Making the constraints visible: testing the ecological approach to interface design

Clear and present danger? Applying ecological interface design to develop an aviation risk management interface

Ecological Interface Design (EID) is a framework for developing dynamic interfaces that support operators to understand and take appropriate actions within highly-complex systems. This two-part study involved the development and evaluation of a novel EID-based static aviation risk management display. A within-subjects survey-based experiment employed measures of decision accuracy, situation awareness, user workload, usability, and user perceptions. Results from 23 participants showed that when compared to a risk interface utilised by a large aviation company, the EID display achieved higher usability and lower workload ratings with large effect sizes, with no differences in decision accuracy and situation awareness. The findings provide evidence that the EID framework can improve upon static traditional displays. Research contributions also include a novel model of an aviation ground operations system and an example application of EID to the development of a static display. Further research is necessary to identify the extent of the applications and benefits to static displays.

Organizing Audible Alarm Sounds in the Hospital: A Card-Sorting Study

In hospitals, clinicians are presented with varied and disorganized alarm sounds from disparate devices. While there has been attention to reducing inactionable alarms to address alarm overload, little effort has focused on organizing, simplifying, or improving the informativeness of alarms. We sought to elicit nurses' tacit interpretation of alarm events to create an organizational structure to inform the design of advanced alarm sounds or integrated alert systems. We used open card sorting to evaluate nurses' perception of the relatedness of different alarm events. Seventy hospital nurses sorted 89 alarm events into groups they believed could or should be indicated by the same sound. We conducted factor analysis on a similarity matrix of frequency of alarm event pairings to interpret how strongly alarm events loaded on different alarm groups (factors). We interpreted participants' grouping rationale from their group labels and comments. Urgency of response was the most common grouping rationale. Participants also grouped: 1) monitoring-related events, 2) device-related events, and 3) events related to calls and patients. Our findings support standardization and integration of alarm sounds across devices toward a simpler and more informative hospital alarm environment.

Novel Interface Designs for Patient Monitoring Applications in Critical Care Medicine: Human Factors Review

Background

The patient monitor (PM) is one of the most commonly used medical devices in hospitals worldwide. PMs are used to monitor patients’ vital signs in a wide variety of patient care settings, especially in critical care settings, such as intensive care units. An interesting observation is that the design of PMs has not significantly changed over the past 2 decades, with the layout and structure of PMs more or less unchanged, with incremental changes in design being made rather than transformational changes. Thus, we believe it well-timed to review the design of novel PM interfaces, with particular reference to usability and human factors.

Objective

This paper aims to review innovations in PM design proposed by researchers and explore how clinicians responded to these design changes.

Methods

A literature search of relevant databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, identified 16 related studies. A detailed description of the interface design and an analysis of each novel PM were carried out, including a detailed analysis of the structure of the different user interfaces, to inform future PM design. The test methodologies used to evaluate the different designs are also presented.

Results

Most of the studies included in this review identified some level of improvement in the clinician’s performance when using a novel display in comparison with the traditional PM. For instance, from the 16 reviewed studies, 12 studies identified an improvement in the detection and response times, and 10 studies identified an improvement in the accuracy or treatment efficiency. This indicates that novel displays have the potential to improve the clinical performance of nurses and doctors. However, the outcomes of some of these studies are weakened because of methodological deficiencies. These deficiencies are discussed in detail in this study.

Conclusions

More careful study design is warranted to investigate the user experience and usability of future novel PMs for real time vital sign monitoring, to establish whether or not they could be used successfully in critical care. A series of recommendations on how future novel PM designs and evaluations can be enhanced are provided.

Critical care information display approaches and design frameworks: A systematic review and meta-analysis

OBJECTIVE

To systematically review original user evaluations of patient information displays relevant to critical care and understand the impact of design frameworks and information presentation approaches on decision-making, efficiency, workload, and preferences of clinicians.

METHODS

We included studies that evaluated information displays designed to support real-time care decisions in critical care or anesthesiology using simulated tasks. We searched PubMed and IEEExplore from 1/1/1990 to 6/30/2018. The search strategy was developed iteratively with calibration against known references. Inclusion screening was completed independently by two authors. Extraction of display features, design processes, and evaluation method was completed by one and verified by a second author.

