Threshold Differences on Figure and Ground: Gelb and Granit (1923)

In 1923, Gelb and Granit, using a method of adjustment for a small red light, reported a lower threshold for the target when presented on a ground region than on an adjacent figural region. More recent work in perceptual organization has found precisely the opposite-a processing advantage seems to go to items presented on the figure, not the ground. Although Gelb and Granit continue to be cited for their finding, it has not previously been available as an English translation. Understanding their methodology and results is important for integrating early Gestalt theory with more recent investigations

Together apart: the influence of increased crowd heterogeneity on crowd dynamics at bottlenecks

Individual differences in mobility (e.g., due to wheelchair use) are often ignored in the prediction of crowd movement. Consequently, engineering tools cannot fully describe the impact of vulnerable populations on egress performance. To contribute to closing this gap, we performed laboratory experiments with 25 pedestrians with varying mobility profiles. The control condition comprised only participants without any additional equipment; in the luggage condition and the wheelchair condition, two participants at the center of the group either carried suitcases or used a wheelchair. We found that individuals using wheelchairs and to a lesser degree those carrying luggage needed longer to pass through the bottleneck, which also affected those walking behind them. This led to slower times to fully clear the bottleneck in the wheelchair and luggage condition compared to the control group. The results challenge the status quo in existing approaches to calculating egress performance and other key performance metrics in crowd dynamics

Exploring Perceived Vulnerability of Pedestrians: Insights from a Forced-Choice Experiment

Individual differences in mobility (e.g., due to wheelchair use) during crowd movement are not well understood. Perceived vulnerability of neighbors in a crowd could affect, for example, how much space is given to them by others. To explore how pedestrians perceive people moving in front of them, in particular, how vulnerable they believe them to be, we asked \SI{51}{} participants to complete a Two-Alternatives-Forced Choice task (2AFC) in an internet browser. Participants were shown pairs of images, each showing a person, and then asked to select the person who appeared more vulnerable to them. For example, participants would choose between a male person in a wheelchair and a female person carrying a suitcase. In total 16 different stimuli (male vs female; no item/device, 1 suitcase, 2 suitcases, small backpack, large backpack, stroller, cane, and wheelchair), yielding n(n-1)/2 = 120 potential pairwise comparisons per participant. Results showed that wheelchair users appeared the most vulnerable and persons without any items/devices the least vulnerable. Persons carrying two suitcases were in the middle. These results informed the design of a main behavioral study (not reported here)

The Effect of Non-lexical Verbal Signals on the Perceived Authenticity, Empathy and Understanding of a Listener

Active listening plays an important role in the relationship between clients and therapists. Here, we investigated whether variations of the confirmatory nonlexical verbal communication signal "mmh" influenced perceived authenticity, empathy and understanding of a listener. Eighty-one participants were in a conversation with an interviewer and reported about a difficult work experience. They were randomly assigned to one of three groups: The control group did not receive any verbal feedback from the interviewer; In one experimental group (1x-mmh), the interviewer uttered several monosyllabic confirmatory nonlexical verbal signals ("mmh") during the presentation; In a second experimental group (3x-mmh) the interviewer voiced several three syllable "mmh-mmh-mmh" while listening. All participants were then asked to rate the perceived authenticity, empathy and understanding of the interviewer. Participants in the 3x-mmh condition rated the interviewer to be significantly less authentic than those in the other two groups. No differences in reported empathy and understanding were found. The use of consecutive confirmatory nonlexical verbal signals ("mmh") - at least as currently implemented - may influence the perceived authenticity of a listener

An augmented reality sign-reading assistant for users with reduced vision

People typically rely heavily on visual information when finding their way to unfamiliar locations. For individuals with reduced vision, there are a variety of navigational tools available to assist with this task if needed. However, for wayfinding in unfamiliar indoor environments the applicability of existing tools is limited. One potential approach to assist with this task is to enhance visual information about the location and content of existing signage in the environment. With this aim, we developed a prototype software application, which runs on a consumer head-mounted augmented reality (AR) device, to assist visually impaired users with sign-reading. The sign-reading assistant identifies real-world text (e.g., signs and room numbers) on command, highlights the text location, converts it to high contrast AR lettering, and optionally reads the content aloud via text-to-speech. We assessed the usability of this application in a behavioral experiment. Participants with simulated visual impairment were asked to locate a particular office within a hallway, either with or without AR assistance (referred to as the AR group and control group, respectively). Subjective assessments indicated that participants in the AR group found the application helpful for this task, and an analysis of walking paths indicated that these participants took more direct routes compared to the control group. However, participants in the AR group also walked more slowly and took more time to complete the task than the control group. The results point to several specific future goals for usability and system performance in AR-based assistive tools.Peer reviewed: YesNRC publication: Ye

