Developmental changes in the processing of hierarchical shapes continue into adolescence

The present study was designed to trace the normal development of local and global processing of hierarchical visual forms. We presented pairs of hierarchical shapes to children and adults and asked them to indicate whether the two shapes were the same or different at either the global or the local level. In Experiments 1 (6-year-olds, 10-year-olds, adults) and 2 (10-year-olds, 14-year-olds, adults), we presented stimuli centrally. All age groups responded faster on global trials than local trials (global precedence effect), but the bias was stronger in children and diminished to the adult level between 10 and 14 years of age. In Experiment 3 (10-year-olds, 14-year-olds, adults), we presented stimuli in the left or right visual field so that they were transmitted first to the contralateral hemisphere. All age groups responded faster on local trials when stimuli were presented in the right visual field (left hemisphere); reaction times on global trials were independent of visual field. The results of Experiment 3 suggest that by 10 years of age the hemispheres have adult-like specialization for the processing of hierarchical shapes, at least when attention is directed to the global versus local level. Nevertheless, their greater bias in Experiments 1 and 2 suggests that 10-year-olds are less able than adults to modulate attention to the output from local versus global channels-perhaps because they are less able to ignore distractors and perhaps because the cerebral hemispheres are less able to engage in parallel processing.     

A developmental study of attention to auditory and visual signals

Three experiments tested for developmental changes in attention to simple auditory and visual signals. Subject pressed a single button in response to the onset (Experiment 1) or offset (Experiment 2) of either a tone or a light. During one block of trials subjects knew which stimulus would come on or go off on each trial (precue condition) whereas during the other block of trials no precue was provided. In both experiments subjects as young as 4 years old responded more rapidly with precues, indicating that they were able to allocate their attention to the indicated modality. Experiment 3 utilized a choice reaction paradigm (in which subjects pressed different buttons in response to the onset of the light and the tone) in order to examine their attention allocation when no precues were provided. It was found that the adults and 7-year-olds tended to allocate their attention to vision rather than audition when no precue was provided. The results with the 4-year-olds were not entirely consistent, but suggested a similar biasing of attention to vision on their part as well.     

Age-related changes in children's use of external representations.

This study explored children's use of external representations. Experiment 1 focused on representations of self: Self-recognition was assessed by a mark test as a function of age (3 vs. 4 years), delay (5 s vs. 3 min), and media (photographs vs. drawings). Four-year-olds outperformed 3-year-olds; children performed better with photographs than drawings; and there was no effect of delay. In Experiment 2, 3- and 4-year-olds used a delayed video image to locate a sticker on themselves (self task) or a stuffed animal (other task). The 2 tasks were positively correlated with age and vocabulary partialed out. Experiment 3 used a search task to assess whether children have particular difficulty using external representations that conflict with their expectations: 3- and 4-year-olds were informed of an object's location verbally or through video: on half of the trials, this information conflicted with children's initial belief. Three-year-olds performed worse than 4-year-olds on conflict trials, indicating that assessments of self and other understanding may reflect children's ability to reason about conflicting external representations.     

Age-Correlated Incremental Consideration of Velocity Information in Relative Time-to-Arrival Judgments

One hundred fifty-one children and 43 adults judged which of 2 cartoon birds would be the first to arrive at a common finish line. Objects moved unidirectionally along parallel trajectories, either at the same or different speeds, and disappeared at different distances from the goal. Overall, 9–10-year-old children performed as well as adults, but 4–5- and 6–8-year-olds erred significantly more often. On trials for which distance to goal at disappearance was a valid cue, 4–5-year-olds scored 80% correct, and no differences were seen between 6–10-year-olds and adults. On the opposite type of trials, where the trailing bird would win the race, only adults retained their level of performance, and all age groups differed markedly. Findings suggest a gradual developmental transition from a distance-based to a time-based understanding of the task.     