RESULTS

Fifty-six manuscripts evaluating 32 critical care and 22 anesthesia displays were included. Primary outcome metrics included clinician accuracy and efficiency in recognizing, diagnosing, and treating problems. Implementing user-centered design (UCD) processes, especially iterative evaluation and redesign, resulted in positive impact in outcomes such as accuracy and efficiency. Innovative display approaches that led to improved human-system performance in critical care included: (1) improving the integration and organization of information, (2) improving the representation of trend information, and (3) implementing graphical approaches to make relationships between data visible.

CONCLUSION

Our review affirms the value of key principles of UCD. Improved information presentation can facilitate faster information interpretation and more accurate diagnoses and treatment. Improvements to information organization and support for rapid interpretation of time-based relationships between related quantitative data is warranted. Designers and developers are encouraged to involve users in formal iterative design and evaluation activities in the design of electronic health records (EHRs), clinical informatics applications, and clinical devices.

Ecological Interface Design: Thirty-Plus Years of Refinement, Progress, and Potential

OBJECTIVE

The objective is to provide a review of ecological interface design (EID), to illustrate its value to human factors/ergonomics, and to identify areas for future research and development.

BACKGROUND

EID uses mature interface technologies to provide decision making and problem solving support. A variety of theoretical concepts and analytical tools have been developed to meet the associated challenges. EID provides support that is simultaneously grounded in the practical realities of a work domain and tailored to human capabilities and limitations.

METHOD

EID's theoretical foundation is discussed briefly. Concrete examples of ecological and traditional interfaces are provided. Different categories of work domains are described, as well as the associated implications for interface design. A targeted literature review is conducted and the experimental outcomes are summarized. A representative evaluation is discussed, and interpretations of performance are provided.

RESULTS

The evidence reveals that EID has been remarkably successful in significantly improving performance for work domains with constraints that are law driven (e.g., process control). In contrast, work domains that are intent-driven (e.g., information retrieval) have, by and large, been ignored. Also, few studies have addressed nonvisual displays.

CONCLUSION

EID has not yet realized its potential to improve safety and efficiency across the entire continuum of work domains.

APPLICATION

EID provides a single integrated framework that is (a) sufficiently comprehensive to deal with complicated work domains and (b) capable of producing innovative support that will generalize to actual work settings.

Research Article

In this study, we demonstrate the effects of anxiety and cognitive load on eye movement planning in an instrument flight task adhering to a single-sensor-single-indicator data visualisation design philosophy. The task was performed in neutral and anxiety conditions, while a low or high cognitive load, auditory n-back task was also performed. Cognitive load led to a reduction in the number of transitions between instruments, and impaired task performance. Changes in self-reported anxiety between the neutral and anxiety conditions positively correlated with changes in the randomness of eye movements between instruments, but only when cognitive load was high. Taken together, the results suggest that both cognitive load and anxiety impact gaze behavior, and that these effects should be explored when designing data visualization displays.

A Review of Visual Representations of Physiologic Data

Background

Physiological data is derived from electrodes attached directly to patients. Modern patient monitors are capable of sampling data at frequencies in the range of several million bits every hour. Hence the potential for cognitive threat arising from information overload and diminished situational awareness becomes increasingly relevant. A systematic review was conducted to identify novel visual representations of physiologic data that address cognitive, analytic, and monitoring requirements in critical care environments.

Objective

The aims of this review were to identify knowledge pertaining to (1) support for conveying event information via tri-event parameters; (2) identification of the use of visual variables across all physiologic representations; (3) aspects of effective design principles and methodology; (4) frequency of expert consultations; (5) support for user engagement and identifying heuristics for future developments.

Methods

A review was completed of papers published as of August 2016. Titles were first collected and analyzed using an inclusion criteria. Abstracts resulting from the first pass were then analyzed to produce a final set of full papers. Each full paper was passed through a data extraction form eliciting data for comparative analysis.

Results

In total, 39 full papers met all criteria and were selected for full review. Results revealed great diversity in visual representations of physiological data. Visual representations spanned 4 groups including tabular, graph-based, object-based, and metaphoric displays. The metaphoric display was the most popular (n=19), followed by waveform displays typical to the single-sensor-single-indicator paradigm (n=18), and finally object displays (n=9) that utilized spatiotemporal elements to highlight changes in physiologic status. Results obtained from experiments and evaluations suggest specifics related to the optimal use of visual variables, such as color, shape, size, and texture have not been fully understood. Relationships between outcomes and the users’ involvement in the design process also require further investigation. A very limited subset of visual representations (n=3) support interactive functionality for basic analysis, while only one display allows the user to perform analysis including more than one patient.