New approaches to evacuation modelling for fire safety engineering applications

This paper presents the findings of the workshop “New approaches to evacuation modelling”, which took place on the 11th of June 2017 in Lund (Sweden) within the Symposium of the International Association for Fire Safety Science (IAFSS). The workshop gathered international experts in the field of fire evacuation modelling from 19 different countries and was designed to build a dialogue between the fire evacuation modelling world and experts in areas outside of fire safety engineering. The contribution to fire evacuation modelling of five topics within research disciplines outside fire safety engineering (FSE) have been discussed during the workshop, namely 1) Psychology/Human Factors, 2) Sociology, 3) Applied Mathematics, 4) Transportation, 5) Dynamic Simulation and Biomechanics. The benefits of exchanging information between these two groups are highlighted here in light of the topic areas discussed and the feedback received by the evacuation modelling community during the workshop. This included the feasibility of development/application of modelling methods based on fields other than FSE as well as a discussion on their implementation strengths and limitations. Each subject area is here briefly presented and its links to fire evacuation modelling are discussed. The feedback received during the workshop is discussed through a set of insights which might be useful for the future developments of evacuation models for fire safety engineering

Roxborough park community wildfire evacuation drill: data collection and model benchmarking

Wildfires are increasing in scale, frequency and longevity, and are affecting new locations as environmental conditions change. This paper presents a dataset collected during a community evacuation drill performed in Roxborough Park, Colorado (USA) in 2019. This is a wildland-urban interface community including approximately 900 homes. Data concerning several aspects of community response were collected through observations and surveys: initial population location, pre-evacuation times, route use, and arrival times at the evacuation assembly point. Data were used as inputs to benchmark two evacuation models that adopt different modelling approaches. The WUI-NITY platform and the Evacuation Management System model were applied across a range of scenarios where assumptions regarding pre-evacuation delays and the routes used were varied according to original data collection methods (and interpretation of the data generated). Results are mostly driven by the assumptions adopted for pre-evacuation time inputs. This is expected in communities with a low number of vehicles present on the road and relatively limited traffic congestion. The analysis enabled the sensitivity of the modelling approaches to different datasets to be explored, given the different modelling approaches adopted. The performance of the models were sensitive to the data employed (derived from either observations or self-reporting) and the evacuation phases addressed in them. This indicates the importance of monitoring the impact of including data in a model rather than simply on the data itself, as data affects models in different ways given the modelling methods employed. The dataset is released in open access and is deemed to be useful for future wildfire evacuation modelling calibration and validation efforts.This study was supported by National Institute of Standards and Technology, U.S. Department of Commerce under award 60NANB18D255. The EMS was developed by the University of Cantabria within the ASSISTANCE project funded by the European Union’s H2020 research and innovation programme under grant agreement No. 832576

