Direct touches to clear barriers: Developmental sensitivity of a new measure of the production of ineffective responses in infancy

Current interpretation of the object retrieval task (Diamond, 1990 Diamond, A. 1990. The Development and the Neural Bases of Higher Cortical Functions, New York, NY: New York Academy of Sciences.  [Google Scholar]) as an infant assessment of response inhibition requires evidence that younger infants make more ineffective attempts to retrieve toys through clear barriers. On two 30-second trials, infants (9 or 11 months of age) saw an inaccessible toy in the front or back of a clear box. The location of the infants touches corresponded with the toy's location and, on the second trial, the younger infants touched the box more. In previous research nonhuman primates with orbital-frontal, but not dorsa-lateral, lesions also made ineffective barrier touches. The current developmental decreases in barrier touches may selectively tap developmental increases in inhibitory control supported by the developing orbital-frontal cortex.     

Going around transparent and grid‐like barriers: detour ability as a perception–action skill

Early detour ability may not generalize immediately across similar problems in different perception–action systems, but instead may reveal a pattern of developmental onset that is more domain‐specific. To investigate this possibility, we examined how 10‐month‐old (n = 24) and 12‐month‐old (n = 24) infants performed detours via different action modes and around barriers that differed in transparency. Infants made reaching and locomotor detours to retrieve an object located behind either an upright transparent barrier or an upright transparent barrier overlaid with a grid pattern. The results indicated that infants were more likely to make reaching than locomotor detours and explored the transparent and grid barriers differently. Additionally, younger infants more often attempted to contact the object through the entirely transparent barrier than did older infants, especially when making a reaching detour. The results suggest that during detour development, infants learn to coordinate relevant perceptual information with emerging actions.     

Infants' representations of three-dimensional occluded objects

Infants' ability to represent objects has received significant attention from the developmental research community. With the advent of eye-tracking technology, detailed analysis of infants' looking patterns during object occlusion have revealed much about the nature of infants' representations. The current study continues this research by analyzing infants' looking patterns in a novel manner and by comparing infants' looking at a simple display in which a single three-dimensional (3D) object moves along a continuous trajectory to a more complex display in which two 3D objects undergo trajectories that are interrupted behind an occluder. Six-month-old infants saw an occlusion sequence in which a ball moved along a linear path, disappeared behind a rectangular screen, and then a ball (ball-ball event) or a box (ball-box event) emerged at the other edge. An eye-tracking system recorded infants' eye-movements during the event sequence. Results from examination of infants' attention to the occluder indicate that during the occlusion interval infants looked longer to the side of the occluder behind which the moving occluded object was located, shifting gaze from one side of the occluder to the other as the object(s) moved behind the screen. Furthermore, when events included two objects, infants attended to the spatiotemporal coordinates of the objects longer than when a single object was involved. These results provide clear evidence that infants' visual tracking is different in response to a one-object display than to a two-object display. Furthermore, this finding suggests that infants may require more focused attention to the hidden position of objects in more complex multiple-object displays and provides additional evidence that infants represent the spatial location of moving occluded objects.     

Executive Functioning Demands of the Object Retrieval Task for 8-month-old Infants

At 8 to 11 months of age, infants are more successful in negotiating opaque relative to transparent barriers. However, 7-month-old infants have more difficulty with opaque barriers relative to semitransparent barriers. Here, 8-month-old infants spent more time in ineffective direct reaches with more the transparent barriers (Experiments 1 & 2) and were faster with the fully opaque barrier (Experiment 2). This demonstration of the graded effects of transparency confirms the working memory and/or response inhibition demands of the object retrieval task.     

