Multisensory and biomechanical influences on postural control in children

Children's ability to maintain balance requires effective integration of multisensory and biomechanical information. The current project examined the interaction between such sensory inputs, manipulating visual input (presence vs. absence), haptic (somatosensory) input (presence vs. absence of contact with a stable or unstable finger support surface), and biomechanical (sensorimotor) input (varying stance widths). Analyses of mean velocity of the center of pressure and the percentage stability gain highlighted the role of varying multisensory inputs in postural control. Developmentally, older children (6-11 years) showed a multisensory integration advantage compared with their younger counterparts (3-5.9 years), with the impact of varying sensory inputs more closely akin to that seen in adults. Subsequent analyses of the impact of anthropometric individual difference parameters (e.g., height, leg length, weight, areas of base of support) revealed a shifting pattern across development. For younger children, these parameters were positively related to postural stability across experimental conditions (i.e., increasing body size was related to increasing postural control). This pattern transitioned for older children, who showed a nonsignificant relation between body size and balance. Interestingly, because adults show a negative relation between anthropometric factors and stability (i.e., increasing body size is related to decreasing postural control), this shift for the older children can be seen as a developmental transition from child-like to adult-like balance control.

Motor constraints on infant search: The impact of reaching around a barrier on search performance

This study investigated the impact of perceptual-motor context on a classic paradigm used to assess cognitive-spatial reasoning. Specifically, this project explored the effect on search behavior of reaching around a barrier versus not reaching around a barrier during the A portion in the B phase of the well-known A-not-B task. In examining 8- and 16-month-old infants, this study found that both age groups demonstrated poorer performance on A trials when needing to reach around a barrier than when there was no barrier present. More interestingly, for the younger infants, needing to reach around a barrier on A trials led to better performance on B trials relative to infants who did not reach around a barrier. Older infants, however, showed no difference in B trial performance. These results demonstrate that inducing constraints on reaching (e.g., reaching around a barrier) has a significant impact on search behavior, a finding that theoretically fits with a literature demonstrating a fundamental role in behavior of perceptual and motor influences in A-not-B behavior.

Rhythm contour drives musical memory

Listeners' use of contour information as a basis for memory of rhythmic patterns was explored in two experiments. Both studies employed a short-term memory paradigm in which listeners heard a standard rhythm, followed by a comparison rhythm, and judged whether the comparison was the same as the standard. Comparison rhythms included exact repetitions of the standard, same contour rhythms in which the relative interval durations of successive notes (but not the absolute durations of the notes themselves) were the same as the standard, and different contour rhythms in which the relative duration intervals of successive notes differed from the standard. Experiment 1 employed metric rhythms, whereas Experiment 2 employed ametric rhythms. D-prime analyses revealed that, in both experiments, listeners showed better discrimination for different contour rhythms relative to same contour rhythms. Paralleling classic work on melodic contour, these findings indicate that the concept of contour is both relevant to one's characterization of the rhythm of musical patterns and influences short-term memory for such patterns.

Auditory influences on walking: Children's walking to the beat

Research on the multisensory control of locomotion has demonstrated that adults exhibit auditory-motor entrainment across an array of contexts. In such work adults will consciously modulate the cadence of their walking when instructed to match their footfalls to an auditory metronome equal to, slower than, or faster than, their natural walking cadence. The current study extends such investigations to young toddlers between 14 and 24 months (n = 59, drawn from Toronto, Ontario), as well as adults (n = 20, drawn from Toronto, Ontario), demonstrating that even new walkers will modify their gait when presented with auditory input at or faster than their natural walking cadence. Additionally, the current study demonstrates that such modulations will occur in the absence of explicit instructions to modify gait for both toddlers and adults, suggesting an automatic level of auditory-motor entraining across ages. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Dual-task interference as a function of varying motor and cognitive demands