Conclusions

Results from the review suggest positive outcomes when visual representations extend beyond the typical waveform displays; however, there remain numerous challenges. In particular, the challenge of extensibility limits their applicability to certain subsets or locations, challenge of interoperability limits its expressiveness beyond physiologic data, and finally the challenge of instantaneity limits the extent of interactive user engagement.

Evaluation of a configural vital signs display for intensive care unit nurses

OBJECTIVE

The objective was to evaluate a configural vital signs (CVS) display designed to support rapid detection and identification of physiological deterioration by graphically presenting patient vital signs data.

BACKGROUND

Current display technology in the intensive care unit (ICU) is not optimized for fast recognition and identification of physiological changes in patients. To support nurses more effectively, graphical or configural vital signs displays need to be developed and evaluated.

METHOD

A CVS display was developed based on findings from studies of the cognitive work of ICU nurses during patient monitoring. A total of 42 ICU nurses interpreted data presented either in a traditional, numerical format (n = 21) or on the CVS display (n = 21). Response time and accuracy in clinical data interpretation (i.e., identification of patient status) were assessed across four scenarios.

RESULTS

Data interpretation speed and accuracy improved significantly in the CVS display condition; for example, in one scenario nurses required only half of the time for data interpretation and showed up to 1.9 times higher accuracy in identifying the patient state compared to the numerical display condition.

CONCLUSION

Providing patient information in a configural display with readily visible trends and data variability can improve the speed and accuracy of data interpretation by ICU nurses.

APPLICATION

Although many studies, including this one, support the use of configural displays, the vast majority of ICU monitoring displays still present clinical data in numerical format. The introduction of configural displays in clinical monitoring has potential to improve patient safety.

Improving information recognition and performance of recycling chimneys

The aim of this study was to assess and improve how recyclers (individuals carrying out the task of recycling) make use of visual cues to carryout recycling tasks in relation to 'recycling chimneys' (repositories for recycled waste). An initial task analysis was conducted through an activity sampling study and an eye tracking experiment using a mobile eye tracker to capture fixations of recyclers during recycling tasks. Following data collection using the eye tracker, a set of recommendations for improving information representation were then identified using the widely researched skills, rules, knowledge framework, and for a comparative study to assess the performance of improved interfaces for recycling chimneys based on Ecological Interface Design principles.

PRACTITIONER SUMMARY

Information representation on recycling chimneys determines how we recycle waste. This study describes an eco-ergonomics-based approach to improve the design of interfaces for recycling chimneys. The results are valuable for improving the performance of waste collection processes in terms of minimising contamination and increasing the quantity of recyclables.

Informing the design of hemodynamic monitoring displays

In the ICU, an extensive array of variables from the hemodynamic monitoring display is routinely analyzed. However, the development of new display technologies is proceeding without adequate study of the monitoring tasks and behaviors of a primary user group--critical-care nurses. Semistructured interviews focusing on the cognitive aspects of the hemodynamic monitoring task were conducted with 14 critical-care nurses. A systematic content analysis of qualitative data identified cognitive tasks that had applicability to the design of monitoring displays. The cognitive tasks of hemodynamic monitoring were (1) selective data acquisition, (2) applying meaning to the variables and understanding relationships between parameters, (3) controlling hemodynamics by titrating medications and intravenous fluids, and (4) monitoring complex trends of multiple interacting variables and patient response to interventions. Recommendations include designing the monitoring display to match the mental constructs and cognitive tasks of the user by applying conceptual meaning to the variables, highlighting relationships between variables, and presenting a "big picture" view of the patient's condition. Monitoring displays must also present integrated trends that illustrate the dynamic relationship between interventions and patient response.