Can dogs defy gravity? A comparison with the human infant and a non-human primate

We conducted four experiments with 56 adult dogs (Canis lupus familiaris) involving tasks where food was dropped through an opaque tube connected either vertically or diagonally to one of two or three goal boxes. In the first experiment, modelled after studies with children and primates, the dogs first searched significantly more often in the location directly beneath the drop-off point (a gravity bias), although this box was not connected with the tube. These results are comparable to those of human infants and cotton-top tamarins. Experiments 2–4 tested which problem solving strategy the dogs applied to find the food. Results show that they do not understand the physical mechanism of the tube itself, and they apply one of three search strategies: search the gravity box (the one below the drop-off box); search the box in the middle; learn the correct location of the goal box. When the goal box was in the same location the dogs learned to search there over trials, that is, they learned to ‘defy gravity’, but when the location of the goal box changed over trials they showed no learning. These findings are compared with those from human infants and cotton-top tamarins: like these species, the dogs can learn to overcome a gravity bias, but only when the reward is to be found in a consistent location.     

The ontogeny of infant bimanual reaching during the first year

Handedness and pattern of coordination during bimanual reaching were assessed separately for six groups of infants, 7 to 12 months old. Infants reached bimanually for a transparent toy-filled box. On some presentations of the box a low barrier was placed in the path of either the right or left hand, while on other presentations there was no barrier. The youngest and two oldest groups of infants were more likely than the other age groups to perform simultaneous bimanual reaches with no barrier present, but when a barrier was present the 11-month-olds were most likely to continue to perform simultaneous reaches. This suggests that while infants as young as 7 months perform simultaneous reaches, the organization of these reaches may be different than for older infants. Hand-use preference contributed significantly to selection of a lead hand in non-simultaneous bimanual reaching. The 8-month group, which had the highest proportion of infants with a hand preference, was the only group likely to hit the barrier when it was placed on the nonpreferred side. Hand preference may, thus, bias the use of information about what the environment affords for action.     

Can an agent's false belief be corrected by an appropriate communication? Psychological reasoning in 18-month-old infants

Do 18-month-olds understand that an agent's false belief can be corrected by an appropriate, though not an inappropriate, communication? In Experiment 1, infants watched a series of events involving two agents, a ball, and two containers: a box and a cup. To start, agent1 played with the ball and then hid it in the box, while agent2 looked on. Next, in agent1's absence, agent2 moved the ball from the box to the cup. When agent1 returned, agent2 told her "The ball is in the cup!" (informative-intervention condition) or "I like the cup!" (uninformative-intervention condition). During test, agent1 reached for either the box (box event) or the cup (cup event). In the informative-intervention condition, infants who saw the box event looked reliably longer than those who saw the cup event; in the uninformative-intervention condition, the reverse pattern was found. These results suggest that infants expected agent1's false belief about the ball's location to be corrected when she was told "The ball is in the cup!", but not "I like the cup!". In Experiment 2, agent2 simply pointed to the ball's new location, and infants again expected agent1's false belief to be corrected. These and control results provide additional evidence that infants in the second year of life can attribute false beliefs to agents. In addition, the results suggest that by 18 months of age infants expect agents' false beliefs to be corrected by relevant communications involving words or gestures.     

Infants' reasoning about opaque and transparent occluders in an individuation task

There has been some debate about whether infants 10 months and younger can use featural information to individuate objects. The present research tested the hypothesis that negative results obtained with younger infants reflect limitations in information processing capacities rather than the inability to individuate objects based on featural differences. Infants aged 9.5 months saw one object (i.e. a ball) or two objects (i.e. a box and a ball) emerge successively to opposite sides of an opaque occluder. Infants then saw a single ball either behind a transparent occluder or without an occluder. Only the infants who saw the ball behind the transparent occluder correctly judged that the one-ball display was inconsistent with the box-ball sequence. These results suggest that: (a) infants categorize events involving opaque and transparent occluders as the same kind of physical situation (i.e. occlusion) and (b) support the notion that infants are more likely to give evidence of object individuation when they need to reason about one kind of event (i.e. occlusion) than when they must retrieve and compare categorically distinct events (i.e. occlusion and no-occlusion).     

