Hwan-Jin Yoon

Eye-Tracking Analysis of User Behavior and Performance in Web Search on Large and Small Screens

In recent years, searching the web on mobile devices has become enormously popular. Because mobile devices have relatively small screens and show fewer search results, search behavior with mobile devices may be different from that with desktops or laptops. Therefore, examining these differences may suggest better, more efficient designs for mobile search engines. In this experiment, we use eye tracking to explore user behavior and performance. We analyze web searches with 2 task types on 2 differently sized screens: one for a desktop and the other for a mobile device. In addition, we examine the relationships between search performance and several search behaviors to allow further investigation of the differences engendered by the screens. We found that users have more difficulty extracting information from search results pages on the smaller screens, although they exhibit less eye movement as a result of an infrequent use of the scroll function. However, in terms of search performance, our findings suggest that there is no significant difference between the 2 screens in time spent on search results pages and the accuracy of finding answers. This suggests several possible ideas for the presentation design of search results pages on small devices.

Australian Graziers Value Sparse Trees in Their Pastures: A Viewshed Analysis of Photo-Elicitation

The temperate grazing region of southeastern Australia is experiencing a rapid decline in tree cover that threatens key ecosystem functions. Graziers are stewards of most of the trees remaining outside reserves, and hold the power to reverse the decline. Influencing graziers’ decision making about vegetation management requires an understanding of their landscape values. We asked 25 graziers to photograph features they considered significant on their farms. Their choices were analyzed using viewsheds, the spatial delineations of all areas visible in a photograph. Photos taken by landholders depicted woody vegetation more often than would be expected by chance, particularly the isolated and scattered trees that are declining most rapidly. Grazier awareness and appreciation of isolated and scattered trees should be harnessed by policymakers keen to reverse their decline. More generally, our work demonstrates the utility of simultaneously employing photo-elicitation and quantitative viewshed analysis.

Habitat Selection and Post-Release Movement of Reintroduced Brown Treecreeper Individuals in Restored Temperate Woodland

It is essential to choose suitable habitat when reintroducing a species into its former range. Habitat quality may influence an individual’s dispersal decisions and also ultimately where they choose to settle. We examined whether variation in habitat quality (quantified by the level of ground vegetation cover and the installation of nest boxes) influenced the movement, habitat choice and survival of a reintroduced bird species. We experimentally reintroduced seven social groups (43 individuals) of the brown treecreeper (Climacteris picumnus) into two nature reserves in south-eastern Australia. We radio-tracked 18 brown treecreepers from release in November 2009 until February 2010. We observed extensive movements by individuals irrespective of the release environment or an individual’s gender. This indicated that individuals were capable of dispersing and actively selecting optimum habitat. This may alleviate pressure on wildlife planners to accurately select the most optimum release sites, so long as the species’ requirements are met. There was significant variation in movement between social groups, suggesting that social factors may be a more important influence on movement than habitat characteristics. We found a significant effect of ground vegetation cover on the likelihood of settlement by social groups, with high rates of settlement and survival in dry forests, rather than woodland (where the species typically resides), which has implications for the success of woodland restoration. However, overall the effects of variation in habitat quality were not as strong as we had expected, and resulted in some unpredicted effects such as low survival and settlement in woodland areas with medium levels of ground vegetation cover. The extensive movement by individuals and unforeseen effects of habitat characteristics make it difficult to predict the outcome of reintroductions, the movement behaviour and habitat selection of reintroduced individuals, particularly when based on current knowledge of a species’ ecology.

Do Australian graziers have an offset mindset about their farm trees

Worldwide, the footprint of agriculture is higher than that of any other land use, making the local decisions of millions of farmers a global force for achieving the maintenance of ecosystem services. Biodiversity offsets are increasingly used to attempt to reconcile conflicts between production and conservation. Offset policies operate on the principle of habitat substitutability, but little work has considered whether those targeted by such policies perceive nature that way. For instance, do landholders perceive trees of different arrangements, ages or species to be interchangeable? We used a large-scale landholder survey to understand how graziers manage their farm trees, and whether their beliefs are amenable to substitution. Three natural clusters were found, that: (A) liked a tidy farm but did not differentiate trees by species, age or arrangement; (B) strongly supported the need for diversity in tree cover; and, (C) preferred woodlands and connective strips to sparse trees. Those positions were consistent with their beliefs about the costs and benefits of different arrangements of trees, but were largely inconsistent with their declared tree planting and protection activities. Tree management activities were more easily explained by commodity (pro-woodland graziers (C) were most likely to be cropping) or by career stage and what that meant for time and money resources to do conservation work (contrasting A and B). Offset policies and policy incentives encouraging vegetative heterogeneity would motivate at least these first two clusters, helping to sustain a diversity of tree cover and thus ecosystem services on farms.

