Eigenbehaviors: identifying structure in routine

Longitudinal behavioral data generally contains a significant amount of structure. In this work, we identify the structure inherent in daily behavior with models that can accurately analyze, predict, and cluster multimodal data from individuals and communities within the social network of a population. We represent this behavioral structure by the principal components of the complete behavioral dataset, a set of characteristic vectors we have termed eigenbehaviors. In our model, an individual’s behavior over a specific day can be approximated by a weighted sum of his or her primary eigenbehaviors. When these weights are calculated halfway through a day, they can be used to predict the day’s remaining behaviors with 79% accuracy for our test subjects. Additionally, we demonstrate the potential for this dimensionality reduction technique to infer community affiliations within the subjects’ social network by clustering individuals into a “behavior space” spanned by a set of their aggregate eigenbehaviors. These behavior spaces make it possible to determine the behavioral similarity between both individuals and groups, enabling 96% classification accuracy of community affiliations within the population-level social network. Additionally, the distance between individuals in the behavior space can be used as an estimate for relational ties such as friendship, suggesting strong behavioral homophily amongst the subjects. This approach capitalizes on the large amount of rich data previously captured during the Reality Mining study from mobile phones continuously logging location, proximate phones, and communication of 100 subjects at MIT over the course of 9 months. As wearable sensors continue to generate these types of rich, longitudinal datasets, dimensionality reduction techniques such as eigenbehaviors will play an increasingly important role in behavioral research. This contribution is part of the special issue “Social Networks: new perspectives” (Guest Editors: J. Krause, D. Lusseau and R. James). An erratum to this article can be found at     

The use of supervisory practices as leverage to improve safety behavior: a cross-level intervention model

Introduction: The paper presents three intervention studies designed to modify supervisory monitoring and rewarding of subordinates' safety performance. Method: Line supervisors received weekly feedback concerning the frequency of their safety-oriented interactions with subordinates, and used this to self-monitor progress toward designated improvement goals. Managers higher up in the organizational hierarchy received the same information, coupled with synchronous data concerning the frequency of workers' safety behaviors, and highlighting co-variation of supervisory action and workers' behavior. Results: In all the companies involved, supervisory safety-oriented interaction increased significantly, resulting in significant changes in workers' safety behavior and safety climate scores. Continued improvement during the post-intervention period suggests the inclusion of workers' safety behavior as in-role supervisory responsibility. Applied and theoretical implications are discussed.     

Visitor Response to Management Regulations—A Study Among Recreationists in Southern Norway

/ The objectives of nature area management are often twofold: To protect the natural environment and to facilitate recreational use. In order to maintain the natural setting, it is sometimes necessary to regulate the recreational use of an area. In deciding on a management action, one problem can be the lack of knowledge about the effects of management actions on visitors. In order to enhance the knowledge base for future management practices, this study empirically evaluates the effects of management regulations in a Norwegian nature area. In this area camping outside commercial campgrounds was restricted in 1992. The management regulations seems to have influenced the use of Sjodalen for camping in several ways. The number of campers using the area has decreased. The user composition seems to have changed, with new campers in the area after the regulation being more tolerant of human influence on the natural environment than the campers before the regulations. In addition, a considerable proportion of the existing users ceased to stay overnight in Sjodalen, totally or partly due to the regulations. The behavioral response among existing users is related both to environmental preferences and place attachment. Implications for management and future research studies on impact assessment in general, and displacement specifically, are discussed.KEY WORDS: Outdoor recreation; Management regulations; Behavioral response; Displacement, Place attachment     

The safety observer effect: the effects of conducting safety observations

INTRODUCTION: Some research suggests that conducting safety observations of another's safety performance may serve as an effective tool in increasing the safety performance of the observer. The primary purpose of the present study was to assess the effects of conducting safety observations on the postural safety performance of observers engaging in an assembly task for short time periods. The secondary objectives of the study were: (a) to measure productivity, and (b) to measure the accuracy of participant safety observations. METHOD: An ABC (A: baseline, B: information, C: observation) multiple-baseline design counterbalanced across postural behaviors (back, shoulder, and feet position) was implemented with six participants. RESULTS AND DISCUSSION: Substantial improvements in postural safety occurred after participants conducted safety observations, and these improvements did not appear to negatively affect productivity. Results also suggest that there is no relation between the accuracy of an observer's safety observation and their subsequent safety performance. IMPACT ON INDUSTRY: This research provides evidence that a safety observation process can function to increase safe postural behavior of observers. Thus, the implementation of such a process may contribute to the prevention of musculoskeletal disorders and related costs in the workplace.     