Multitasking is a critical feature of our daily lives. Using a dual-task paradigm, this experiment explored adults’ abilities to simultaneously engage in everyday motor and cognitive activities, counting while walking, under conditions varying the difficulty of each of these tasks. Motor difficulty was manipulated by having participants walk forward versus backward, and cognitive difficulty was manipulated by having participants count forward versus backward, employing either a serial 2 s or serial 3 s task. All of these manipulations were performed in single-task conditions (walk only, count only) and dual-task conditions (walk and count simultaneously). Both motor performance variables (cycle time, stride length, walking velocity) and cognitive variables (counting fluency, counting accuracy) were assessed in these conditions. Analyses of single-task conditions revealed that both motor and cognitive manipulations predictably influenced performance. Analyses of dual-task performance revealed influences of motor and cognitive factors on both motor and cognitive performance. Most centrally, dual-task costs (normalized difference between single- and dual-task conditions) for motor variables revealed that such costs occurred primarily for temporal or spatiotemporal gait parameters (cycle time, walking velocity) and were driven by cognitive manipulations. Dual-task cost analyses for cognitive measures revealed negative dual-task costs, or dual-task benefits, for cognitive performance. Finally, the effects of dual-task manipulations were correlated for motor and cognitive measures, indicating dual-task performance as a significant individual difference variable. These findings are discussed with reference to theories of attentional allocation, as well as the possible role of auditory–motor entrainment in dual-task conditions.

Investigating the detection of parent-child relationships in early childhood: The role of partiality in resource distributions

By early childhood, children possess clear expectations about how resources should be, and typically are, distributed, expecting and advocating for equal resource distributions to recipients. Moreover, recent evidence suggests that children may be able to use deviations from equality in resource distributions to make inferences about the nature of social relationships. Here, we investigated whether children use partiality in resource distributions displayed by adults toward children in third-party contexts to identify parent-child relationships, whether children anticipate preferential treatment based upon knowledge of third-party parent-child relationships, and whether children anticipate different emotional reactions to impartiality in resource distributions in parent-child interactions compared to neighbor-child interactions. Four-to seven-year-old children were presented with hypothetical vignettes about an adult character who distributed resources to two children either equally, or systematically favoring one child. By the age of 4, children used resource distribution partiality to identify an adult as a child’s parent, and also used these expectations to guide their anticipated emotional reactions to impartiality. By the age of 6, children were also more likely to anticipate partiality to be displayed in parent-child compared to neighbor-child relationships. The findings from the current study reveal that partiality in resource distributions acts as a valuable cue to aid in identifying and understanding social relationships, highlighting the integral role that resources play in children’s understanding of their social world. More broadly, our findings support the claim that children use cues that signal interpersonal investment to specify and evaluate parent-child relationships in third-party contexts.

Striking a balance in sports: the interrelation between children's sports experience, body size, and posture

This study investigated the relation between sports participation, body size, and postural control in children between 3 and 11 years of age. To explore this question, children's body sway was measured across multisensory conditions manipulating visual input (the presence versus absence of visual information) and proprioceptive input (varying stance widths), with postural sway in these conditions then related to reports of children's sports participation, and anthropometric measures. Corroborating well-known findings, postural sway was systematically influenced by multisensory factors, with the removal of visual information and narrower stance widths decreasing postural stability. Of more novelty, postural sway in the most stable stance, but without vision, was significantly predicted by measures of sports participation and body size variables, with these factors contributing independently to this prediction. Moreover, the impact on postural sway of having visual input, relative to removing visual input in unstable stances, was significantly predicted by sports participation in activities stressing changing stances and bases of support (e.g., dance, martial arts). Generally, these findings support multisensory and dynamic systems theories of perceptual-motor behavior, and also support sports specificity effects in assessments of the relation between posture and sports.

