Infants' concept of animacy

Nine- and 12-month-old infants' concept of animacy was investigated by exposing them to autonomous motion by an animate and by an inanimate object in a series of three experiments. In the first experiment, increases in negative affect in comparison to a baseline condition were taken to indicate that children considered an event to be anomalous. Results showed that 12-month-old infants consider self-propulsion by a small robot to be anomalous, but not self-propulsion by a human stranger. Experiment 2 indicated that 9- and 12-month-old infants expressed similar affective reactions when the robot's motion was contingent on verbal commands given by the mother, suggesting that these children are aware that it is not appropriate for an inanimate object's movements to be contingent on events occuring at a distance. The third experiment was designed to rule out the possibility that the infants' reactions in Experiment 2 were a function of the incongruity of the mother's behavior rather than due to the violation of the infant's concept of animacy. In this experiment, 12-month-olds' levels of attentiveness are increased when the robot obeyed verbal commands but not when a human stranger did so. These results suggest that infants discriminate animate from inanimate objects on the basis of motion cues by the age of 9 months.     

Infant's Inductive Generalization of Bodily,Motion, and Sensory Properties to Animals and People

It has been proposed that infants can form global categories such as animate and inanimate objects (Mandler, 2004). The inductive generalization paradigm was used to examine inferences made by infants about the bodily, motion, and sensory capabilities of people and animals. In Experiment 1, 14-month-old infants generalized bodily and sensory properties from dogs to cats and vice-versa. In Experiment 2, 16- and 20-month-olds generalized motion and sensory properties modeled with a person more often to mammals than to vehicles. Findings from Experiment 3 indicated that motion properties are generalized broadly to people and mammals but that by 20 months of age, infants may be beginning to attribute sensory properties preferentially to people more than to animals.     

A nonhuman primate's expectations about object motion and destination: The importance of self-propelled movement and animacy

Human infants have considerable understanding of why objects move and what causes them to take one trajectory over another. Here, we explore the possibility that this capacity is shared with other nonhumans and present results from preferential looking time tests with a New World monkey, the cotton-top tamarin. Experiments examined whether individuals form different expectations about an object's potential capacity to change locations. Test objects were: 1) self-propelled, moving, animate; 2) self-propelled, moving, inanimate; 3) non-self-propelled, moving due to an external agent, inanimate; 4) non-self-propelled, motionless, inanimate. When category 1 objects, either a live mouse or frog, emerged from behind an occluder in a novel location, this did not affect looking time; subjects appeared to expect such changes. In contrast, when the other objects emerged in a novel location following occlusion from view, subjects looked longer than when the object emerged in the location seen prior to occlusion; such locational changes were apparently not expected. Some feature other than self-propelled motion accounts for the tamarins’ looking time responses and at least one candidate feature is whether the object is animate or inanimate.     

Visual impressions of active and inanimate resistance to impact from a moving object

ABSTRACT

Images of moving objects presented on computer screens may be perceived as animate or inanimate. A simple hypothesis, consistent with much research evidence, is that objects are perceived as inanimate if there is a visible external contact from another object immediately prior to the onset of motion, and as animate if that is not the case. Evidence is reported that is not consistent with that hypothesis. Objects (targets) moving on contact from another object (launcher) were perceived as actively resisting the impact of the launcher on them if the targets slowed rapidly. Rapid slowing is consistent with the laws of mechanics for objects moving in an environment that offers friction and air resistance. Despite that, ratings of inanimate motion were lower than ratings of active resistance for objects that slowed rapidly. The results are consistent with the hypothesis that there is a perceptual impression of active (animate) resistance that is evoked by the kinematic pattern of rapid slowing from an initial speed after contact from another object.     

Do 5-month-old infants see humans as material objects?

Infants expect objects to be solid and cohesive, and to move on continuous paths through space. In this study, we examine whether infants understand that human beings are material objects, subject to these same principles. We report that 5-month-old infants apply the constraint of continuous motion to inanimate blocks, but not to people. This suggests that young infants have two separate modes of construal: one for inanimate objects and another for humans.     

Adaptive memory: Animacy effects persist in paired-associate learning

Recent evidence suggests that animate stimuli are remembered better than matched inanimate stimuli. Two experiments tested whether this animacy effect persists in paired-associate learning of foreign words. Experiment 1 randomly paired Swahili words with matched animate and inanimate English words. Participants were told simply to learn the English “translations” for a later test. Replicating earlier findings using free recall, a strong animacy advantage was found in this cued-recall task. Concerned that the effect might be due to enhanced accessibility of the individual responses (e.g., animates represent a more accessible category), Experiment 2 selected animate and inanimate English words from two more constrained categories (four-legged animals and furniture). Once again, an advantage was found for pairs using animate targets. These results argue against organisational accounts of the animacy effect and potentially have implications for foreign language vocabulary learning.     

