constitute a single object, and the resource demands of the two tasks. The resource allocation policy is inferred from changes in the amplitude of the P300 component of the event-related brain potential. Twelve subjects participated in three experimental sessions in which they performed both single and dual tasks. The primary task was a pursuit step tracking task. The secondary tasks required subjects to discriminate between different intensities or different spatial positions of a stimulus. Task pairs that required the processing of different properties of the same object resulted in better performance than task pairs that required the processing of different objects. Furthermore, these same object task pairs led to a positive relation between primary task difficulty and the resources allocated to secondary task stimuli. Intertask redundancy and the physical proximity of task displays produced similar effects of reduced magnitude.

Adolescent↗
PubMed1976

The effects of divided attention on information processing in manual tracking.

Six subjects performed a manual tracking task concurrently uith each of two secondary tasks: in input task (auditory signal detection) and an output task (application of a constant force). A feedback-control analysis of tracking performance was utilized to analyze the time-sharing decrements observed in mean squared errer, in terms of components due to processing delay, addition of internal processing noise, and change in response bias (tracking gain). The results indicated that only the parameters measuring noise and gain were sensitive to time-sharing conditions, and these only to concurrent performance of the force application task. It is concluded that limits of attention in dual-task performance are more severe in output than in input stages of processing, but that these limits are not necessarily those of a single-channel bottleneck. Instead, a broader conception of attention is proposed: one that included changes in processing noise and shifts in response bias, as attention-related phenomena.

Attention↗
PubMedDate not supplied

CO2 waveforms revisited.

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Blood Pressure Monitors↗