Years of life lost and mortality due to heat and cold in the three largest English cities.

There is a well-established relationship between temperature and mortality, with older individuals being most at risk in high-income settings. This raises the question of the degree to which lives are being shortened by exposure to heat or cold. Years of life lost (YLL) take into account population life expectancy and age at which mortality occurs. However, YLL are rarely used as an outcome-metric in studies of temperature-related mortality. This represents an important gap in knowledge; to better comprehend potential impacts of temperature in the context of climate change and an ageing population, it is important to understand the relationship between temperature and YLL, and also whether the risks of temperature related mortality and YLL have changed over recent years. Gridded temperature data derived from observations, and mortality data were provided by the UK Met Office and the Office for National Statistics (ONS), respectively. We derived YLL for each death using sex-specific yearly life expectancy from ONS English-national lifetables. We undertook an ecological time-series regression analysis, using a distributed-lag double-threshold model, to estimate the relationship between daily mean temperature and daily YLL and mortality between 1996 and 2013 in Greater London, the West Midlands including Birmingham, and Greater Manchester. Temperature-thresholds, as determined by model best fit, were set at the 91st (for heat-effects) and 35th (for cold-effects) percentiles of the mean temperature distribution. Secondly, we analysed whether there had been any changes in heat and cold related risk of YLL and mortality over time. Heat-effects (lag 0-2 days) were greatest in London, where for each 1 °C above the heat-threshold the risk of mortality increased by 3.9% (CI 3.5%, 4.3%) and YLL increased by 3.0% (2.5%, 3.5%). Between 1996 and 2013, the proportion of total deaths and YLL attributable to heat in London were 0.50% and 0.40% respectively. Cold-effects (lag 0-27 days) were greatest in the West Midlands, where for each 1 °C below the cold-threshold, risk of mortality increased by 3.1% (2.4%, 3.7%) and YLL also increased by 3.1% (2.2%, 3.9%). The proportion of deaths and YLL attributable to cold in the West Midlands were 3.3% and 3.2% respectively. We found no evidence of decreasing susceptibility to heat and cold over time. The addition of life expectancy information into calculations of temperature-related risk and mortality burdens for English cities is novel. We demonstrate that although older individuals are at greatest risk of temperature-related mortality, heat and cold still make a significant contribution to the YLL due to premature death.

What is cold-related mortality? A multi-disciplinary perspective to inform climate change impact assessments.

BACKGROUND: There is a growing discussion regarding the mortality burdens of hot and cold weather and how the balance between these may alter as a result of climate change. Net effects of climate change are often presented, and in some settings these may suggest that reductions in cold-related mortality will outweigh increases in heat-related mortality. However, key to these discussions is that the magnitude of temperature-related mortality is wholly sensitive to the placement of the temperature threshold above or below which effects are modelled. For cold exposure especially, where threshold effects are often ill-defined, choices in threshold placement have varied widely between published studies, even within the same location. Despite this, there is little discussion around appropriate threshold selection and whether reported associations reflect true causal relationships - i.e. whether all deaths occurring below a given temperature threshold can be regarded as cold-related and are therefore likely to decrease as climate warms. OBJECTIVES: Our objectives are to initiate a discussion around the importance of threshold placement and examine evidence for causality across the full range of temperatures used to quantify cold-related mortality. We examine whether understanding causal mechanisms can inform threshold selection, the interpretation of current and future cold-related health burdens and their use in policy formation. METHODS: Using Greater London data as an example, we first illustrate the sensitivity of cold related mortality to threshold selection. Using the Bradford Hill criteria as a framework, we then integrate knowledge and evidence from multiple disciplines and areas- including animal and human physiology, epidemiology, biomarker studies and population level studies. This allows for discussion of several possible direct and indirect causal mechanisms operating across the range of 'cold' temperatures and lag periods used in health impact studies, and whether this in turn can inform appropriate threshold placement. RESULTS: Evidence from a range of disciplines appears to support a causal relationship for cold across a range of temperatures and lag periods, although there is more consistent evidence for a causal effect at more extreme temperatures. It is plausible that 'direct' mechanisms for cold mortality are likely to occur at lower temperatures and 'indirect' mechanisms (e.g. via increased spread of infection) may occur at milder temperatures. CONCLUSIONS: Separating the effects of 'extreme' and 'moderate' cold (e.g. temperatures between approximately 8-9 °C and 18 °C in the UK) could help the interpretation of studies quoting attributable mortality burdens. However there remains the general dilemma of whether it is better to use a lower cold threshold below which we are more certain of a causal relationship, but at the risk of under-estimating deaths attributable to cold.