Changes in the structure of children's isometric force variability with practice

This study examined the effect of age and practice on the structure of children's force variability to test the information processing hypothesis that a reduction of sensorimotor system noise accounts in large part for age-related reductions in perceptual-motor performance variability. In the study, 6-year-olds, 10-year-olds, and young adults practiced on 5 consecutive days (15 trials/day), maintaining for 15-s trials a constant level of force (5 or 25% of maximum voluntary contraction) against an object using a pinch grip (thumb and index finger). With increasing age, the amount of force error and variability decreased, but the sequential structure of variability increased in irregularity. With practice, children reduced the amount of variability by changing the structure of the force output so as to be more similar to that of their older counterparts. The findings provide further evidence that practice-driven changes in the structure of force output, rather than a decline in the amount of white noise, largely account for age-related reductions in the amount of force variability.     

Bimanual stereotypes: bimanual coordination in children as a function of movements and relative velocity

Five-, 7-, and 9-year-old children were trained and tested in a bimanual coordination task that required them to rotate two cranks (either at the same or at different velocities) using mirror (inwards or outwards) or parallel movements (clockwise or counterclockwise). The task consisted of tracing two lines of different slants, by turning the two cranks either at the same velocity (to draw the 45 degrees slanted line) or at different velocities (to draw the 22 degrees line). The same-velocity condition resulted in significantly better performance than the different-velocities condition with the age x angle interaction: the performance in the different-velocities condition improved considerably at 9 years of age. Mirror movement induced faster and more accurate performance relative to parallel movements in the same-velocity condition but not in the different-velocities condition. This difference was much greater in 5- and 7-year-olds than in 9-year-olds. The results are interpreted as reflecting a decreasing influence of motor constraints on bimanual coordination.     

Sustained attention to a predictable,unengaging Go/No-Go task shows ongoing development between 6 and 11 years

Response time variability (RTV) is a useful measure of sustained attention; however, little is known about developmental changes in RTV at different temporal frequencies. Thirty-five 6-year-olds, 31 8-year-olds, and 37 10-year-olds completed the fixed-sequence Sustained Attention to Response Task on three occasions, six months apart. Fast Fourier Transform and ex-Gaussian analyses of response time (RT) data assessed momentary fluctuations in RT, gradual changes in RT, and very long responses, thought to reflect attentional control fluctuations, slow-shifting arousal, and infrequent lapses in attention, respectively. A half-by-half analysis measured within-occasion time-on-task effects. The 10-to 11-year-olds performed with less momentary fluctuations in RT, fewer long responses, and fewer commission and omission errors than the younger groups. This group performed well in the first half of the task but showed time-on-task effects on measures of momentary fluctuations in RT, very long responses, target sensitivity (d’), and commission errors. The 6- to 7-year-olds performed less well than the older groups, and showed time-on-task effects, on almost all measures. The 8- to- 9-year-olds mostly performed at an intermediate level compared with the other groups; however, this group performed with a similar level of momentary fluctuations in RT and very long responses as the 6- to 7-year-olds. These findings indicate that there is ongoing maturation of various aspects of sustained attention on a predictable task, with a period of relative stability in performance between 8 and 9 years of age.     

Children's selective attention with variation in amount of stimulus exposure

Selective attention in children was measured by means of a central-incidental learning paradigm. Children performed a central task requiring attention to one element in each of several stimuli, after which their incidental learning was assessed by a combination of two tests measuring: (a) recognition of the second, or incidental, element in each stimulus, and (b) association between the incidental and central elements. Principal independent variables were the age of the children (9 vs 12 years) and the amount of exposure time per trial in the central task (6 vs 12 sec). Douling the exposure time increased the incidental as well as the central scores for 9-year-olds, while it increased only the central scores for 12-year-olds. It would appear that younger children maintain a relatively nonselective orientation during an extended exposure period, distributing attention between both relevant and irrelevant stimulus elements, whereas adolescents adopt a more selective approach and concentrate exclusively on task-relevant information. The results are discussed in relation to hypotheses regarding development of selective attention.     

