title: A behavioural perspective of visual search and the low prevalence effect

authors: Hollands, David M.

abstract: In visual search, rare items are missed disproportionately often. This Low Prevalence Effect (LPE) is a robust phenomenon with important societal consequences. We asked the question, “Is the schedule of signal presentation controlling eye movements and if so, how?” and hypothesised that visual search is an operant behaviour. To answer this question, we examined the LPE using eye-tracking and incorporated a rich schedule of signal presentation (medium-prevalence condition: 0.50 target probability across 200 trials) and a lean schedule (low-prevalence condition: 0.02 or 0.00 target probability across 1,000 trials) over three experiments. Experiment One was the control, in Experiments Two and Three we increased task difficulty by incorporating a staircase titration procedure, and in Experiment Three we also removed all target-present trials in the low-prevalence condition. We replicated the LPE in all experiments and observed increased levels of searching eye movements throughout the medium-prevalence condition due to an increase in behaviour for the first correct rejection immediately following a correct target-present response which we attribute to the local effects of reinforcement and the strengthening of search behaviour when we find what we are looking for. We also observed that visual attention was being guided towards the densest population of stimulus items (centroid) at the beginning of their search as a search strategy and conclude that this centroid zone is acting as a discriminative stimulus signalling the availability of reinforcement. We contend that eye movements are an operant behaviour controlled by environmental contingencies and reinforcement mechanisms are behind the LPE phenomenon.

text: A behavioural perspective of visual search and the low prevalence effect In visual search, rare items are missed disproportionately often. This Low Prevalence Effect (LPE) is a robust phenomenon with important societal consequences. We asked the question, “Is the schedule of signal presentation controlling eye movements and if so, how?” and hypothesised that visual search is an operant behaviour. To answer this question, we examined the LPE using eye-tracking and incorporated a rich schedule of signal presentation (medium-prevalence condition: 0.50 target probability across 200 trials) and a lean schedule (low-prevalence condition: 0.02 or 0.00 target probability across 1,000 trials) over three experiments. Experiment One was the control, in Experiments Two and Three we increased task difficulty by incorporating a staircase titration procedure, and in Experiment Three we also removed all target-present trials in the low-prevalence condition. We replicated the LPE in all experiments and observed increased levels of searching eye movements throughout the medium-prevalence condition due to an increase in behaviour for the first correct rejection immediately following a correct target-present response which we attribute to the local effects of reinforcement and the strengthening of search behaviour when we find what we are looking for. We also observed that visual attention was being guided towards the densest population of stimulus items (centroid) at the beginning of their search as a search strategy and conclude that this centroid zone is acting as a discriminative stimulus signalling the availability of reinforcement. We contend that eye movements are an operant behaviour controlled by environmental contingencies and reinforcement mechanisms are behind the LPE phenomenon.

year: 2024

title: Methodology of a population-based stroke and TIA incidence and outcomes study: The Auckland Regional Community Stroke Study (ARCOS IV) 2011–2012

authors: Krishnamurthi, Rita

subjects: incidence

abstract: Background
Stroke is a leading cause of death and disability worldwide. Stroke burden is immense as it leads to premature deaths, leaves survivors with ongoing disabilities, and has a major financial impact on the individual, their families, and the community. Reliable, high-quality evidence is needed on stroke risk factors, incidence, and outcomes to provide information on how best to reduce this burden. Population-based studies are regarded as the ‘gold-standard’ of measuring disease burden but are not common due to the logistical and financial challenges they present. The Auckland Regional Community Stroke Studies are among a few in the world that have been carried out at a population level and at regular intervals.
Aim
The aim of the fourth Auckland Regional Community Stroke Studies IV is to examine the current measures of stroke incidence, prevalence, and outcomes as well the trends over four decades. This article describes the methodology of the Auckland Regional Community Stroke Studies IV with stroke and transient ischemic attacks cases registered over a 12-month period from March 1, 2011 to February 29, 2012.
Conclusions
The methodology described may be used as a guide in order to design similar population-based stroke incidence and outcome studies in other countries and populations, thus facilitating the collection of most consistent and accurate stroke epidemiological data.

text: Methodology of a population-based stroke and TIA incidence and outcomes study: The Auckland Regional Community Stroke Study (ARCOS IV) 2011–2012 Background
Stroke is a leading cause of death and disability worldwide. Stroke burden is immense as it leads to premature deaths, leaves survivors with ongoing disabilities, and has a major financial impact on the individual, their families, and the community. Reliable, high-quality evidence is needed on stroke risk factors, incidence, and outcomes to provide information on how best to reduce this burden. Population-based studies are regarded as the ‘gold-standard’ of measuring disease burden but are not common due to the logistical and financial challenges they present. The Auckland Regional Community Stroke Studies are among a few in the world that have been carried out at a population level and at regular intervals.
Aim
The aim of the fourth Auckland Regional Community Stroke Studies IV is to examine the current measures of stroke incidence, prevalence, and outcomes as well the trends over four decades. This article describes the methodology of the Auckland Regional Community Stroke Studies IV with stroke and transient ischemic attacks cases registered over a 12-month period from March 1, 2011 to February 29, 2012.
Conclusions
The methodology described may be used as a guide in order to design similar population-based stroke incidence and outcome studies in other countries and populations, thus facilitating the collection of most consistent and accurate stroke epidemiological data.