A multi-country analysis on potential adaptive mechanisms to cold and heat in a changing climate.

BACKGROUND: Temporal variation of temperature-health associations depends on the combination of two pathways: pure adaptation to increasingly warmer temperatures due to climate change, and other attenuation mechanisms due to non-climate factors such as infrastructural changes and improved health care. Disentangling these pathways is critical for assessing climate change impacts and for planning public health and climate policies. We present evidence on this topic by assessing temporal trends in cold- and heat-attributable mortality risks in a multi-country investigation. METHODS: Trends in country-specific attributable mortality fractions (AFs) for cold and heat (defined as below/above minimum mortality temperature, respectively) in 305 locations within 10 countries (1985-2012) were estimated using a two-stage time-series design with time-varying distributed lag non-linear models. To separate the contribution of pure adaptation to increasing temperatures and active changes in susceptibility (non-climate driven mechanisms) to heat and cold, we compared observed yearly-AFs with those predicted in two counterfactual scenarios: trends driven by either (1) changes in exposure-response function (assuming a constant temperature distribution), (2) or changes in temperature distribution (assuming constant exposure-response relationships). This comparison provides insights about the potential mechanisms and pace of adaptation in each population. RESULTS: Heat-related AFs decreased in all countries (ranging from 0.45-1.66% to 0.15-0.93%, in the first and last 5-year periods, respectively) except in Australia, Ireland and UK. Different patterns were found for cold (where AFs ranged from 5.57-15.43% to 2.16-8.91%), showing either decreasing (Brazil, Japan, Spain, Australia and Ireland), increasing (USA), or stable trends (Canada, South Korea and UK). Heat-AF trends were mostly driven by changes in exposure-response associations due to modified susceptibility to temperature, whereas no clear patterns were observed for cold. CONCLUSIONS: Our findings suggest a decrease in heat-mortality impacts over the past decades, well beyond those expected from a pure adaptation to changes in temperature due to the observed warming. This indicates that there is scope for the development of public health strategies to mitigate heat-related climate change impacts. In contrast, no clear conclusions were found for cold. Further investigations should focus on identification of factors defining these changes in susceptibility.

Community Response and Engagement During Extreme Water Events in Saskatchewan, Canada and Queensland, Australia.

Technology alone cannot address the challenges of how societies, communities, and individuals understand water accessibility, water management, and water consumption, particularly under extreme conditions like floods and droughts. At the community level, people are increasingly aware challenges related to responses to and impacts of extreme water events. This research begins with an assessment of social and political capacities of communities in two Commonwealth jurisdictions, Queensland, Australia and Saskatchewan, Canada, in response to major flooding events. The research further reviews how such capacities impact community engagement to address and mitigate risks associated with extreme water events and provides evidence of key gaps in skills, understanding, and agency for addressing impacts at the community level. Secondary data were collected using template analysis to elucidate challenges associated with education (formal and informal), social and political capacity, community ability to respond appropriately, and formal government responses to extreme water events in these two jurisdictions. The results indicate that enhanced community engagement alongside elements of an empowerment model can provide avenues for identifying and addressing community vulnerability to negative impacts of flood and drought.

The health effects of hotter summers and heat waves in the population of the United Kingdom: a review of the evidence.

