What we don't know about what babies know: Reconsidering psychophysics, exploration, and infant behavior.

Researchers must infer "what babies know" based on what babies do. Thus, to maximize information from doing, researchers should use tasks and tools that capture the richness of infants' behaviors. We clarify Gibson's views about the richness of infants' behavior and their exploration in the service of guiding action - what Gibson called "learning about affordances."

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.

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).

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.

Musical groove shapes children's free dancing.

The drive to move to music is evident across a variety of contexts, from the simple urge to tap our toe to a song on the radio, to massive crowds dancing in time at a rock concert. Though seemingly effortless, beat synchronization is difficult to master and children are often poor beat synchronizers. Nevertheless, auditory-motor integration is fundamental for many daily processes, such as speech. A topic that has been relatively understudied concerns how stimulus properties affect young children's movement in responses to auditory stimuli. In the present study, we examined how musical groove (adult-rated desire to move) affected 3.0- to 6.9-year-old children's free dancing in the comfort of their home (n = 78). In the high groove conditions, children danced more and with more energy compared to the low groove conditions. Moreover, in the high groove condition, children's movement tempos corresponded better with the tempos of the music. