Supporting inferences in space – A wayfinding task in amultilevel building
Carsten P. J. Gondorf 1, Cui Jian2
1

Transregional Collaborative Research Center SFB/TR 8 Spatial Cognition, University of Bremen,
Enrique-Schmidt-Str. 5, D-28359 Bremen, Germany
1
gondorf@uni-bremen.de, 2ken@informatik.uni-bremen.de

Abstract. The explorative study presented in this paper investigates indoor wayfinding strategies and inferences of users in an unknown building. Participants wereasked to find two consecutive targets in a multilevel building with the help of written
route instructions. Routes were generated by a dialogue system and tested against
adjusted instructions containing additional architectural information. The empiricalfindings suggest that selectively adding structural information can help (1) to build up
a participant’s cognitive map and support inferences about returning paths, (2) aguidance system optimize its wayfinding process to avoid redundancy with respect tothe human-friendly principle, and (3) to improve to a great extent the effectivenessand efficiency of the system itself, and generate more adaptive and intuitive routeinstructions.
Keywords: indoor wayfinding strategies, spatial inferences, cognitive map

1Introduction

The purpose of the study was to test whether selectively adding information about thearchitectural structure of a building to a set of instructions provides additional inferences
about the returning path, leading the user to choose another, perhaps shorter way back.
As for the instructions we used a dialogue system that automatically generates indoor
route instructions when asked about locations, using text-based natural language input andoutput (cf. [2]). We are interested in how the behavioral findings could help (1) to improveroute instruction generation according to cognitive principles underlying human routedescriptions [6], and (2) to improve, to some extent, the effectiveness and efficiency of thesystem itself and generate more adaptive and intuitive route instructions.
Recent approaches to indoor wayfinding have encountered difficulties in theirinvestigation in conference centers [3], libraries [1], and others. Hölscher et al. [4, 5] forinstance, suggest the following taxonomy in cases of incomplete spatial information forcomplex multilevel buildings (a) central point strategy – more likely to be used by firsttime-visitors/unexperienced users – hanging on to well-known parts of the building (e.g.
main entry hall, main stairs etc.); (b) direction strategy; (c) floor strategy.
According to Kuipers [7] places can be connected by associated movement responses;
concatenating such place recognition-triggered responses then constructs a linear route. If
two or more crossing routes are merged together, a network occurs, i.e. an internal mental
representation of the environment. This representation is dynamic enough to describe
intuitive spatial relationships and relative positions of places.

2Infokiosk

The written instructions given in-advance were derived from a dialogue system – called
Infokiosk – which was developed and implemented in our research group I5-DiaSpace.

The route instructions generator of the current system runs on a combined computationalmodel that consists of three sequential processing steps:• GUARD (Generation of Unambiguous, Adapted Route Directions, cf. [2]) generates
the “context-specific” low level route directions out of raw route paths that lead to agiven destination.
• GOHLI (Generation of High Level Instructions, cf. [2]) segments the low-level route
directions coming from GUARD and generates the high-level route instructions on
the basis of major direction changes.
• GOSLRI (Generation of Structuring Landmarks Related Instructions), which is theprimary focus in this paper, takes high-level route instructions from GOHLI as input,
and generates High-level structuring landmarks-based route instructions.

3Experiment32 participants (20 women/12 men) with little or no prior familiarity were asked toundertake wayfinding tasks in a multi-level building (GW2 – University of Bremen). They
were all German native speakers and university students with an average age of 22.91 (agerange 20-35, SD=4.518). For participation they received either course credit or were paid
€6 Euro each. With the given detailed written paper-based route instructions, they had tofind two consecutive targets - as well as their way back to the starting point.

Fig. 1. Map views of the test environment, GW2, University of Bremen. (a) Shows building
segments A/B, 1st and 2nd floor. Continuous lines indicate the path from the start point to first target(T1) and to target (2a) and (2b) on 2nd floor; dashed lines present a continuum of chosen returning
paths. (b) Block scenario on 2nd floor.

Instructions were always given with respect to the point of departure. The movement
commands in the instructions were all aligned to an egocentric frame of reference, e.g.
"Turn around and go straight until the next hallway on the left-hand side." Adjusted
versions were preceded by a short description, containing the floor and section of thebuilding, in or on which the target is determined. Furthermore and most importantly for thescenario, on the 2nd floor we provided the explicit naming of an additional structuringpath+landmark: go around the block. The block is a salient, structuring element of thisparticular environment (22x7meter), already perceivable while going up the stairs (see Fig.
1b).
The first target to reach was situated on the 1st floor and stayed the same for each subject– room B1620. The only difference was that each participant was given only either asystem-generated (IS) or an adjusted instruction (IA). The second goal was on the 2nd floorand was divided into target (2a), room A2420, and target (2b), room A2500 (see Fig. 1b) –selection was done by taking into account the block structure and visibility of the stairs.
That is, participants with target 2b had to walk further around the block (see Fig. 1b). The
transition took place at a staircase in building segment A. The task started and ended on the1st floor at room B1420. For this, as well as for the whole wayfinding task the users wereinstructed to think aloud and verbalize their thoughts and considerations. After reachingtarget (2a/b) the participants were instructed to hand back the instructions and walk to thestarting point (they were not given any restrictions or assignments). After the task wascompleted, each participant was asked to fill two questionnaires – one for individual
differences in spatial orientation, and the other asked about the performed task.