It is widely acknowledged that the climate is warming globally and within the UK. In this paper, studies which assess the direct impact of current increased temperatures and heat-waves on health and those which project future health impacts of heat under different climate change scenarios in the UK are reviewed.This review finds that all UK studies demonstrate an increase in heat-related mortality occurring at temperatures above threshold values, with respiratory deaths being more sensitive to heat than deaths from cardiovascular disease (although the burden from cardiovascular deaths is greater in absolute terms). The relationship between heat and other health outcomes such as hospital admissions, myocardial infarctions and birth outcomes is less consistent. We highlight the main populations who are vulnerable to heat. Within the UK, these are older populations, those with certain co-morbidities and those living in Greater London, the South East and Eastern regions.In all assessments of heat-related impacts using different climate change scenarios, deaths are expected to increase due to hotter temperatures, with some studies demonstrating that an increase in the elderly population will also amplify burdens. However, key gaps in knowledge are found in relation to how urbanisation and population adaptation to heat will affect health impacts, and in relation to current and future strategies for effective, sustainable and equitable adaptation to heat. These and other key gaps in knowledge, both in terms of research needs and knowledge required to make sound public- health policy, are discussed.

The use of climate information to estimate future mortality from high ambient temperature: A systematic literature review.

BACKGROUND AND OBJECTIVES: Heat related mortality is of great concern for public health, and estimates of future mortality under a warming climate are important for planning of resources and possible adaptation measures. Papers providing projections of future heat-related mortality were critically reviewed with a focus on the use of climate model data. Some best practice guidelines are proposed for future research. METHODS: The electronic databases Web of Science and PubMed/Medline were searched for papers containing a quantitative estimate of future heat-related mortality. The search was limited to papers published in English in peer-reviewed journals up to the end of March 2017. Reference lists of relevant papers and the citing literature were also examined. The wide range of locations studied and climate data used prevented a meta-analysis. RESULTS: A total of 608 articles were identified after removal of duplicate entries, of which 63 were found to contain a quantitative estimate of future mortality from hot days or heat waves. A wide range of mortality models and climate model data have been used to estimate future mortality. Temperatures in the climate simulations used in these studies were projected to increase. Consequently, all the papers indicated that mortality from high temperatures would increase under a warming climate. The spread in projections of future climate by models adds substantial uncertainty to estimates of future heat-related mortality. However, many studies either did not consider this source of uncertainty, or only used results from a small number of climate models. Other studies showed that uncertainty from changes in populations and demographics, and the methods for adaptation to warmer temperatures were at least as important as climate model uncertainty. Some inconsistencies in the use of climate data (for example, using global mean temperature changes instead of changes for specific locations) and interpretation of the effects on mortality were apparent. Some factors which have not been considered when estimating future mortality are summarised. CONCLUSIONS: Most studies have used climate data generated using scenarios with medium and high emissions of greenhouse gases. More estimates of future mortality using climate information from the mitigation scenario RCP2.6 are needed, as this scenario is the only one under which the Paris Agreement to limit global warming to 2°C or less could be realised. Many of the methods used to combine modelled data with local climate observations are simplistic. Quantile-based methods might offer an improved approach, especially for temperatures at the ends of the distributions. The modelling of adaptation to warmer temperatures in mortality models is generally arbitrary and simplistic, and more research is needed to better quantify adaptation. Only a small number of studies included possible changes in population and demographics in their estimates of future mortality, meaning many estimates of mortality could be biased low. Uncertainty originating from establishing a mortality baseline, climate projections, adaptation and population changes is important and should be considered when estimating future mortality.

Exploring International Views on Key Concepts for Mass-gathering Health through a Delphi Process.

