The Effects of Graded Occlusion on Manual Search and Visual Attention in 5‐ to 8‐Month‐Old Infants

Young infants may be limited in searching for hidden objects because they lack the means‐end motor skill to lift occluders from objects. This account was investigated by presenting 5‐ to 8‐month‐old infants with objects hidden behind transparent, semitransparent, and opaque curtains. If a means—end deficit explains search limitations, then infants should search no more for an object behind a transparent curtain than for objects behind semitransparent or opaque curtains. However, level of occlusion had a significant effect on manual search and visual attention. Infants retrieved and contacted the object more, contacted the curtain more, and looked away less with the transparent curtain than with the semi transparent or opaque curtains. Adding a time delay before allowing search and presenting a distraction after occlusion further depressed infants' behavior. The findings fail to support the means—end deficit hypothesis, but are consistent with the account that young infants lack object permanence.     

Decalage in Infants' Search for Mothers Versus Toys Demonstrated With a Delayed Response Task

Thirty‐one infants, 7 to 14 months of age, were tested on object and mother permanence using a delayed response task (Diamond, 1985), in which a delay period is enforced before infants are allowed to search for hidden objects. Infants were tested in 2 separate conditions in which they searched for their mothers and a large toy, both of which were hidden under curtained tables. The delay period before search was allowed was incremented after each successful trial until infants either failed to search or searched in the wrong location. Infants were scored for the maximum delay preceding a successful search. The results from 17 infants showed that infants were able to withstand significantly longer delays before successful search for the mother than for the toy. These results support previous studies showing that mother permanence precedes object permanence in infants older than 8 months.     

Common Coding of Observation and Execution of Action in 9‐Month‐Old Infants

Do 9‐month‐old infants motorically simulate actions they perceive others perform? Two experiments tested whether action observation, like overt reaching, is sufficient to elicit the Piagetian A‐not‐B error. Infants recovered a toy hidden at location A or observed an experimenter recover the toy. After the toy was hidden at location B, infants in both conditions perseverated in reaching to A, demonstrating that active search by the infant is not necessary for the A‐not‐B error. Consistent with prior research, infants displayed an ipsilateral bias when reaching, the so‐called mysterious midline barrier. A similar ipsilateral bias was also observed depending on the manner in which the experimenter reached; infants perseverated following observation of ipsi‐ but not contralateral reaches by the experimenter. Thus, infants perseverated only following observation of actions they themselves were able to perform, suggesting that they coded others' actions in terms of motor simulation.     

The Goal Trumps the Means: Highlighting Goals is More Beneficial than Highlighting Means in Means‐End Training

Means‐end actions are an early‐emerging form of problem solving. These actions require initiating initial behaviors with a goal in mind. In this study, we explored the origins of 8‐month‐old infants’ means‐end action production using a cloth‐pulling training paradigm. We examined whether highlighting the goal (toy) or the means (cloth) was more valuable for learning to perform a well‐organized means‐end action. Infants were given the opportunity to both practice cloth‐pulling and view modeling of the action performed by an adult throughout the session. Infants saw either the same toy or the same cloth in successive trials, so that the goal or means were highlighted prior to modeling of the action. All infants improved throughout the session regardless of which aspect of the event was highlighted. Beyond this general improvement, repetition of goals supported more rapid learning and more sustained learning than did repetition of means. These findings provide novel evidence that, at the origins of means‐end action production, emphasizing the goal that structures an action facilitates the learning of new means‐end actions.     

Means‐End Behavior in Young Infants: The Interplay of Action Perception and Action Production

In 2 experiments, the interplay of action perception and action production was investigated in 6‐month‐old infants. In Experiment 1, infants received 2 versions of a means‐end task in counterbalanced order. In the action perception version, a preferential looking paradigm in which infants were shown an actor performing means‐end behavior with an expected and an unexpected outcome was used. In the action production version, infants had to pull a cloth to receive a toy. In Experiment 2, infants' ability to perform the action production task with a cloth was compared to their ability to perform the action production task with a less flexible board. Finally, Experiment 3 was designed to control for alternative low‐level explanations of the differences in the looking times toward the final states presented in Experiment 1 by only presenting the final states of the action perception task without showing the initial action sequence. Results obtained in Experiment 1 showed that in the action perception task, infants discriminated between the expected and the unexpected outcome. This perceptual ability was independent of their actual competence in executing means‐ end behavior in the action production task. Experiment 2 showed no difference in 6‐month‐olds' performance in the action production task depending on the properties of the support under the toy. Similarly, in Experiment 3, no differences in looking times between the 2 final states were found. The findings are discussed in light of theories on the development of action perception and action production.     

