Cogn Tech Work (2009) 11:119–127 DOI 10.1007/s10111-007-0103-y
ORIGINAL ARTICLE
Experimental evaluation of a tide prediction display based on the ecological interface design framework Thierry Morineau Æ Eric Beuzet Æ Alain Rachinel Æ Laurence Tobin
Received: 20 December 2006 / Accepted: 28 June 2007 / Published online: 1 September 2007 Springer-Verlag London Limited 2007
Abstract This study evaluates whether the approach of ecological interface design (EID) can be applied to natural systems. Whereas the EID has proved its worth in a number of studies done at interfaces for complex artificial systems, its application to natural systems is just emerging. A display was designed for tide predictions. This new tidal display, referred to as the ecological document (ED), was evaluated against a classical table format and a commercially available graphical display, to assess the cognitive contribution of the ED to user performance for maritime novices and experts. The results are that the ED leads to less misreading, shorter response times, and a subjective preference among novices and experts. In particular, response times to questions concerning abstract functions of the domain decrease with the use of the ED. Thus, a document reflecting the domain can significantly improve information retrieval, and in particular cognitive processing on abstract functions. Keywords Ecological interface design Natural system Tide prediction display Evaluation
1 Introduction The many activities that tie humans to sea (sailing, fishing, aquafarming, etc.) are strongly dependent on the natural astrophysical phenomenon of the tide. However, the complexity of this crucial maritime information has led to incidents and deadly accidents particularly among sailors T. Morineau (&) E. Beuzet A. Rachinel L. Tobin University of Southern Brittany, Vannes, France e-mail:
[email protected]
(Desgagne´s 2000) and shell pickers (Health and Safety Executive 2004), who drown because they fail to anticipate the rise of water. Explanations of such accidents traditionally focus on the individuals concerned, citing their lack of experience at sea, or their lack of vigilance. However, from an ergonomic viewpoint, we question not individuals but the information used to characterize the tide. We believe that some incidents relate to poor presentation of information. The amateur may not have a clear mental representation of expected tides because of an unsuitable display of tide predictions. Our objective is to provide sea users with a better information system to avoid such human error. To cope with this challenge, we think that it is necessary to render the natural constraints coming from the tide more visible. Our general hypothesis is that if users saw the features of the tide phenomenon more clearly through an improved tidal document, they would be less prone to errors of reading, and would have a better situation awareness concerning this natural process. In cognitive ergonomics research, the cognitive engineering framework is particularly well fitted as regards this objective and hypothesis. Cognitive engineering proposes to match the ecological constraints coming from a work domain with cognitive constraints coming from the agents involved in the work system (Rasmussen 1986; Vicente 1999). The priority given to the display of domain constraints through systems and user interfaces to achieve a better performance of the work system led researchers to develop a methodology of interface design, called ecological interface design (EID). The purpose of EID is to represent the work-domain constraints elicited during a work-domain analysis in such a way that these constraints shape the agent’s behaviour as an adapted response to the domain requirements (Vicente and Rasmussen 1992). This purpose is achieved through
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two design principles: First, the functions related to the objects and properties included in the domain are modelled. Second, these domain functions are displayed in such a way that direct perception of them and the constraints that they bring is facilitated. The first ecological interface designed and tested was based on a microworld called DURESS and extensively used by Vicente and his colleagues to show the benefits coming from the direct perception of abstract functions of the work domain (Vicente 2002). Following this work, numerous researchers have developed ecological interfaces (see Vicente 2002 for a review). Classically, EID has been applied to sociotechnical systems as are found in aviation, medicine or nuclear plants. But recently, Burns et al. (2005) had to tackle the natural domain (sea, air and ground) in their analysis to specify the information requirements for a naval command-and-control system (a frigate). This topic led them to state that sea as a natural domain presents some particular aspects. It is an open domain, without any general purpose teleogical function to explain its presence, nor is it a controlled system. However, this natural domain shows a set of relevant functions for a frigate that must be taken into account to develop ecological interfaces for the naval system. Our purpose was to design and to test an ecological display format for tidal information. To present this research, we will first outline our analysis of the tide domain. Then, we will describe some current modes of information display in comparison with this domain analysis, and in particular in comparison with some critical functions of the domain that we elicited (see Morineau et al. 2005, for another example of the same approach). A new tidal display format will be presented next, along with the principles of its design based on the EID approach. Analysis of the different documents will allow us to propose some hypotheses. Finally, these hypotheses will be tested experimentally via evaluation by novices and experts of the new format compared with older types of tide presentations.
