Exploration of human search behaviour: a multidisciplinary perspective

The following work presents an exploration of human search behaviour both from biological and computational perspectives. Search behaviour is defined as the movements made by an organism while attempting to find a resource. This work describes some of the principal procedures used to record movement, methods for analysing the data and possible ways of interpreting the data. In order to obtain a database of searching behaviour, an experimental setup was built and tested to generate the search paths of human participants. The test arena occupied part of a football field and the targets consisted of an array of 20 golf balls. In the first set of experiments, a random and regular distribution of targets were tested. For each distribution, three distinct conspicuity levels were constructed: a cryptic level, in which targets were painted the same colour as the grass, a semi-conspicuous level in which targets were left white and a conspicuous condition in which the position of each target was marked by a red flag, protruding one metre from the ground. The subjects tested were 9-11 year old children and their search paths were collected using a GPS device. Subjects did not recognise the spatial cues regarding the way targets were spatially distributed. A minimal decision model, the bouncing search model, was built based on the characteristics of the childrens search paths. The model produced an outstanding fit of the children’s behavioural data. In the second set of experiments, a new group of children were tested for two new distributions obtained by arranging the targets in patches. Again, children appeared unable to recognise spatial information during the collection processes. The children’s behaviour once again produced a good match with that of the bouncing search model. This work introduces several new methodological aspects to be explored to further understand the decision processes involved when humans search. Also, it illustrates that integrating biology and computational science can result in innovative research

Visual search and VDUS

This wide-ranging study explored various parameters of visual search in relation to computer screen displays. Its ultimate goal was to help identify factors which could result in improvements in commercially available displays within the 'real world’. Those improvements are generally reflected in suggestions for enhancing efficiency of locatabolity of information through an acknowledgement of the visual and cognitive factors involved. The thesis commenced by introducing an ergonomics approach to the presentation of information on VDUs. Memory load and attention were discussed. In the second chapter, literature on general and theoretical aspects of visual search (with particular regard for VDUs) was reviewed. As an experimental starting point, three studies were conducted involving locating a target within arrays of varying configurations. A model concerning visual lobes was proposed. Two text-editing studies were then detailed showing superior user performances where conspicuity and the potential for peripheral vision are enhanced. Relevant eye movement data was combined with a keystroke analysis derived from an automated protocol analyser. Results of a further search task showed icons to be more quickly located within an array than textual material. Precise scan paths were then recorded and analyses suggested greater systematicity of search strategies for complex items. This led on to a relatively 'pure' search study involving materials of varying spatial frequencies. Results were discussed in terms of verbal material generally being of higher spatial frequencies and how the ease of resolution and greater cues available in peripheral vision can result in items being accessed more directly. In the final (relatively applied) study, differences in eye movement indices were found across various fonts used. One main conclusion was that eye movement monitoring was a valuable technique within the visual search/VDU research area in illuminating precise details of performance which otherwise, at best, could only be inferred

Motorcycle Conspicuity: The Effects Of Age And Vehicular Daytime Running Lights

Research has shown that riding a motorcycle can potentially be much more dangerous than operating a conventional vehicle. There are factors inherent in driving or riding a small two wheeled vehicle, such as a motorcycle, moped or even bicycle that can potentially decrease their ability to be seen or noticed by other drivers. This disadvantage is reflected in the disproportionate over-representation of injuries and/or fatalities incurred by this particular driving group. This creates a significant problem which deserves dedicated evaluation as to causative factors and/or influential variables. The following research was conducted with intentions to investigate the topic of motorcycle conspicuity so as to further explain the variables which positively contribute to a motorcycle being seen and to supplement the body of knowledge that currently exists on this topic. This study specifically evaluated the influence of sex, age, motorcycle lighting conditions, and vehicular daytime running lights upon one\u27s ability to effectively detect a motorcycle within a high fidelity simulated environment. This research additionally sought to examine the feasibility and validity of using a novel fixed base high fidelity simulator for the evaluation of motorcycle conspicuity. The results from this research clearly indicate a link between vehicular DRLs and the effective detection of motorcycles and also support previous research as to the effectiveness of motorcycle DRLs. Additionally, these results suggest that as one ages, certain degradations in vision, cognition, and physiology occur which decrease one\u27s performance in detecting and responding to a motorcycle. These findings additionally provide support for the use of a high definition fixed base simulator as a valid technology for the evaluation of motorcycle conspicuity

A Focus on Selection for Fixation

A computational explanation of how visual attention, interpretation of visual stimuli, and eye movements combine to produce visual behavior, seems elusive. Here, we focus on one component: how selection is accomplished for the next fixation. The popularity of saliency map models drives the inference that this is solved, but we argue otherwise. We provide arguments that a cluster of complementary, conspicuity representations drive selection, modulated by task goals and history, leading to a hybrid process that encompasses early and late attentional selection. This design is also constrained by the architectural characteristics of the visual processing pathways. These elements combine into a new strategy for computing fixation targets and a first simulation of its performance is presented. A sample video of this performance can be found by clicking on the "Supplementary Files" link under the "Article Tools" heading

