William Simcox

Controllability of Nonlinear Electromyographic Processors

Proceedings of the Sixth New England Bioengineering Conference, 1978

Publisher Summary This chapter presents the results of experiments conducted to study controllabi... more Publisher Summary This chapter presents the results of experiments conducted to study controllability of nonlinear electromyographic (EMG) processors. The demodulation process is usually a low-pass filter whose band width is related to the amount of noise rejection and hence a smoother signal. However, by decreasing the band width, the system's step response is increased leading to a sluggish system response detrimental to control. This condition indicates that to optimize the total man-machine system, signal-to-noise ratio (SNR) of the processor must be degraded. This apparent tradeoff in SNR for control has led to new processing schemes employing nonlinear demodulation in the hopes of optimizing SNR without degradation in control. The experiment results showed that longer overall control times are possible using the square root processor in the demodulation circuitry.

A framework for the inclusion of human factors in the design of videotex systems

Information Design Journal, 1983

Λ structured approach f or proper inclusion of Human Factors in the design of videotex systems is... more Λ structured approach f or proper inclusion of Human Factors in the design of videotex systems is presented. The framework describes the process of information communication by videotex in terms of user tasks and functions. Behavioral descriptions of each task serve to delineate the equipment requirements necessary for their proper execution. These requirements are of two types-physical and operational. For each task, design issues arising from these requirements are discussed and empirical support for resolving these issues is presented.

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Cognitive Considerations in Display Design

This invegtigation of.the encoding features of graphs begins with a description of a cognitive fr... more This invegtigation of.the encoding features of graphs begins with a description of a cognitive framework which allows designers to factor into the process of 'designing displays how people interpret the information'found and what display properties are responsible for this interpretation. The framework also provides a performance measure for use in assessing alternative designs and cognitive effort. Properties of displays-features, dimensions, and,' configurations-that can-be mentally represented and serve as a basis for response are also discussed, as well as the strategy used to determine which display property is actually being represented and a processing jusiification for its use. An experiment is then described in detail which used a speeded classification task to test whether any of the display properties discussed were actually the encoding* features and to assess the.degree of interference in two univariate and two orthogonal conditions. It Was found that, if the display format was not compatible with the inforMation to be presented, classification errors increased, which in turn would increase the' likelihood of miscommunication at higher levels of processing. A 38-item bibliography, 7 figures, and 4 tables are attached. (LMM)

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Memorial Consequences of Display Coding

This investigation of cognitive effort begins with-a review of cognitive principles relating to-m... more This investigation of cognitive effort begins with-a review of cognitive principles relating to-memory and graphic encoding of information. The cognitive framework described allows explanation of improved memory due to reparsing of graphic representations. It also provides the basis for optimizing graphical material design to insure best retention of encoded material. An experiment is described using a 4 (graph type) by 3 (question) within-subjects design, each subject (N=10) participating under all conditions. Thirty-six graphs were displayed complete3y at random. Subjects were informed that the purpose was to test perception of certain display properties and told to respond as quickly as possible without making errors. A graph was shown and subjects executed the response. The experimenter recorded latency and noted errors. Tests were then administered, one to recall a missing property, the other simple recognition'of graphs rated on a confidence scale. The results support the hypothesis that incongruency between information to be communicated and its graphic representation leads to reparsing and better memory. A list of eight references, three figures, and five tables are attached. (JM)

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A Method for Pragmatic Communication in Graphic Displays

Human Factors: The Journal of the Human Factors and Ergonomics Society, 1984

This paper presents a method for connotatively weighting information presented in graphic display... more This paper presents a method for connotatively weighting information presented in graphic displays. The method involves determining a compatibility (unction that describes the degree of correspondence between an implied attribute of the display and the linguistic category that summarizes values of this attribute. Compatibility functions can then be used to guide the graph-construction process.

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A Comprehensive Process for Display Systems Development

A comprehensive development process for display design, focusing on computer-generated cathode ra... more A comprehensive development process for display design, focusing on computer-generated cathode ray tube (CRT) displays is presented. A framework is created for breaking the display into its component parts, used to guide the design process. The objective is to design or select the most cost effective graphics solution (hardware and software) to meet any problem situation. The framework is divided into informational structure/medium of display; these are broken into constituent elements and discussed with associated, design issues. The informational structure includes content, format, and organization. The CRT is analyzed for display design criteria such as light, geometric parameters, and CRT display properties. Viewing area criteria are discussed. The components of medium and informational structure provide the framework for specifying hardware/software requirements for graphics systems. The process of display design fs presented, beginning with feasibility studies, resulting in a set of useful solutions. Steps to obtaining a 'best' solution are summarized, creating an optimal candidate system which is physically realized and tested through detailed desigr activity. Results may indicate a need for revision/redesign requiring alternative solutions. The criterion for selecting the most effective solution is based on integrity of design. A list of 24 references, 18 figures and 6 tables are attached. (JM)

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A framework for the inclusion of human factors in the design of videotex systems

Applied Ergonomics, 1984

Λ structured approach f or proper inclusion of Human Factors in the design of videotex systems is... more Λ structured approach f or proper inclusion of Human Factors in the design of videotex systems is presented. The framework describes the process of information communication by videotex in terms of user tasks and functions. Behavioral descriptions of each task serve to delineate the equipment requirements necessary for their proper execution. These requirements are of two types-physical and operational. For each task, design issues arising from these requirements are discussed and empirical support for resolving these issues is presented.