Sperm traits in the quacking frog (<Emphasis Type="Italic">Crinia georgiana</Emphasis>), a species with plastic alternative mating tactics

In species where males use alternative reproductive tactics and male phenotypes are confronted with different risks of sperm competition, theory predicts that between-male-type differences in sperm expenditure may evolve. In the frog Crinia georgiana big males can monopolize females, whereas small males often engage in polyandrous matings. Consequently, big males may experience a lower risk of sperm competition than do small males. We tested if the predictions from theoretical models can be applied to the mating system of C. georgiana. Our results showed that small males do not have larger testes relative to their body size compared to their larger counterparts and that the efficiency with which sperm number, size, motility, and longevity are produced by the testes does not differ between small and large males in the predicted way. These results are not in alignment with predictions from a loaded raffle model of sperm competition on sperm expenditure in males with alternative phenotypes. The plasticity in mating tactics used by C. georgiana males and a high intraseasonal variation in male densities may have prevented the evolution of enhanced sperm performance in smaller males. A fair raffle in the sperm competition game played by C. georgiana males could also explain the observed patterns in sperm traits. Future investigations determining the parameters responsible for the deviation from theoretical predictions in this system will test the degree to which current theoretical models can indeed be applied to species with plastic reproductive tactics.     

Accident data for the Semantic Web

This paper describes concerns about the documentation, dissemination and use of lessons learned from mishap investigations, impediments posed by current practices, and opportunities for improvement. Lessons are presently developed, documented and stored primarily in narrative form and relational databases, and disseminated in many forms and media, including the Internet. Current practices pose many impediments to maximized development, dissemination and use. Investigation process research and new data concepts behind the Semantic Web, exploited elsewhere, offer potential opportunities to overcome these impediments. To exploit these opportunities, formation of a working group to develop an improved Semantic Web-friendly mishap investigation lessons learning system is proposed. An example illustrating an alternative approach is described to support a reasonable expectation that an alternative lessons learning system could be developed.     

Protecting the planet and its people: how do interventions to promote environmental sustainability and occupational safety and health overlap?

Problem: The challenges of both occupational safety and health and environmental sustainability require large-scale behavior change for meaningful improvements to occur. Environmental sustainability, or the ‘green movement’ has received far more attention recently, and certain strategies and recommendations from interventions designed for promoting pro-environmental behaviors may inform efforts to intervene on critical behaviors for improving occupational safety and health. Method: A survey of the literature regarding behavioral interventions for both environmental sustainability and occupational safety and health was conducted. Several theoretical approaches are reviewed, and successful approaches from each domain are identified, as well as parallel challenges and points for crossover. Recommendations are provided for adapting environmental sustainability intervention approaches for occupational safety and health applications. Impact on Industry: Safety and health leaders may achieve sustainable improvements in worker safety and health by harnessing the momentum of the green movement and adapting successful intervention approaches from the environmental sustainability domain.     