Comprehension of the Referential Intent of Looking and Pointing Between 12 and 15 Months

Butler, Caron, & Brooks (2000) tested the gaze following of 14-and 18-month-olds under 3 conditions: (1) when the adult's view of the targets was blocked by barriers, (2) when the barriers contained open windows, and (3) no barriers. Contrary to a nonmentalist "ecological" model (adult turns serve as cues to the location of interesting events), frequency of gaze following by 14-month-olds was not equivalent across the 3 conditions. Contrary to a mentalist model (infant wants to see what the adult is seeing), gaze following was not substantially less in the barrier than in the window and no-barrier conditions (as was the case for 18-month-olds). To examine whether the barriers posed vector projection problems for essentially nonmentalist, or line-of-sight problems for essentially mentalist younger infants, 3 experiments were conducted. In Experiment 1, a 12-month group was tested in the same 3 conditions to determine if, being younger, they might yield a more clearcut nonmentalist pattern. Contrarily, they behaved like Butler et al.'s 14-month-olds. In Experiment 2, a 14-month group was tested in the barrier and window conditions, but now combining pointing with turning. Infants behaved as predicted by the mentalist model: strong responding in the window condition and minimal in the barrier (where many strained to look inside the partitions). In Experiment 3, an attempt was made to differentiate between mentalist and "geometric" (vector projection) interpretations of the results of Experiment 2 by testing another 14-month group with the adult's eyes closed while pointing. Gaze following now dropped precipitously in the window condition as did looking inside the solid barriers, indicating (1) that infants in Experiment 2 had not simply been guided to target by an extended arm, but construed it as part of a referential act that was as much visual as gestural, and (2) that by 14 months, infants may have acquired a mentalistic concept of seeing.     

Early perception-action coupling: eye movements and the development of object perception

We investigated the scanning strategies used by 2- to 3.5-month-old infants when viewing partly occluded object displays. Eye movements were recorded with a corneal reflection system as the infants observed stimuli depicting two rod parts above and below an occluding box. Stimulus parameters were chosen on the basis of past research demonstrating the importance of motion, occluder width, and edge alignment to perception of object unity. Results indicated that the infants tailored scanning to display characteristics, engaging in more extensive scanning when unity perception was challenged by a wide occluder or misaligned edges. In addition, older infants tended to scan the lower parts of the displays more frequently than did younger infants. Exploration of individual differences, however, revealed marked contrasts in specific scanning styles across infants. The findings are consistent with views of perceptual development stressing the importance of information processing skills and self-directed action to the acquisition of object knowledge.     

Reasoning about the height and location of a hidden object in 4.5- and 6.5-month-old infants

The present experiments examined 6.5- and 4.5-month-old infants' ability to represent and to reason about the height and location of a hidden object. In Experiments 1 and 2, the infants were habituated to a screen that rotated back and forth through a 180 degree arc, in the manner of a drawbridge. Following habituation, a box was placed behind the screen, and the infants saw two test events. In one (possible event), the screen rotated until it reached the occluded box; in the other (impossible event), the screen rotated through either the top 80% or the top 50% of the space occupied by the box. The results indicated that (a) the 6.5-month-old infants were surprised when the screen rotated through the top 80%, but not the top 50%, of the box and (b) the 4.5-month-old infants failed to be surprised even when the screen rotated through the top 80% of the box (4.5-month-old infants do show surprise, however, when the screen rotates through the entire (100%) box (Baillargeon, 1987a]. Experiments 3 and 4 tested whether infants would be better at detecting that the screen rotated farther than it should if provided with a second, identical box to the side of the box behind the screen. This second box stood out of the screen's path and so remained visible throughout the test trials. The results indicated that with the second box present (a) the 6.5-month-old infants showed surprise when the screen rotated through the top 50% of the occluded box and (b) the 4.5-month-old infants were surprised when the screen rotated through either the top 80% or the top 50% of the box. The results of Experiment 5 revealed that the improvement in performance brought about by the second box disappeared when this box was no longer in the same fronto-parallel plane as the box behind the screen. Different models are considered to describe the impressive quantitative and qualitative physical reasoning abilities revealed by these findings.     