2 Tide domain analysis 2.1 Methodology Ecological interface design aims to make functional and physical constraints of a work domain directly perceptible through an ‘‘ecological interface’’. The first step of the design process consists in analysing the domain and describing it through a model. This model is classically depicted using two hierarchies. The abstraction hierarchy (AH) captures the means–ends relationship between different functional viewpoints on the domain. The lower
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levels of the hierarchy are concrete viewpoints of the domain components, while the higher levels are abstract descriptions of the same domain. The lower levels are means to attain the higher levels of the AH. Five levels of functionalities are described and articulated by the means– ends relationship: physical forms (location and appearance of objects), physical functions (functions associated with these objects), processes (processes in which the objects are implemented), abstract functions (laws and principles driving the subsequent processes), and general purposes (the fundamental purposes justifying the presence of the work system). Note that as Burns et al. (2005) noticed, a natural environment does not present a general purpose. The second hierarchy describing the domain is the decomposition, or ‘‘part-whole’’ hierarchy (PWH). The work domain is decomposed into aggregated entities, called subsystems and components. While the AH is based on functional links, the PWH describes structural links defining the domain. This domain modelling shares the ecological approach to cognition proposed by Gibson (1979). The work domain is seen as offering a set of affordances, i.e. environmental properties relevant for straightforward adaptation by an agent, properties that can be picked up and used to perform a task (Vicente and Rasmussen 1990). To render directly visible the domain as a set of affordances, the ecological interface must trigger perceptual and motors skills, in such way that abstract functions of the domain can be directly manipulated by users. In the Rasmussen’s taxonomy of cognitive modalities of behaviour control, called skill-ruleknowledge (SRK, Rasmussen 1986), this purpose involves the design of an interface that allows for migrating knowledge-based behaviour onto rule-based and skillbased behaviour, which reduces the user’s cognitive load when perceiving and interpreting the data on displays.
2.2 Main functions elicited from the tide-domain analysis The tide domain as a natural domain is very complex, involving the physical laws of hydrodynamic and astrophysical phenomena. The complexity of tide-domain modelling led us to use the classical abstraction hierarchy technique as a template to guide our analysis and to elicit some critical domain constraints. To analyse the tide domain, we studied relevant documents, like navigation guides (Les Gle´nans 1999). We then interviewed 15 participants, including 5 experts (one commercial fisherman, three oyster farmers, and a competition sailor) and 10 hobbyists (all shell pickers). Having description of the tide domain through a set of functions, we compared this set with information displayed
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by the classical printed table and by the graphical format with the trade name Mare´egraf. This comparison highlighted five important functions, more-or-less displayed in the above two documents, which could be improved in visibility through implementation of a more ecological format. These functions are the following: –
The monthly envelope of extreme water flows (F1: abstract function).
The tide is a continuous cyclic wave with a monthly modulation of amplitude that is experienced on the Earth as the result of the combination of various geophysical and astrophysical forces (terrestrial centrifugal and Coriolis forces, lunar and solar gravitational attraction). Knowledge about this modulation allows mariners to gain a deep understanding of the phenomenon and its evolution from day to day. For instance, it describes variations in tidal ranges (neap and spring tides). –
The daily evolution of sea level (F2: process)
This function refers to the daily change of sea level. While the long-term modulation of the flow is a global monthly function, the daily variation of sea level is a rapid process giving amongst other things, the times of the rise and fall. Information concerning this function is very important for judging the state of the tide and its current trend at a given time. –
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3 Analysis of printed tidal displays This section describes printed tidal displays commonly used in France by amateurs and some expert mariners, which will be used as a reference in our experimental evaluation. We make an initial evaluation of their ability to make directly visible the main functions elicited during our domain analysis. This evaluation leads us to present a proposal for a new ecological document.