year: 2013

title: Community Based Coastal Monitoring: Developing Tools For Sustainable Management

authors: Rickard, Darcel

subjects: Science

abstract: Burgeoning coastal development, recreational use, and the future affects of climate change are placing increasing strain on regulators to manage risk associated with coastal hazards.  Low-lying coastal communities in particular are vulnerable to a range of natural hazards including coastal erosion, storm surge inundation, tsunami and water safety that come with varying levels of risk to life and property. New Zealand's coastal hazard monitoring network is patchy and resources are limited. As a consequence there is considerable potential for coastal communities are going to need to take a more active role in monitoring their environment and building data bases and knowledge that can be used to better manage their coast. This paper describes simple methodologies based on the needs of various community groups and sound science principles that can be used to monitor beaches and the coastal environment. By employing these tools councils, technical experts and community groups will be able to make better-informed decisions for managing activities in the coastal environment. 
One of the keys to the successful uptake of a monitoring programme by a community group is its relevance to the group. The programme and the tools provided must fit the interests, needs, capability and resources of the group. This project develops tools for coastal monitoring and targets coastal community groups such as Coast Care, Coastal Hapu, Secondary Schools, and Surf Life Saving Clubs. The monitoring methodologies have been developed in consultation with Tainui ki Whaingaroa hapu, Raglan Area School, and the Waikato Beach Care and Coast Care Bay of Plenty.
Successful methodologies for measuring changes on the coast are also those that are matched to the type of beach, use appropriate equipment, collect structured data, provide data to which analysis can be applied, incorporate local knowledge of the environment, and feed results back to the community and other interested parties such as councils and science organisations. This project provides the target groups with simple monitoring methodologies, field forms/checklists, and appropriate survey and measurement equipment (which have undergone field trials) to carry out coastal monitoring.  A web-based facility has been developed to input, check and store data; and provide immediate feedback using graphs and images. It also provides background information on coastal processes relevant to monitoring programmes.  In this manner, a scientifically robust data set is collected and stored within a secure and future proofed archive, providing valuable information to coastal groups for years to come.
Although the primary objective of this research is to develop a means for coastal communities to monitor changes in their environment, there are additional benefits associated with engaging communities in the study of their environment. These benefits include increasing awareness of coastal hazards, capacity building, providing valuable educational resources, and improving the temporal and spatial data coverage of information for the New Zealand coastline.

text: Community Based Coastal Monitoring: Developing Tools For Sustainable Management Burgeoning coastal development, recreational use, and the future affects of climate change are placing increasing strain on regulators to manage risk associated with coastal hazards.  Low-lying coastal communities in particular are vulnerable to a range of natural hazards including coastal erosion, storm surge inundation, tsunami and water safety that come with varying levels of risk to life and property. New Zealand's coastal hazard monitoring network is patchy and resources are limited. As a consequence there is considerable potential for coastal communities are going to need to take a more active role in monitoring their environment and building data bases and knowledge that can be used to better manage their coast. This paper describes simple methodologies based on the needs of various community groups and sound science principles that can be used to monitor beaches and the coastal environment. By employing these tools councils, technical experts and community groups will be able to make better-informed decisions for managing activities in the coastal environment. 
One of the keys to the successful uptake of a monitoring programme by a community group is its relevance to the group. The programme and the tools provided must fit the interests, needs, capability and resources of the group. This project develops tools for coastal monitoring and targets coastal community groups such as Coast Care, Coastal Hapu, Secondary Schools, and Surf Life Saving Clubs. The monitoring methodologies have been developed in consultation with Tainui ki Whaingaroa hapu, Raglan Area School, and the Waikato Beach Care and Coast Care Bay of Plenty.
Successful methodologies for measuring changes on the coast are also those that are matched to the type of beach, use appropriate equipment, collect structured data, provide data to which analysis can be applied, incorporate local knowledge of the environment, and feed results back to the community and other interested parties such as councils and science organisations. This project provides the target groups with simple monitoring methodologies, field forms/checklists, and appropriate survey and measurement equipment (which have undergone field trials) to carry out coastal monitoring.  A web-based facility has been developed to input, check and store data; and provide immediate feedback using graphs and images. It also provides background information on coastal processes relevant to monitoring programmes.  In this manner, a scientifically robust data set is collected and stored within a secure and future proofed archive, providing valuable information to coastal groups for years to come.
Although the primary objective of this research is to develop a means for coastal communities to monitor changes in their environment, there are additional benefits associated with engaging communities in the study of their environment. These benefits include increasing awareness of coastal hazards, capacity building, providing valuable educational resources, and improving the temporal and spatial data coverage of information for the New Zealand coastline.

year: 2008