A far-view intensive care unit monitoring display enables faster triage

Although nurses perform the majority of the clinical tasks in an intensive care unit, current patient monitors were not designed to support a nurse's workflow. Nurses constantly triage patients, deciding which patient is currently in the most need of care. To make this decision, nurses must observe the patient's vital signs and therapeutic device information from multiple sources. To obtain this information, they often have to enter the patient's room. This study addresses 3 hypotheses. Information provided by far-view monitoring displays (1) reduces the amount of time to determine which patient needs care first, (2) increases the accuracy of assigning priority to the right patient, and (3) reduces nurses mental workload. We developed 2 far-view displays to be read from a distance of 3 to 5 m without entering the patient's room. Both display vital signs, trends, alarms, infusion pump status, and therapy support indicators. To evaluate the displays, nurses were asked to use the displays to decide which of 2 patients required their attention first. They made 60 decisions: 20 with each far-view display and 20 decisions with a standard patient monitor next to an infusion pump. Sixteen nurses (median age of 27.5 years with 2.75 years of experience) participated in the study. Using the 2 far-view displays, nurses more accurately and rapidly identified stable patients and syringe pumps that were nearly empty. Median decision times were 11.3 and 12.4 seconds for the 2 far-view displays and 17.2 seconds for the control display. The 2 far-view displays reduced median decision-making times by 4.8 to 5.9 seconds, increased accuracy in assignment of priority in 2 of 7 patient conditions, and reduced nurses' frustration with the triaging task. In a clinical setting, the proposed far-view display might reduce nurses' mental workload and thereby increase patient safety.

A systematic review of the designs of clinical technology: findings and recommendations for future research

Human factors (HF) studies are increasingly important as technology infuses into clinical settings. No nursing research reviews exist in this area. The authors conducted a systematic review on designs of clinical technology, 34 articles with 50 studies met inclusion criteria. Findings were classified into 3 categories on the basis of HF research goals. The majority of studies evaluated effectiveness of clinical design; efficiency was fewest. Current research ranges across many interface types examined with no apparent pattern or obvious rationale. Future research should expand types, settings, and participants; integrate displays; and expand outcome variables.

Using what we know: Consequences of intentionally retrieving gist versus item-specific information

The effect of a prior gist-based versus item-specific retrieval orientation on recognition of objects and words was examined. Prior item-specific retrieval increased item-specific recognition of episodically related but not previously tested objects relative to both conceptual- and perceptual-gist retrieval. An item-specific retrieval advantage also was found when the stimuli were words (synonyms) rather than objects but not when participants overtly named objects during gist-based recognition testing, which suggests that they did not always label objects under general gist-retrieval instructions. Unlike verbal overshadowing, labeling objects during recognition attenuated (but did not eliminate) test- and interference-related forgetting. A full understanding of how retrieval affects subsequent memory, even for events or facts that are not themselves retrieved, must take into account the specificity with which that retrieval occurs.

Evaluation of Graphic Cardiovascular Display in a High-Fidelity Simulator

"Human error" in anesthesia can be attributed to misleading information from patient monitors or to the physician's failure to recognize a pattern. A graphic representation of monitored data may provide better support for detection, diagnosis, and treatment. We designed a graphic display to show hemodynamic variables. Twenty anesthesiologists were asked to assume care of a simulated patient. Half the participants used the graphic cardiovascular display; the other half used a Datex As/3 monitor. One scenario was a total hip replacement with a transfusion reaction to mismatched blood. The second scenario was a radical prostatectomy with 1.5 L of blood loss and myocardial ischemia. Subjects who used the graphic display detected myocardial ischemia 2 min sooner than those who did not use the display. Treatment was initiated sooner (2.5 versus 4.9 min). There were no significant differences between groups in the hip replacement scenario. Systolic blood pressure deviated less from baseline, central venous pressure was closer to its baseline, and arterial oxygen saturation was higher at the end of the case when the graphic display was used. The study lends some support for the hypothesis that providing clinical information graphically in a display designed with emergent features and functional relationships can improve clinicians' ability to detect, diagnose, manage, and treat critical cardiovascular events in a simulated environment.

IMPLICATIONS

A graphic representation of monitored data may provide better support for detection, diagnosis, and treatment. A user-centered design process led to a novel object-oriented graphic display of hemodynamic variables containing emergent features and functional relationships. In a simulated environment, this display appeared to support clinicians' ability to diagnose, manage, and treat a critical cardiovascular event in a simulated environment. We designed a graphic display to show hemodynamic variables. The study provides some support for the hypothesis that providing clinical information graphically in a display designed with emergent features and functional relationships can improve clinicians' ability to detect, diagnosis, mange, and treat critical cardiovascular events in a simulated environment.

Evaluation of two new ecological interface approaches for the anesthesia workplace

OBJECTIVE

Currently, vital parameters are commonly displayed as trends along a timeline. However, clinical decisions are more often based upon concepts, such as the depth of anesthesia, that are derived by combining parameter relationships and additional context information. The current displays do not visualize such concepts and therefore do not optimally support the decision process. A new display should present an ecological interface (EI). The principle of EI design is to visualize all of the information necessary for decision making in one single display.