3.1 The classical printed tide table The printed tide table is the traditional mode of presentation found in almanacs, newspapers and nautical publications (Fig. 1). The information is categorised in columns and sub-columns. The highest-level columns differentiate high and low tides. The sub-columns indicate the time of morning and evening tides (F4: physical function), and the tidal range (F3. physical function). In the table used in our experiment, colour coding highlights the evolution
Tidal range (F3: physical function)
Tidal range corresponds to the difference between the maximal low and high level attained by the tide on the shore. Classically, this variable is calculated in meter. In France, tidal range is indicated by a coefficient which varies from 20 (very low) to 120 (very high). This will be the indicator used in the documents evaluated in this research. We consider that this indicator corresponds to a physical function reflecting a particular state of the physical form of the tide. The tidal range is a critical indicator for mariners to characterise the scope of the tide. –
Tide time (F4: physical function)
The tide time is a variable associated with the sea level. It is the moment during which the level of tide is lowest or highest. –
Water flow on the shore (F5: physical form)
Mainly, the tide can be summarised as a wave on the shore. Estimates of the anticipated tidal effects can be made by reference to time and landmarks on the seabed (rocks) and man-made artefacts at sea (buoys and sticks) and as of function of indexes in the sky (full moon) and information about the weather (strength and direction of wind).
Fig. 1 The classical table format for tidal information (version used in the experiment). From the tidal predictions calculated by the SHOM. Extracted from the Internet site http://www.shom.fr. Authorisation: no. 378/2005
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of the tidal range from day to day. Thus, it gives information on the envelope of extreme water flows (F1: abstract function). However, this piece of information requires an inference in order to extract this abstract function as such. Concerning the daily evolution of sea level (F2: process), the table document yields no direct information on this function. Calculations must be made involving numerical information taken from several subcolumns. Thus, the tide tables report discrete stages of a continuous phenomenon. In industrial process monitoring, this structure corresponds to the ‘‘single-sensor, singleindicator’’ (SSSI) format, in which each individual measured parameter is presented as a distinct digital readout. This sort of display requires operators to infer relationships between parameters in order to access task-relevant properties, which are typically specified by patterns of data (Vicente and Rasmussen 1990; Christoffersen and Woods 2003). Finally, no document feature makes it possible to access information through a concrete representation of how the sea interacts with the shore (F5. physical form).
3.2 A non-classical tidal display: the Mare´egraf Addressing the difficulty of mentally picturing the continuous flow of tides, a French company developed a new presentation format called the Mare´egraf1 (Fig. 2). The Mare´egraf is a graphic display with day–time hours marked on a horizontal axis. Triangular pictograms approximate the rise and fall of the sea (F2: process). These pictograms allow the perception of information contributing to the idea that the tide is a continuous cycle of water mass flow (F1: abstract function). But, this form of display breaks the tidal curve from day to day. The mental representation of the user is enriched by the approximate analogue representation of the ebb and flow of the sea, thus obviating the need to mentally recombine the relations between numbers in a table. Note that the Mare´egraf1 only gives an incomplete iconic representation of the temporal process of water flow (F4: physical function). In most cases, the vertices of the triangles are marked with the minutes corresponding to high or low tide. But when such information is required between 10 p.m. and 4 a.m., the user must refer to the otherwise redundant traditional table on the right, which lists high- and low-water times. In the first column of the Mare´egraf1, one can read the date and two values corresponding to the tidal coefficients measuring the level of high and low tide (F3: physical function). The graphical document is an attempt at making an analogy with the tide flow (F5: physical form). The blue and yellow colours represent the sea and the sand. But this format is still an abstract graphical object composed of triangles and digits. The triangles are not sufficiently
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Fig. 2 The graphical format called Mare´egraf1 (version simplified used in the experiment). Model registred. From the tidal predictions calculated by the SHOM. Extracted from the Internet site http://www.shom.fr. Authorisation: no. 378/2005
concrete to describe the flow on the shore. Moreover, the horizontal position of the ‘‘triangular curve’’ preserves the abstract scheme of scientific figures. The triggering of skillbased behaviour by a direct perception of the domain constraints as a set of affordances requires a better contextualisation of the abstract functions and processes involved in the tide phenomenon.