Development of categorization in infancy: advancing forward to the animate/inanimate level

Three experiments are reported on the development of object categorization skills during the second year of life. Experiment 1 examined whether 14- and 18-month-old infants were capable of performing categorization at the animate/inanimate (A/I) level using a sequential touching task. The 18-month-olds were significantly above chance and the 14-month-olds were also approaching above-chance significance, which is the highest level of inclusiveness ever tested in infancy. In Experiments 2 and 3, 14-month-old infants participated in a sequential touching task in which the part features of animate and inanimate objects were modified, allowing for a test of partonomic (i.e., legs and wheels) vs. taxonomic (i.e., animates and inanimates) categorization. Infants did not favor partonomic categorization, suggesting that A/I categories are not formed solely based on object parts such as legs and wheels.     

Animacy and propulsion in infancy: Tracking,waving and reaching to self-propelled and induced moving objects

Infants from 16 to 20 weeks were videotaped while being presented with objects traversing a 60 cm distance. Four conditions were tested: (1) induced movement, holding the object; (2) induced movement, pushing the object; (3) self-propelled mechanical movement, object moving by an internal clockwork; (4) self-propelled biological movement, animate object moving by internal impulse. In tracking, the self-propelled but inanimate and mechanically moving object with the more straight and predictable trajectory attracted most visual attention. In arm movements, the self-propelled but relatively unpredictably moving animate object was reliably distinguished from inanimate objects. It appeared that the action system was less dependent on objects taking a straight and predictable course. Emerging with the onset of goal-directed reaches, the distinction of an internal locus of propulsion in objects was overriding the nearly exclusive response towards animacy occurring in waving. Thus, a distinction of different types of object motion could be found in infants’ developing action system.     

A categorical recall strategy does not explain animacy effects in episodic memory

Animate stimuli are better remembered than matched inanimate stimuli in free recall. Three experiments tested the hypothesis that animacy advantages are due to a more efficient use of a categorical retrieval cue. Experiment 1 developed an “embedded list” procedure that was designed to disrupt participants’ ability to perceive category structure at encoding; a strong animacy effect remained. Experiments 2 and 3 employed animate and inanimate word lists consisting of tightly constrained categories (four-footed animals and furniture). Experiment 2 failed to find an animacy advantage when the categorical structure was readily apparent, but the advantage returned in Experiment 3 when the embedded list procedure was employed using the same target words. These results provide strong evidence against an organizational account of the animacy effect, indicating that the animacy effect in episodic memory is probably due to item-specific factors related to animacy.     

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.     

Visual cues of motion that trigger animacy perception at birth: the case of self‐propulsion

Self‐propelled motion is a powerful cue that conveys information that an object is animate. In this case, animate refers to an entity's capacity to initiate motion without an applied external force. Sensitivity to this motion cue is present in infants that are a few months old, but whether this sensitivity is experience‐dependent or is already present at birth is unknown. Here, we tested newborns to examine whether predispositions to process self‐produced motion cues underlying animacy perception were present soon after birth. We systematically manipulated the onset of motion by self‐propulsion (Experiment 1) and the change in trajectory direction in the presence or absence of direct contact with an external object (Experiments 2 and 3) to investigate how these motion cues determine preference in newborns. Overall, data demonstrated that, at least at birth, the self‐propelled onset of motion is a crucial visual cue that allowed newborns to differentiate between self‐ and non‐self‐propelled objects (Experiment 1) because when this cue was removed, newborns did not manifest any visual preference (Experiment 2), even if they were able to discriminate between the stimuli (Experiment 3). To our knowledge, this is the first study aimed at identifying sensitivity in human newborns to the most basic and rudimentary motion cues that reliably trigger perceptions of animacy in adults. Our findings are compatible with the hypothesis of the existence of inborn predispositions to visual cues of motion that trigger animacy perception in adults.     