METHODS

In the first approach, we developed an EI that visualizes 35 relevant parameters for anesthesia monitoring. All of the parameters are generated by an anesthesia software simulator. Sixteen anesthetists had to administer two simulated general anesthetics: in one setting working only with the simulator's monitors ("Sim Only"), and in another setting working with the simulator's monitors in combination with the EI ("Combi1"). During each experiment, one unexpected critical incident (either blood loss or a cuff leakage) had to be identified. The control and monitoring behavior was analyzed by recording the subjects' eye movements and think-aloud protocol. With the help of the eye-tracking results, we re-designed the EI. The new EI was then tested with no eye tracking ("Combi2") on eight anesthetists under analogous conditions as in "Combi1."

RESULTS

Cuff leakage was identified significantly quicker in "Combi1" (7 of 8 cases; time (T): 65 s +/- 73 s) than in "SimOnly" (6 of 8 cases; T: 222 s +/- 187 s). Blood loss was identified in 5 of 8 cases (T: 215 s +/- 76 s) in "Combi1" as quickly as in "SimOnly" (all cases; T: 217 s +/- 72 s). In "Combi1," the EI was used as the main source of information (in 43 +/- 19% of time) and was frequently favored when identifying an evolving critical incident. In "Combi2," cuff leakage was identified in 7 of 8 cases (T: 70 s +/- 111 s) as quickly as in "Combi1." Blood loss was identified significantly quicker in all cases (T: 147 s +/- 62 s) in "Combi2" than in "Combi1" and in "SimOnly."

CONCLUSION

The results have shown that appropriately designed EIs may improve the anesthetist's decision making and focus attention on specific problems. Now, the findings have to be tested in future studies by widening the scope using other simulated scenarios and being closer to reality under real conditions in the OR. Eye tracking proved to be a useful method to analyze the anesthetists' decision making and appropriately re-design interfaces.

Different lenses, improved outcomes: a new approach to the analysis and design of healthcare information systems

Healthcare systems are complex sociotechnical systems in which many information system innovations fail because of problems in planning or design. One of the reasons for this is that traditional analysis methods were designed for stable, relatively simple systems and single users. New analytical approaches are needed that can encompass the complexity of changing systems and multiple, interacting users. The author suggests that integrating two seemingly disparate approaches may be helpful in achieving successful designs for the complexities of healthcare systems. The first is derived from Carper's four ways of knowing; the second is Cognitive Work Analysis (CWA). The utility of the approach is demonstrated via a case study.

Aiding planning in air traffic control: an experimental investigation of the effects of perceptual information integration

Prior research examined how controllers plan in their traditional environment and identified various information uncertainties as detriments to planning. A planning aid was designed to reduce this uncertainty by perceptually representing important constraints. This included integrating spatial information on the radar screen with discrete information (planned sequences of air traffic). Previous research reported improved planning performance and decreased workload in the planning aid condition. The purpose of this paper was to determine the source of these performance improvements. Analysis of computer interactions using log-linear modeling showed that the planning interface led to less repetitive--but more integrated--information retrieval compared with the traditional planning environment. Ecological interface design principles helped explain how the integrated information retrieval gave rise to the performance improvements. Actual or potential applications of this research include the design and evaluation of interface automation that keeps users in active control by modification of perceptual task characteristics.

Informational basis for expert intuition

AIM

Intuition has been cited as an integral part of nursing clinical expertise. Responding to the recent scholarly debate over the status of expert nursing intuition as part of the art or science of nursing, this article proposes an alternative view that may provide an informational basis for what has been described phenomenologically as intuition.

RATIONALE

Two reasons for the dispute over the status of nursing intuition as 'art' or 'science' are proposed: The first is methodological. The second relates to intuition's close link with perception and underlying assumptions about perception. By examining intuition through an ecological psychology framework, the problem takes on a different character, one that is no longer focused solely on the expert's cognitive (or perceptual) processes, but also on the information provided by the patient and the context of care.