3.3 The design of an ecological document for tidal information On the basis of our tide domain analysis and the criticism of the two previous document formats, we devised a new tidal presentation format, which we call the ecological document (ED, Fig. 3). The creative process was not documented per se. It took the form of several meetings between the authors. As required by the ecological interface design framework, we attempted to give direct access to the functions of the domain. Especially, we rendered the display of two critical functions, which are not sufficiently represented in
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Fig. 3 The ecological document designed for tidal information. Model registred. From the tidal predictions calculated by the SHOM. Extracted from the Internet site http://www.shom.fr. Authorisation: no. 378/2005
the table and graphical documents (see Table 1): the continuous monthly modulation of extreme of water flow (F1: abstract function) and the foreshore and water surfaces (F5: physical form).
Table 1 Direct perception of some main functions of the tide domain in the document tested
We considered the monthly modulation of water flows as an abstract function for two reasons. First, an observer cannot commonly see directly such a phenomenon in the natural environment. The monthly frequency of this modulation is too low to be observed in its continuity. Second, this temporal cycle is difficult to depict through a mental representation, since it corresponds to a dynamic and nonlinear phenomenon. An observer can access some parts of this phenomenon through the observation of more concrete critical functions: the daily evolution of sea level (F2). As a process, this can be seen during an interval of time by an observer. The perception of this temporal evolution requires making mental links between observations made at different moments. Through an external or mental representation, it can be represented as a trend of the water flow during an interval of time. In a more concrete manner, an observer can judge the tide level and tide times just at one moment. This is the level of physical functions that can be easily represented by alphanumeric data, and corresponds to a sampling of the tide process, and as such, of the cycle of water flow. As we can see, abstract function, process and physical functions of the tide domain are tied by a means–ends relationship linking different levels of abstraction. In the ED, we chose to display the monthly envelope of extreme water flows through a continuous tidal curve (F1: abstract function). This curve directly shows the cyclic fluctuation of the mass flow in the ocean. But in order to break with classical abstract scientific figures, we permuted the positions of the amplitudes and time dimensions. In the ED, the amplitude is on the abscissa and the time dimension is on the ordinate. This permutation provides the overall perceptual aspect of the ocean rising and falling on the foreshore as seen by an observer from a vantage point. In articulation with this analogical representation of the abstract function, we represented the foreshore ground in yellow (sand) and water surface in blue (F5: physical form). This concrete representation of information should facilitate its mental processing (Vicente and Rasmussen 1992). Finally, note that the ecological document shows the tide coefficient in the same way that the Mare´egraf1 through the first column near the date (F3: physical function). The rise and fall times are indicated in the extremities of the curve (F4: physical function). A new item of information is presented concerning the tide level in meters through a horizontal axis at the top of the document. However, this information was not relevant for the subsequent evaluation that we made.
Table
Mare´egraf
Ecological document
Abstract function: monthly envelope of extreme water flow (F1)
Somewhat
Somewhat
Yes
Process: daily evolution of sea level (F2)
No
Yes
Yes
Physical function: tidal range (coefficient—F3)
Yes
Yes
Yes
Yes
Yes
Yes
3.4 Hypothesis emerging from the document analysis
No
Somewhat
Yes
Table 1 sums up the gains in information given by each kind of document that we analysed with regards the five
Tide time (F4) Physical form: sea and sand (F5)
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functions elicited from and for the tide domain. Note that the table and the Mare´egraf1 sometimes give cues for perceiving certain tide-domain functions. But these cues do not correspond to a direct perception of the function. The tide table gives a cue about the temporal cycle of the mass flow through a series of colours capturing the trend towards neap- and spring-tide periods. The Mare´egraf1 yields information concerning this function through the different triangular pictograms, but without a continuous link between them. The Mare´egraf1 also attempts to give a concrete representation of the sea and sand but through the use of abstract triangles. In accordance with the EID framework, our hypothesis was that the better the presentation of the domain functions involved above, the easier the understanding of the tide information would be. Table 1 shows us that logically the ED should provide users with a better performance than the Mare´egraf1 or tide table. This latter format should lead to the poorest performance. This prediction was evaluated via the following experiment with experts and novices.