Age difference on a coincident anticipation task: influence of stereotypic or "preferred" movement speed

Two experiments were performed as an initial attempt to explain age related limitations in response accuracy on a coincident anticipation task. Five- to 9-year-old boys and adult males participated in each experiment. They made horizontal arm movements in response to stimuli from a Bassin Anticipation Timer. The results of Experiment l confirmed the findings of previous studies, which showed that young children respond early to slow moving stimuli. They were most accurate at intermediate speeds; their responses deteriorated as speed was increased. older children and adults were more accurate at slow to intermediate speeds; their performances also declined at fast stimulus velocities. Experiment ll examined use of a stereotypic or default movement speed as an explanation for these results, particularly for young children. A most comfortable movement pace was determined for each subject and was used as a baseline speed for a subsequent timing task. Four other stimuli were selected in 0.8 mph increments from the baseline speed (two faster, two slower). In addition, selected trials for 6 subjects at each age were filmed at 32 fps. X-coordinates for these trials were obtained and smoothed at 5 Hz. Movement time data suggested that 5-year-olds used a preferred or stereotypic speed, since they were accurate only when responding to their baseline speed. older subjects matched stimuli up to and including their baselines. Kinematic characteristics confirmed the general notion of preferred speed for 5-year-olds. These same measures demonstrated that older subjects were increasingly adaptable in their responses, despite a failure to respond more accurately. Consequently, the term "preferred speed" lacks generality as an explanatory concept. Age-related shifts in the ability to modify components of a response, like average movement velocity and number of corrections, were used to explain accuracy differences.     

Age Differences on a Coincident Anticipation Task

Two experiments were performed as an initial attempt to explain age related limitations in response accuracy on a coincident anticipation task. Five- to 9-year-old boys and adult males participated in each experiment. They made horizontal arm movements in response to stimuli from a Bassin Anticipation Timer. The results of Experiment I confirmed the findings of previous studies, which showed that young children respond early to slow moving stimuli. They were most accurate at intermediate speeds; their responses deteriorated as speed was increased. Older children and adults were more accurate at slow to intermediate speeds; their performances also declined at fast stimulus velocities. Experiment II examined use of a stereotypic or default movement speed as an explanation for these results, particularly for young children. A most comfortable movement pace was determined for each subject and was used as a baseline speed for a subsequent timing task. Four other stimuli were selected in 0.8 mph increments from the baseline speed (two faster, two slower). In addition, selected trials for 6 subjects at each age were filmed at 32 fps. X-coordinates for these trials were obtained and smoothed at 5 Hz. Movement time data suggested that 5-year-olds used a preferred or stereotypic speed, since they were accurate only when responding to their baseline speed. Older subjects matched stimuli up to and including their baselines. Kinematic characteristics confirmed the general notion of preferred speed for 5-year-olds. These same measures demonstrated that older subjects were increasingly adaptable in their responses, despite a failure to respond more accurately. Consequently, the term “preferred speed” lacks generality as an explanatory concept. Age-related shifts in the ability to modify components of a response, like average movement velocity and number of corrections, were used to explain accuracy differences.     

Aligning body and world: Stable reference frames improve young children’s search for hidden objects

This study investigated how young children’s increasingly flexible use of spatial reference frames enables accurate search for hidden objects by using a task that 3-year-olds have been shown to perform with great accuracy and 2-year-olds have been shown to perform inaccurately. Children watched as an object was rolled down a ramp, behind a panel of doors, and stopped at a barrier visible above the doors. In two experiments, we gave 2- and 2.5-year-olds a strong reference frame by increasing the relative salience and stability of the barrier. In Experiment 1, 2.5-year-olds performed at above-chance levels with the more salient barrier. In Experiment 2, we highlighted the stability of the barrier (or ramp) by maximizing the spatial extent of each reference frame across the first four training trials. Children who were given a stable barrier (and moving ramp) during these initial trials performed at above-chance levels and significantly better than children who were given a stable ramp (and moving barrier). This work highlights that factors central to spatial cognition and motor planning—aligning egocentric and object-centered reference frames—play a role in the ramp task during this transitional phase in development.     