Infants’ enumeration of dynamic displays

This study examined infants’ enumeration of puppet jumping tasks. In Experiment 1, 5–7-month-old infants were familiarized to a puppet jumping two or three times, and tested with both numbers of jumps. Infants looked significantly longer at the new number, replicating Wynn [Psychol. Sci. 7 (1996) 164]. To probe further the stability of infants’ ability to enumerate, Experiment 2 varied the rate of the jumps during habituation and controlled for rate across test trials. At test, infants showed no preference for either event, suggesting that rate changes can overpower infants’ responses to number. Experiment 3 explored an alternative explanation to infants’ enumeration, namely discrimination based on the amount of time the puppet spent jumping. Infants were familiarized to two or three jumps, then tested with alternating displays of either a familiar number of jumps with a novel jump time, or a novel number of jumps with the familiar jump time. Infants dishabituated to the display that changed in jump time, but not to the display that changed in number. Results suggest that infants’ looking in event sequences is based on amount of motion, not enumeration. This finding is consistent with studies finding perceptual processes behind infants’ supposed precocious numerical abilities.     

The Role of Animacy in Children's Interpretation of Relative Clauses in English: Evidence From Sentence–Picture Matching and Eye Movements

Subject relative clauses (SRCs) are typically processed more easily than object relative clauses (ORCs), but this difference is diminished by an inanimate head-noun in semantically non-reversible ORCs (“The book that the boy is reading”). In two eye-tracking experiments, we investigated the influence of animacy on online processing of semantically reversible SRCs and ORCs using lexically inanimate items that were perceptually animate due to motion (e.g., “Where is the tractor that the cow is chasing”). In Experiment 1, 48 children (aged 4;5–6;4) and 32 adults listened to sentences that varied in the lexical animacy of the NP1 head-noun (Animate/Inanimate) and relative clause (RC) type (SRC/ORC) with an animate NP2 while viewing two images depicting opposite actions. As expected, inanimate head-nouns facilitated the correct interpretation of ORCs in children; however, online data revealed children were more likely to anticipate an SRC as the RC unfolded when an inanimate head-noun was used, suggesting processing was sensitive to perceptual animacy. In Experiment 2, we repeated our design with inanimate (rather than animate) NP2s (e.g., “where is the tractor that the car is following”) to investigate whether our online findings were due to increased visual surprisal at an inanimate as agent, or to similarity-based interference. We again found greater anticipation for an SRC in the inanimate condition, supporting our surprisal hypothesis. Across the experiments, offline measures show that lexical animacy influenced children's interpretation of ORCs, whereas online measures reveal that as RCs unfolded, children were sensitive to the perceptual animacy of lexically inanimate NPs, which was not reflected in the offline data. Overall measures of syntactic comprehension, inhibitory control, and verbal short-term memory and working memory were not predictive of children's accuracy in RC interpretation, with the exception of a positive correlation with a standardized measure of syntactic comprehension in Experiment 1.     

Infants’ reasoning about ambiguous motion events: The role of spatiotemporal and dispositional status information

Two experiments investigate whether 7-month-olds reason about the origin of motion events by considering two sources of causally relevant information: spatiotemporal cues and dispositional status information derived from the identification of an object as either animate (with the enduring causal property of self-initiated motion) or inanimate (requiring an external cause of motion). Infants were shown a ball, a human hand, and an animal engaged in a motion event. While dispositional status information remained constant, spatiotemporal relations varied across conditions. Based on looking time data, we conclude that infants attend flexibly to both types of information. Without spatiotemporal cues, infants rely on dispositional status information. When two objects provide dispositional cues to motion origin, but only one also provides corresponding spatiotemporal information, infants attribute the motion to the object providing both types of information. Given an ambiguous motion event with two dispositional motion originators but no additional spatiotemporal cues, infants may prefer either of the two.     

Patterns of 4-month-old infant responses to hidden silent and sounding people and objects

Responses of 4-month-old infants to hidden people and objects were investigated with equated task demands. Twenty-one 4-month-old infants were administered a combined task, in which they were shown a sounding stimulus that continued to sound after hiding, an auditory task, in which sound was the only source of information about the position of the object in space, and a vision task, in which a silent stimulus was shown to the infants prior to hiding. Five infant behaviours were coded: reaching, gazing, body movements, vocalizations and smiles. The infants reached significantly more for hidden objects than for people, to whom they vocalized instead. They further smiled, and moved their bodies more towards their invisible mother than to the other stimuli. Thus infants responded differentially to people and objects whether the stimuli were soundless (so that there was no cue to their presence) or not. This suggested that infants appreciated (a) that an object had been hidden; (b) this object was either animate or inanimate; and (c) different procedures were appropriate for the retrieval of, or for interacting with animate and inanimate objects. Discussion centres on the underlying representational system that allows for such appreciation.     

Can chimpanzee infants (Pan troglodytes) form categorical representations in the same manner as human infants (Homo sapiens)?

