Developmental changes in infants' sensitivity to octave-band noises

Localization responses to octave-band noises with center frequencies at 200, 400, 1000, 2000, 4000, and 10,000 Hz were obtained from infants 6, 12, and 18 months of age. During an experimental trial, an octave-band noise was presented on one of two speakers located 45° to each side of the infant. A head turn to the noise (correct response) was rewarded by activating an animated toy on top of the speaker. The intensity of the noise was varied over trials (method of constant stimuli) to determine thresholds at each center frequency. Thresholds for the lower frequencies were approximately 5–8 db higher in the 6-month-old infants compared to the older infants. However, there were no consistent differences among groups at the higher frequencies. Infant thresholds were found to be 20–30 db higher than adult thresholds at the lower frequencies. At the higher frequencies thresholds for infants were approaching those of adults.     

A happy story: Developmental changes in children’s sensitivity to facial expressions of varying intensities

Using 20 levels of intensity, we measured children’s thresholds to discriminate the six basic emotional expressions from neutral and their misidentification rates. Combined with the results of a previous study using the same method (Journal of Experimental Child Psychology, 102 (2009) 503-521), the results indicate that by 5 years of age, children are adult-like, or nearly adult-like, for happy expressions on all measures. Children’s sensitivity to other expressions continues to improve between 5 and 10 years of age (e.g., surprise, disgust, fear) or even after 10 years of age (e.g., anger, sad). The results indicate that there is a slow development of sensitivity to the expression of all basic emotions except happy. This slow development may impact children’s social and cognitive development by limiting their sensitivity to subtle expressions of disapproval or disappointment.     

Developmental changes in response preparation to visual stimuli

We examined how preparation to respond changes with age. Subjects from four age groups (5- to 7-, 8- to 11-, 12- to 17-, and 18- to 24-yr.-olds) were given a simple visual RT task with foreperiod duration varied between 300 and 2000 msec. Analysis showed that in addition to the expected effects of age and foreperiod, there were qualitative differences between the performance of adults and children: 5- to 7-yr.-olds reacted quickest after a foreperiod shorter than that required by adults to perform best. Conversely, preadolescents' optimal foreperiod was relatively longer than that of either older or younger subjects. In addition, the youngest subjects showed an inability to maintain preparation as efficiently as older subjects. Implications for the development of response preparation are discussed.     

Developmental changes in the response to obstacles during prehension

Adults are proficient at reaching to grasp objects of interest in a cluttered workspace. The issue of concern, obstacle avoidance, was studied in 3 groups of young children aged 11-12, 9-10, and 7-8 years (n=6 in each) and in 6 adults aged 18-24 years. Adults slowed their movements and decreased their maximum grip aperture when an obstacle was positioned close to a target object (the effect declined as the distance between target and obstacle increased). The children showed the same pattern, but the magnitude of the effect was quite different. In contrast to the adults, the obstacle continued to have a large effect when it was some distance from the target (and provided no physical obstruction to movement).     

Developmental changes in infants' bisensory response to synchronous durations

The present set of studies was concerned with the development of bisensory response to synchronous durations. Infants viewed pairs of checkerboards where each member of the pair flashed at the same rate but differed in the duration of each flash. Visual preferences were studied in silence as well as in the presence of a tone whose duration and onset/offset characteristics corresponded to one member of the visual pair of stimuli. Results indicated that 3-month-old infants did not make bisensory matches of duration. In contrast, 6- and 8-month-old infants exhibited evidence of bisensory matching in that, in general, their looking at the visual stimulus corresponding in duration to the auditory stimulus was greater than was their looking at the non-corresponding stimulus. Synchrony played a major part in this matching in that when the corresponding auditory and visual stimuli were put out of phase with one another, no evidence of bisensory matching was obtained.     

Developmental changes in mental rotation

Subjects from Grades 3, 4, 6, and college judged whether pairs of stimuli were identical or mirror-image reversals. One stimulus of a pair was presented upright; the other was rotated 0 to 150° from the standard. The pairs were either alphanumeric symbols or unfamiliar, letter-like characters of the type found on the PMA Spatial Ability Test. Response latencies were measured. The primary results were that (a) the speed of mental rotation increased with development, (b) unfamiliar characters were rotated more slowly than alphanumeric characters, by approximately the same amount at each grade, and (c) unfamiliar characters were encoded and compared more slowly than alphanumeric symbols, by an amount that declined with development. The results are discussed in terms of the component processes that underlie developmental change and individual variation in mental rotation skill.     

Developmental changes in attention-deployment skills

The ability to efficiently allocate attention between two tasks differing in payoff was investigated developmentally. Ten subjects from each of three grade levels (second, fourth, and college) performed an auditory and a visual memory task simultaneously. Modality of the primary task, difficulty of the primary task, and difficulty of the secondary task were varied factorially within subjects. The difference between primary and secondary performances increased with age: All college students, about half of the fourth graders, and none of the second graders showed a meaningful degree of differentiation between primary and secondary tasks.     

Developmental changes in source memory

Remembering how one learned a fact can be important in itself (e.g. for considering the value of information). However, source memory is also important, along with the temporal and perceptual information on which it is based, in giving memory an episodic or autobiographical quality. The present study investigated developmental changes in children’s ability to monitor source, in a paradigm adapted from Schacter, Harbluk and McLachlan (1984). This task, unlike previous source monitoring tasks used with children, has the potential to show the existence of a serious kind of source error called source amnesia. Children of 4, 6 and 8 years participated. They also completed measures believed to assess prefrontal function. Children showed a steady improvement with age in their ability to remember facts, but showed abrupt improvement between 4 and 6 years in their ability to monitor the source of those facts. Most notably, 4–year–old children displayed a great deal of source amnesia (i.e. errors of the kind committed by populations with frontal dysfunction), but 6– and 8–year–old children showed very few such errors. In addition, source memory was related, in some analyses although not in others, to behavioral measures often used to assess prefrontal functioning. The timing of the transition in source monitoring ability is discussed, including implications for childhood amnesia.     