The development of landmark and beacon use in young children: evidence from a touchscreen search task

Children ages 2, 3 and 4 years participated in a novel hide-and-seek search task presented on a touchscreen monitor. On beacon trials, the target hiding place could be located using a beacon cue, but on landmark trials, searching required the use of a nearby landmark cue. In Experiment 1, 2-year-olds performed less accurately than older children on landmark trials but performed equivalently on beacon trials. In Experiment 2, the number of items on the screen was reduced and 2-year-olds' performance improved. Use of the landmark transformation technique in Experiment 3 revealed that older children formed a more precise landmark-target spatial relationship than 2-year-olds. Experiment 4 showed that the transformation itself was not responsible for the youngest participants' decreased accuracy in Experiment 3. Overall, beacons were utilized effectively by all participants, but the use of landmark cues is refined between the ages of 2 and 4.     

Development of the coordination between posture and manual control

Studies have suggested that proper postural control is essential for the development of reaching. However, little research has examined the development of the coordination between posture and manual control throughout childhood. We investigated the coordination between posture and manual control in children (7- and 10-year-olds) and adults during a precision fitting task as task constraints became more difficult. Participants fit a block through an opening as arm kinematics, trunk kinematics, and center of pressure data were collected. During the fitting task, the precision, postural, and visual constraints of the task were manipulated. Young children adopted a strategy where they first move their trunk toward the opening and then stabilize their trunk (freeze degrees of freedom) as the precision manual task is being performed. In contrast, adults and older children make compensatory trunk movements as the task is being performed. The 10-year-olds were similar to adults under the less constrained task conditions, but they resembled the 7-year-olds under the more challenging tasks. The ability to either suppress or allow postural fluctuations based on the constraints of a suprapostural task begins to develop at around 10 years of age. This ability, once developed, allows children to learn specific segmental movements required to complete a task within an environmental context.     

The power of well-connected arguments: early sensitivity to the connective because

Connectives, such as because, are routinely used by parents when addressing their children, yet we do not know to what extent children are sensitive to their use. Given children's early developing abilities to evaluate testimony and produce arguments containing connectives, it was hypothesized that young children would show an appropriate reaction to the presence of connectives. Three experiments were conducted to test this hypothesis. In each, two informants gave contradicting statements regarding the location of an object and justified their positions by using a similar argument. Only one of the informants used the connective because to link his argument to the statement. In each experiment, the 3-year-olds performed at chance in selecting choices containing the connective because, but the 4- and 5-year-olds performed above chance. Moreover, in Experiments 2 and 3, the 4-year-olds, 5-year-olds, and adults performed significantly better than the 3-year-olds. These findings show that 4-year-olds, 5-year-olds, and adults are sensitive to the presence of connectives. An interpretation of the difference in performance between the 3-year-olds and the 4- and 5-year-olds in terms of metarepresentational skills is suggested.     

Once in contact, always in contact: contagious essence and conceptions of purification in American and Hindu Indian children

Cultural and age differences in responses to contamination and conceptions of purification were examined in Hindu Indian (N = 125) and American (N = 106) 4- to 5-year-olds and 8-year-olds, who were provided with stories of juice contaminated by contact with a cockroach, a human hair, and a stranger (via sipping). Children who rejected the juice as being fit to drink were probed to determine whether their rejection was based on material essence (reduced by boiling), association (reduced by color change), or spiritual essence (reduced by sipping by the mother). A majority of 4- to 5-year-olds showed some form of contamination response, as did the great majority of 8-year-olds. Younger children's judgments were often based on spiritual essence or association, whereas material essence was more important for the older children, particularly Americans. However, for many children in both cultures, no purifiers were effective. In keeping with Hindu culture, the Indian children responded significantly more strongly to stranger or cockroach contamination and, with increasing age, viewed contamination as more impervious to any kind of purification.     