Introduction The science underpinning mass-gathering health (MGH) is developing rapidly. However, MGH terminology and concepts are not yet well defined or used consistently. These variations can complicate comparisons across settings. There is, therefore, a need to develop consensus and standardize concepts and data points to support the development of a robust MGH evidence-base for governments, event planners, responders, and researchers. This project explored the views and sought consensus of international MGH experts on previously published concepts around MGH to inform the development of a transnational minimum data set (MDS) with an accompanying data dictionary (DD). Report A two-round Delphi process was undertaken involving volunteers from the World Health Organization (WHO) Virtual Interdisciplinary Advisory Group (VIAG) on Mass Gatherings (MGs) and the MG section of the World Association for Disaster and Emergency Medicine (WADEM). The first online survey tested agreement on six key concepts: (1) using the term "MG HEALTH;" (2) purposes of the proposed MDS and DD; (3) event phases; (4) two MG population models; (5) a MGH conceptual diagram; and (6) a data matrix for organizing MGH data elements. Consensus was defined as ≥80% agreement. Round 2 presented five refined MGH principles based on Round 1 input that was analyzed using descriptive statistics and content analysis. Thirty-eight participants started Round 1 with 36 completing the survey and 24 (65% of 36) completing Round 2. Agreement was reached on: the term "MGH" (n=35/38; 92%); the stated purposes for the MDS (n=38/38; 100%); the two MG population models (n=31/36; 86% and n=30/36; 83%, respectively); and the event phases (n=34/36; 94%). Consensus was not achieved on the overall conceptual MGH diagram (n=25/37; 67%) and the proposed matrix to organize data elements (n=28/37; 77%). In Round 2, agreement was reached on all the proposed principles and revisions, except on the MGH diagram (n=18/24; 75%). Discussion/Conclusions Event health stakeholders require sound data upon which to build a robust MGH evidence-base. The move towards standardization of data points and/or reporting items of interest will strengthen the development of such an evidence-base from which governments, researchers, clinicians, and event planners could benefit. There is substantial agreement on some broad concepts underlying MGH amongst an international group of MG experts. Refinement is needed regarding an overall conceptual diagram and proposed matrix for organizing data elements. Steenkamp M , Hutton AE , Ranse JC , Lund A , Turris SA , Bowles R , Arbuthnott K , Arbon PA . Exploring international views on key concepts for mass-gathering health through a Delphi process. Prehosp Disaster Med. 2016;31(4):443-453.

Changes in population susceptibility to heat and cold over time: assessing adaptation to climate change.

BACKGROUND: In the context of a warming climate and increasing urbanisation (with the associated urban heat island effect), interest in understanding temperature related health effects is growing. Previous reviews have examined how the temperature-mortality relationship varies by geographical location. There have been no reviews examining the empirical evidence for changes in population susceptibility to the effects of heat and/or cold over time. The objective of this paper is to review studies which have specifically examined variations in temperature related mortality risks over the 20(th) and 21(st) centuries and determine whether population adaptation to heat and/or cold has occurred. METHODS: We searched five electronic databases combining search terms for three main concepts: temperature, health outcomes and changes in vulnerability or adaptation. Studies included were those which quantified the risk of heat related mortality with changing ambient temperature in a specific location over time, or those which compared mortality outcomes between two different extreme temperature events (heatwaves) in one location. RESULTS: The electronic searches returned 9183 titles and abstracts, of which eleven studies examining the effects of ambient temperature over time were included and six studies comparing the effect of different heatwaves at discrete time points were included. Of the eleven papers that quantified the risk of, or absolute heat related mortality over time, ten found a decrease in susceptibility over time of which five found the decrease to be significant. The magnitude of the decrease varied by location. Only two studies attempted to quantitatively attribute changes in susceptibility to specific adaptive measures and found no significant association between the risk of heat related mortality and air conditioning prevalence within or between cities over time. Four of the six papers examining effects of heatwaves found a decrease in expected mortality in later years. Five studies examined the risk of cold. In contrast to the changes in heat related mortality observed, only one found a significant decrease in cold related mortality in later time periods. CONCLUSIONS: There is evidence that across a number of different settings, population susceptibility to heat and heatwaves has been decreasing. These changes in heat related susceptibility have important implications for health impact assessments of future heat related risk. A similar decrease in cold related mortality was not shown. Adaptation to heat has implications for future planning, particularly in urban areas, with anticipated increases in temperature due to climate change.