Multisensory postural control in adults: Variation in visual, haptic, and proprioceptive inputs

Maintaining balance is fundamentally a multisensory process, with visual, haptic, and proprioceptive information all playing an important role in postural control. The current project examined the interaction between such sensory inputs, manipulating visual (presence versus absence), haptic (presence versus absence of contact with a stable or unstable finger support surface), and proprioceptive (varying stance widths, including shoulder width stance, Chaplin [heels together, feet splayed at approximately 60°] stance, feet together stance, and tandem stance) information. Analyses of mean velocity of the Centre of Pressure (CoP) revealed significant interactions between these factors, with stability gains observed as a function of increasing sensory information (e.g., visual, haptic, visual + haptic), although the nature of these gains was modulated by the proprioceptive information and the reliability of the haptic support surface (i.e., unstable versus stable finger supports). Subsequent analyses on individual difference parameters (e.g., height, leg length, weight, and areas of base of support) revealed that these variables were significantly related to postural measures across experimental conditions. These findings are discussed relative to their implications for multisensory postural control, and with respect to inverted pendulum models of balance. (185 words).

Multisensory factors in postural control: Varieties of visual and haptic effects

Background Previous work on balance control in children and adults highlights the importance of multisensory information. Work in this vein has examined two principal input sources - the role of visual and haptic information on balance. Recent work has explored the impact of a different form of haptic input - object holding - on balance in young infants. Research question This experiment examined the impact of simultaneous visual input and haptic input on balance in children and adults, employing two novel forms of haptic input. Methods Static balance was measured in 3-5 year olds, 7-9 year olds, and young adults, in the presence of all possible combinations of manipulated visual input (eyes open, eyes closed) and haptic input (no touch, object hold, touch an unstable support, touch a stable support). Results Analysis of postural stability (mean velocity) indicated that stability was influenced by visual input, haptic input, and age group. For visual input stability increased in eyes open versus eyes closed conditions. For haptic input, stability systematically increased with increasing levels of fixed haptic input (e.g., no touch, object hold, unstable touch, stable touch). Stability also increased as a function of increasing age group. There were no interactions between the factors. Significance The finding that the two novel forms of haptic input - object hold and touch with an unstable support surface - increased stability relative to no touch input, but not as much as touch with a stable support, indicates that children use haptic information in a self-referential fashion for controlling posture. The failure to observe any interactions between visual and haptic inputs with age suggests that multisensory processing is generally additive across development, and has implications for the occurrence of sensory weighting across developmental epochs.

Tonal and textural influences on musical sight-reading

Two experiments investigated the impact of two structural factors-musical tonality and musical texture-on pianists' ability to play by sight without prior preparation, known as musical sight-reading. Tonality refers to the cognitive organization of tones around a central reference pitch, whereas texture refers to the organization of music in terms of the simultaneous versus successive onsets of tones as well as the number of hands (unimanual versus bimanual) involved in performance. Both experiments demonstrated that tonality and texture influenced sight-reading. For tonality, both studies found that errors in performance increased for passages with lesser perceived psychological stability (i.e., minor and atonal passages) relative to greater perceived stability (i.e., major passages). For texture, both studies found that errors in performance increased for passages that were more texturally complex, requiring two-handed versus one-handed performance, with some additional evidence that the relative simultaneity of note onsets (primarily simultaneous versus primarily successive) also influenced errors. These experiments are interpreted within a perception-action framework of music performance, highlighting influences of both top-down cognitive factors and bottom-up motoric processes on sight-reading behavior.

Learning of hierarchical serial patterns emerges in infancy

Recursive, hierarchically organized serial patterns provide the underlying structure in many cognitive and motor domains including speech, language, music, social interaction, and motor action. We investigated whether learning of hierarchical patterns emerges in infancy by habituating 204 infants to different hierarchical serial patterns and then testing for discrimination and generalization of such patterns. Results indicated that 8- to 10-month-old and 12- to 14-month-old infants exhibited sensitivity to the difference between hierarchical and non-hierarchical structure but that 4- to 6-month-old infants did not. These findings demonstrate that the ability to perceive, learn, and generalize recursive, hierarchical, pattern rules emerges in infancy and add to growing evidence that general-purpose pattern learning mechanisms emerge during the first year of life.

