Daniel Gopher

A look into the nature and causes of human errors in the intensive care unit

OBJECTIVES The purpose of this study was to investigate the nature and causes of human errors in the intensive care unit (ICU), adopting approaches proposed by human factors engineering. The basic assumption was that errors occur and follow a pattern that can be uncovered. DESIGN Concurrent incident study. SETTING Medical-surgical ICU of a university hospital. MEASUREMENTS AND MAIN RESULTS Two types of data were collected: errors reported by physicians and nurses immediately after an error discovery; and activity profiles based on 24-hr records taken by observers with human engineering experience on a sample of patients. During the 4 months of data collection, a total of 554 human errors were reported by the medical staff. Errors were rated for severity and classified according to the body system and type of medical activity involved. There was an average of 178 activities per patient per day and an estimated number of 1.7 errors per patient per day. For the ICU as a whole, a severe or potentially detrimental error occurred on the average twice a day. Physicians and nurses were about equal contributors to the number of errors, although nurses had many more activities per day. CONCLUSIONS A significant number of dangerous human errors occur in the ICU. Many of these errors could be attributed to problems of communication between the physicians and nurses. Applying human factor engineering concepts to the study of the weak points of a specific ICU may help to reduce the number of errors. Errors should not be considered as an incurable disease, but rather as preventable phenomena.

Cognition and Motor Processes

I Motor Control and Action Planning.- 1 Cognitivism and Future Theories of Action: Some Basic Issues.- 2 A Distributed Processing View of Human Motor Control.- 3 The Apraxias, Purposeful Motor Behavior, and Left-Hemisphere Function.- 4 A Motor-Program Editor.- 5 Eye Movement Control During Reading: The Effect of Word Units.- II Motor Contributions to Perception and Cognition.- 6 Motor Theories of Cognitive Structure: A Historical Review.- 7 Context Effects and Efferent Factors in Perception and Cognition.- 8 Saccadic Eye Movements and Visual Stability: Preliminary Considerations Towards a Cognitive Approach.- 9 Scanning and the Distribution of Attention: The Current Status of Herons Sensory-Motor Theory.- 10 The Relationship Between Motor Processes and Cognition in Tactile Vision Substitution.- III Mediating Structures and Operations Between Cognition and Action.- 11 Mechanisms of Voluntary Movement.- 12 Evaluation: The Missing Link Between Cognition and Action.- 13 Modes of Linkage Between Perception and Action.- 14 The Contribution of Vision-Based Imagery to the Acquisition and Operation of a Transcription Skill.- 15 Speech Production and Comprehension: One Lexicon or Two?.- IV Attention, Cognition, and Skilled Performance.- 16 S-Oh-R: Oh Stages! Oh Resources!.- 17 Automatic Processing: A Review of Recent Findings and a Plea for an Old Theory.- 18 Motor Learning as a Process of Structural Constriction and Displacement.- V Interactions Between Cognition and Action in Development.- 19 Cognition and Action in Development: A Tutorial Discussion.- 20 Biodynamic Structures, Cognitive Correlates of Motive Sets and the Development of Motives in Infants.- 21 Discontinuity in the Development of Motor Control in Children.- Author Index.

Transfer of skill from a computer game trainer to flight

An experimental study was conducted to test the transfer of skills from a complex computer game to the flight performance of cadets in the Israeli Air Force flight school. The context relevance of the game to flight was argued on the basis of a skill-oriented task analysis, using the framework provided by contemporary models of the human processing system. The influence of two embedded training strategies was compared, one focusing on the specific skills involved in performing the game, the other designed to improve the general ability of trainees to cope with the high processing and response demands of the flight task and teach better strategies of attention control. Efficient control and management of attention under high task load are argued to be skills that can improve with proper training and generalize to new situations. Flight performance scores of two groups of cadets who received 10 h of training in the computer game were compared with those of a matched group without game experience. Both game groups performed significantly better than the no-game group in the subsequent test flights. The results are discussed with reference to the theoretical framework within which the context relevance of the game was supported. Also considered are the effects of the different training schedules and the significance of the data to the study of attention control. The game has now been incorporated into the regular training program of the Air Force.

Task coordination and aging : explorations of executive control processes in the task switching paradigm

A number of models of cognitive aging suggest that older adults exhibit disproportionate performance decrements on tasks which require executive control processes. In a series of three studies we examined age-related differences in executive control processes and more specifically in the executive control processes which underlie performance in the task switching paradigm. Young and old adults were presented with rows of digits and were required to indicate whether the number of digits (element number task) or the value of the digits (digit value task) were greater than or less than five. Switch costs were assessed by subtracting the reaction times obtained on non-switch trials from trials following a task switch. Several theoretically interesting results were obtained. First, large age-related differences in switch costs were found early in practice. Second, and most surprising, after relatively modest amounts of practice old and young adults switch costs were equivalent. Older adults showed large practice effects on switch trials. Third, age-equivalent switch costs were maintained across a two month retention period. Finally, the main constraint on whether age equivalence was observed in task switching performance was memory load. Older adults were unable to capitalize on practice under high memory loads. These data are discussed in terms of their implications for both general and process specific cognitive aging models.