We directly compared chimpanzee infants and human infants for categorical representations of three global-like categories (mammals, furniture and vehicles), using the familiarization-novelty preference technique. Neither species received any training during the experiments. We used the time that participants spent looking at the stimulus object while touching it as a measure. During the familiarization phase, participants were presented with four familiarization objects from one of three categories (e.g. mammals). Then, they were tested with a pair of novel objects, one was a familiar-category object and another was a novel-category object (e.g. vehicle) in the test phase. The chimpanzee infants did not show significant habituation, whereas human infants did. However, most important, both species showed significant novelty-preference in the test phase. This indicates that not only human infants, but also chimpanzee infants formed categorical representations of a global-like level. Implications for the shared origins and species-specificity of categorization abilities, and the cognitive operations underlying categorization, are discussed.     

The role of animacy in the real time comprehension of Mandarin Chinese: Evidence from auditory event-related brain potentials

Two auditory ERP studies examined the role of animacy in sentence comprehension in Mandarin Chinese by comparing active and passive sentences in simple verb-final (Experiment 1) and relative clause constructions (Experiment 2). In addition to the voice manipulation (which modulated the assignment of actor and undergoer roles to the arguments), both arguments were either animate or inanimate. This allowed us to examine the interplay of animacy with thematic interpretation. In Experiment 1, we observed no effect of animacy at NP1, but N400 effects for inanimate actor arguments in second position. This result mirrors previous findings in German, thus suggesting that an initial undergoer universally leads to the prediction of an ideal (animate) actor. We also observed an N400 effect for passive sentences with an inanimate initial (undergoer) argument. We attribute this effect to a language-specific property of the passive construction in Chinese, namely that the first argument is negatively affected by the event described (i.e. bears an experiencer role). Experiment 2 showed that both of these effects can also be observed in sentence constructions of another type, in which the critical information sources become available in a different order. These findings provide the first demonstration that the N400 is not only sensitive to general (universal) aspects of thematic processing (i.e. "who is acting on whom") but also to the interaction between thematic interpretation and language-specific pragmatic principles.     

Children's reasoning about physics within and across ontological kinds

Reasoning about seven physics principles within and across ontological kinds was examined among 188 5- and 7-year-olds and 59 adults. Individuals in all age groups tended to appropriately generalize what they learned across ontological kinds. However, children also showed sensitivity to ontological kind in their projections: when learning principles with reference to people they were more likely to assume that the principles apply to another person than to an inanimate object, and when learning with reference to an inanimate object they were more likely to assume that the principles apply to another inanimate object than to a person. Five-year-olds, but not 7-year-olds, projected concepts learned about people to a greater extent than principles learned about inanimate objects, closely paralleling the findings of Carey for the biological domain (Carey, S. (1985). Conceptual change in childhood. Cambridge, MA: MIT Press). Results from a separate sample of 22 5-year-olds suggest that the primary findings cannot be explained by response perseveration. The present findings indicate that children understand physics principles that apply to both animate and inanimate objects, but distinguish between these ontological kinds.     

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.     

Infants' understanding of object-directed action

When and in what ways do infants recognize humans as intentional actors? An important aspect of this larger question concerns when infants recognize specific human actions (e.g. a reach) as object-directed (i.e. as acting toward goal-objects). In two studies using a visual habituation technique, 12-month-old infants were tested to assess their recognition that an adult's reach is directed toward its target object. Infants in the experimental condition were habituated to a display in which an actor reached over a wall-like barrier with an arcing arm movement, to pick up a ball. After habituation infants saw two test displays, for which the barrier was removed. In the direct test event the actor reached directly for the ball, the arm tracing a visually new path, but the action consistent with attempting to reach for the object as directly as possible. In the indirect test event the actor traced the old path, reaching over in an arc, even though the wall was no longer present. This arm movement was identical to that in habituation but no longer displayed a reach going directly to its object. In a control condition infants saw the same movements but in a situation with no goal-object. In the experimental conditions, with a goal object present, infants looked longer at the indirect test event in comparison to the direct test event. In the control conditions infants looked equally at both indirect and direct test events. We conclude that sensitivity to human object-directed action is established by 12-month-olds and compare these results to recent findings by [Gergely, G., Nadasdy, Z., Csibra, G., & Biro S. (1995). Taking the intentional stance at 12 months of age. Cognition, 56, 165-193] and [Woodward, A. (1998). Infants selectively encode the goal object of an actor's reach. Cognition, 69, 1-34].