Cotton‐Top Tamarins' (Saguinus oedipus) Expectations About Occluded Objects: A Dissociation Between Looking and Reaching Tasks

Recent work with human infants and toddlers suggests a dissociation between performance on looking and reaching tasks. Specifically, infants appear to generate accurate representations of occluded objects and their actions when tested in expectancy violation looking tasks but often fail to use this information when reaching for occluded objects. We explore a similar dissociation in cotton‐top tamarin monkeys (Saguinus oedipus). We presented adult tamarins with an event in which a piece of food rolled behind an occluder and into a solid barrier. In Experiment 1, subjects were required to retrieve the hidden food using the location of the solid barrier. Like human toddlers, adult tamarins failed to take into account solidity information when reaching for an invisibly displaced object. In Experiments 2 and 3, we presented subjects with expectancy violation looking versions of the same solidity problem using an identical apparatus and setup. We presented subjects with an event in which a piece of food appeared to roll unexpectedly through a solid barrier or stopped at the appropriate spot. Although tamarins failed to locate the food in Experiment 1, the same subjects successfully detected violations of solidity in these 2 looking studies. This performance dissociation is discussed in light of similar dissociations in human toddlers and other primate species.     

Infants' Rapid Learning About Self‐Propelled Objects

Six experiments investigated 7‐month‐old infants' capacity to learn about the self‐propelled motion of an object. After observing 1 wind‐up toy animal move on its own and a second wind‐up toy animal move passively by an experimenter's hand, infants looked reliably longer at the former object during a subsequent stationary test, providing evidence that infants learned and remembered the mapping of objects and their motions. In further experiments, infants learned the mapping for different animals and retained it over a 15‐min delay, providing evidence that the learning is robust and infants' expectations about self‐propelled motion are enduring. Further experiments suggested that infants' learning was less reliable when the self‐propelled objects were novel or lacked faces, body parts, and articulated, biological motion. The findings are discussed in relation to infants' developing knowledge of object categories and capacity to learn about objects in the first year of life.     

How Manual Object Exploration is Associated with 7‐ to 8‐Month‐Old Infants’ Visual Prediction Abilities in Spatial Object Processing

The present experiment examined whether infants’ visual prediction performance of the appearance of objects moving in space is related to their manual object exploration ability. Fifty‐five 7‐ to 8‐month‐old infants were tested. A visual object prediction paradigm was developed during which a three‐dimensional object was presented in a live eye‐tracking setting. During familiarization, the object rotated back and forth along the vertical axis. While the object was moving, two target parts of it were briefly occluded from view and uncovered again as the object changed its direction of motion. In the test phase, the entire object was rotated around 90° and now rotated along the horizontal axis. We recorded infants’ eye movements directed at the target locations and analyzed the prediction rates. All of the infants also participated in a manual object exploration task, in which they freely explored five toy blocks. Infants with a higher level of object exploration skill had higher prediction rates during test trials as compared to infants with less proficient object exploratory actions. The results support the interpretation that advanced manual object exploration experience is associated with infants’ advanced visual prediction ability of the appearance of objects moving in space.     

Rational Imitation in 12‐Month‐Old Infants Christiane Schwier,Catharine van Maanen,Malinda Carpenter

Gergely, Bekkering, and Király (2002) demonstrated that 14‐month‐old infants engage in “rational imitation.” To investigate the development and flexibility of this skill, we tested 12‐month‐olds on a different but analogous task. Infants watched as an adult made a toy animal use a particular action to get to an endpoint. In 1 condition there was a barrier that prevented a more straightforward action and so gave the actor no choice but to use the demonstrated action. In the other condition there was no barrier, so the actor had a free choice to use the demonstrated action or not. Twelve‐month‐olds showed the same pattern of results as in Gergely and colleagues' study: They copied the particular action demonstrated more often when the adult freely chose to use the action than when she was forced to use it. Twelve‐month‐olds, too, thus show an understanding of others' intentions as rational choices and can use this understanding in cultural learning contexts.     

Onset of Voluntary Communication: Smiling Looks to Mother

Playing infants often direct smiling looks toward social partners. In some cases the smile begins before the look, so it cannot be a response to the sight or behavior of the social partner. In this study we asked whether smiles that anticipate social contact are used by 8‐ to 12‐month‐old infants as voluntary social signals. Eighty infants—20 at each of 8, 9, 10, and 12 months of age—completed 5 tasks. The tasks assessed anticipatory smiling during toy play, means‐end understanding (2 tasks), intentional communication via gesture and vocalizations, and memory for mother's location. Across all ages, anticipatory smiling was strongly predicted by intentional gestural and vocal communication and by means‐end understanding. The findings are discussed in terms of the nature and origins of infants' voluntary communications.     