Health and climate related ecosystem services provided by street trees in the urban environment.

Urban tree planting initiatives are being actively promoted as a planning tool to enable urban areas to adapt to and mitigate against climate change, enhance urban sustainability and improve human health and well-being. However, opportunities for creating new areas of green space within cities are often limited and tree planting initiatives may be constrained to kerbside locations. At this scale, the net impact of trees on human health and the local environment is less clear, and generalised approaches for evaluating their impact are not well developed.In this review, we use an urban ecosystems services framework to evaluate the direct, and locally-generated, ecosystems services and disservices provided by street trees. We focus our review on the services of major importance to human health and well-being which include 'climate regulation', 'air quality regulation' and 'aesthetics and cultural services'. These are themes that are commonly used to justify new street tree or street tree retention initiatives. We argue that current scientific understanding of the impact of street trees on human health and the urban environment has been limited by predominantly regional-scale reductionist approaches which consider vegetation generally and/or single out individual services or impacts without considering the wider synergistic impacts of street trees on urban ecosystems. This can lead planners and policymakers towards decision making based on single parameter optimisation strategies which may be problematic when a single intervention offers different outcomes and has multiple effects and potential trade-offs in different places.We suggest that a holistic approach is required to evaluate the services and disservices provided by street trees at different scales. We provide information to guide decision makers and planners in their attempts to evaluate the value of vegetation in their local setting. We show that by ensuring that the specific aim of the intervention, the scale of the desired biophysical effect and an awareness of a range of impacts guide the choice of i) tree species, ii) location and iii) density of tree placement, street trees can be an important tool for urban planners and designers in developing resilient and resourceful cities in an era of climatic change.

International Consensus on Key Concepts and Data Definitions for Mass-gathering Health: Process and Progress.

Mass gatherings (MGs) occur worldwide on any given day, yet mass-gathering health (MGH) is a relatively new field of scientific inquiry. As the science underpinning the study of MGH continues to develop, there will be increasing opportunities to improve health and safety of those attending events. The emerging body of MG literature demonstrates considerable variation in the collection and reporting of data. This complicates comparison across settings and limits the value and utility of these reported data. Standardization of data points and/or reporting in relation to events would aid in creating a robust evidence base from which governments, researchers, clinicians, and event planners could benefit. Moving towards international consensus on any topic is a complex undertaking. This report describes a collaborative initiative to develop consensus on key concepts and data definitions for a MGH "Minimum Data Set." This report makes transparent the process undertaken, demonstrates a pragmatic way of managing international collaboration, and proposes a number of steps for progressing international consensus. The process included correspondence through a journal, face-to-face meetings at a conference, then a four-day working meeting; virtual meetings over a two-year period supported by online project management tools; consultation with an international group of MGH researchers via an online Delphi process; and a workshop delivered at the 19thWorld Congress on Disaster and Emergency Medicine held in Cape Town, South Africa in April 2015. This resulted in an agreement by workshop participants that there is a need for international consensus on key concepts and data definitions.

Euro 2012 European Football Championship Finals: planning for a health legacy.

The revised international health regulations offer a framework that can be used by host countries to organise public health activities for mass gatherings. From June 8, to July 1, 2012, Poland and Ukraine jointly hosted the Union of European Football Associations European Football Championship Finals (Euro 2012). More than 8 million people from around the world congregated to watch the games. Host countries and international public health agencies planned extensively to assess and build capacity in the host countries and to develop effective strategies for dissemination of public health messages. The effectiveness of public health services was maximised through rapid sharing of information between parties, early use of networks of experienced individuals, and the momentum of existing national health programmes. Organisers of future mass gatherings for sporting events should share best practice and their experiences through the WHO International Observer Program. Research about behaviour of large crowds is needed for crowd management and the evidence base translated into practice. A framework to measure and evaluate the legacy of Euro 2012 is needed based on the experiences and the medium-term and long-term benefits of the tournament.

