Infants' Processing of Causal and Noncausal Events at 3.5 Months of Age

Infants' processing of causal (direct launching) and noncausal (delayed reaction, launching without collision) events was investigated with 30 infants who were 3.5 months old. The habituation-dishabituation technique was used. Results showed that the infants did not process direct launching as causal. However, their pattern of responding revealed a tendency to key on the spatial and temporal properties of the events. Those findings are discussed in terms of their compatibility with a modular, an information-processing, and a Piagetian framework.     

The perception of causality in infancy

Michotte proposed a rationalist theory of the origin of the human capacity to represent causal relations among events. He suggested that the input analyzer that underlies the causal perception in launching, entraining, and expulsion events is innate and is the ultimate source of all causal representations. We review the literature on infant causal representations, providing evidence that launching, entraining and expulsion events are interpreted causally by young infants. However, there is as of yet no good evidence that these representations are innate. Furthermore, there is considerable evidence that these representations are not the sole source of the human capacity for causal representation.     

Precursors to infants'' perception of the causality of a simple event

Three habituation experiments examined the perception of causal and non-causal events by infants at 6 1/4, 5 1/2, and 4 months of age. Experiment 1 replicated previous studies showing that by 6 1/4 months, infants begin to respond to the interaction of simple objects in Michottian type launching events on the basis of causality. In Experiments 2 and 3, however, younger infants exposed to the identical event sequences responded on the basis of simpler perceptual features of the launching events, and not on the basis of causality. 4-month-old infants responded to continuous versus non-continuous movement. 5 1/2-month-old infants also responded somewhat on the basis of continuous movement. However, in addition they responded on the basis of the spatial and temporal perceptual features of the events. This change in the pattern of results over age suggests a multi-step developmental progression.     

Bayes nets and babies: infants' developing statistical reasoning abilities and their representation of causal knowledge

A fundamental assumption of the causal graphical model framework is the Markov assumption, which posits that learners can discriminate between two events that are dependent because of a direct causal relation between them and two events that are independent conditional on the value of another event(s). Sobel and Kirkham (2006) demonstrated that 8-month-old infants registered conditional independence information among a sequence of events; infants responded according to the Markov assumption in such a way that was inconsistent with models that rely on simple calculations of associative strength. The present experiment extends these findings to younger infants, and demonstrates that such responses potentially develop during the second half of the first year of life. These data are discussed in terms of a developmental trajectory between associative mechanisms and causal graphical models as representations of infants' causal and statistical learning.     

Infants’ developing expectations of possible and impossible tool-use events between ages 8 and 12 months

Infants’ developing causal expectations for the outcome of a simple tool-use event from ages 8 to 12 months were investigated. Causal expectations were studied by comparing infants’ developing tool-use actions (i.e. as tool-use agents) with their developing perceptual reactions (i.e. as tool-use observers) to possible and impossible tool-use events. In Experiment 1, tool-use actions were studied by presenting infants, ages 8 and 12 months, with tool-use object-retrieval problems. In Experiment 2, a second age-matched sample of infants watched a comparable series of possible and impossible tool-use events in which a tool was used to retrieve a goal-object. Two core related findings were made. First, infants’ causal action and causal perception develop in parallel. In both action and perception, supporting tool-use develops before surrounding tool-use. Second, infants’ tool-use action develops before their causal perception of comparable tool-use events. The findings support the constructivist hypothesis that infants’ causal actions may develop before and inform their causal perceptions.     

Causal perception of action-and-reaction sequences in 8- to 10-month-olds

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.     

Spatiotemporal continuity and the perception of causality in infants

Infant perception of a Michottean launching event in which one object causes another to move through collision is examined in a series of habituation-test experiments. A number of hypotheses concerning how infants aged around 30 weeks might perceive and encode launching and its noncausal variants are identified and tested. The results of the first experiment indicate that infants can perceive direct launching as an event with internal structure, that is, as composed of two temporally ordered movements. The nature of the encoding by the infants is perceptual and not specifically motor-based. The second experiment makes it seem unlikely that the infants encode independent spatial and temporal features (for example, contact and successivity), while the third experiment suggests a spatiotemporal continuity gradient. Some implications for the origins of causality are discussed.     