The developing role of prosody in novel word interpretation

This study examined whether children use prosodic correlates to word meaning when interpreting novel words. For example, do children infer that a word spoken in a deep, slow, loud voice refers to something larger than a word spoken in a high, fast, quiet voice? Participants were 4- and 5-year-olds who viewed picture pairs that varied along a single dimension (e.g., big vs. small flower) and heard a recorded voice asking them, for example, “Can you get the blicket one?” spoken with either meaningful or neutral prosody. The 4-year-olds failed to map prosodic cues to their corresponding meaning, whereas the 5-year-olds succeeded (Experiment 1). However, 4-year-olds successfully mapped prosodic cues to word meaning following a training phase that reinforced children’s attention to prosodic information (Experiment 2). These studies constitute the first empirical demonstration that young children are able to use prosody-to-meaning correlates as a cue to novel word interpretation.     

Choosing an optimal motor-task difficulty is not trivial: The influence of age and expertise

An accurate estimate of one’s performance is an important prerequisite for success, and prevents people from taking excessive risks. Based on the selection-margins paradigm (Riediger et al., 2006), the current paper assessed maximum speed rope-skipping (study 1), soccer dribbling (study 2), and the fine motor task of tracing (study 3) in 5- to 37-year-olds. Participants predicted their performances for the upcoming trial. The better the predicted performance, the more points were gained in case of success. To discourage overestimations, participants received no points for unsuccessful trials. In rope skipping, older and more experienced athletes outperformed the beginners, and had fewer trials with 0 points. In soccer dribbling and tracing, older individuals again showed less overestimation, as reflected by a smaller deviation of predicted and actual performance (selection margins) and fewer 0 point trials. Athletes and coaches should be aware that younger and less-experienced athletes tend to overestimate their motor performances.     

Baseline differences,attention, and age differences in time-sharing performance

The purpose of this experiment was to determine whether age differences noted when two tasks are performed concurrently can be accounted for in terms of age differences in single task baseline performance. Two groups of 12 8-year-olds and one group of 12 13-year-olds performed a compensatory tracking task and an auditory matching task, first alone and then time shared. The 8- and 13-year-old baseline groups performed baseline trials on each task prior to time-sharing trials. Each training group 8-year-old was randomly paired with a 13-year-old and given sufficient single task practice before time sharing to equate the 8- and 13-year-old pair members' baselines on both tasks. Results showed trained 8-year-olds to be indistinguishable from 13-year-olds in time sharing, whereas the 8-year-old baseline group showed significantly greater decrements in time-sharing and higher baseline scores on both tasks. These data provide support for the hypothesis that time-shared performance is directly related to level of baseline performance.     

Helping children apply their knowledge to their behavior on a dimension-switching task

To investigate why 3-year-olds have difficulty in switching sorting dimensions, children of 3 and 4 years were tested in one of four conditions on Zelazo's card sort task: standard, sleeve, label and face-up. In the standard condition, children were required to sort blue-truck and red-star cards under either a blue-star or red-truck model card, first by color or shape, and then by the other dimension. Here 3-year-olds sorted correctly until the dimension changed; they continue to sort by the initial dimension. The sleeve condition (placing the sorting cards in an envelope prior to sorting) had little effect. In the label condition, the child labeled the relevant sorting dimension on each trial. Most 3-year-olds succeeded; evidently their labeling helped them refocus their attention, overcoming ‘attentional inertia’ (the pull to continue attending to the previously relevant dimension). In the face-up condition, attentional inertia was strengthened because sorted cards were left face-up; 4-year-olds performed worse than in the standard condition. We posit that attentional inertia is the core problem for preschoolers on the card sort task.     

The development of regret

In two experiments, 4- to 9-year-olds played a game in which they selected one of two boxes to win a prize. On regret trials the unchosen box contained a better prize than the prize children actually won, and on baseline trials the other box contained a prize of the same value. Children rated their feelings about their prize before and after seeing what they could have won if they had chosen the other box and were asked to provide an explanation if their feelings had changed. Patterns of responding suggested that regret was experienced by 6 or 7 years of age; children of this age could also explain why they felt worse in regret trials by referring to the counterfactual situation in which the prize was better. No evidence of regret was found in 4- and 5-year-olds. Additional findings suggested that by 6 or 7 years, children's emotions were determined by a consideration of two different counterfactual scenarios.