Object permanence in five-month-old infants

A new method was devised to test object permanence in young infants. Five- month-old infants were habituated to a screen that moved back and forth through a 180-degree arc, in the manner of a drawbridge. After infants reached habituation, a box was centered behind the screen. Infants were shown two test events: a possible event and an impossible event. In the possible event, the screen stopped when it reached the occluded box; in the impossible event, the screen moved through the space occupied by the box. The results indicated that infants looked reliably longer at the impossible than at the possible event. This finding suggested that infants (1) understood that the box continued to exist, in its same location, after it was occluded by the screen, and (2) expected the screen to stop against the occluded box and were surprised, or puzzled, when it failed to do so. A control experiment in which the box was placed next to the screen provided support for this interpretation of the results. Together, the results of these experiments indicate that, contrary to Piaget's (1954) claims, infants as young as 5 months of age understand that objects continue to exist when occluded. The results also indicate that 5-month-old infants realize that solid objects do not move through the space occupied by other solid objects.     

Infants' understanding of occlusion of others' line-of-sight: Implications for an emerging theory of mind

Infants' gaze following provides information about their understanding of others' perception and attention. Gaze following when the other looks in the presence (and absence) of visual obstacles can be especially informative. In the present study the gaze-following behaviour of 14- and 18-month-old infants was examined in opaque barrier, clear barrier, and non-barrier situations in order to investigate whether infants at this age understand the referential nature of looking. A hypothesis positing that infants grasp the referential nature of gaze would predict that infants would not follow gaze when the looker's gaze is blocked (as in an opaque barrier situation), but would follow gaze in both non-barrier and clear barrier situations. This hypothesis was contrasted with two other “leaner” interpretations predicting contrasting patterns of looking in the same situations. Results showed that both 18- and 14-month-old infants followed gaze as predicted by the richer, referential account.     

Finger drawing by infant chimpanzees (<Emphasis Type="Italic">Pan troglodytes</Emphasis>)

We introduced a new technique to investigate the development of scribbling in very young infants. We tested three infant chimpanzees to compare the developmental processes of scribbling between humans and chimpanzees. While human infants start to scribble on paper at around the age of 18 months, our 13- to 23-month-old infant chimpanzees had never been observed scribbling prior to this study. We used a notebook computer with a touch-sensitive screen. This apparatus was able to record the location of the subjects touches on the screen. Each touch generated a fingertip-sized dot at the corresponding on-screen location. During spontaneous interactions with this apparatus, all three infants and two mother chimpanzees left scribbles with their fingers on the screen. The scribbles contained not only simple dots or short lines, but also curves and hook-like lines or loops, most of which were observed in the instrumental drawings of adult chimpanzees. The results suggest that perceptual-motor control for finger drawing develops in infant chimpanzees. Two of the infants performed their first scribble with a marker on paper at the age of 20–23 months. Just prior to this, they showed a rapid increase in combinatory manipulation of objects. These findings suggest that the development of combinatory manipulation of objects as well as that of perceptual-motor control may be necessary for the emergence of instrumental drawing on paper.     

Tactile localization performance in children with developmental coordination disorder (DCD) corresponds to their motor skill and not their cognitive ability

When localizing touches to the hands, typically developing children and adults show a “crossed hands effect” whereby identifying which hand received a tactile stimulus is less accurate when the hands are crossed than uncrossed. This demonstrates the use of an external frame of reference for locating touches to one’s own body. Given that studies indicate that developmental vision plays a role in the emergence of external representations of touch, and reliance on vision for representing the body during action is atypical in developmental coordination disorder (DCD), we investigated external spatial representations of touch in children with DCD using the “crossed hands effect”. Nineteen children with DCD aged 7–11 years completed a tactile localization task in which posture (uncrossed, crossed) and view (hands seen, unseen) were varied systematically. Their performance was compared to that of 35 typically developing controls (19 of a similar age and cognitive ability, and 16 of a younger age but similar fine motor ability). Like controls, the DCD group exhibited a crossed hands effect, whilst their overall tactile localization performance was weaker than their peers of similar age and cognitive ability, but in line with younger controls of similar motor ability. For children with movement difficulties, these findings indicate tactile localization impairments in relation to age expectations, but apparently typical use of an external reference frame for localizing touch.     

