Blurring the distinctions between on and off the job injuries: similarities and differences in circumstances.

OBJECTIVES: To compare the causes of non-fatal work and non-work injuries and the places or environments where they occur. It has been suggested that many injuries may have similar etiologies on and off the job and thus involve some common prevention strategies. However lack of comparable data on work relatedness has prevented testing this proposition. METHODS: The National Health Interview Survey (NHIS) now collects information on the cause, location, and work relatedness of all medically attended injuries. National US estimates of non-fatal work and non-work injuries were compared by cause and place/location for working age adults (18-64 years). RESULTS: Overall 28.6% of injuries to working age adults were work related (37.5% among employed people). The causes and locations of many work and non-work injuries were similar. Falls, overexertion, and struck/caught by were leading causes for work and non-work injuries. Motor vehicle injuries were less likely to be work related (3.4% at work v 19.5% non-work) and overexertion injuries more likely to be work related (27.1% v 13.8%). Assaults were less than 1% of work injuries and 1.8% of non-work injuries. Both work and non-work injuries occurred in every location examined-including the home where 3.5% of injuries were work related. CONCLUSIONS: Work and non-work injuries share many similarities suggesting opportunities to broaden injury prevention programs commonly restricted to one setting or the other. Comprehensive efforts to prevent both non-work and work injuries may result in considerable cost savings not only to society but also directly to employers, who incur much of the associated costs.

Using narrative text and coded data to develop hazard scenarios for occupational injury interventions.

OBJECTIVE: To determine whether narrative text in safety reports contains sufficient information regarding contributing factors and precipitating mechanisms to prioritize occupational back injury prevention strategies.Design, setting, subjects, and MAIN OUTCOME MEASURES: Nine essential data elements were identified in narratives and coded sections of safety reports for each of 94 cases of back injuries to United States Army truck drivers reported to the United States Army Safety Center between 1987 and 1997. The essential elements of each case were used to reconstruct standardized event sequences. A taxonomy of the event sequences was then developed to identify common hazard scenarios and opportunities for primary interventions. RESULTS: Coded data typically only identified five data elements (broad activity, task, event/exposure, nature of injury, and outcomes) while narratives provided additional elements (contributing factor, precipitating mechanism, primary source) essential for developing our taxonomy. Three hazard scenarios were associated with back injuries among Army truck drivers accounting for 83% of cases: struck by/against events during motor vehicle crashes; falls resulting from slips/trips or loss of balance; and overexertion from lifting activities. CONCLUSIONS: Coded data from safety investigations lacked sufficient information to thoroughly characterize the injury event. However, the combination of existing narrative text (similar to that collected by many injury surveillance systems) and coded data enabled us to develop a more complete taxonomy of injury event characteristics and identify common hazard scenarios. This study demonstrates that narrative text can provide the additional information on contributing factors and precipitating mechanisms needed to target prevention strategies.

The emergence of children's causal explanations and theories: evidence from everyday conversation.

This research examines the content of explanations that 4 English-speaking children gave or asked for in everyday conversations recorded from 2 1/2 to 5 years of age. Analyses of nearly 5,000 codable explanations (identified by markers like why or because) focused on the entity targeted for explanation (e.g., person, animal, object), the explanatory mode of causal reasoning (e.g., psychological, physical), and interrelations between these elements. Children's explanations focused on varied entities (animals, objects, and persons) and incorporated diverse modes (psychological, physical, social-conventional, and even biological reasoning). Children's pairings of entities with explanatory modes suggest appropriately constrained yet flexible causal reasoning. These data are consistent with the hypothesis that young children draw on several complementary causal-explanatory theories to make sense of real-life events.

Meta-analysis of theory-of-mind development: the truth about false belief.

Research on theory of mind increasingly encompasses apparently contradictory findings. In particular, in initial studies, older preschoolers consistently passed false-belief tasks-a so-called "definitive" test of mental-state understanding-whereas younger children systematically erred. More recent studies, however, have found evidence of false-belief understanding in 3-year-olds or have demonstrated conditions that improve children's performance. A meta-analysis was conducted (N = 178 separate studies) to address the empirical inconsistencies and theoretical controversies. When organized into a systematic set of factors that vary across studies, false-belief results cluster systematically with the exception of only a few outliers. A combined model that included age, country of origin, and four task factors (e.g., whether the task objects were transformed in order to deceive the protagonist or not) yielded a multiple R of .74 and an R2 of .55; thus, the model accounts for 55% of the variance in false-belief performance. Moreover, false-belief performance showed a consistent developmental pattern, even across various countries and various task manipulations: preschoolers went from below-chance performance to above-chance performance. The findings are inconsistent with early competence proposals that claim that developmental changes are due to tasks artifacts, and thus disappear in simpler, revised false-belief tasks; and are, instead, consistent with theoretical accounts that propose that understanding of belief, and, relatedly, understanding of mind, exhibit genuine conceptual change in the preschool years.