To Cue or Not to Cue: Toddlers' Use of Beacons and Associative Cues in Object-displacement Tasks

Two experiments examined 24- and 30-month-olds' use of different forms of landmark information in an object-displacement task involving a car rolling down a ramp whose trajectory was occluded by a screen containing doors. A pompom attached to the car, visible through a transparent window running across the screen, served as a cue for the car's location and functioned either as a beacon cue, directly guiding search to a given location, or an associative cue, indirectly marking target location. Interestingly, one way in which the cue information was modified from a beacon to an associative cue was in terms of the structure of the search apparatus, and not necessarily the cue information itself. Consistent with previous literature, 24-month-olds' search was significantly influenced by the shift from beacon to associative cue information, whereas 30-month-olds, although affected by the shift from one to the other, were less affected by this variation. These findings suggest that the cue drives attention to specific locations in space, with search behavior being more accurate when the cue directly marks the hiding location (i.e., beacon) than when the cue indirectly marks it (i.e., associative cue).

Looming Responses to Obstacles and Apertures: The Role of Accretion and Deletion of Background Texture

Successful navigation in the world requires differentiating an obstacle in one's path from an aperture through which one could pass. An approaching obstacle is specified by texture expansion within the obstacle's contour and the deletion of background texture outside the object. In contrast, an approaching aperture contains texture expansion within the aperture's frame and accretion of background texture within the aperture's contour. This study investigated 3- to 5-month-old infants' discrimination of obstacles from apertures, examining eyeblink responses to the movement of both kinds of objects against backgrounds varying in salience. Obstacles produced stronger looming reactions than apertures, and the salience of the background influenced responses to apertures but not obstacles. These findings imply that infants differentiate obstacles from apertures based on their relative patterns of accretion versus deletion of background texture, and suggest that infants recognize the functional consequences of contact with these objects.

Memory for musical tones: the impact of tonality and the creation of false memories

Although the relation between tonality and musical memory has been fairly well-studied, less is known regarding the contribution of tonal-schematic expectancies to this relation. Three experiments investigated the influence of tonal expectancies on memory for single tones in a tonal melodic context. In the first experiment, listener responses indicated superior recognition of both expected and unexpected targets in a major tonal context than for moderately expected targets. Importantly, and in support of previous work on false memories, listener responses also revealed a higher false alarm rate for expected than unexpected targets. These results indicate roles for tonal schematic congruency as well as distinctiveness in memory for melodic tones. The second experiment utilized minor melodies, which weakened tonal expectancies since the minor tonality can be represented in three forms simultaneously. Finally, tonal expectancies were abolished entirely in the third experiment through the use of atonal melodies. Accordingly, the expectancy-based results observed in the first experiment were disrupted in the second experiment, and disappeared in the third experiment. These results are discussed in light of schema theory, musical expectancy, and classic memory work on the availability and distinctiveness heuristics.

The role of stimulus novelty on children's inflexible dimensional switching

Children's ability to flexibly shift attention between different representational schemes was investigated using the dimensional change card sorting task. Across three experiments (N = 56 three-year-olds and N = 40 four-year-olds in ; N = 14 three-year-olds in ; and N = 14 three-year-olds in ) the role of perceptual information on children's cognitive flexibility was investigated by manipulating different aspects of the task materials between pre- and postswitch phases. Better performance was observed when either task-relevant (the color or shape of the images on the cards) or task-irrelevant information (the background color or shape of the actual cards) was changed, with this improvement occurring when the changes were salient enough to induce a stimulus novelty effect.

The role of perceptual similarity of the task environments in children's perseverative responding

Perseverative responding is often seen in children's performance in a variety of contexts. One such context is symbolic comprehension in which 2- and 2½-year-olds demonstrate difficulty in appreciating the association of symbols (pictures and scale models) and their referents and show a high proportion of perseverative responding. Representational-level explanations of perseveration were explored in the current studies via examination of the impact of perceptual similarity of visual environments across trials. Across two experiments, children saw either a picture (Experiment 1) or a scale model (Experiment 2) of a hiding location of a room and were then encouraged to recover the toy from an identical room. Manipulating the perceptual similarity of the environments across successive trials affected performance and perseverative responding. These results highlight the critical role played by perceptual information not only in symbolic tasks but also in many other tasks and have important implications for theories of perseveration.