Sozialer Einfluss in Notfallsituationen - Studien in virtueller Realität

In 1999, a tragic catastrophe occurred in the Mont Blanc Tunnel, one of the most important transalpine road tunnels. Twenty-seven of the victims never left their vehicles as a result of which they were trapped in smoke and suffocated (Beard & Carvel, 2005). Immediate evacuation is crucial in tunnel fires, but still many tunnel users stay passive. During emergency situations people strongly influence each other’s behavior (e.g. Nilsson & Johansson, 2009a). So far, only few empirical experimental studies investigated the interaction of individuals during emergencies. Recent developments of advanced immersive virtual worlds, allow simulating emergency situations which makes analogue studies possible. In the present dissertation project, theoretical aspects of human behavior and SI in emergencies are addressed (Chapter 1). The question of Social Influence in emergency situations is investigated in five simulation studies during different relevant stages of the evacuation process from a simulated road tunnel fire (Chapter 2). In the last part, the results are discussed and criticized (Chapter 3). Using a virtual reality (VR) road tunnel scenario, study 1 (pilot study) and 2 investigated the effect of information about adequate behavior in tunnel emergencies as well as Social Influence (SI) on drivers’ behavior. Based on a classic study of Darley and Latané (1968) on bystander inhibition, the effect of passive bystanders on self-evacuation was analyzed. Sixty participants were confronted with an accident and smoke in a road tunnel. The presence of bystanders and information status was manipulated and consequently, participants were randomly assigned into four different groups. Informed participants read a brochure containing relevant information about safety behavior in emergency situations prior to the tunnel drives. In the bystander conditions, passive bystanders were situated in a car in front of the emergency situation. Participants who had received relevant information left the car more frequently than the other participants. Neither significant effect of bystanders nor interaction with information status on the participants’ behavior was observed. Study 3 (pilot study) examined a possible alternative explanation for weak SI in VR. Based on the Threshold Theory of Social Influence (Blascovich, 2002b) and the work of Guadagno et al. (2007), the perception of virtual humans as an avatar (a virtual representation of a real human being) or as an agent (a computer-controlled animated character) was manipulated. Subsequently, 32 participants experienced an accident similar to the one in study 1. However, they were co-drivers and a virtual agent (VA) was the driver. Participants reacted differently in avatar and agent condition. Consequently, the manipulation of the avatar condition was implemented in study 4. In study 4, SI within the vehicle was investigated, as drivers are mostly not alone in their car. In a tunnel scenario similar to the first study, 34 participants were confronted with an emergency situation either as drivers or co-drivers. In the driver group, participants drove themselves and a VA was sitting on the passenger seat. Correspondently, participants in the co-driver group were seated on the passenger seat and the VA drove the vehicle on a pre-recorded path. Like in study 1, the tunnel was blocked by an accident and smoke was coming from the accident in one drive. The VA initially stayed inactive after stopping the vehicle but started to evacuate after ca. 30 seconds. About one third of the sample left the vehicle during the situation. There were no significant differences between drivers and co-drivers regarding the frequency of leaving the vehicle. Co-drivers waited significantly longer than drivers before leaving the vehicle. Study 5 looked at the pre-movement and movement phase of the evacuation process. Forty participants were repeatedly confronted with an emergency situation in a virtual road tunnel filled with smoke. Four different experimental conditions systematically varied the presence and behavior of a VA. In all but one conditions a VA was present. Across all conditions at least 60% of the participants went to the emergency exit. If the VA went to the emergency exit, the ratio increased to 75%. If the VA went in the opposite direction of the exit, however, only 61% went there. If participants were confronted with a passive VA, they needed significantly longer until they started moving and reached the emergency exit. The main and most important finding across all studies is that SI is relevant for self-evacuation, but the degree of SI varies across the phases of evacuation and situation. In addition to the core findings, relevant theoretical and methodological questions regarding the general usefulness and limitations of VR as a research tool are discussed. Finally, a short summary and outlook on possible future studies is presented.In der Mont Blanc Tunnel Katastrophe im Jahr 1999 starben 39 Menschen, von denen 27 nicht versucht hatten rechtzeitig zu flüchten. In der Folge wurden diese Personen vom Rauch eingeschlossen und erstickten in ihren Fahrzeugen. Bisher gibt es nur vereinzelt empirische Studien, die sich mit Fragestellungen zu menschlichem Verhalten in Gefahrensituationen beschäftigen. Noch weniger Arbeiten beschäftigen sich mit der gegenseitigen Beeinflussung von Individuen in Gefahrensituationen. Die wohl wahrscheinlichste Erklärung ist, dass es bisher kaum möglich oder zu aufwändig war, Gefahrensituationen experimentalpsychologisch zu untersuchen. Die Entwicklung immersiver virtueller Welten erlaubt es allerdings, solche Situationen ökologisch valide zu simulieren. Erstes Ziel des Promotionsvorhabens war deshalb sozialen Einfluss in virtuell simulierten Gefahrensituationen mittels experimentalpsychologischer Studien zu untersuchen. Zweites Ziel war die Untersuchung methodischer Grundlagen zur Untersuchung von sozialem Einfluss in virtueller Realität. Die Dissertation gliedert sich in drei Teile: Kapitel 1 führt zunächst in die Themen menschliches Verhalten in Gefahrensituationen, Evakuierung und sozialer Einfluss während Notfällen ein. In Kapitel 2 werden die eigenen empirischen Arbeiten dargestellt. Dabei wurde sozialer Einfluss in verschiedenen kritischen Phasen des Evakuierungsprozesses während eines Tunnelbrandes untersucht. Insgesamt wurden fünf unabhängige Erhebungen mit insgesamt 194 Studienteilnehmern durchgeführt. Studie 1 (Vorstudie) und 2 untersuchte den sozialen Einfluss passiver virtueller Bystander sowie den Effekt von Informationen auf das Fluchtverhalten. Die Probanden wurden mit einem Unfall und sich ausbreitendem Rauch in einem Straßentunnel konfrontiert. In einer Probandengruppe befanden sich passive Bystander am Unfallort. Die Ergebnisse zeigten erstens, dass nur wenige uninformierte Probanden überhaupt das Fahrzeug verließen um aus sich zum Notausgang zu begeben. Zweitens, konnten Information das Verhalten während des Unfalls verbessern. Drittens fand sich nur ein schwacher Einfluss passiver virtueller Bystander auf das Verhalten der Probanden in der Notfallsituation. Studie 3 (Vorstudie) untersuchte eine mögliche alternative Erklärung für schwachen sozialen Einfluss in virtueller Realität. Hier wurde die Wahrnehmung virtueller Menschen als Avatar (eine von realen Menschen gesteuerte virtuelle Repräsentation) oder als Agent (vom Computer gesteuerte animierte Figuren) manipuliert. Anschließend erlebten die Probanden einen ähnlichen Unfall wie in Studie 1. Allerdings waren sie nun Beifahrer und erlebten den Unfall gemeinsam mit einem animierten virtuellen Menschen der das Fahrzeug lenkte. Probanden ließen sich eher von einer animierten Menschen beeinflussen, wenn sie überzeugt waren, dass es sich um einen Avatar handelt. Studie 4 untersuchte den Einfluss von anderen Personen im Fahrzeug auf das Verhalten in einer Notfallsituation. Dabei erlebten die Probanden die gleiche Gefahrensituation wie in Studie 1 entweder als Fahrer oder als Beifahrer. Gleichzeitig befand sich ein virtueller Agent im Fahrzeug, der sich zunächst passiv verhielt aber nach einer gewissen Zeit das Fahrzeug verließ. Es zeigte sich, dass Probanden zügiger dem Verhalten des virtuellen Agenten folgten, wenn der Agent Fahrer und die Probanden Beifahrer waren. In Studie 5 wurde das eigentliche Evakuierungsverhalten während eines simulierten Tunnelbrandes untersucht. Dabei befanden sich die Probanden wiederholt in einem stark verrauchten Tunnel und das Verhalten eines virtuellen Agenten wurde systematisch manipuliert. Die meisten Probanden suchten den Notausgang auf, jedoch zeigte sich, dass das Verhalten des virtuellen Agenten die Probanden beeinflusste: Ging der Agent in die entgegengesetzte Richtung des Notausgangs oder blieb dieser passiv, so gingen die Probanden seltener zum Notausgang und benötigten signifikant länger um diesen zu erreichen. Kapitel 3 enthält schließlich die Zusammenfassung und Diskussion der Studien. Dabei werden die Ergebnisse der Arbeit in den aktuellen Stand der Forschung eingeordnet, praktische Implikationen abgeleitet und der weitere Forschungsbedarf beschrieben. Insgesamt konnte gezeigt werden, dass sozialer Einfluss in Gefahrensituationen von Bedeutung ist, aber während verschiedener Phasen des Evakuierungsprozesses unterschiedlich stark ist. Abschließen werden die theoretischen und methodischen Kritikpunkte der Forschungsarbeiten genannt und erörtert