CONCLUSIONS

This perspective has several implications for nursing. By investigating information sources (i.e. higher order variables or constraints) in the nurse-patient encounter, the problem of intuition may be clarified, and perhaps simplified. We may find that what nurse researchers have called 'intuition' is what Gibson (1966, 1986) termed 'direct perception.' Intuition as direct perception is information-based and lawful. Finally, although some aspects of intuition may be hard-wired through evolution, intuition as direct perception can be developed through education and extensive, deliberate practice with appropriate exemplars. Characterized as direct perception, intuition is an observable, lawful phenomenon that is measurable, potentially teachable, and appropriately part of nursing science.

Plant a tree in cyberspace: metaphor and analogy as design elements in Web-based learning environments

Analogy and metaphor are figurative forms of communication that help people integrate new information with prior knowledge to facilitate comprehension and appropriate inferences. The novelty and versatility of the Web place cognitive burdens on learners that can be overcome through the use of analogies and metaphors. This paper explores three uses of figurative communication as design elements in Web-based learning environments, and provides empirical illustrations of each. First, extended analogies can be used as the basis of cover stories that create an analogy between the learner's position and a hypothetical situation. The Dragonfly Web pages make extensive use of analogous cover stories in the design of interactive decision-making games. Feedback from visitors, patterns of usage, and external reviews provide evidence of effectiveness. A second approach is visual analogies based on the principles of ecological psychology. An empirical example suggests that visual analogies are most effective when there is a one-to-one correspondence between the base and visual target analogs. The use of learner-generated analogies is a third approach. Data from an offline study with undergraduate science students are presented indicating that generating analogies are associated with significant improvements in the ability to place events in natural history on a time line. It is concluded that cyberspace itself might form the basis of the next guiding metaphor of mind.

Information structure and the relative efficacy of tables and graphs

Users and system designers often prefer to display information with graphs rather than with tables. However, empirical studies that compared task performance with the two display types frequently revealed either an advantage of tables over graphs or no differences between the displays. This apparent contradiction may result from previous studies in which the importance of the structure that usually exists in displayed information is overlooked. We predict that graphic displays will have an advantage over tables when the displayed information has structure and when this structure is relevant for the task. These conditions generally exist in the actual use of information displays, but have seldom been assessed in experiments. In the present study participants in an experiment performed an information extraction task and a prediction task with unstructured or structured data and with different levels of prior information about the structure. The results showed that the information structure and prior knowledge about the existence of structure affected the advantage of graphic displays over tables when task performance depended on the use of structure. Existing approaches to the study of displays were analyzed in view of these findings. Actual or potential applications of this research include the development of better displays for process control and decision support and better operator training programs.

Ergonomic evaluation of an ecological interface and a profilogram display for hemodynamic monitoring

OBJECTIVE

Comprehensive monitoring of the patient state and subsequent decision making is an essential part of the task of an anaesthetist. The physicians' decision making process is based upon a concept of partly abstract physiologic parameters such as depth of anaesthesia or contractility. This concept is derived from the measured parameters given on todays' trend displays in addition to context information available for the anaesthetist. We investigated two alternative approaches of display design for hemodynamic monitoring: 1) integrated displays based on ecological interface design, and 2) profilogram displays based on intelligent alarms.

METHOD

To evaluate differences in decision making, the two displays and a trend display were compared in an experimental set-up with computer simulated vital parameter curves. From a start state with random parameter deviations from the ideal state, subjects had to achieve the ideal circulatory performance as fast as possible by manipulating vasomotor tone, heart rate, blood volume and contractility. To analyse subjects' decision making process, eye-tracking, event-logging, and the method of think aloud protocols were used. Twenty anaesthesiologists performed 113 experiments (approximately 2 with each display).

RESULTS

The anaesthetists failed to achieve the task in 37% using the trend display, in 19% using the profilogram display, and in 13% using the ecological interface. Hence, a safer task solution was possible with the ecological interface and the profilogram display but at the expense of various performance parameters such as higher trial time, more interactions with the simulated system, and more frequent eye movements. In contrast to the trend display and the profilogram display, where anaesthetists were mainly focussed on controlling the left atrial pressure, such an behaviour was less observed with the ecological interface.

CONCLUSION

Our results have shown that subjects came to more effective solutions with the traditional trend display. The main reason for this result may be their years of experience with this kind of display type. Regarding safe and goal-intended decision finding, the results are encouraging for further experiments with redesigned ecological displays. But these displays ought to have smoother changes with respect to the traditional trend displays. Furthermore, new experiments have to be performed under real or fairly real (e.g. together with an anaesthesia simulator) conditions to underline the positive results for ecological interfaces.