Perseveration in barrier crossing

The phenomenon of response perseveration has captivated psychologists for years, with the majority of theories of this effect focusing primarily on the cognitive, spatially oriented nature of this behavior. The current project examined whether response perseveration would also occur within a task requiring little cognitive spatial resources--barrier crossing. Across three experiments, significant response perseveration was observed in toddlers' choices of which side of a barrier to cross. Specifically, Experiment 1 demonstrated the basic effect of response perseveration in barrier crossing, Experiment 2 showed that perseveration would continue even when the chosen side was more difficult to cross than the nonchosen side, and Experiment 3 demonstrated that perseverations were based on an environment-centered reference frame, as opposed to a body-centered reference frame. These findings are discussed in terms of their implications for theoretical accounts of response perseveration specifically, and with regard to perceptual-motor relations more generally.

What's in a cue? The role of cue orientation in object displacement tasks

The current study looked at two theoretical proposals explaining toddlers' abilities to use cue information for recovering a hidden object that had rolled down a ramp behind an occluded screen. These two approaches, the theory of object directed attention and a landmark-based account, make different predictions regarding the efficacy of an obliquely aligned cue to object position. Accordingly, the search by forty 24-month olds, forty-two 30-month olds, and forty-one 36-month olds for a hidden toy that was cued using either a short versus a long cue, or a vertically aligned versus an obliquely aligned cue, were compared. Analyses of search accuracy revealed that children were more successful when faced with short as opposed to long cues, and when using vertical as opposed to oblique cues. These findings support a landmark-based approach, as opposed to an object-directed attention account, and are discussed with reference to their implications for spatial orientation more generally.

Dial A440 for absolute pitch: absolute pitch memory by non-absolute pitch possessors

Listeners without absolute (or "perfect") pitch have difficulty identifying or producing isolated musical pitches from memory. Instead, they process the relative pattern of pitches, which remains invariant across pitch transposition. Musically untrained non-absolute pitch possessors demonstrated absolute pitch memory for the telephone dial tone, a stimulus that is always heard at the same absolute frequency. Listeners accurately classified pitch-shifted versions of the dial tone as "normal," "higher than normal" or "lower than normal." However, the role of relative pitch processing was also evident, in that listeners' pitch judgments were also sensitive to the frequency range of stimuli.

Infants' visual-proprioceptive intermodal perception with imperfect contingency information

Two experiments explored 5-month-old infants' recognition of self-movement in the context of imperfect contingencies between felt and seen movement. Previous work has shown that infants can discriminate a display of another child's movements from an on-line video display of their own movements, even when featural information is removed. These earlier findings were extended by demonstrating self versus other discrimination when the visual information for movement was an unrelated object (a fluorescent mobile) directly attached to the child's leg, thus producing imperfect spatial and temporal contingency information. In contrast, intermodal recognition failed when the mobile was indirectly attached to infants' legs, thus eliminating spatial contingencies altogether and further weakening temporal contingencies. Together, these studies reveal that even imperfect contingency information can drive intermodal perception, given appropriate levels of spatial and temporal contingency information.

Perceptual Tests of an Algorithm for Musical Key-Finding

Perceiving the tonality of a musical passage is a fundamental aspect of the experience of hearing music. Models for determining tonality have thus occupied a central place in music cognition research. Three experiments investigated 1 well-known model of tonal determination: the Krumhansl-Schmuckler key-finding algorithm. In Experiment 1, listeners' percepts of tonality following short musical fragments derived from preludes by Bach and Chopin were compared with predictions of tonality produced by the algorithm; these predictions were very accurate for the Bach preludes but considerably less so for the Chopin preludes. Experiment 2 explored a subset of the Chopin preludes, finding that the algorithm could predict tonal percepts on a measure-by-measure basis. In Experiment 3, the algorithm predicted listeners' percepts of tonal movement throughout a complete Chopin prelude. These studies support the viability of the Krumhansl-Schmuckler key-finding algorithm as well as a model of listeners' tonal perceptions of musical passages.