Theory of mind and conceptual change.

We agree with the commentaries by Scholl and Leslie, and also by Moses, that the meta-analytic findings do not definitively rule out early competence accounts. But they do make extant versions of such accounts increasingly unlikely. In particular, the meta-analytic findings argue against executive function expression accounts, including the Theory-of-Mind Mechanism/Selection Processor account advocated by Scholl and Leslie. Specifically, Scholl and Leslie articulate two explicit predictions of their account: that task manipulations that attenuate inhibitory demands should differentially advantage older children, and that theory-of-mind developments should occur with consistent timetables. Both of these specific predictions are clearly contradicted, not supported, by the meta-analytic findings.

Thinking about the past: early knowledge about links between prior experience, thinking, and emotion.

In two studies the authors investigated the situations where 3- to 7-year-olds and adults (N = 152) will connect a person's current feelings to the past, especially to thinking or being reminded about a prior experience. Study 1 presented stories featuring a target character who felt sad, mad, or happy after an event in the past and who many days later felt that same negative or positive emotion upon seeing a cue related to the prior incident. For some story endings, the character's emotion upon seeing the cue matched, or was congruent, with the current situation, whereas for others, the emotion mismatched the present circumstances. Participants were asked to explain the cause of each character's current feelings. As a further comparison, children and adults listened to behavior cuing stories and provided explanations for characters' present actions. Study 2 presented emotional scenarios that varied by emotion-situation fit (whether the character's emotion matched the current situation), person-person fit (whether the character's emotion matched another person's), and past history information (whether information about the character's past was known). Results showed that although there were several significant developments with increasing age, even most 3-year-olds demonstrated some knowledge about connections between past events and present emotions and between thinking and feeling. Indeed, children 5 years and younger revealed strikingly cogent understanding about historical-mental influences in certain situations, especially where they had to explain why a person, who had experienced a negative event in the past, was currently feeling sad or mad in a positive situation. These findings help underwrite a more general account of the development of children's coherent understandings of life history, mind, and emotion.

Young children's understanding of perception, desire, and emotion.

Very young children seem to know that people experience several mental states: desires, perceptions, emotions. In three studies, we investigated 2- and young 3-year-olds' judgments and communications about how these states connect together in people's lives and minds. Two experimental studies with 56 participants demonstrated young children's understanding of at least one set of connections: In appropriate circumstances, a person's perception of desirable or undesirable objects leads to related emotional experiences. A complementary investigation of four young children's everyday conversations demonstrated their awareness of and expression of several additional connections between people's desires, perceptions, and emotions.

Acquisition of mental state language in Mandarin- and Cantonese-speaking children.

Children's theory of mind appears to develop from a focus on desire to a focus on belief. However, it is not clear (a) whether this pattern is universal and (b) whether it could also be explained by linguistic and sociocultural factors. This study examined mental state language in 10 Mandarin-speaking (21-27 months) and 8 Cantonese-speaking (18-44 months) toddlers. The results suggest a pattern of theory-of-mind development similar to that in English, with early use of desire terms followed by other mental state references. However, the Chinese-speaking children used desire terms much earlier, and the use of terms for thinking was very infrequent, even for Mandarin-speaking adults. This finding suggests a consistency in the overall sequence, but variation in the timing of beginning and end points, in children's theory-of-mind development across cultures.

Culture, variation, and levels of analysis in folk psychologies: comment on Lillard (1998)

Not only do folk psychologies differ for adults in different cultures, but naive psychological conceptions begin early in life and develop. Understanding cultural variation requires understanding these beginnings and developments as well as considering naive psychological conceptions at several different levels of analysis.

Explaining human movements and actions: children's understanding of the limits of psychological explanation.