高风险婴儿前瞻性纵向研究与孤独症谱系障碍早期识别

孤独症谱系障碍(Autism Spectrum Disorder, ASD)早期识别有助于早期诊断和早期干预的实施, 对于改善ASD儿童发育结果至关重要。高风险前瞻性纵向研究以高风险婴儿(ASD儿童的年幼同胞, 入组年龄小于12个月)作为主要研究对象, 通过对ASD高风险婴儿(24至36个月之间诊断为ASD的高风险婴儿)的早期发育轨迹的描绘和核心症状早期表现的识别, 为ASD早期识别提供了重要依据。未来可以增加被试数量、延长观察时间并密集观察时间点、关注伴发障碍、综合考虑遗传、环境和文化因素影响, 并结合早期干预研究进行深入探索。未来在中国开展相关研究具有重要的科学价值和临床意义。     

Determinants of infants' understanding of supporting relations: amount of contact versus position of the center of gravity

This study investigated the developmental age at which infants recognize about supporting relations between objects and what information they use to judge whether a supported object will fall down or not. Four kinds of events were used. All events involved support in relation of two boxes, which differed in the amount of contact between objects and the amount of discrepancy between the supported object's position and its most balanced position. 115 infants (3 to 13 mo.) saw 4 events which differed on these two variables. Infants 10 months and older looked longer at the event in which the center of a supported box was just outside of the edge of a supporting box, that is, a support relation in which it was difficult to anticipate whether the box would fall down or not. Analysis suggested that infants' attention is not determined by only one simple stimulus variable but by more complicated variables (such as uncertainty of prediction).     

Touching behaviors of winners and losers in swimming races

This study compared touching behaviors of swimmers who were winners and losers. The number and location of interpersonal touches given and received by winners and losers of swimming races were recorded. Winners gave and received significantly more touches than losers. Most touches were hands, back, or shoulders, confirming earlier findings for college men and women.     

Developmental changes in infants’ visual short-term memory for location

To examine the development of visual short-term memory (VSTM) for location, we presented 6- to 12-month-old infants (N = 199) with two side-by-side stimulus streams. In each stream, arrays of colored circles continually appeared, disappeared, and reappeared. In the changing stream, the location of one or more items changed in each cycle; in the non-changing streams the locations did not change. Eight- and 12.5-month-old infants showed evidence of memory for multiple locations, whereas 6.5-month-old infants showed evidence of memory only for a single location, and only when that location was easily identified by salient landmarks. In the absence of such landmarks, 6.5-month-old infants showed evidence of memory for the overall configuration or shape. This developmental trajectory for spatial VSTM is similar to that previously observed for color VSTM. These results additionally show that infants’ ability to detect changes in location is dependent on their developing sensitivity to spatial reference frames.     

Development of upper visual field bias for faces in infants

The spatial location of the face and body seen in daily life influences human perception and recognition. This contextual effect of spatial locations suggests that daily experience affects how humans visually process the face and body. However, it remains unclear whether this effect is caused by experience, or innate neural pathways. To address this issue, we examined the development of visual field asymmetry for face processing, in which faces in the upper visual field were processed preferentially compared to the lower visual field. We found that a developmental change occurred between 6 and 7 months. Older infants aged 7–8 months showed bias toward faces in the upper visual field, similar to adults, but younger infants of 5–6 months showed no such visual field bias. Furthermore, older infants preferentially memorized faces in the upper visual field, rather than in the lower visual field. These results suggest that visual field asymmetry is acquired through development, and might be caused by the learning of spatial location in daily experience.