Augmented Reality HUDs: Warning Signs and Drivers’ Situation Awareness

Drivers must search dynamic and complex visual environments to perceive relevant environmental elements such as warning signs, pedestrians and other vehicles to select the appropriate driving maneuver. The objective of this research was to examine how an Augmented Reality Head Up Display (AR HUD) for warning signs affects driver Situation Awareness (SA) and attention. Participants viewed videos of real driving scenes with an AR HUDs or no display and were asked to report what elements in the driving scene attracted their attention. At the completion of the first driving video participants were given a warning sign recognition test. Participants then watched a second video and the Situation Awareness Global Assessment Technique (SAGAT), a measure of global SA was administered. Participants eye movements were recorded when watching the videos to investigate how drivers interacting with an AR HUD attend to the environment compared to drivers with no AR HUD. AR HUDs for warning signs are effective in making warning signs more attentionally conspicuous to drivers in both low and high clutter driving environments. The HUD did not lead to increased fixation duration or frequency to warning signs in many situations. However when two driving items were in sight (sign and car) and participants needed to decide where to attend, they experienced attentional tunneling. In complex driving situations participants spent a significantly longer proportion of time looking at warning signs in the HUD. In simple driving situations, AR HUDs appear to make warning signs more salient and conspicuous. However, in complex situations in high clutter driving environments AR HUDs may lead to attentional tunneling

The Effect of Distracted Driving on the Conspicuity of Pedestrians at Night

Between 2008 and 2018, pedestrian fatalities have increased 35 percent in the United States and nighttime fatalities are responsible for a substantial portion of this increase. There are two significant problems that limit drivers\u27 ability to respond to pedestrians at night: the degradation of drivers\u27 visual abilities due to low illumination and the low contrast of pedestrians against the background. Pedestrians can make themselves more visible to nighttime drivers by strategically placing retroreflective material on the major joints of the body to highlight their biological motion (biomotion). However, past research on pedestrian conspicuity has largely focused on drivers who are not distracted. Distracted driving is the one of most common causal factor of vehicle crashes and is increasing with advancements in technology. The purpose of this project was to assess the effect of driver distraction on the effectiveness of biomotion to enhance the conspicuity of pedestrians at night. Participants were driven along a predetermined route and asked to respond to all pedestrians they encountered. A test pedestrian was either walking or standing in place while wearing retroreflective biomotion markings. Approximately half of the participants were distracted by a secondary task that demanded cognitive, visual, and manual resources. Although highlighting the pedestrian\u27s biomotion maximized conspicuity, there was no evidence that biomotion mitigated the detrimental effects of distraction. Important limitations with the study, including the possibility that the standing pedestrian was too inconspicuous to allow for a strong test of the hypothesis, are discussed

APPLYING VISUAL ATTENTION THEORY TO TRANSPORTATION SAFETY RESEARCH AND DESIGN: EVALUATION OF ALTERNATIVE AUTOMOBILE REAR LIGHTING SYSTEMS

This experiment applies methodologies and theories of visual search and attention to the subject of conspicuity in automobile rear lighting. Based on these theories, this experiment has four goals. First, it is proposed that current research methods used to investigate rear lighting are inadequate and a proposed methodology based on the visual search paradigm is introduced. Second, demonstrate that current rear lighting on automobiles does not effectively meet the stated purpose of regulators. Third, propose a more effective system for increasing the conspicuity of brake lamps. A fourth goal is to validate and extend previous simulator research on this same topic. This experiment demonstrates that detection of red automobile brake lamps will be improved if tail lamps are another color (amber) rather than red, as currently mandated. The experiment is an extension and validation of previous simulation studies. Results indicate that RT and error are reduced in detecting the presence and absence of red brake lamps with multiple lead vehicles when tail lamps are not red compared to current rear lighting which mandates red tail lamps. This performance improvement is attributed to parallel visual processing that automatically segregates tail (amber) and brake (red) lamp colors into distractors and targets respectively

Seeing, sensing, and selection: modeling visual perception in complex environments

The purpose of this thesis is to investigate human visual perception at the level of eye movements by describing the interaction between vision and action during natural, everyday tasks in a real-world environment. The results of the investigation provide motivation for the development of a biologically-based model of selective visual perception that relies on the relative perceptual conspicuity of certain regions within the field of view. Several experiments were designed and conducted that form the basis for the model. The experiments provide evidence that the visual system is not passive, nor is it general-purpose, but rather it is active and specific, tightly coupled to the requirements of planned behavior and action. The implication for an active and task-specific visual system is that an explicit representation of the environment can be eschewed in favor of a compact representation with large potential savings in computational efficiency. The compact representation is in the form of a topographic map of relative perceptual conspicuity values. Other recent attempts at compact scene representations have focused mainly on low-level maps that code certain salient features of the scene including color, edges, and luminance. This study has found that the low-level maps do not correlate well with subjects\u27 fixation locations, therefore, a map of perceptual conspicuity is presented that incorporates high-level information. The high-level information is in the form of figure/ground segmentation, potential object detection, and task-specific location bias. The resulting model correlates well with the fixation densities of human viewers of natural scenes, and can be used as a pre-processing module for image understanding or intelligent surveillance applications