4 Experimental evaluation Forty male participants took part in this 2 (expertise) · 3 (display format) experiment. The group of experts included 18 members of the French Military Naval Academy (15 instructors and 3 officer cadets) and 2 members of the French Sailing Academy (an instructor and an advanced pupil). The mean age for this expert group was 34 years (range 22–53 years). All 20 participants had used tide schedules for professional purposes, and 13 also for water sports. Nine participants used tide predictions daily, 10 weekly and one had used them semi-annually, but all had a good knowledge of the tide process. The group of novices consisted of 20 students in Human Sciences at the University of Rennes II. The mean age for this group was 24 years (range 19–27 years). Among the novices, 16 had never used tide schedules while 4 had used them as often as twice a year. The second variable (an intra-subject variable) was the type of document. Participants were asked to extract tidal information from all three types: Ecological format, Mare´egraf, and table format.
4.1 Variables controlled The type and size of font were controlled as well as the size of each document. Each document was coloured and presented on a separate sheet. The Mare´egraf format was not familiar to any of the participants; it was as novel as the ecological document. The dates presented on each
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document were different, but all three spanned the first 15 days of a month.
4.2 Variables measured The participants were asked to answer pairs of questions involving extraction of information from each document. The first pair of questions concerned a search for basic data: tidal range (F3: physical function) and high- or lowtide time (F4: physical function), with the following forms: (1) and (2) Coefficient questions (F3): ‘‘During these 15 days, what is the smallest [greatest] tide coefficient?’’ (3) and (4) Tide time questions (F4): ‘‘What are the high- [low-] tide times for the 4th of the month?’’ The next pair of questions concerned a search for abstract information involving the monthly envelope of extreme water flow (F1: abstract function), and the daily evolution of sea level (F2: process), i.e. two functions which had been influential in our ecological document design. The questions were: (5) and (6) Daily evolution of sea level questions (F2): ‘‘On the 5th, find the time span during which the tide rises [falls].’’1 (7) Navigation question (F1): ‘‘On the 10th, a sailing ship wants to leave the port in the morning after 6 a.m., with the outgoing tide. At what times can it leave?’’ Like previous questions on temporal flows, navigation problems require a representation of a temporal span. But, while previous questions just required the detection of the duration of a flow, these problems involve the determination of a span subject to a constraint. Navigation problems also involve a mechanism of the tide process, which assumes that a sailing ship leaves a port with the help of the falling sea. The other question was formulated as follows: (8) ‘‘On the 10th, a sailing ship wants to arrive at the port in the afternoon, before 7 p.m., with the rising tide. At what times can it arrive?’’ Finally, participants were asked to rank the three document formats by order of preference and to fill in a questionnaire concerning age, etc., and frequency of prior experience with tide schedules. These eight questions correspond to typical examples of tide display use. Each participant answered 25 questions (8 questions * 3 documents + 1 question of preferential choice) and filled in a questionnaire.
1
When answering question (5, tide rising time span) with the Mare´egraf1, the exact information is neither provided by the rough triangles nor by inserted minutes for the low tide. Although one is put on the right track, the precise answer can only be given by resorting to the side table.