The Perception of Tonal Structure Through the Differentiation and Organization of Pitches

The role of 2 psychological processes, differentiation and organization, were examined in the perception of musical tonality. Differentiation distinguishes elements from one another and was varied in terms of the distribution of pitch durations within tone sequences. Organization establishes relations between differentiated elements and was varied in terms of either conformity with or deviation from a hierarchical description of tonality. Multiple experiments demonstrated that the perception of tonality depended on a minimal degree of differentiation in the distribution of the duration--but not frequency of occurrence --of pitches and only when pitch distributions were hierarchically organized. Moreover, the mere differentiation of the tonic from nontonic pitches was not sufficient to induce tonal percepts. These results are discussed in relation to tonal strength, musical expressiveness, and principles of auditory pattern processing.

Visual-proprioceptive intermodal perception using point light displays

Three experiments explored 5- and 7-month-old infants' intermodal coordination of proprioceptive information produced by leg movements, and visual movement information specifying these same motions. The visual information took the form of point light information for leg and feet movements, with visual displays presented in upright, ego-centered on-joint (Experiment 1, N = 48); upright, ego-centered off-joint (Experiment 2, N = 48); and inverted, observer-centered off-joint (Experiment 3, N = 48) orientations. Measures of preferential looking indicated intermodal perception in infants of both ages while seeing on-joint, ego-centered orientations, and for 7-month-olds (and possibly 5-month-olds) while seeing off-joint, ego-centered displays; neither age group demonstrated intermodal perception for off-joint, observer-centered displays. These results suggest that coordination of visual and proprioceptive inputs is constrained by infants' information processing of the displays, and have implications for infants' growing understanding of their self-movement and the development of knowledge of the self.

The role of visual and body movement information in infant search

Three experiments investigated the use of visual input and body movement input arising from movement through the world on spatial orientation. Infants between 9 1/2 and 18 months participated in a search task in which they searched for a toy hidden in 1 of 2 containers. Prior to beginning search, either the infants or the containers were rotated 180 degrees; these rotations occurred in a lit or dark environment. These experiments were distinguished by the environmental cues for object location; Experiment 1 used a position cue, Experiment 2 a color cue, and Experiment 3 both position and color cues. Accuracy was better in Experiments 2 and 3 than in Experiment 1. All studies found that search was best after infant movement in the light; all other conditions led to equivalently worse performance. These results are discussed relative to a theoretical characterization of spatial coding focusing on the uses of spatial information.

Expectancy effects in memory for melodies

Two experiments explored the relation between melodic expectancy and melodic memory. In Experiment 1, listeners rated the degree to which different endings confirmed their expectations for a set of melodies. After providing these expectancy ratings, listeners received a recognition memory test in which they discriminated previously heard melodies from new melodies. Recognition memory in this task positively correlated with perceived expectancy, and was related to the estimated tonal coherence of these melodies. Experiment 2 extended these results, demonstrating better recognition memory for high expectancy melodies, relative to medium and low expectancy melodies. This experiment also observed asymmetrical memory confusions as a function of perceived expectancy. These findings fit with a model of musical memory in which schematically central events are better remembered than schematically peripheral events.

Interkey timing in piano performance and typing

In typing, when the fingers executing two successive movements are on the same hand, the time between keystrokes is longer than when the fingers are on different hands. Biomechanical limitations of the hands are thought to account for this difference. The generality of this finding was explored by investigating skilled pianists' performance of two successive notes. Experiment 1 failed to find comparable differences in timing as a function of the hands involved. Experiment 2, employing both a piano production and a typing task, replicated the previous piano performance results, and revealed that the timing differences in typing were limited to letter sequences requiring fore-aft and lateral finger movements. Experiment 3 extended this finding to piano performance. Together, these findings clarify the nature of biomechanical constraints on skilled manual performance.