Human actions and movements can be caused by psychological states (e.g. beliefs and desires), physical forces (e.g. gravity) and biological processes (e.g. reflexes). In three studies we explored young children's understanding of the causes of human movements in order to examine their ability to differentiate and coordinate psychological, physical and biological reasoning to account for the activities of one single entity--a human being. In Study 1, 4-year-olds explained characters' voluntary actions, mistakes, physically-caused and biologically-caused behaviors and movements. Children gave psychological explanations for the intended actions and mistakes, but biological and physical explanations for the biologically-caused and physically-caused movements. Studies 2 and 3 extended the investigation to younger children (3-year-olds), encompassed a greater variety of items, and used several converging methods in order to examine children's judgments and explanations. Consistently, 3- and 4-year-olds gave appropriately different responses and explanations to the different item types. These findings show that far from viewing people in strictly psychological terms, young children evidence multiple causal-explanatory construals of human behavior. We discuss the implications of these findings for children's everyday psychological, physical, and biological theories. One implication of the findings is that young children do not assume a match between entities and theories (persons-psychology, objects-physics). If they do not, this raises the question of what information they use to decide which explanatory system fits which events.

Preschoolers' understanding of the link between thinking and feeling: cognitive cuing and emotional change.

In 3 studies we investigated 3- through 6-year-olds' knowledge of thinking and feeling by examining their understanding of how emotions can change when memories of past sad events are cued by objects in the current environment. In Study 1, 48 4-, 5-, and 6-year-olds were presented with 4 illustrated stories in which focal characters experience minor sad events. Later, each story character encounters a visual cue that is related to one of his or her previous sad experiences. Children were told that the character felt sad, and they were asked to explain why. Study 1 suggested considerable competence as well as substantial development in the years between 4 and 6 in the understanding of the influence of mental activity on emotions. Studies 2 and 3 more systematically explored preschoolers' understanding of cognitive cuing and emotional change with different types of situations and cues. Across these 2 studies, 108 3-, 4-, and 5-year-olds listened to illustrated stories that featured story characters who each experienced a sad event and who were later exposed to a related cue. Children were not only asked to explain why the characters suddenly felt sad, but in some stories, they were also asked to predict and explain how another character, who was never at the past sad event, would feel. Results of Studies 2 and 3 showed an initial understanding of cognitive cuing and emotion in some children as young as 3, replicated and extended the evidence for significant developmental changes in that understanding during the preschool years, and revealed that the strength and consistency of preschoolers' knowledge of cognitive cuing and emotion was affected by whether cues were the same, or only similar to, parts of the earlier events.

Young children's understanding of thought bubbles and of thoughts.

In a series of 4 studies, we explored preschoolers' understanding of thought bubbles. Very few 3-year-olds or 4-year-olds we tested knew what a thought-bubble depiction was without instruction. But, if simply told that the thought bubble "shows what someone is thinking," the vast majority of 3-year-olds and 4-year-olds easily understood the devices as depicting thoughts generally and individual thought contents specifically. In total, these children used thought-bubble depictions to ascertain the contents of characters' thoughts in a variety of situations; appropriately distinguished such depictions from mere associated actions or objects; described thought bubbles in the language of mental states; judged that persons' thoughts in these depictions were subjective in the sense of person-specific (and hence 2 people can have different thoughts about the same state of affairs); and judged that thought-bubble thoughts (a) were representational in the sense of depicting or showing some other state of affairs, (b) were mental and thus showed intangible, private, internal thoughts unlike real pictures or photographs, and (c) can be false, that is, can depict a person's misrepresentation of some state of affairs. We discuss the implications of these findings for young children's understanding of thoughts and thought bubbles, for their learning and comprehension of pictorial conventions, and for the use of thought bubbles to assess children's early understanding of mind.

The mind's "I": children's conception of the mind as an active agent.

1 hypothesis about children's developing conception of the mind is that preschoolers are limited to an understanding that persons have internal, mental contents like thoughts and beliefs, whereas older children and adults conceive of the mind itself as an independent, active structure or processor. Adults' conception of the mind in this independent active fashion seems evident in their use of personified mental metaphor (e.g., "My mind tricked me"). 3 studies examined the development and consolidation of this active, personified view. Study 1 provided an analysis of natural language data regarding 1 child's uses of vision words such as see and look from age 2 1/2 to 8 years. We examined the child's use of such words to refer literally to perception (e.g., "I see the TV") and also to refer nonliterally to active mental processes such as comprehension and inference (e.g., "I see what you mean"). Studies 2 and 3 examined 6-, 8-, and 10-year-olds' comprehension and production of mental metaphors. In a metaphor comprehension task, we asked children to interpret personified metaphoric statements about the mind (e.g., "My mind wandered") and 3 comparison domains, mechanics (e.g., "The car is dead"), nature (e.g., "The wind is howling"), and emotion (e.g., "Her heart was smiling"). In an explanation task, we asked children to explain the processes underlying the making of both instant photos and mental images. The findings reveal a developing ability to interpret and produce statements personifying the mind and provide considerable evidence about children's movement toward a conception of the mind as an independent entity deserving reference and conceptualization in its own right.

