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Background: Causes produce effects via underlying mechanisms that must be inferred from observable and unobservable structures. Preschoolers show sensitivity to mechanisms in machine-like systems with perceptually distinct causes and effects, but little is known about how children extend causal reasoning to the natural continuous processes studied in elementary school science, or how other abilities impact on this. Aims: We investigated the development of children's ability to predict, observe, and explain three causal processes, relevant to physics, biology, and chemistry, taking into account their verbal and non-verbal ability. Sample: Children aged 5-11 years (N = 107) from London and Oxford, with wide ethnic/linguistic variation, drawn from the middle/upper socioeconomic status (SES) range. Methods: Children were tested individually on causal tasks focused on sinking, absorption, and dissolving, using a novel approach in which they observed contrasting instances of each, to promote attention to mechanism. Further tasks assessed verbal (expressive vocabulary) and non-verbal (block design) ability. Results: Reports improved with age, though with differences between tasks. Even young participants gave good descriptions of what they observed. Causal explanations were more strongly related to observation than to prediction from prior knowledge, but developed more slowly. Non-verbal but not generic verbal ability predicted performance. Conclusions: Reasoning about continuous processes is within the capacity of children from school entry, even using verbal reports, though they find it easier to address more rapid processes. Mechanism inference is uncommon, with non-verbal ability an important influence on progress. Our research is the first to highlight this key factor in children's progress towards thinking about scientific phenomena.

Under the normative Expected Value (EV) model, multiple outcomes are additive, but in everyday worth judgement intuitive averaging prevails. Young children also use averaging in EV judgements, leading to a disordinal, crossover violation of utility when children average the part worths of simple gambles involving independent events (Schlottmann, 2000). This study explored the origins of this averaging bias in children's worth judgements, assessing whether averaging also appears for riskless judgements and for other types of risky judgements. In Experiment 1, 8-year-olds judged the worth of having either one or two squares of chocolates in two formally equivalent tasks: Children made additive worth judgements when chocolates varied in size, but used averaging when they varied in winning probability. Performance on the EV task was slightly more advanced when risky followed riskless judgements, with some evidence of transfer. In Experiment 2, 5-year-olds gave additive worth judgements when judging variable fractions of chocolate pies, with displays closely parallel to the spinner discs used for the gambles in Experiment 1. In Experiment 3, 5-year-olds gave additive worth judgements of gambles in which to win either one or two prizes, with alternative rather than independent probabilities of winning. Thus the overgeneralisation of averaging processes to EV judgement, while persistent, neither reflects a general difficulty with additive value judgement, nor with displays showing positive and negative information, nor with risky judgement per se. It may come into play because children have difficulty appreciating the implications of independence, apparent also in other domains. Despite such difficulty, children realize that risky game outcomes go beyond what they can see, and so may apply averaging, as default strategy for population judgement, whereas addition might be the default for judging the sample itself. (Contains 5 figures and 1 table.)

Studies using an Information Integration approach have shown that children from four years have a good intuitive understanding of probability and expected value. Experience of skill-related uncertainty may provide one naturalistic opportunity to develop this intuitive understanding. To test the viability of this view, 16 5- and 16 7-year-olds played a marble rolling game in which size of the target and distance from it varied factorially. Task difficulty judgements (prior to practical experience with the game) reflected both objective task structure and subsequent performance for both age groups. Children then judged how happy they would be playing games of variable difficulty for different prizes. These judgements had the multiplicative structure predicted by the normative expected value model, again for both age groups. Thus children can use task difficulties as estimates of personal success probability in skill-related tasks. Our findings therefore extend previous work on early probability understanding from games of chance to games of skill. (Contains 2 figures and 1 table.)