Children's postural sway in response to low- and high-frequency visual information for oscillation

Two experiments examined postural responses of 3- to 6-year-old children to visual information for oscillation. In Experiment 1, children saw oscillations of the surround, with these movements ranging in frequency between 0.2 and 0.8 Hz. Analyses of anterior-posterior postural sway revealed that, similar to previous developmental investigations, the frequency of sway matched the frequency of oscillations. Analyses of sway amplitude and timing, however, revealed patterns of results more in keeping with research on adults. Experiment 2 extended these findings, presenting oscillations in which the frequency changed during the trial. Analyses of anterior-posterior sway revealed that sway frequency matched both speeds of movement. In contrast, amplitude and timing measures were again in line with adult data. These results suggest that the postural sway of children contains both adultlike and nonadult-like parameters of balance control.

The McGurk effect in infants

In the McGurk effect, perceptual identification of auditory speech syllables is influenced by simultaneous presentation of discrepant visible speech syllables. This effect has been found in subjects of different ages and with various native language backgrounds. But no McGurk tests have been conducted with prelinguistic infants. In the present series of experiments, 5-month-old English-exposed infants were tested for the McGurk effect. Infants were first gaze-habituated to an audiovisual /va/. Two different dishabituation stimuli were then presented: audio /ba/-visual /va/ (perceived by adults as /va/), and audio /da/-visual /va/ (perceived by adults as /da/). The infants showed generalization from the audiovisual /va/ to the audio /ba/-visual /va/ stimulus but not to the audio /da/-visual /va/ stimulus. Follow-up experiments revealed that these generalization differences were not due to a general preference for the audio /da/-visual /va/ stimulus or to the auditory similarity of /ba/ to /va/ relative to /da/. These results suggest that the infants were visually influenced in the same way as English-speaking adults are visually influenced.

Children's postural sway in response to low- and high-frequency visual information for oscillation

Two experiments examined postural responses of 3- to 6-year-old children to visual information for oscillation. In Experiment 1, children saw oscillations of the surround, with these movements ranging in frequency between 0.2 and 0.8 Hz. Analyses of anterior-posterior postural sway revealed that, similar to previous developmental investigations, the frequency of sway matched the frequency of oscillations. Analyses of sway amplitude and timing, however, revealed patterns of results more in keeping with research on adults. Experiment 2 extended these findings, presenting oscillations in which the frequency changed during the trial. Analyses of anterior-posterior sway revealed that sway frequency matched both speeds of movement. In contrast, amplitude and timing measures were again in line with adult data. These results suggest that the postural sway of children contains both adultlike and nonadult-like parameters of balance control.

Harmonic and rhythmic influences on musical expectancy

The effects of harmony and rhythm on expectancy formation were studied in two experiments. In both studies, we generated musical passages consisting of a melodic line accompanied by four harmonic (chord) events. These sequences varied in their harmonic content, the rhythmic periodicity of the three context chords prior to the final chord, and the ending time of the final chord itself. In Experiment 1, listeners provided ratings for how well the final chord in a chord sequence fit their expectations for what was to come next; analyses revealed subtle changes in ratings as a function of both harmonic and rhythmic variation. Experiment 2 extended these results; listeners made a speeded reaction time judgment on whether the final chord of a sequence belonged with its set of context chords. Analysis of the reaction time data suggested that harmonic and rhythmic variation also influenced the speed of musical processing. These results are interpreted with reference to current models of music cognition, and they highlight the need for rhythmical weighting factors within the psychological representation of tonal/pitch information.

Infants' perception of kinetic depth and stereokinetic displays

Studies examined infants' perceptions of 3-dimensional form, using a kinetic depth effect (KDE) display and displays containing subsets of the motion present in the KDE display. One subset consisted of "between-contour" motion, and the second consisted of "within-contour" motion. Research with adults has suggested that only between-contour motion leads to a compelling depth percept. In Experiments 1 and 2, infants generalized habituation from a KDE display to the between-contour but not the within-contour changes. In Experiments 3 and 4, infants generalized habituation from a KDE display to the between-contour display viewed from a novel orientation but not to the within-contour display viewed from the original orientation. Results indicate sensitivity to between-contour but not within-contour information, suggesting that infants perceive the 3-dimensional form of these displays.