The representational locus of spatial influence on backward inhibition.

When one is sequentially switching among three tasks, performance is impaired when tasks alternate (ABA) relative to when one is switching between all three tasks (CBA), an effect known as backward inhibition (BI). BI is not observed when component tasks are uniquely located in space, however (Arbuthnott, 2005). In this study, the locations of task precues and target stimuli were manipulated independently to determine whether this elimination of BI is related to distinct cue location or to distinct target location. Results clearly indicated that BI is eliminated with distinct cue localization independent of the location of target stimuli. This indicates that BI, which reflects suppression of task-set representations, can be influenced by cue characteristics that are associated with task representations.

The use of autobiographical knowledge in age estimation.

Event dates are not directly associated with memories, so the processes by which we maintain a sense of time and sequence in our autobiographical memories is of considerable interest. The present study examined participants' reported age estimation strategies for childhood memories retrieved using a Galton-Crovitz cueing technique. The results indicate that all three categories of autobiographical knowledge in Conway and Pleydell-Pearce's (2000) self-memory system model-lifetime periods, general events, and event-specific details-support temporal inferences. However, participants most frequently used lifetime period knowledge to provide an initial age range, and event-specific knowledge was used to confirm or narrow the range of their estimated age.

Asymmetric switch cost and backward inhibition: Carryover activation and inhibition in switching between tasks of unequal difficulty.

Asymmetric switch cost, observed when switching between tasks varying in difficulty, shows that the difference between repeat and switch trials is greater when switching to the easier task. Early explanations of this effect attributed this pattern to both positive priming of the difficult task and negative priming of the easier task, but more recent models have focused only on activation processes. The role of inhibition in asymmetric switch cost was examined using backward inhibition, a more direct measure of task-set inhibition. The results indicated asymmetric backward inhibition, with greater sequential inhibition of the easier task (i.e., easy-difficult-easy sequences). Switch costs, however, showed both typical and reversed asymmetry (greater cost when switching from the easy to the difficult task), depending on the relative difficulty of task pairs. This pattern of results indicates that switch costs are attributable to both activation and inhibition processes.

The effect of task location and task type on backward inhibition.

Alternating tasks in a sequence of task switches results in impaired performance, relative to switches across three different tasks, an effect known as backward inhibition. Despite the robustness of this effect across task and response variations, backward inhibition is not observed when tasks are uniquely located at different points in space (Arbuthnott, 2005). Three hypotheses about the source of this anomaly were tested. Experiment 1 indicated that perceptually distinct task features other than location did not eliminate backward inhibition. Experiment 2 indicated that when switches across task and location were manipulated independently (i.e., all tasks appeared at all locations), backward inhibition was observed for task switches even when consecutive trials appeared at different spatial locations, ruling out eye movement as the source of the difference. The third experiment indicated that when component tasks involved judgments of spatial location, backward inhibition was observed across unique task-location switches. These results indicate that sequential inhibition is a very flexible mechanism that is sensitive to the amount of interference from previous tasks.

Stability and change in children's division strategies.

Age-related changes in children's performance on simple division problems (e.g., 6/2, 72/9) were investigated by asking children in Grades 4 through 7 to solve 32 simple division problems. Differences in performance were found across grade, with younger children performing more slowly and less accurately than older children. Problem size effects were also found in that children were faster and more accurate on small problems than on large problems. Two strategies changed across age, with children in Grade 4 relying heavily on the strategy of "addition" (adding the divisor until the dividend was reached) to solve the problems and children in Grades 5 through 7 relying primarily on the strategy of "multiplication" (recasting the division problem as a multiplication problem) to solve the problems. Surprisingly, the frequency of direct retrieval (retrieving the answer directly from memory) did not increase across grade and never became the dominant strategy of choice. Reasons for why retrieval use remains infrequent and age invariant are discussed. Overall, the results suggest that division is a unique operation and that the continued study of division may have implications for further understanding of how procedural and conceptual knowledge of arithmetic develops.