Evidence for the Stepwise Behavioral Response Model (SBRM): the effects of Carbamate Pesticides on medaka (Oryzias latipes) in an online monitoring system

The Stepwise Behavioral Response Model (SBRM), which is a conceptual model, postulated that an organism displays a time-dependent sequence of compensatory Stepwise Behavioral Response (SBR) during exposure to pollutants above their respective thresholds of resistance. In order to prove the model, in this study, the behavioral responses (BRs) of medaka (Oryzias latipes) in the exposure of Arprocarb (A), Carbofuran (C) and Methomyl (M) were analyzed in an online monitoring system (OMS). The Self-Organizing Map (SOM) was utilized for patterning the obtained behavioral data in 0.1 TU (Toxic Unit), 1 TU, 2 TU, 5 TU, 10 TU and 20 TU treatments with control. Some differences among different Carbamate Pesticides (CPs) were observed in different concentrations and the profiles of behavior strength (BS) on SOM were variable depending upon levels of concentration. The time of the first significant decrease of BS (SD-BS) was in inverse ratio to the CP concentrations. Movement behavior showed by medaka mainly included No effect, Stimulation, Acclimation, Adjustment (Readjustment) and Toxic effect, which proved SBRM as a time-dependence model based on the time series BS data. Meanwhile, it was found that SBRM showed evident stress-dependence. Therefore, it was concluded that medaka SBR was both stress-dependent and time-dependent, which supported and developed SBRM, and data mining by SOM could be efficiently used to illustrate the behavioral processes and to monitor toxic chemicals in the environment.     

Testing the ability of males and females to respond to altered songs in the dueting green lacewing, Chrysoperla plorabunda (Neuroptera: Chrysopidae)

Green lacewings in the carnea group of Chrysoperla engage in species-specific heterosexual duets using low-frequency substrate-borne signals. Within each species, both sexes sing nearly identical songs. Songs are the principal barriers to hybridization between sympatric species in the complex. Here, we investigated the responsiveness of males and females of Chrysoperla plorabunda to synthesized, prerecorded songs that differed from the species mean in the period between repeated volleys of abdominal vibration. We tested 15–16 males and 15–16 females using playbacks of two signals that gradually increased or decreased in volley period, starting at the species mean. We found that (1) duets during courtship are accurate, interactive, and adjustable by each participant; (2) in staged duets, both sexes respond best to song tempos near the mean volley period of their population, but can nonetheless maintain duets with signals of nearly twice, or half, the normal volley period; (3) individuals fine-tune their adjustments to signals of different volley periods by changing their own volley duration and latent period, or less often by inserting extra volleys or skipping every other volley; (4) males are significantly better at matching signals of changing tempo than females; and (5) the range of song responsiveness of C. plorabunda does not overlap the natural range of volley periods found in Chrysoperla adamsi, an acoustically similar sibling species, thus reaffirming strong behavioral isolation. In sum, the precise, almost unbreakable heterosexual duets characteristic of song species of the carnea group result from tight mutual feedback between partners. Effective reproductive isolation between species can be based on song differences alone.     

RNAi-mediated silencing of vitellogenin gene function turns honeybee (Apis mellifera) workers into extremely precocious foragers

The switch from within-hive activities to foraging behavior is a major transition in the life cycle of a honeybee (Apis mellifera) worker. A prominent regulatory role in this switch has long been attributed to juvenile hormone (JH), but recent evidence also points to the yolk precursor protein vitellogenin as a major player in behavioral development. In the present study, we injected vitellogenin double-stranded RNA (dsVg) into newly emerged worker bees of Africanized genetic origin and introduced them together with controls into observation hives to record flight behavior. RNA interference-mediated silencing of vitellogenin gene function shifted the onset of long-duration flights (>10 min) to earlier in life (by 3–4 days) when compared with sham and untreated control bees. In fact, dsVg bees were observed conducting such flights extremely precociously, when only 3 days old. Short-duration flights (<10 min), which bees usually perform for orientation and cleaning, were not affected. Additionally, we found that the JH titer in dsVg bees collected after 7 days was not significantly different from the controls. The finding that depletion of the vitellogenin titer can drive young bees to become extremely precocious foragers could imply that vitellogenin is the primary switch signal. At this young age, downregulation of vitellogenin gene activity apparently had little effect on the JH titer. As this unexpected finding stands in contrast with previous results on the vitellogenin/JH interaction at a later age, when bees normally become foragers, we propose a three-step sequence in the constellation of physiological parameters underlying behavioral development. David Santos Marco Antonio and Karina Rosa Guidugli-Lazzarini contributed equally to the present study.