Two roads diverged: young children's ability to judge distance.

In the present studies, we investigated 4- and 5- to 6-year-old's ability to compare the distances covered by a direct route to a location and an indirect route to the same location. The distances ranged between 16 and 22 feet. The routes were visible from a single vantage point, and objects serving as landmarks were sometimes located along the routes. We found clear demonstrations of the two classic Piagetian distance errors--the direct-indirect error, in which children judge that a direct route and an indirect route cover the same distance, and the interposed object error, in which children judge that a route is shorter when it is segmented by an object located somewhere along the route. The interposed object error occurred because children focused on only one segment of the route, which was consistent with Piaget's explanation of the error. However, in contrast to Piaget, we found that about 40% of 4-year-olds could successfully avoid the direct-indirect error, and in addition, when the routes were visually displayed, they could also avoid the interposed object error. It is important that they also gave correct explanations for why the indirect route was longer, by referring to the fact that it was not straight. For these children at least, the interposed object error was due to difficulty they had representing routes, rather than to a misconception of distance. We suggest that future research should examine whether that may also be true for younger children.

Origin and truth: young children's understanding of imaginary mental representations.

In 2 studies, we address young children's understanding of the origin and representational relations of imagination, a fictional mental state, and contrast this with their understanding of knowledge, an epistemic mental state. In the first study, 54 3- and 4-year-old children received 2 tasks to assess their understanding of origins, and 4 stories to assess their understanding of representational relations. Children of both ages understood that, whereas perception is necessary for knowledge, it is irrelevant for imagination. Results for children's understanding of representational relations revealed intriguing developmental differences. Although children understood that knowledge represents reality more truthfully than imagination, 3-year-olds often claimed that imagination reflected reality. The second study provided additional evidence that younger 3-year-olds judge that imaginary representations truthfully reflect reality. We propose that children's responses indicate an early understanding of the distinction between mental states and the world, but also a confusion regarding the extent to which mental contents represent the physical world.

Insides and essences: early understandings of the non-obvious.

Insides and essences are both critical concepts for appreciating the importance of non-obvious entities: neither are observable, both contrast with external appearances, and both can be more important than external appearances. The present research examined understandings of insides and essences in 3- to 5-year-old children. In Study 1, children were asked questions requiring them to think about both the insides and the outer appearances of a series of objects. In Study 2, children were tested on their understanding that insides are typically more important than outer surfaces for an object's identity and functioning. In Studies 3, 4, and 5, children were tested on their understanding of innate potential, a concept that reflects understanding of an inborn essence. Contrary to the traditional view of children as externalists (cf. Piaget, 1951), these studies demonstrate that by age 4 children have a firm grasp of the importance of both insides and essences. Even by age 3 children reason clearly about the inside-outside distinction. These results suggest that preschool children attend to non-obvious features and realize their privileged status. They may also indicate a more basic predisposition toward psychological essentialism in young children.

Young children's understanding of realities, nonrealities, and appearances.

In 2 studies we uncover some of children's earliest conceptions of various realities, nonrealities, and appearances. In the first study, we investigated children's early understanding by examining their use of the words real and really in spontaneous speech. These natural language data consisted of longitudinal samples of 6 children's speech between the ages of 1 and 6 from the Childes database. Analyses of these samples showed that by age 3 children clearly distinguished between reality and a variety of nonreal contrasts in their everyday speech. For example, young children distinguished between toys, pictures, and pretend actions versus their real natures. We claim that, in making these distinctions, children often are considering appearances, broadly construed. To confirm this, we conducted a second experimental study with 3-year-olds, in which we questioned children about the reality and appearance of a variety of items. Results from this study confirm and clarify our findings from the natural language data. We discuss the implications of these studies for current descriptions of young children's understanding of realities and nonrealities, including their understanding of the distinction between reality and appearance.

From simple desires to ordinary beliefs: the early development of everyday psychology.

We provide evidence for the claim that before young children construe human action in terms of beliefs and desires they understand action only in terms of simple desires. This type of naive psychology--a simple desire psychology--constitutes a coherent understanding of human action, but it differs from the belief--desire psychology of slightly older children and adults. In this paper we characterize what we mean by a simple desire psychology and report two experiments. In Experiment 1 we demonstrate that 2-year-old can predict actions and reactions related to simple desires. In Experiment 2 we demonstrate that many 2-year-old pass desire reasoning tasks while at the same time failing belief reasoning tasks that are passed by slightly older children, and that are as comparable as possible to the desire tasks they pass with ease.