4Results

All participants reached the two described targets (1, 2a/b) and got back to the starting
point. By coding the chosen paths back by total numbers it was feasible to apply a set of
nonparametric tests to the collected data. Analysis was carried out particularly for the typeof instruction, i.e. target to reach on 2nd floor (T2a/b), and floor.
A total number of 23 participants chose the same returning path on the 2nd floor. Just 6
out of 32 participants continued walking around the block and used it as shortcut on the 2ndfloor – 5 of them got the adjusted instruction (Target 2b) vs. one with a system generated
instruction (T2b). A chi-square test was used for analysis based on floors and bycomparable conditions, i.e. IS1 → T2a vs. IA1 → T2a on the one hand, and IS2 → T2b vs.
IA2 → T2b on the other hand. For 1st floor for conditions IS(1) and IA(1) from target (2a)to the starting point (χ2 =1.3, df=4, p>0.85; Cramér's V=0.28), and for IS(2) and IA(2) fromtarget (2b) ((χ2 =0.34, df=2, p>0.84; Cramér's V=0.14). For 2nd floor from target (2a) (χ2=1.1, df=2, p>0.58; Cramér's V=0.25), from target (2b) ((χ2 =4.26, df=1, p<0.05; Cramér's
V=0.51). This result supports the above described distribution of returning paths by total
numbers for respective floors. Participants who handed out instruction IA2 were more
likely to take the shortcut on their way back on 2nd floor in order to reach the stairs, i.e. togo back to the starting point, compared with their counterparts with IS(2).
This holds also for the evaluation of the walking distance of IS(2) compared with IA(2).
A one-way ANOVA revealed a significant effect for walking distance on 2nd floor: F (1,14)=5.091, p<0.05; η2=0.27. This is mainly due to the fact that 7 out of 8 participants incondition IS(2) chose the same and thus longer returning path (~29.4m) – compared to 3 incondition IA(2). The shortcut (~21m) further around the block and thus in the direction of
the stairs was selected by four participants in both conditions.
Participants’ walking paths used for their return on the 1st floor back to the starting point
showed a wide continuum of total returning paths across all conditions (see Fig.1a). Thissuggests a combination of central-point strategy and recognition-triggered response. The
first review of the elicited data confirmed the behavioral findings for 1st floor: the centralpoint strategy was applied by 17 and recognition-triggered response by 13 people.
Furthermore, the analysis of question (9a) of the general questionnaire revealed, thatparticipants who started with the system generated instruction (IS2) would change their
walking preferences if confronted with a bird’s-eye view of the scenario on the 2nd floor.
Six out of eight would choose the shortcut (χ2 =8.0, df=2, p<0.05; Cramér's V=1.0).

5Discussion

The task was to reach two consecutive targets in a multilevel building with the help of agiven route instruction. Both types of instruction served their purpose – all participantssuccessfully reached their respective target on the 2nd floor and starting point. The
qualitative analyses support the assumption that, due to the additional structural cue block +path, the participants built up (or faster updated) a more detailed internal mental
representation of the environmental setting and thus were more likely to choose another,
shorter returning path.
Therefore, the presented block structure is believed to be a good landmark, regarding thechoice of a cognitively efficient return path. This in turn could be utilized for the generationof route descriptions by the presented guidance system. By accordingly annotating maps
and implementing these kind of block structures as salient structuring landmarks it is not
only possible to save user/body turns and make the generated adaptive instructions briefer
and thus easier to recall, but also help novice building users with this cue to build up (i.e.
faster update) their internal mental representation.
One key feature of an adaptive wayfinding guidance system is that, route instructions
should be generated according to the cognitive principles underlying human routedescriptions [6]. However, good general cognitive principles that can provide useful
wayfinding information specifically suitable to human users within certain situations are infact very difficult to discover. The empirical finding involving structuring landmarks suchas blocks in this paper can help a guidance system optimize its wayfinding process to avoid
redundancy with respect to the human-friendly principle, and therefore, improve to a great
extent the effectiveness and efficiency of the system itself and generate more adaptive andintuitive route instructions. Specific landmarks such as blocks will be instantiated as salient
structuring landmarks and used by the GOSLRI component to generate high-levelstructuring landmark-based route instructions.
Further research will address the degree of complexity and accuracy regarding additionalarchitectural information implemented in indoor wayfinding instructions, e.g. regarding
block size etc.

Acknowledgments
Thanks go to the German Science Fund (DFG) for funding and the research team of I5DiaSpace of SFB/TR8 Spatial Cognition at the University of Bremen.

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