Infants' perception of illusions in sound localization: reaching to sounds in the dark.

Sixteen infants each at 4, 6, and 8 months of age were tested for reaching to sounding toys in the dark under two auditory illusion conditions: the Haas-effect, which creates the illusion of a single lateralized sound based on an interaural intensity difference (the toy was visible and invisible under some test conditions); and the midline illusion, which creates the illusion of a single sound at midline due to an absence of any interaural time or intensity differences (invisible toy condition only). No-sound control trials indicated the level of spontaneous reaching in the dark. Results indicate that by 4 months infants perceive both the Haas-effect and midline illusions. The ability to reach both for invisible and visible sounding objects in the dark was well developed by 4 months of age, although developmental changes in aspects of reaching behavior were observed and, at all ages, object contact was most frequent when visual localization cues accompanied sound localization cues. The incidence of spontaneous reaching in the dark was low and did not vary with age. Theoretical and methodological implications of this research are discussed.     

Auditory sensitivity in school-age children

Thresholds for octave-band noises with center frequencies of 0.4, 1, 2, 4, and 10 kHz and 1/3-octave-band noises centered at 10 and 20 kHz were obtained from children 6 to 16 years of age. Such thresholds, combined with those obtained previously for infants, preschool children, and adults, provide a detailed picture of developing auditory sensitivity between infancy and maturity. Continuing improvements in sensitivity are evident from infancy through the preschool period, well into the school years. For stimuli with center frequencies of 0.4 and 1 kHz, maximal sensitivity is achieved at about 10 years of age, compared to 8 years for stimuli of 2 and 4 kHz. For 10-kHz stimuli, there is little change beyond 4 or 5 years of age. Finally, 20-kHz stimuli yield maximal sensitivity at about 6 or 8 years of age, followed by a progressive decline to adult levels. These findings are considered in relation to auditory sensitivity in nonhuman species, to structural and functional development of the ear, and to possible changes in the efficiency of neural processing.     

Children's perception of melodies: the role of contour, frequency, and rate of presentation

Children 4 to 6 years of age were exposed to repetitions of a six-tone melody, then tested for their detection of transformations that either preserved or changed the contour of the standard melody. Discrimination performance was examined as a function of contour condition, magnitude of contour change, rate of presentation, and the presence of novel frequencies. Performance was superior for transformations that changed contour compared to those that did not, for greater changes in contour, and for faster presentation rates. Melodies transformed by a reordering of component tones were no less discriminable than those transformed by the addition of novel frequencies.     

Parents teaching young children home safety rules: Implications for childhood injury risk

Teaching safety rules is a common practice but little is known about this. Fifty-eight parents of children 2 to 2.5 or 3 to 3.5 years of age reported on the safety rules they have, the factors that prompted these rules, the strategies used to teach these rules, and how they react to noncompliance with these rules. Results revealed more safety rules for children in the older group than the younger group, and greater emphasis on teaching the rule than teaching the basis for the rule at younger than older ages. Only about half the rules restricted the child from doing the risk behavior completely, whereas the remaining rules allowed for the behavior under certain circumstances. Parents assumed safety rules would prevent injuries and mostly implemented rules in reaction to evidence of injury risk. Parents equated noncompliance with not understanding, assuming that if children understood they would comply. Implications for childhood injury risk are discussed.     

Infants' learning,memory, and generalization of learning for bimodal events

Study 1 investigated whether infants 3 and 7 months of age show differential learning of and memory for sight-sound pairs depending on whether or not temporal synchrony was present; memory was assessed after a 10-min and 1-week interval. Study 2 examined whether 7-month-olds show generalization of learning when they encounter novel bimodal events that are similar (changes in size, orientation, or color, and spectral sound properties) to the sight-sound pairs learned 1 week earlier based on temporal synchrony. For Study 1, infants received a familiarization phase followed by a paired-comparison preference procedure to assess for learning of the sight-sound pairs. One week later a memory test was given. Results confirmed that 7-month-olds had no difficulty learning auditory-visual pairings regardless of whether or not events were temporally synchronous, and they remembered these 10 min and 1 week later. In contrast, 3-month-olds showed poorer learning of sight-sound associations in the no-synchrony than synchrony conditions, and memory for sight-sound pairs 1 week later was shown only for the synchrony conditions. Results for Study 2 revealed generalization of learning of bimodal pairings under all stimulus conditions after a 1-week interval at 7 months of age. Implications of these findings for development of intersensory knowledge are discussed.     