The influence of cue type on backward inhibition.

Backward inhibition is proposed as a process of lateral inhibition that operates during response selection in task switching, reducing interference caused by the most recently abandoned task set. The effect has been observed across a wide range of contexts but is eliminated by using spatial location to cue tasks (K. D. Arbuthnott & T. S. Woodward, 2002). The present studies replicated this finding, showing that spatial cues are also associated with greater response congruity than verbal cues, consistent with the lateral inhibition model. Spatial cues may introduce greater discriminability between competing category-response rules, reducing the need for lateral inhibition. However, when participants named the task before target presentation, backward inhibition was observed with spatial cues, suggesting that verbalization increased competition between sets, despite spatial localization.

Visual search irregularities in schizophrenia depend on display size switching.

INTRODUCTION: In past research it has been demonstrated that when performing a visual search task with either one or multiple (4, 7 or 10) stimuli displayed, patients with schizophrenia demonstrate slow response times (RTs) in the display size of one, target-absent (one-absent) condition. The goals of the present investigation were to replicate this effect, and to gain an understanding of the underlying cognitive operations by comparing display-size switch to display-size repeat trials. METHODS: In two experiments, patients and controls performed a visual search task with either one or four stimuli displayed. In Experiment 1 (one block with mixed switch and repeat trials), RT for display-size switch trials was compared to RT from display-size repeat trials. In Experiment 2, the display-size one and display-size four conditions were run in separate, homogeneous blocks. RESULTS: The results demonstrate that the one-absent slowing effect was eliminated on repeat trials, regardless of whether the switch and repeat trials were mixed or presented in separate blocks. CONCLUSIONS: This set of results suggests that a combination of cueing and switching effects may underlie the one-absent slowing observed in patients, such that switching to the one-absent condition is difficult due to insufficient cueing of the relevant cognitive operations. This visual search paradigm is an excellent candidate for inclusion in the development of a neurocognitive profile specific to schizophrenia.

Adults' representations of division facts: a consequence of learning history?

There has been a recent increase in the study of adults' performance on simple division problems. Researchers up to now have focused on the relationship between multiplication and division and have found that multiplication often has a mediating role in the solution of division problems (Campbell, 1997, 1999; LeFevre & Morris, 1999; Mauro, LeFevre, & Morris, 2002). In this study, division was exclusively examined to determine the strategies that are used to solve these problems and to identify factors relating to particular strategy use. Thirty-two participants were asked to solve two sets of 64 simple division problems (from 4 divided by 2 to 81 divided by 9) and error, latency, and strategy report data were collected. Fewer errors were made on easy problems, which were also solved more quickly than difficult problems. Participants used retrieval, multiplication, and other strategies to solve the problems and tended to use retrieval more on easy than difficult problems and used multiplication more on difficult problems than easy problems. Unexpected age differences in strategy use were also found. Older participants tended to rely more heavily on retrieval than younger participants. These results suggest that older participants may have stronger representations for simple division problems than younger participants.

Phenomenal characteristics of guided imagery, natural imagery, and autobiographical memories.

Research indicates that guided imagery experiences can be mistaken for actual experiences under some circumstances. One explanation for such effects is that memory representations of guided imagery and actual events contain similar phenomenal characteristics such as sensory and contextual details, making the source of the events less distinguishable. This study examined this prediction, comparing memory characteristic ratings for guided imagery experiences with those for memories of perceived and natural imagery events (e.g., fantasies). Results replicated previous findings for the difference between perceived and natural imagery memories. Guided imagery ratings were also lower than those for perceived memories for most sensory details (sound, smell, and taste) and temporal details. However, guided imagery ratings for reflective details were lower than both perceived and natural imagery memory ratings. Thus, guided imagery was similar to natural imagery with respect to sensory details, but similar to perceived memories with respect to reflective details.