Practice under changing priorities: An approach to the training of complex skills☆

Abstract The present paper discusses the theoretical foundations and methodological rationale of a novel approach to the training of complex skills. This approach is based on the introduction of multiple emphasis changes on subcomponents of a complex task. The approach links together arguments from models of skills and theories of attention. It is construed that the core of expert performance is an organized set of response strategies that can be employed flexibly to meet task demands. Strategies can be constructed through emphasis change. This approach was applied to the training of 4 groups of players in a highly demanding computer game. Subjects trained under emphasis manipulations performed significantly better than control players who played the game for the same duration without instruction. Moreover, the advantage of the trained groups continued to increase after formal training had been terminated. Low-ability subjects benefitted more than high ability subjects from multiple emphasis changes. The proposed approach appears capable of resolving several of the difficulties that were hitherto encountered by traditional part-whole training methods.

On the Psychophysics of Workload: Why Bother with Subjective Measures?

Psychophysical functions describe the relationship between variations in the amplitude of a defined physical quantity and the psychological perception of these changes. Examples are brightness, loudness, and pain. The regularities of these relationships have been formulated into psychophysical laws. The measurement methodology of psychophysical scaling has been refined by the Harvard group led by S. S. Stevens, who proposed a power function as a general form for such laws. The main argument of the present article is that a similar scaling approach can be adapted to the measurement of workload and task demands based upon subjective estimates. The rationale is that these estimates, like other psychophysical judgments, reflect the individuals perception of the amount of processing resources that the subject invests to meet the demand imposed by a task. This approach was successfully applied to the assessment of 21 experimental conditions given to a group of 60 subjects. The paper discusses the main results of this effort and their implications to theory and application in human performance.

Switching tasks and attention policies.

The determinants and costs of control were studied in 6 experiments examining the performance costs of changing stimulus dimension (digit value/number of elements) or attention strategies (speed/accuracy) on the first trial after task transition. Costs were compared for task shift and reconsideration only. Preparation ability was studied by presenting all transition information at the beginning of a 2-part block or only prior to each part. Results showed pronounced first-trial transition costs. Different factors were associated with stop-start and task-switching requirements. Transition costs were separate from those of basic task performance. Costs were sensitive to global control considerations and were larger for task dimension changes than for attention strategy shifts. Costs involving task dimension change, but not strategy shifts, were reduced with advanced preparation. These results are discussed in relation to contemporary models of control. A new distinction is proposed between activation and execution of control strategies.

Individual differences in attention and the prediction of flight criteria.

A dichotic listening test was constructed which requires S to monitor a relevant message and to ignore a concurrent message presented to the other ear. The test has promising validity for predicting different criteria of proficiency in flying high-performance aircraft. An analysis of the most valid type of errors suggests that a change in an existing orientation is accompanied by a transient instability of selective attention. Most errors in continuous attention are omissions, which indicate a failure of the listening set. Intrusions, which indicate a failure of selectivity, are rare and their frequency is not correlated to flight criteria.

Different difficulty manipulations interact differently with task emphasis: Evidence for multiple resources.

To test the notion of multiple resources, a two-dimensional pursuit tracking task was paired with a letter-typing task, the difficulty of which was manipulated by varying cognitive (size of stimulus set) and motor (repetitiveness of finger chords) factors. In addition, task priority was manipulated. The latter factor had a large effect on the performance of the two tasks, which indicates that they compete for resources. Both types of typing difficulty manipulations affected typing performance, but only motor difficulty interacted with priorities. Since difficulty manipulations that tap resources common to both tasks are predicted to interact with priorities, the results are interpreted to indicate that in joint performance, typing and tracking compete mainly for motor-related concept, the letter-typing task is argued to require at least two kinds of resources.

A Selective Attention Test as a Predictor of Success in Flight Training

Incorporation of a dichotic listening task of selective attention in the pilot selection test battery of the Israeli Air Force was studied using a group of 2000 flight cadets. In this test, subjects are presented with 48 auditory messages. Each message is composed of strings of words and digit names. Different strings are simultaneously presented to the two ears. Subjects are required to detect digit names in the relevant channel and to reconsider channel relevance upon indication. Three types of selective listening errors are recorded: omissions, intrusions, and switching errors. Flight cadets who had completed a two-year training program had significantly lower error scores on all attention measures. In addition, these measures had low correlations with all other tests of the pilot selection battery. Thus, attention capabilities appear to be an independent dimension that enhances the predictive validity of the present test battery.