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4.3 Procedure
Table 2 Global mean number of errors, mean response times and format preference rankings as a function of expertise and document
The experiment lasted approximately 20 min per participant. Before the beginning of the experiment, the three documents were presented to the participants. The use the Mare´egraf1 and the ecological document were explained through an example. Display of questions and response-time measurement were done using software designed with the HyperCard language (AppleTM). Questions were displayed following an experimenter’s mouse click. This click also started a stop watch measuring time in 1/60th of a second. The order of presentation of the three tide formats was permuted between participants in order to eliminate any order effects. The order of the questions was randomized, except for the first question for each format, which was always a simple question about tide coefficients in order to introduce the participants to each format gently. Once the subject had given an oral answer, the experimenter clicked again, which stopped the timer and recorded the response time in a data base. A second experimenter noted on a grid whether the answers were correct.
Group
5 Results We made ANOVA analyses concerning the average response time and number of errors made for each kind of AH question. We made a non-parametric analysis concerning the document preferences using Wilcoxon’s test for within-subject comparison and Mann–Whitney’s test for between-subject comparisons.
5.1 Reading errors The error rate allowed us to differentiate experts and novices through an ANOVA analysis, F(1,114) = 4.0, MSE = 0.6, P \ 0.01. The novices made significantly more errors (mean = 0.7 errors) than experts (mean = 0.3). Moreover, we observed a powerful effect of the document variable, F(2,114) = 4.5, MSE = 0.6, P \ 0.02, but no interaction between the ‘‘expertise level’’ and ‘‘document’’ variables despite a certain trend, F(2,114) = 1.8, MSE = 0.6, P = 0.18. Table 2 shows that on average the use of the ecological document allowed novices to perform an information search with the same reliability as experts, but because of the strong dispersions, much larger sample sizes would be needed to reveal any difference, if present. A post hoc Tukey’s HSD test on the data from all participants revealed an overall significant difference in numbers of errors between the ED (mean = 0.2 errors) and the tabular format (mean = 0.7, P \ 0.02), but not between the ED and the Mare´egraph or between the Mare´egraph
Mean
SD
n
1.0
1.1
20
0.9
1.1
20
0.2
0.4
20
Table Mare´egraph
0.5
0.6
20
0.3
0.6
20
ED
0.2
0.5
20
16
Mean number of errors Novice Table Mare´egraph ED Expert
Mean response times in second Novice Table Mare´egraph
17.3
5.0
17.6
3.7
16
ED
13.9
3.2
20
Table Mare´egraph
16.0
7.0
20
16.6
5.0
20
ED
12.2
4.0
19
Group
Median
Mode
n
20
Expert
Format preference ranking Novice Table Mare´egraph
2
2
3
3
20
ED
1
1
20
Table Mare´egraph
3
3
20
2
2
20
ED
1
1
20
Expert
The mean response times presented here concern only correct responses to the AH questions
and the table format. Finally, concerning the number of errors as a function of the kind of question posed (tide time, coefficient, daily evolution of sea level, navigation), we did not find any particular effect. However, we noticed some indication of an expertise effect on the daily evolution indicator, F(1,114) = 3.7, MSE = 0.2, P = 0.06, and navigation indicator, F(1,114) = 3.7, MSE = 0.2, P = 0.06. The experts made less errors than novices on these two variables which correspond to the abstract functions specifically implemented in the ED.
5.2 Response times We carried out an ANOVA analysis on the response times by excluding the incorrect answers which in cognitive
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terms are not comparable with correct answers (Table 2). Let us recall that these response times include the differing times required to read the question—the questions on navigation in particular, took significantly longer to read. In contrast with the error rate, no significant difference is apparent between experts and novices in global response times, F(1,105) = 2.0, MSE = 23.6, P = 0.17. We observed an effect of the document format, F(2,105) = 7.9, MSE = 23.6, P \ 0.0007. The ecological document yielded significantly better response times (global mean = 13.0 s) than the other two formats, which did not differ significantly (Mare´egraph, mean = 17.1, P \ 0.002; table, mean = 16.7, P \ 0.007). We also noticed no interaction between the two factors, F(2,105) = 0.05, MSE = 23.6, P = 0.95.
5.2.1 Response times to questions on coefficients and tide times (physical functions) Whilst significant differences were not observed for questions about tide coefficients, we found a significant effect of the document variable for questions about tide times, F(2,113) = 6.6, MSE = 13.3, P \ 0.003. A post hoc analysis showed that the Mare´egraf led participants to greater response times (mean = 12.7 s) than with the table format (mean = 10.2 s, P \ 0.008) and with the ecological format (mean = 10.1 s, P \ 0.006).