Social influence on evacuation behavior in real and virtual environments

Virtual reality (VR) is a promising tool to study evacuation behavior as it allows experimentally controlled, safe simulation of otherwise dangerous situations. However, validation studies comparing evacuation behavior in real and virtual environments are still scarce. We compare the decision to evacuate in response to a fire alarm in matched physical and virtual environments. 150 participants were tested individually in a one-trial experiment in one of three conditions. In the Control condition, the fire alarm sounded while the participant performed a bogus perceptual matching task. In the Passive bystander condition, the participant performed the task together with a confederate who ignored the fire alarm. In the Active bystander condition, the confederate left the room when the fire alarm went off. Half of the participants in each condition experienced the scenario in the real laboratory, and the other half in a matched virtual environment with a virtual bystander, presented in a head-mounted display. The active bystander group was more likely to evacuate, and the passive bystander group less likely to evacuate, than the control group. This pattern of social influence was observed in both the real and virtual environments, although the overall response to the virtual alarm was reduced; positive influence was comparable, whereas negative influence was weaker in VR. We found no reliable gender effects for the participant or the bystander. These findings extend the bystander effect to the decision to evacuate, revealing a positive as well as the previous negative social influence. The results support the ecological validity of VR as a research tool to study evacuation behavior in emergency situations, with the caveat that effect sizes may be smaller in VR