Examining the impact of traffic environment and executive functioning on children's pedestrian behaviors

The process of integrating visual information and planning a safe crossing is cognitively demanding for many young children. We assessed relations between traffic characteristics, aspects of children's executive functioning (EF), and pedestrian behavior, with the aim being to determine whether well-developed EF would predict safer pedestrian behaviors beyond the contributions of child demographic and traffic environment factors. Using the pretend road method, we studied a sample of 83 children aged 6-9 in a series of 5 crossing trials beside a real road in response to actual traffic conditions. Traffic characteristics and pedestrian behaviors were observed and measured across crossing trials. Both traffic characteristics and EF, most notably cognitive efficiency, were strongly related to children's pedestrian crossing behaviors. Traffic characteristics were also found to interact with children's ability to monitor their crossing performance. Examining developmental influences in pedestrian injury etiology broadens researchers' knowledge of and ability to prevent injuries by moving beyond describing what happens to children and examining why pedestrian injuries occur.     

Infants' localization of sounds in the median vertical plane: estimates of minimum audible angle

Infants 6, 9, 12, 15, and 18 months of age were seated in a dark room directly facing an array of nine loudspeakers positioned along the median vertical plane. One loudspeaker was positioned at ear level, 0 degree, and four others each were positioned above and below 0 degree. To examine infants' resolution of auditory space in the median vertical plane we sought to determine the smallest angular shift in the vertical location of a sound that infants could reliably detect (i.e., minimum audible angle). A two-alternative forced-choice procedure was used in which a sequence of white noise bursts was presented initially at 0 degree, and then shifted vertically (i.e., above or below 0 degree) and continued to be presented until the infant made a directional response; correct responses were visually reinforced. The smallest angular shift in vertical location that was reliably detected systematically decreased with increasing age between 6 months (15 degrees) and 18 months (4 degrees), suggesting a finer partitioning of auditory space along the vertical axis over this age range. By 18 months infants' performance matched that of a group of adults tested under the same circumstances.     

Children's memory for new songs: integration or independent storage of words and tunes?

The present study investigated how young children encode a song in memory, specifically, whether they integrate or store independently in memory the text and the tune of a song. Preschool children and, for purposes of comparison, adults, each participated in two test sessions: in one they were presented three novel tunes each with rhyming text and in the other they heard the same three tunes but with nonrhyming text. Following this familiarization phase they received a recognition test. On each trial, they heard one of five types of songs; the original song, a completely new song (new words, new tune), a mismatch of the tune of one song with the words of another, old words with a new tune, and new words with an old tune. The subject's task was to decide if each test song was "exactly the same," "somewhat the same," or "not at all the same" as any one of the three original songs. At both ages the proportion of "same" responses was significantly greater for the original than mismatch songs, indicating that listeners were more likely to remember the exact pairing of text and tune than to retain the components independently. However, integration was significantly greater for adults than children. At both ages, for songs judged as similar to the original songs, the words more often than the tune proved to be the most salient feature, particularly for children. There were no significant effects of rhyme on performance at either age. The results are discussed in terms of Serafine, Crowder, and Repp's (1984) hypothesis that one integrates the tune and text of a song in memory, rather than storing components separately.     

The influence of peers on children''s judgments about engaging in behaviors that threaten their safety

Unintentional injuries are the number one cause of death among children beyond one year of age. Many injuries among school-age children happen when they are away from home and in the company of peers. The aim in this study was to examine peer influences on children's judgments about engaging in behaviors that threaten their physical safety. Children were shown pictures depicting play situations which involved different paths of travel, each of which posed different degrees of injury risk. Children were asked to select the path they would take, and to assign a danger rating to reflect their beliefs about the likelihood of injury along this path. A peer-influence session followed, in which a same-sex friend attempted to persuade the child to take another path. Following exposure to the friend's arguments, children made their final decision about a path of travel in each play situation; the peer was not present during this decision and the experimenter present was unaware of the child's initial path choice. A number of other measures were taken in an effort to determine factors that influence children's risk-taking decisions. Results revealed that friends were successful in their persuasion efforts: for two of the three play situations, a significant number of children who initially selected low-risk paths switched to more risky paths. Appraisal of danger related to initial path decisions, but number of hazards identified and injury history did not significantly relate to initial decisions. The implications of these results for our understanding of injury-outcome processes are discussed.