Developmental changes in neural activity to familiar words and gestures

Infants younger than 20 months of age interpret both words and symbolic gestures as object names. Later in development words and gestures take on divergent communicative functions. Here, we examined patterns of brain activity to words and gestures in typically developing infants at 18 and 26 months of age. Event-related potentials (ERPs) were recorded during a match/mismatch task. At 18 months, an N400 mismatch effect was observed for pictures preceded by both words and gestures. At 26 months the N400 effect was limited to words. The results provide the first neurobiological evidence showing developmental changes in semantic processing of gestures.     

Developmental changes in face processing skills

Expertise in processing differences among faces in the spacing among facial features (second-order relations) is slower to develop than expertise in processing the shape of individual features or the shape of the external contour. To determine the impact of the slow development of sensitivity to second-order relations on various face-processing skills, we developed five computerized tasks that require matching faces on the basis of identity (with changed facial expression or head orientation), facial expression, gaze direction, and sound being spoken. In Experiment 1, we evaluated the influence of second-order relations on performance on each task by presenting them to adults (N=48) who viewed the faces either upright or inverted. Previous studies have shown that inversion has a larger effect on tasks that require processing the spacing among features than it does on tasks that can be solved by processing the shape of individual features. Adults showed an inversion effect for only one task: matching facial identity when there was a change in head orientation. In Experiment 2, we administered the same tasks to children aged 6, 8, and 10 years (N=72). Compared to adults, 6-year-olds made more errors on every task and 8-year-olds made more errors on three of the five tasks: matching direction of gaze and the two facial identity tasks. Ten-year-olds made more errors than adults on only one task: matching facial identity when there was a change in head orientation (e.g., from frontal to tilted up). Together, the results indicate that the slow development of sensitivity to second-order relations causes children to be especially poor at recognizing the identity of a face when it is seen in a new orientation.     

Loving-kindness language exposure leads to changes in sensitivity to imagined pain

To better understand the cultivation of positive intra- and interpersonal emotions, we examined an argument that some effects of contemplative training result from language processing. We presented participants with loving-kindness language used in kindness-meditation training studies and asked them to rate imagined pain. If loving-kindness language processing is responsible for some effects recently reported we expected this language could affect intra- and interpersonal sensitivity. Loving-kindness-language participants rated imagined other-pain significantly higher and imagined self-pain significantly lower than closely matched control participants. As a result of this interaction, the loving-kindness-language group showed no significant difference between self-pain and other-pain, whereas controls rated self-pain significantly higher than other-pain. These results suggest that exposure to loving-kindness-language in Loving-Kindness Meditation leads to changes in sensitivity to own and vicarious distress without explicit training. These findings underscore that meditation-like effects may be easily induced. Further research is needed to determine duration and degree of effect.     

Developmental changes in mother-infant face-to-face communication: birth to 3 months

This study documented the growth of the earliest form of face-to-face communication in 16 mother-infant dyads, videotaped weekly during a naturalistic face-to-face interaction, between 1 and 14 weeks, in 2 conditions: with the infant in the mother's arms and with the infant semi-reclined on a sofa. Results showed a curvilinear development of early face-to-face communication, with a significant increase occurring between Week 4 and Week 9 depending on the dyad. After 2 months, trajectories diverged into 2 groups: I whose duration of face-to-face communication continued to increase and I whose duration peaked and then began to decrease. After the 1st month, the duration of face-to-face communication was significantly longer when the infant was on the sofa rather than in the mother's arms. In the latter condition, during the 3rd month, girls spent a significantly longer time than boys in face-to-face communication. These findings suggest that context (infant being held vs. not being held) interacts with the infant's age and sex in affecting mother-infant communication.     

Developmental changes in death anxiety in childhood

A sample of 49 children divided into three age groups (3–4 years, 7–8 years, and 10–11 years) responded to a pictorial derivation of Spielberger's State Anxiety Inventory for Children (STAIC). Three pictures were used as stimuli, in addition to words, for the measure of death anxiety. The intensity measure was the response to six Hebrew mood adjectives as the child chose one of seven schematic face drawings ranging from positive to negative expressions. Reliabilities were comporable to the longer versions of the Hebrew STAIC with older children. Findings indicated significant differences in anxiety scores between the age groups, with older subjects showing higher levels of anxiety. The advantage of a single measure of death anxiety appropriate for a wide age range is discussed, as well as the implication for a developmental pattern of death anxiety.     

Developmental changes in judgments of authentic objects

This study examined the development of an understanding of authenticity among 112 children (preschoolers, kindergarten, 1st graders, and 4th graders) and 119 college students. Participants were presented with pairs of photographs depicting authentic and non-authentic objects and asked to pick which one belongs in a museum and which one they would want to have. Results suggest that both children and adults recognize the special nature of authentic objects by reporting that they belong in a museum. However, this belief broadens with age, at first just for famous associations (preschool), then also for original creations (kindergarten), and finally for personal associations as well (4th grade). At all ages, an object's authentic nature is distinct from its desirability. Thus, from an early age, children appear to understand that the historical path of an authentic object affects its nature. This work demonstrates the importance of non-obvious properties in children's concepts. For preschool as well as older children, history (a non-visible property) adds meaning beyond the material or functional worth of an object.