Two experiments (N=136) studied how 4- to 6-month-olds perceive a simple schematic event, seen as goal-directed action and reaction from 3 years of age. In our causal reaction event, a red square moved toward a blue square, stopping prior to contact. Blue began to move away before red stopped, so that both briefly moved simultaneously at a distance. Primarily, our study sought to determine from what age infants see the causal structure of this reaction event. In addition, we looked at whether this causal percept depends on an animate style of motion and whether it correlates with tasks assessing goal perception and goal-directed action. Infants saw either causal reactions or noncausal delayed control events in which blue started some time after red stopped. These events involved squares that moved either rigidly or nonrigidly in an apparently animate manner. After habituation to one of the four events, infants were tested on reversal of the habituation event. Spatiotemporal features reversed for all events, but causal roles changed only in reversed reactions. The 6-month-olds dishabituated significantly more to reversal of causal reaction events than to noncausal delay events, whereas younger infants reacted similarly to reversal of both. Thus, perceptual causality for reaction events emerges by 6 months of age, a younger age than previously reported but, crucially, the same age at which perceptual causality for launch events has emerged in prior research. On our second question, animate/inanimate motion had no effect at any age, nor did significant correlations emerge with our additional tasks assessing goal perception or goal-directed object retrieval. Available evidence, here and elsewhere, is as compatible with a view that infants initially see A affecting B, without differentiation into physical or psychological causality, as with the standard assumption of distinct physical/psychological causal perception. (Contains 1 table and 5 figures.)

Infants are sensitive to biological motion, but do they recognize it as animate? As a first step towards answering this question, two experiments investigated whether 6-month-olds selectively attribute goals to shapes moving like animals. We habituated infants to a square moving towards one of two targets. When target locations were switched, infants reacted more to movement towards a new goal than a new location--but only if the square moved non-rigidly and rhythmically, in a schematic version of bio-mechanical movement older observers describe as animal-like (Michotte, 1963). Goal attribution was specific to schematic animal motion: It did not occur if the square moved rigidly with the same rhythm as the animate stimulus, or if the square had the same amount of non-rigid deformation, but in an inanimate configuration. The data would seem to show that perception of schematic animal motion is linked to a system for psychological reasoning from infancy. This in turn suggests that 6-month-olds may already interpret biological motion as animate.

We investigated perception of social and physical causality and animacy in simple motion events, for high-functioning children with autism (CA = 13, VMA = 9.6). Children matched 14 different animations to pictures showing physical, social or non-causality. In contrast to previous work, children with autism performed at a high level similar to VMA-matched controls, recognizing physical causality in launch and social causality in reaction events. The launch deficit previously found in younger children with autism, possibly related to attentional/verbal difficulties, is apparently overcome with age. Some events involved squares moving non-rigidly, like animals. Children with autism had difficulties recognizing this, extending the biological motion literature. However, animacy prompts amplified their attributions of social causality. Thus children with autism may overcome their animacy perception deficit strategically.

Four experiments with 202 8- to 10-month-old infants studied their sensitivity to causation-at-a-distance in schematic events seen as goal-directed action and reaction by adults and whether this depends on attributes associated with animate agents. In Experiment 1, a red square moved toward a blue square without making contact; in "reaction" events blue moved away while red was approaching, whereas in "delay" events blue started after red stopped. Infants were habituated to one event and then tested on its reversal. Spatiotemporal features reversed for both events, but causal roles changed only in reversed reactions. Infants dishabituated more to reversed reaction events than to reversed delay events. Squares moved rigidly or in a nonrigid animal-like fashion. Infants discriminated these, but motion pattern did not affect responses to reversal. Infants also discriminated reactions from launching and dishabituated to reversed reactions lacking self-initiated motion. These results suggest that sensitivity to causation-at-a-distance depends on the event structure but not pattern or onset typical of animal motion. (Contains 5 figures and 1 table.)

This study investigated perceptual causality in launch and reaction events in children with ASD (CA = 8.4, VMA = 5.1) and mental age matched controls with typical development and learning difficulties. This is of interest because difficulties with global processing in autism suggest that individuals with ASD may not "see" causal Gestalts in general, and specific difficulties with reaction perception could be related to difficulties with TOM. Participants matched pictures depicting mechanical and psychological cause and non-causality to computer animated launch and reaction events and delayed control events. Children with ASD showed the typical response to reaction events, matching them with the picture for psychological cause, but they were impaired in launch perception compared to control participants. We discuss the possibility that event duration may be the critical difference between the causal events. The information allowing identification of a reaction is conveyed over a longer time frame (600 ms here) than in launching (21 ms here). This may allow for the deployment of global processes and/or attentional shifts in reaction, but not launch perception.

Two studies investigated how 5- to 10-year-olds integrate perceptual causality with their knowledge of the underlying causal mechanism, using two devices in which a bell would ring when a ball was dropped in, either immediately or after a delay, depending on the mechanism inside. Findings suggest a link between temporal contiguity and causality in children's understanding. (JPB)