How infants use perceptual information to guide action

Children do not distinguish efficient from inefficient actions during observation

Observation is a powerful way to learn efficient actions from others. However, the role of observers' motor skill in assessing efficiency of others is unknown. Preschoolers are notoriously poor at performing multi-step actions like grasping the handle of a tool. Preschoolers (N = 22) and adults (N = 22) watched video-recorded actors perform efficient and inefficient tool use. Eye tracking showed that preschoolers and adults looked equally long at the videos, but adults looked longer than children at how actors grasped the tool. Deep learning analyses of participants' eye gaze distinguished efficient from inefficient grasps for adults, but not for children. Moreover, only adults showed differential action-related pupil dilation and neural activity (suppressed oscillation power in the mu frequency) while observing efficient vs. inefficient grasps. Thus, children observe multi-step actions without "seeing" whether the initial step is efficient. Findings suggest that observer's own motor efficiency determines whether they can perceive action efficiency in others.

Which way to take? Infants select an efficient path to their goal

In two experiments, we examined the development of the ability to select efficient means in order to attain a goal in 1.5- and 2-year-olds (N = 79) using a setup in which two paths led to a goal. One of the paths was shorter, and thus more efficient, than the other path. Experiment 1 showed a strong tendency in both age groups to choose the shorter path. In Experiment 2, the shorter path was initially blocked and became available only after infants repeatedly took the longer path. Children demonstrated increasing use of the more efficient path over time. The results of both experiments point to some abilities of efficient action selection in infants.

On the origin of the understanding of time, speed, and distance interrelations

We examined 18- and 24-month-old infants' sensitivity to the functional relationships between time, speed, and distance. The task included a train moving first visibly and then into a tunnel. The movement of the train was always accompanied by a train-characteristic sound signalling the travel duration. After the train concluded its travel, infants were requested to search for it in two possible locations inside the tunnel. Infants' reaching and head turn behavior indicated that 24-month-olds were sensitive to time-speed-distance interrelations, while 18-month-olds showed no such understanding. Reducing occlusion duration (by shortening the tunnel's length) revealed an increase in 18-month-olds' reaching and anticipatory head turns. Results are discussed in terms of the developmental course of the understanding of time-speed-distance interrelations and the strength of infants' representations.

What's in a cue? The role of cue orientation in object displacement tasks

The current study looked at two theoretical proposals explaining toddlers' abilities to use cue information for recovering a hidden object that had rolled down a ramp behind an occluded screen. These two approaches, the theory of object directed attention and a landmark-based account, make different predictions regarding the efficacy of an obliquely aligned cue to object position. Accordingly, the search by forty 24-month olds, forty-two 30-month olds, and forty-one 36-month olds for a hidden toy that was cued using either a short versus a long cue, or a vertically aligned versus an obliquely aligned cue, were compared. Analyses of search accuracy revealed that children were more successful when faced with short as opposed to long cues, and when using vertical as opposed to oblique cues. These findings support a landmark-based approach, as opposed to an object-directed attention account, and are discussed with reference to their implications for spatial orientation more generally.

Beyond the search barrier: A new task for assessing object individuation in young infants

Object individuation, the capacity to track the identity of objects when perceptual contact is lost and then regained, is fundamental to human cognition. A great deal of research using the violation-of-expectation method has been conducted to investigate the development of object individuation in infancy. At the same time, there is a growing need for converging methods of study. Reported here are data obtained with from a newly developed search task that can be used with infants as young as 5 months of age. The results suggest that this method is a sensitive measure of object individuation in young infants and demonstrate the advantages of using converging methods of study.

Occlusion is hard: Comparing predictive reaching for visible and hidden objects in infants and adults

Infants can anticipate the future location of a moving object and execute a predictive reach to intercept the object. When a moving object is temporarily hidden by darkness or occlusion, 6-month-old infants' reaching is perturbed but performance on darkness trials is significantly better than occlusion trials. How does this reaching behavior change over development? Experiment 1 tested predictive reaching of 6- and 9-month-old infants. While there was an increase in the overall number of reaches with increasing age, there were significantly fewer predictive reaches during the occlusion compared to visible trials and no age-related changes in this pattern. The decrease in performance found in Experiment 1 is likely to apply not only to the object representations formed by infants but also those formed by adults. In Experiment 2 we tested adults with a similar reaching task. Like infants, the adults were most accurate when the target was continuously visible and performance in darkness trials was significantly better than occlusion trials, providing evidence that there is something specific about occlusion that makes it more difficult than merely lack of visibility. Together, these findings suggest that infants' and adults' capacities to represent objects have similar signatures throughout development.

Infants' perseverative search errors are induced by pragmatic misinterpretation

Having repeatedly retrieved an object from a location, human infants tend to search the same place even when they observe the object being hidden at another location. This perseverative error is usually explained by infants' inability to inhibit a previously rewarded search response or to recall the new location. We show that the tendency to commit this error is substantially reduced (from 81 to 41%) when the object is hidden in front of 10-month-old infants without the experimenter using the communicative cues that normally accompany object hiding in this task. We suggest that this improvement is due to an interpretive bias that normally helps infants learn from demonstrations but misleads them in the context of a hiding game. Our finding provides an alternative theoretical perspective on the nature of infants' perseverative search errors.

