Turning the shelves: empirical findings and space syntax analyses of two virtual supermarket variations

The spatial structure of a virtual supermarket was systematically varied to investigate human behavior and cognitive processes in unusual building configurations. The study builds upon experiments in a regular supermarket, which serve as a baseline case. In a between-participant design a total of 41 participants completed a search task in two different virtual supermarket environments. For 21 participants the supermarket shelves were turned towards them at a 45° angle when entering the store, giving high visual access to product categories and products. For 20 participants the shelves were placed in exactly the opposite direction obstructing a quick development of shopping goods dependencies. The obtained differences in search performance between the two conditions are analyzed using space syntax analyses and comparisons made of environmental features and participants’ actual search path trajectories

Adaptive Lévy processes and area-restricted search in human foraging

A considerable amount of research has claimed that animals’ foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods–comparing alternative distributions using maximum likelihood methods–showed the strongest support for bounded power-law distributions (truncated Lévy flights). However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32) participants. Moreover, paths in the patchy environment (but not the dispersed environment) showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments–where search was area-restricted. Furthermore, our results indicate that search strategies cannot be inferred without knowing how organisms respond to resources–as both patched and dispersed conditions led to similar Lévy-like movement distributions

Turning the Shelves: Empirical Findings and Space Syntax Analyses of Two Virtual Supermarket Variations Judgements of Building Complexity and Navigability in Virtual Reality

Finding a product in a new supermarket is a complex, cognitive process. Earlier studies (Kalff & Strube, 2009, Gil et al., 2009)indicate that shopper’s path choice decisions in such environments are strongly influenced by their background knowledge: the placement of products in a store, especially the collocation of semantically similar types of products (e.g., tinned sweetcorn found with tinned goods rather then fresh corn‐on‐the‐cob). Supermarkets provide an apparently spatially homogenous environment, and it could therefore be expected that a shop’s content (the products) and their placement are the paramount factor in shopper movement, with only limited effects of spatial configuration. In the present study, the spatial structure of a virtual supermarket was systematically varied to investigate cognitive processes and behaviour in unusual building configurations. The study builds upon experiments in a regular supermarket, which serve as a baseline case. In a between‐participant design 41 participants completed a search task in two different virtual supermarket environments. For 21 participants the supermarket shelves were turned towards them at a 45° angle when entering the store, providing high visual access to product categories and products from the main aisle. For 20 participants the shelves were placed in the opposite direction. Both the turning angle of the shelves and the level of congruence between expected and actual location of a product had a significant impact on search times. Environmental features were analysed using space syntax techniques both at the global level of the store, and at the level of individual pairs of start and goal locations for each product, including step depth and isovist measures (particular emphasis is on the visual properties of each product’s location). The area of the main aisle, as visible from each product, as well as the compactness of the isovist generated from the product location, proved to be significant predictors of shopper’s search time. It is suggested that this may reflect the importance of having visual access to a product from relatively long lines of sight. Contrary to the initial hypothesis that higher visual access to a product always yields lower search times, we find that it can also provide distraction. Partialling out these geometric variables for an ANOVA analysis (analysis of variance) reveals that they strongly contribute to the obtained difference of search time between the two layout conditions, and they also have a moderating effect on the influence of background knowledge on search performance. Further analysis suggests that participants rely on different path choice strategies that appear to be influenced by local features of geometry as well as inter‐product similarity at choice points such as corridor intersections. A qualitative analysis of movement trajectories and verbal reports from the study participants was conducted and found to characterize typical decision patterns and possible underlying reasoning along a product search path. In conclusion, despite the predicted strong effect of shopper’s preferences and their prior product knowledge, the spatial layout of the shop was still shown to have a consistent effect upon the selection of search paths and search duration

Everyday Navigation in Real and Virtual Environments Informed by Semantic Knowledge

The effect of semantic knowledge on performing an everyday wayfinding task was investigated in real and virtual grocery stores. Participants had to search for 15 food items exhibiting varying degrees of congruency with background knowledge with respect to their placement in a mid-sized supermarket. Food categories and the congruency of categories with the placement of pertinent food items was assessed pre-experimentally using a card-sorting task with customers and store managers. Experiment 1 was conducted in a real supermarket (tracing participants by means of RFID techniques) and replicated in the same market as a virtual environment (Exp. 2), allowing insights into potential differences. Exp. 3 used a VR variation where all the pictures on the shelves of the VR supermarket were replaced with printed labels. Results regarding semantic knowledge yielded stable and fairly high effect sizes across experimental conditions, revealing that semantic congruency with shopping goods ’ placements made the search for food items much more efficient. The results show that even abstract background knowledge (semantic categories) may be involved in human navigation

Turning angle as a function of distance after item encounter for the empirical data (“Experiment dispersed” and “Experiment patched”) and for random locations along the trajectories (“Random dispersed” and “Random patched”).

<p>Participants in the patched condition significantly increased turning in response to resource encounters relative to both the dispersed condition (<i>F(1,30) = </i>5.31, <i>P = </i>.03, repeated measures analysis of variance) and ‘random’ baseline turning (<i>F(1,15) = </i>5.71, <i>P</i> = .03, repeated measures analysis of variance). Turning angles in the dispersed condition were not different from the ‘random’ baseline turning (<i>F(1,15) = </i>1.68, <i>P = </i>.21, repeated measures analysis of variance). Data show mean±sem.</p

Model comparisons for aggregated data.

<p>Note: PL = power law, Exp = unbounded exponential, PLB = bounded power-law, ExpB = bounded exponential.</p

Rank/frequency plots of aggregated and individual data along with model fits on logarithmic axes.

<p>Black circles are movement lengths ≥ <i>x</i>. The four model fits are power-law (blue-straight line), bounded power-law (curved blue-dashed line), unbounded exponential (curved red line), and bounded exponential (curved red-dashed line). <b>A.</b> The aggregated data for the dispersed condition. The inset shows the results of logarithmic binning with best fitting power-law. <b>B.</b> The aggregated data for the patched condition. The inset shows the results of logarithmic binning with best fitting power-law. <b>C.</b> Data for each individual in the dispersed condition. <b>D.</b> Data for each individual in the patched condition.</p

The virtual foraging environment, resource distributions, and representative paths.

<p><b>A.</b> Participants’ perspective during the task. One of the global landmarks (a mountain) is visible in the distance. The number in the lower left hand corner is the number of resources collected so far. <b>B.</b> The resource distribution in the dispersed environment with a path generated by one participant. <b>C.</b> The resource distribution in the patchy environment with a path generated by one participant.</p

Comparing path performance across environments.

<p>We compared path performance by randomly simulating paths from the alternative environment using 100 simulated versions of each observed path in the alternative resource distribution. Paths from the patched condition simulated in the dispersed environment performed as well as dispersed paths in the dispersed environment (<i>t</i>(15) = 0.05, <i>P</i> = .97, two-tailed t-test). However, paths from the dispersed environment simulated in the patchy environment were outperformed by the original paths from the patchy environment (<i>t</i>(14) = −3.91, <i>P = </i>.002, two-tailed t-test).</p