That’s the way the ball bounces: infants’ and adults’ perception of spatial and temporal contiguity in collisions involving bouncing balls

Three experiments investigated the perception of collisions involving bouncing balls by 7- and 10-month-old infants and adults. In previous research, 10-month-old infants perceived the causality of launching collisions (events in which one object moves along a smooth horizontal trajectory toward a second object, apparently launching it into motion) in relatively simple event contexts. In more complex event contexts, infants failed to discriminate among the events or respond to changes in individual features. Experiments 1 and 2 of the present investigation revealed that 7- and 10-month-old infants attended to spatial and temporal contiguity, but not causality, in collisions involving the movement of bouncing balls. In Experiment 3, both spatiotemporal contiguity and general knowledge about movement trajectories influenced adults’ judgments of causality for these collisions. The present results add to a growing understanding of infants’ event perception as constructive and a function, in part, of the complexity of the event context.     

The cradle of causal reasoning: newborns’ preference for physical causality

Perception of mechanical (i.e. physical) causality, in terms of a cause–effect relationship between two motion events, appears to be a powerful mechanism in our daily experience. In spite of a growing interest in the earliest causal representations, the role of experience in the origin of this sensitivity is still a matter of dispute. Here, we asked the question about the innate origin of causal perception, never tested before at birth. Three experiments were carried out to investigate sensitivity at birth to some visual spatiotemporal cues present in a launching event. Newborn babies, only a few hours old, showed that they significantly preferred a physical causality event (i.e. Michotte's Launching effect) when matched to a delay event (i.e. a delayed launching; Experiment 1) or to a non‐causal event completely identical to the causal one except for the order of the displacements of the two objects involved which was swapped temporally (Experiment 3). This preference for the launching event, moreover, also depended on the continuity of the trajectory between the objects involved in the event (Experiment 2). These results support the hypothesis that the human system possesses an early available, possibly innate basic mechanism to compute causality, such a mechanism being sensitive to the additive effect of certain well‐defined spatiotemporal cues present in the causal event independently of any prior visual experience.     

Event completion: event based inferences distort memory in a matter of seconds

We present novel evidence that implicit causal inferences distort memory for events only seconds after viewing. Adults watched videos of someone launching (or throwing) an object. However, the videos omitted the moment of contact (or release). Subjects falsely reported seeing the moment of contact when it was implied by subsequent footage but did not do so when the contact was not implied. Causal implications were disrupted either by replacing the resulting flight of the ball with irrelevant video or by scrambling event segments. Subjects in the different causal implication conditions did not differ on false alarms for other moments of the event, nor did they differ in general recognition accuracy. These results suggest that as people perceive events, they generate rapid conceptual interpretations that can have a powerful effect on how events are remembered.     

The larger the cause,the larger the effect: evidence of speed judgment biases in causal scenarios

ABSTRACT

When two motions appear to be causally related, the spatiotemporal features of motions are sometimes distorted in order to increase the consistency with causal impressions. Here, in four experiments, we tested if varying the speed of an object A could affect the judged speed of an object B that appeared to be causally related to A. Participants were presented with classic launching stimuli (Experiment 1), a variant of launching stimuli in which A could move with uniformly accelerated or decelerated motion (Experiment 2), non-launching stimuli that elicited a causal impression (Experiment 3), and stimuli showing a three-object launching event (Experiment 4). Main results showed that the judged speed of B was systematically biased towards the speed of A, and moreover that the judged speed of B depended on the average speed of A, rather than on the speed of A at the moment of collision as it would be predicted by Newtonian mechanics. The results are consistent with the hypothesis that internal representations of causal events based on property transmission (for instance, impetus) can affect judgments of the low-level properties of causal scenarios.     

Emerging perception of causality in action-and-reaction sequences from 4 to 6 months of age: Is it domain-specific?

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.     

The spatiotemporal distinctiveness of direct causation

The launching effect, in which people judge one object to have caused another to immediately move after contact, is often described as the prototype of direct causation. The special status of this interaction may be due to its psychophysical distinctiveness, and this property may be the origin of the formation of causality as a conceptual category. This hypothesis was tested by having participants judge the relative similarity of pairs of events that either had no spatial gap or delay (direct launching) or had small gaps and/or short delays. Direct launching was much easier to discriminate from launches involving small gaps or delays. In a follow-up experiment, participants made similar judgments for a noncausal event.     