Selectivity in Infant Social Referencing

In laboratory studies of social referencing, infants as young as 12 months have been reported to prefer looking at the experimenter over the caregiver for clarifying information. From an expertise perspective, such behavior could be interpreted as if the infant seeks information from others and can discriminate between persons who have or do not have relevant information to provide in the laboratory. If this is the case, higher order cognitive capacities might be involved in infant selectivity in looking in social referencing situations. However, it has also been proposed that associative learning processes might account for infant preferences in such studies. To examine whether an expertise perspective or if more basic learning processes best explain infant selectivity in looking, 40 12‐month‐old infants were assigned to 1 of 2 comparable conditions. The experimenter versus the caregiver presented an ambiguous toy and delivered positive information about the toy. The infants preferred to look at the experimenter and they regulated their behavior more in accordance with information coming from the experimenter. Thus, an associative learning account cannot explain infant preferences in looking. The results are discussed in terms of an expertise perspective.     

Follow My Gaze: Face Race and Sex Influence Gaze‐Cued Attention in Infancy

Using the eye gaze of others to direct one's own attention develops during the first year of life and is thought to be an important skill for learning and social communication. However, it is currently unclear whether infants differentially attend to and encode objects cued by the eye gaze of individuals within familiar groups (e.g., own race, more familiar sex) relative to unfamiliar groups (e.g., other race, less familiar sex). During gaze cueing, but prior to the presentation of objects, 10‐month‐olds looked longer to the eyes of own‐race faces relative to 5‐month‐olds and relative to the eyes of other‐race faces. After gaze cueing, two objects were presented alongside the face and at both ages, infants looked longer to the uncued objects for faces from the more familiar‐sex and longer to cued objects for the less familiar‐sex faces. Finally, during the test phase, both 5‐ and 10‐month‐old infants looked longer to uncued objects relative to cued objects but only when the objects were cued by an own‐race and familiar‐sex individual. Results demonstrate that infants use face eye gaze differently when the cue comes from someone within a highly experienced group.     

Factors affecting infant toy preferences: Age,gender, experience,motor development,and parental attitude

In contrast to the anecdotal claim that “male infants like cars and female infants like dolls,” previous studies have reported mixed findings for gender‐related toy preferences in infancy. In Experiment 1, we explored the emergence of gender‐related preferences using face–car pairs (Experiment 1a, n = 51, 6–20 months) or face–stove pairs (Experiment 1b, n = 54, 6–20 months). In Experiment 2 (n = 42, 14–16 months), we explore the effect of toy properties, infants' past toy exposure, activity levels, and parental attitudes on such preferences using a wider range of toys. For both studies, infants demonstrated a general preference for faced stimuli over other objects, except for male infants who showed no preference between dolls and cars at around 15 months. Infants' prior experience participating in motor‐intensive activities, with wheeled toys and parental attitudes appeared to relate to female infants' preferences for dynamic toys. These results indicate a range of factors influence gendered toy preferences and suggest that nurture plays an important role.     

Spatially Specific Changes in Infants' Muscle Coactivity as They Learn to Reach

Infants first reach out and touch objects between the ages of 3 and 5 months. This article reports changes in muscle coactivity associated with this transition. A group of 4 infants were observed weekly from 3 to 30 weeks and every 2 weeks from 30 to 52 weeks. Hand kinematics of both prereaching and reaching movements were collected, as was electromyographic activity from the trapezius, deltoid, biceps, and triceps. Before infants first reached for toys presented at midline, they used biceps and triceps to move their hands near the toy in front of them and 45° to the side of midline. After the transition, they used trapezius and deltoid to move the hand toward the toy and combinations of multiple muscles when their arms were high and extended near the toy. Thus, infants showed a dramatic change in which muscles worked together across the transition to reaching, even though their hands moved in similar spatial regions.     

The Microstructure of Infants' Gaze as They View Adult Shifts in Overt Attention

We presented infants (5, 6, 9, and 12 months old) with movies in which a female model turned toward and fixated 1 of 2 toys placed on a table. Infants' gaze was measured using a Tobii 1750 eye tracker. Six‐, 9‐, and 12‐month‐olds' first gaze shift from the model's face (after the model started turning) was directed to the attended toy. The 5‐month‐olds performed at random. Following this initial response, 5‐, 6‐, and 9‐month‐olds performed more gaze shifts to the attended target; 12‐month‐olds performed at random. Infants at all ages displayed longer looking times to the attended toy. We discuss a number of explanations for 5‐month‐olds' ability to follow a shift in overt attention by an adult after an initially random response, including the possibility that infants' initial gaze response strengthens the representation of the objects in the peripheral visual field.     