Understanding eye movements on mobile devices for better presentation of search results

Compared to the early versions of smart phones, recent mobile devices have bigger screens that can present more web search results. Several previous studies have reported differences in user interaction between conventional desktop computer and mobile device‐based web searches, so it is imperative to consider the differences in user behavior for web search engine interface design on mobile devices. However, it is still unknown how the diversification of screen sizes on hand‐held devices affects how users search. In this article, we investigate search performance and behavior on three different small screen sizes: early smart phones, recent smart phones, and phablets. We found no significant difference with respect to the efficiency of carrying out tasks, however participants exhibited different search behaviors: less eye movement within top links on the larger screen, fast reading with some hesitation before choosing a link on the medium, and frequent use of scrolling on the small screen. This result suggests that the presentation of web search results for each screen needs to take into account differences in search behavior. We suggest several ideas for presentation design for each screen size.

Habitat selection and behaviour of a reintroduced passerine: linking experimental restoration, behaviour and habitat ecology.

Habitat restoration can play an important role in recovering functioning ecosystems and improving biodiversity. Restoration may be particularly important in improving habitat prior to species reintroductions. We reintroduced seven brown treecreeper (Climacteris picumnus) social groups into two nature reserves in the Australian Capital Territory in south-eastern Australia. This study provided a unique opportunity to understand the interactions between restoration ecology, behavioural ecology and habitat ecology. We examined how experimental restoration treatments (addition of coarse woody debris, variations in ground vegetation cover and nest box installation) influenced the behaviour and microhabitat use of radio-tracked individuals to evaluate the success of restoration treatments. The addition of coarse woody debris benefited the brown treecreeper through increasing the probability of foraging on a log or on the ground. This demonstrated the value of using behaviour as a bio-indicator for restoration success. Based on previous research, we predicted that variations in levels of ground vegetation cover would influence behaviour and substrate use, particularly that brown treecreepers would choose sites with sparse ground cover because this allows better access to food and better vigilance for predators. However, there was little effect of this treatment, which was likely influenced by the limited overall use of the ground layer. There was also little effect of nest boxes on behaviour or substrate use. These results somewhat confound our understanding of the species based on research from extant populations. Our results also have a significant impact regarding using existing knowledge on a species to inform how it will respond to reintroduction and habitat restoration. This study also places great emphasis on the value of applying an experimental framework to ecological restoration, particularly when reintroductions produce unexpected outcomes.

Pagination versus Scrolling in Mobile Web Search

Vertical scrolling is the standard method of exploring search results pages. For touch-enabled mobile devices that are not equipped with a mouse or keyboard, we adopt other methods of controlling the viewport with the aim of investigating user interaction. From the intuition that people are used to reading books by turning pages horizontally, we conducted a user experiment to investigate the effects of horizontal and vertical control types (pagination versus scrolling) on a touch-enabled mobile phone. Our findings suggest that participants using pagination were more likely to find relevant documents, especially those over the fold; spent more time attending to relevant results; and were faster to click while spending less time on the search result pages overall. We also found that the main reason for the difference in search speed is the time taken for the scroll itself. We conclude that search engines need to provide different viewport controls to allow better search experiences on touch-enabled mobile devices.

Local environmental covariates are important for predicting fire history from tree stem diameters

In fire-prone landscapes, knowing when vegetation was last burnt is important for understanding how species respond to fire and to develop effective fire management strategies. However, fire history is often incomplete or non-existent. We developed a fire-age prediction model for two mallee woodland tree species in southern Australia. The models were based on stem diameters from ~1172 individuals surveyed along 87 transects. Time since fire accounted for the greatest proportion of the explained variation in stem diameter for our two mallee tree species but variation in mean stem diameters was also influenced by local environmental factors. We illustrate a simple tool that enables time since fire to be predicted based on stem diameter and local covariates. We tested our model against new data but it performed poorly with respect to the mapped fire history. A combination of different covariate effects, variation in among-tree competition, including above- and below-ground competition, and unreliable fire history may have contributed to poor model performance. Understanding how the influence of covariates on stem diameter growth varies spatially is critical for determining the generality of models that predict time since fire. Models that were developed in one region may need to be independently verified before they can be reliably applied in new regions.