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A Method for Pragmatic Communication in Graphic Displays

Human Factors, Aug 1, 1984

Limits of graphic display design component variation based on cognitive tolerance for imprecision... more Limits of graphic display design component variation based on cognitive tolerance for imprecision were investigated using compatibility functions. The compatibility function is an empirical definition of a perceptual category representing the grade of membership of an implied physical attribute into a corresponding conceptual category,,measuring the degree of compatibility between a particular level of attribute and a category. AgUlts (N=24) were asked to categorize lines as sharply or slightly increasing when presented with li:a and ber graph's with slopes from five to sixty degrees in five degree increments. Crossover point and precision parameters are discussed as part of the statistical analysis. This experiment established compatibility function values for the categorical terms sharply increasing and slightly increasing. A graph designer having an inventory of such functions plus the operations that can be performed OA them can weight the information to be preented by manipulating various aspects of thu graph, specifically the framework and/or specifier. This would allow graphs to be designed to meet specialized requirements. A list of twelve references, figures showing the types of graphs used, and the compatibility functions established fo the categories of interest to this experiment; and a table summarizing parameter values for the mathematical models are attached. (JM)

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Cognitive Considerations in Display Design

This invegtigation of.the encoding features of graphs begins with a description of a cognitive fr... more This invegtigation of.the encoding features of graphs begins with a description of a cognitive framework which allows designers to factor into the process of 'designing displays how people interpret the information'found and what display properties are responsible for this interpretation. The framework also provides a performance measure for use in assessing alternative designs and cognitive effort. Properties of displays-features, dimensions, and,' configurations-that can-be mentally represented and serve as a basis for response are also discussed, as well as the strategy used to determine which display property is actually being represented and a processing jusiification for its use. An experiment is then described in detail which used a speeded classification task to test whether any of the display properties discussed were actually the encoding* features and to assess the.degree of interference in two univariate and two orthogonal conditions. It Was found that, if the display format was not compatible with the inforMation to be presented, classification errors increased, which in turn would increase the' likelihood of miscommunication at higher levels of processing. A 38-item bibliography, 7 figures, and 4 tables are attached. (LMM)

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Configural Properties in Graphic Displays and Their Effects on Processing

This investiga gion into the effects of configural properties (properties determined by the inter... more This investiga gion into the effects of configural properties (properties determined by the interrelationships existing between component parts) used a selective attention task-to determine whether iaersection is a primary encoding feature or is constructed after slopes and heights are perceived. The method for encoding feature identification, primary encoding features, and the question of whether or not configural superiority can be modified are discussed. the subjects(N=12) were, adults with no prior experience in card sorting tasks. The task required subjects to classify stimuli that vary in two of their properties-speed and accuracy. A previous task :th stimuli varying in only one dimension served as a baseline. Results indicate that the configural property of intersection is perceived directly rather than constructed from the stimulus components. Modifications to configurations, the experimental metho4ology and statistical analysis including error analysis are described. The geometric concept of intersection is described as analogous to the statistical concept of crossed interaction and to its mathematical interpretation as a departure from parallelism. The results of the experiment are discussed relative to the usefulness of the findings to graph design. A list of 13 references, 3 figures and 3 tables are attached. (JM)

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A Design Method for Graphic Communication

Abca Bulletin, 1984

Memorial Consequences of Display Coding

This investigation of cognitive effort begins with-a review of cognitive principles relating to-m... more This investigation of cognitive effort begins with-a review of cognitive principles relating to-memory and graphic encoding of information. The cognitive framework described allows explanation of improved memory due to reparsing of graphic representations. It also provides the basis for optimizing graphical material design to insure best retention of encoded material. An experiment is described using a 4 (graph type) by 3 (question) within-subjects design, each subject (N=10) participating under all conditions. Thirty-six graphs were displayed complete3y at random. Subjects were informed that the purpose was to test perception of certain display properties and told to respond as quickly as possible without making errors. A graph was shown and subjects executed the response. The experimenter recorded latency and noted errors. Tests were then administered, one to recall a missing property, the other simple recognition'of graphs rated on a confidence scale. The results support the hypothesis that incongruency between information to be communicated and its graphic representation leads to reparsing and better memory. A list of eight references, three figures, and five tables are attached. (JM)

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