Young infants' actions reveal their developing knowledge of support variables: converging evidence for violation-of-expectation findings

Violation-of-expectation (VOE) tasks have revealed substantial developments in young infants' knowledge about support events: by 5.5 months, infants expect an object to fall when released against but not on a surface; and by 6.5 months, infants expect an object to fall when released with 15% but not 100% of its bottom on a surface. Here we investigated whether action tasks would reveal the same developmental pattern. Consistent with VOE reports, 5.5- and 6.5-month-old infants were more likely to reach for a toy that rested on as opposed to against a surface; and 6.5- but not 5.5-month-olds were more likely to reach for a toy with 100% as opposed to 15% of its bottom on a surface. Infants at each age thus used their support knowledge to determine whether the toys were likely to be retrievable or to be attached to adjacent surfaces and hence irretrievable. These and control findings extend recent evidence that developmental patterns observed in VOE tasks also hold in action tasks, and as such provide further support for the view that VOE and action tasks tap the same physical knowledge.

Infant manual exploration of composite substrates

Everyday environments, even small regions within reach, vary dramatically in terms of material composition. Adapting one's manual behavior to such transitions can be considered to be an important element of skilled action. To investigate the origins of this ability, we presented 8-month-olds (n=24) and 10-month-olds (n=24) hard or soft objects on a composite tabletop substrate that was half rigid and half flexible. Results indicated infants explored the objects selectively and geared their manual behaviors, with or without an object in hand, to the particular substrate they contacted. More broadly, the study suggests that infant manual exploration is flexible even in the face of abrupt transitions in material structure. Such flexibility may support early attempts at problem solving and tool use.

Learning and development in infant locomotion

The traditional study of infant locomotion focuses on what movements look like at various points in development, and how infants acquire sufficient strength and balance to move. We describe a new view of locomotor development that focuses on infants' ability to adapt their locomotor decisions to variations in the environment and changes in their bodily propensities. In the first section of the chapter, we argue that perception of affordances lies at the heart of adaptive locomotion. Perceiving affordances for balance and locomotion allows infants to select and modify their ongoing movements appropriately. In the second section, we describe alternative solutions that infants devise for coping with challenging locomotor situations, and various ways that new strategies enter their repertoire of behaviors. In the third section, we document the reciprocal developmental relationship between adaptive locomotion and cognition. Limits and advances in means-ends problem solving and cognitive capacity affect infants' ability to navigate a cluttered environment, while locomotor development offers infants new opportunities for learning.

Relational spatial reasoning by a nonhuman: the example of capuchin monkeys

The authors review spontaneous manipulation and spatial problem solving by capuchin monkeys to illuminate the nature of relational reasoning (wherein two or more elements of a problem or situation are considered together to arrive at a course of action) that these monkeys use in goal-directed activity. Capuchin monkeys master problems with one, two, or three spatial relations, and if more than one relation, at least two relations may be managed concurrently. They can master static and dynamic relations and, with sufficient practice, can produce specific spatial relations through both direct and distal action. Examining capuchins' spatial problem-solving behavior with objects in the framework of a spatial relational reasoning model leads to new interpretations of previous studies with these monkeys and other nonhuman animals. The model produces a variety of testable predictions concerning the contribution of relational properties to spatial reasoning. It also provides conceptual linkages with neurological processes and cognitive analyses of physical reasoning. Understanding relational spatial reasoning, including tool use, in a wider view is vital to informed, principled comparison of problem solving and the use of technology across species, across ages within species, and across eras in human prehistory.

Familiarity breeds searching: infants reverse their novelty preferences when reaching for hidden objects

What infants appear to know depends heavily on how they are tested. For example, infants seem to understand object permanence (that objects continue to exist when no longer perceptible) within the first few months of life when this understanding is assessed through looking measures, but not until several months later when it is assessed through search measures. One explanation of such results is that infants gradually develop stronger representations of objects through experience, and that stronger representations are required for some tasks than for others. The current study confirms one prediction from this account: Stronger representations of familiar objects (relative to novel objects) should support greater sensitivity to their continued existence. After seeing objects hidden, infants reached more for familiar than novel objects, in striking contrast to their robust novelty preferences with visible objects. Theoretical implications concerning the origins of knowledge are discussed.

Demands on Finite Cognitive Capacity Cause Infants' Perseverative Errors

This research unites traditionally disparate developmental domains-cognition and locomotion-to examine the classic cognitive issue of the development of inhibition in infancy. In 2 locomotor A-not-B tasks, 13-month-old walking infants inhibited a prepotent response under low task demands (walking on flat ground), but perseverated under increased task demands (descending a staircase). Despite elimination of factors previously associated with infant perseveration, infants still perseverated in the difficult stairs condition. Increasing cognitive load by manipulating task difficulty affected infants' ability to inhibit repeated responses that were no longer appropriate. Evidence supports a cognitive capacity account of infant perseveration, in which infants' performance depends on allocation of cognitive and attentional resources.