Visual Access and Attention in Two‐Year‐Olds' Event Reasoning and Object Search

Several recent studies have revealed substantial limitations in 2‐year‐olds' ability to search accurately for objects that have undergone unseen movement, even along highly constrained paths. In many of these studies, children observed a ball as it rolled down a track and behind an occluding panel that contained 4 doors. The track had a barrier that was partly visible and could be placed in locations corresponding to the doors. When the ball came to a rest against the barrier and behind the occluder, the child's task was to find the ball by opening the correct door. The search accuracy of 2‐year‐olds has not differed from chance across several variations of this task. This research was conducted to identify the source of 2‐year‐olds' limitation in this domain. Children were granted a full view of the event before the ball was occluded with a door panel. Children's performance was better under this condition, but was still not systematically accurate unless their gaze remained locked onto the correct location. Two‐year‐olds' weak performance in these search tasks appears to be more a consequence of limitations in spatial integration than in their representation of unseen movement.     

18‐Month‐Olds Predict Specific Action Mistakes Through Attribution of False Belief,Not Ignorance,and Intervene Accordingly

This study employed a new “anticipatory intervening” paradigm to tease apart false belief and ignorance‐based interpretations of 18‐month‐olds’ helpful informing. We investigated in three experiments whether 18‐month‐old infants inform an adult selectively about one of the two locations depending on the adult’s belief about which of the two locations held her toy. In experiments 1 and 2, the adult falsely believed that one of the locations held her toy. In experiment 3, the adult was ignorant about which of the two locations held her toy. In all cases, however, the toy had been removed from the locations and the locations contained instead materials which the adult wanted to avoid. In experiments 1 and 2, infants spontaneously and selectively informed the adult about the aversive material in the location the adult falsely believed to hold her toy. In contrast, in experiment 3, infants informed the ignorant adult about both locations equally. Results reveal that infants expected the adult to commit a specific action mistake when she held a false belief, but not when she was ignorant. Further, infants were motivated to intervene proactively. Findings reveal a predictive action‐based usage of “theory‐of‐mind” skills at 18 months of age.     

Why do Infants Look at and Use Positive Information from Some Informants Rather Than Others in Ambiguous Situations?

Three laboratory experiments on social referencing examined whether infants’ tendencies to look at and use positive information from the experimenter could be interpreted from a perspective of novelty or expertise. In Study 1, novelty was manipulated. Forty‐eight 12‐month‐old infants participated. In a between‐subject design, a more novel or a less novel experimenter presented an ambiguous object and provided positive information. The infants looked more at and regulated their behavior more in accordance with information coming from the less novel experimenter. In Study 2, expertise was manipulated. Forty‐eight 12‐month‐old infants were exposed to one experimenter who showed expertise about the laboratory situation and one experimenter who did not show such competence. The infants looked more at and regulated their behavior more in accordance with information coming from the expert. In Study 3, 40 12‐month‐old infants participated. The infants were exposed to a toy‐expert who was either novel or familiar. The infants, in both groups, looked as much at the toy‐experts and used the information regardless of whether the novel or familiar toy‐expert had provided information. The findings suggest that novelty does not increase looking in ambiguous situations. Instead, the results support the expertise perspective of infant looking preferences.     

Infants' Sensitivity to the Causal Features of Means‐End Support Sequences in Action and Perception

Current work has yielded differential findings regarding infants' ability to perceptually detect the causal structure of a means‐end support sequence. Resolving this debate has important implications for perception‐action dissociations in this domain of object knowledge. In Study 1, 12‐month‐old infants' ability to perceive the causal structure of a cloth‐pulling sequence was assessed via a habituation paradigm. After seeing an event in which a supported toy was moved by pulling a cloth that it sat on, 12‐month‐old infants demonstrated longer looking to events that violated the causal structure of this sequence than to events that preserved the causal structure but varied other perceptual features of the event. Studies 2 and 3 investigated 10‐month‐olds' interpretations of means‐end support sequences using both a habituation paradigm and a task that assessed infants' own means‐end actions. Whereas 10‐month‐olds failed to demonstrate an understanding of the causal structure when tested using a flat cloth as the support (Study 2), sensitivity to this structure was apparent when a rectangular box was the support. These patterns were evident in both action and perception (Study 3). Moreover, individual variation in action task performance was related to visual habituation performance. The results are discussed with respect to the relation between action and perception in infancy.