5.2.2 Response times to daily evolution of sea level questions (process) Concerning responses involving daily evolution of sea level issues, we found a significant effect of expertise, F(1,109) = 4.9, MSE = 26.8, P \ 0.03. Experts showed better response times (mean = 13.1 s) than novices (mean = 15.2 s). Document type had a significant effect, F(2,109) = 12.7, MSE = 26.8, P \ 0.0001, but there was no interaction between these factors. Post-hoc analysis showed an advantage arising from the ecological document (mean = 10.9 s) compared to the tabular format (mean = 16.7 s, P \ 0.0002) and the Mare´egraph (mean = 15.1, P \ 0.002).
5.2.3 Response times to navigation questions (abstract function) Like for the daily evolution questions, we expected to find an effect of expertise on response time for navigation questions. This was not the case. We did find an effect for document type, F(2,111) = 4.5, MSE = 139.9, P \ 0.02.
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This effect was due to the benefit coming from the use of the ED (mean = 21.9 s) in comparison with the table (mean = 28.5 s, P \ 0.05) and the Mare´egraph format (mean = 29.0 s, P \ 0.03). 5.3 Format preferences As indicated from Table 2, rankings show that participants as a whole preferred the ED format, mainly ranking it first, while the other two formats ranked equally on average. Statistical tests validate this description: the ED was significantly better placed than the Mare´egraph (Wilcoxon’s test: T = 104, z = 4.1, P \ 0.0001), and the table (T = 115, z = 4.0, P \ 0.0001), whereas we noted no significant difference between the Mare´egraph and table. However, experts and novices had different second and third preferences. Experts preferred the Mare´egraph over the tabular format, but for novices it was the other way round. This difference was significant (Man-Whitney’s test: U = 124.5, z = 2.2, P = 0.03). 6 Discussion To summarize, this study shows that the ED is an information format that is more reliable (less error-prone) and more efficient (better response time) than the classical data table. The Mare´egraph format, which makes some functions more visible than the table, but less than the ecological document, globally occupied a middle position between the two others. These results illustrate that an EID framework based on functional analysis of the domain to guide the tool design provides a means to develop a better information system. The ED results in faster response times for issues concerning process and abstract function of the domain. Thus, the ecological format specifically improves the search for abstract information. This result is congruent with results obtained during problem-solving with EID (Vicente 2002; Terrier and Cellier 1999). Conversely, the ED does not reduce response times for searches for more concrete information (coefficient and tide time data—physical functions). This could be explained by the fact that this kind of basic information does not benefit from the enrichments made within the Ecological Document. We found that the Mare´egraph format can lengthen response times, presumably due to the spatial dissociation of hours and minutes. The preference attached to the ED by all participants indicates that despite its novelty, it can replace the traditional tabular format. This result is interesting because some research has shown that user habits can hinder the acceptability of new interfaces (Jungk et al. 1999). In fact, display formats similar to our ED are already popular elsewhere (e.g.
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OceanFun Publishing 2006), and incorporate additional items from the tide domain such as phase of the moon, sunrise and sunset, and even fishing prospects. A continuous representation of the sea level becomes particularly pertinent for places such as Los Angeles where the diurnal and semidiurnal tide strengths are similar, with the result that alternate tides can have very different amplitudes. Despite our promising results, we must note that effects of the modelling of some abstract function of the tide domain on the experimental results are embedded within another factor involving the creative activity leading to the design of this particular ecological document. A creative gap exists between functional modelling and the design process (Jansson et al. 2006). That could be studied through the comparison of several tidal ecological interfaces for instance. Also, the current ecological document could be improved and enriched with some others abstract functions of the domain. One example is the sun and moon position, since there are simple rules for mid-latitudes like ‘‘the tide is high when the moon is near the horizon’’. Indeed, our ED is not ‘‘a pure example of EID’’ (Vicente 2002, p. 64). The display content does not represent all of the information identified by the domain model. Dynamic presentation of some other functions could be implemented via an electronic display like the Electronic Chart Display and Information Systems for example. Acknowledgments We are very grateful to Professor William Wong, University of Middlesex, UK, for having significantly contributed to the improvement of this work. We thank the French Military Naval Academy for their participation in this study. We express special gratitude to Lieutenant de Vaisseaux Dupont and Thomas Devogele of the Naval Academy Research Institute (IRENAV). We also thank the French National Sailing Academy (Mr. Mourrot). Many thanks to the 55 participants. Finally, this study would not have been possible without the authorisation of Mr J. M. Pierre (‘‘Le Mare´egraf’’) and that of the French National Hydrographic Office (SHOM): Authorisation no. 378/2005. This study was partly financed by MARSOUIN Research Group funds.