Pigeons' discrimination of Michotte's launching effect

We trained four pigeons to discriminate a Michotte launching animation from three other animations using a go/no-go task. The pigeons received food for pecking at one of the animations, but not for pecking at the others. The four animations featured two types of interactions among objects: causal (direct launching) and noncausal (delayed, distal, and distal & delayed). Two pigeons were reinforced for pecking at the causal interaction, but not at the noncausal interactions; two other pigeons were reinforced for pecking at the distal & delayed interaction, but not at the other interactions. Both discriminations proved difficult for the pigeons to master; later tests suggested that the pigeons often learned the discriminations by attending to subtle stimulus properties other than the intended ones.     

Secret agents: inferences about hidden causes by 10- and 12-month-old infants

Considerable evidence indicates that preverbal infants expect that only physical contact can cause an inanimate object to move. However, very few studies have investigated infants' expectations about the source of causal power. In three experiments, we found that (a) 10- and 12-month-old infants expect a human hand, and not an inanimate object, to be the primary cause of an inanimate object's motion; (b) infants' expectations can lead them to infer a hidden causal agent without any direct perceptual evidence; and (c) infants do not infer a hidden causal agent if the moving object was previously shown to be capable of self-generated motion.     

Does causal action facilitate causal perception in infants younger than 6 months of age?

Previous research has established that infants are unable to perceive causality until 6¼ months of age. The current experiments examined whether infants’ ability to engage in causal action could facilitate causal perception prior to this age. In Experiment 1, 4½‐month‐olds were randomly assigned to engage in causal action experience via Velcro sticky mittens or not engage in causal action because they wore non‐sticky mittens. Both groups were then tested in the visual habituation paradigm to assess their causal perception. Infants who engaged in causal action – but not those without this causal action experience – perceived the habituation events as causal. Experiment 2 used a similar design to establish that 4½‐month‐olds are unable to generalize their own causal action to causality observed in dissimilar objects. These data are the first to demonstrate that infants under 6 months of age can perceive causality, and have implications for the mechanisms underlying the development of causal perception.     

Producing and processing self-propelled motion in infancy

Three experiments investigated 5- through 8-month-olds' ability to encode self-propelled and caused motion and examined whether processing of motion onset changes when crawling begins. Infants were habituated (Experiments 1 and 2) or familiarized (Experiment 3) with simple causal and noncausal launching events. They then viewed the caused-to-move and self-propelled objects from the events both stationary and side-by-side, and their preferential looking to the objects was assessed. Results revealed that 5- and 6-month-olds displayed a different pattern of looking than did 8-month-olds. More notably, noncrawling 7-month-olds and 7-month-olds with crawling experience also demonstrated such a differential pattern. These data suggest that processing of motion onset changes in concert with the commencement of self-locomotion. Findings are discussed in reference to the mechanisms underlying infants' ability to recognize self-propelled motion and the scope of the relationship between action production and action perception in infancy.     

Infants' Perception of Causal Chains

Three experiments examined infants' and adults' perception of causal sequences of events. In a causal-chain sequence, the first action causes a second action that then causes a final outcome; in a temporal-chain sequence, the first two actions are independent and the second action causes a final outcome. Infants and adults were shown the same event sequences; infants were tested using a visual habituation paradigm, whereas adults were given a questionnaire. Experiment 1 indicated that 15-month-old infants perceive the primary cause of the final outcome to be the first action in a causal chain but the second action in a temporal chain. Experiment 2 showed that adults interpret the causal sequences in a manner similar to that of 15-month-olds. Finally, Experiment 3 showed that 10-month-old infants do not yet perceive causal sequences in the same manner as 15-month-olds and adults. These results are interpreted in terms of both infants' developing knowledge of causal events and adults' attributions of causality in complex events.     

Just do it? Investigating the gap between prediction and action in toddlers’ causal inferences

Adults’ causal representations integrate information about predictive relations and the possibility of effective intervention; if one event reliably predicts another, adults can represent the possibility that acting to bring about the first event might generate the second. Here we show that although toddlers (mean age: 24 months) readily learn predictive relationships between physically connected events, they do not spontaneously initiate one event to try to generate the second (although older children, mean age: 47 months, do; Experiments 1 and 2). Toddlers succeed only when the events are initiated by a dispositional agent (Experiment 3), when the events involve direct contact between objects (Experiment 4), or when the events are described using causal language (Experiment 5). This suggests that causal language may help children extend their initial causal representations beyond agent-initiated and direct contact events.