References Burns CM, Bryant DJ, Chalmers BA (2005) Boundary, purpose, and values in work-domain models: models of naval command and control. IEEE Trans Syst Man Cybern 35:603–616
127 Christoffersen K, Woods D (2003) Making sense of change: the challenge of events in operations environments [on line]. Available: http://www.csel.eng.ohio-state.edu/woods/CTA_Studies/ MSoC2.1.pdf Desgagne´s H (2000) Statistiques sur les incidents de recherche et de sauvetage. Re´gion Laurentienne. Statistics on incidents and rescue. Laurentienne area [on line]. Available: http://www.marinfo. gc.ca/fr/statistiques/2000/RapportStatistique00_francais.pdf Gibson EJ (1979) The ecological approach to visual perception. Houghton Mifflin, Boston Health and Safety Executive (2004) Guidelines for safe working in estuaries and tidal areas when harvesting produce such as cockles, mussels and shrimps [on line]. Available: http://www. hse.gov.uk/pubns/estuary.htm Les Gle´nans (1999) Le nouveau cours des Gle´nans. The new course of Gle´nans. Cinquie`me e´dition, Seuil, Paris Jansson A, Olsson E, Erlandsson M (2006) Bridging the gap between analysis and design: improving existing driver interfaces with tools from the framework of cognitive work analysis. Cogn Technol Work 8:41–49 Jungk A, Thull B, Hoeft A, Rau G (1999) Ergonomic evaluation of an ecological interface and a profilogram display for hemodynamic monitoring. J Clin Monit Comput 15:469–479 Morineau T, Blanche C, Tobin L, Gue´guen N (2005) The emergence of the contextual role of the e-book in cognitive processes through an ecological and functional analysis. Int J Hum Comput Stud 62:329–348 OceanFun Publishing (2006) Tide times pocketbooks, solunar times, and tide calendars [on line]. Available: http://www.ofu.co.nz Pejtersen AM, Rasmussen J (1997) Ecological information systems and support of learning: coupling work domain information to user characteristics. In: Helander M, Landauer TK, Prabhu P (eds) Handbook of human–computer interaction, 2nd edn. Elsevier Science, Amsterdam, pp 315–346 Pillich B (1997) Tidal overlay and dynamic ECDIS: a giant step from paper chart and tide tables. OCEANS’97, MTS/IEEE conference proceedings, vol 2, pp 967–973 Rasmussen J (1986) Information processing and human–machine interaction: an approach to cognitive engineering. North-Holland, New York Terrier P, Cellier JM (1999) Depth of processing and designassessment of ecological interfaces: task analysis. Int J Hum Comput Stud 50:287–307 Vicente KJ (1999) Cognitive work analysis, toward safe, productive and healthy computer-based work. Erlbaum, Mahwah, NJ Vicente KJ (2002) Ecological interface design: process and challenges. Hum Factors 44:62–78 Vicente KJ, Rasmussen J (1990) The ecology of human machine systems II: mediating ‘‘direct perception’’ in complex work domain. Ecol Psychol 2:207–249 Vicente KJ, Rasmussen J (1992) Ecological interface design: theoretical foundations. IEEE Trans Syst Man Cybern 22:589– 606
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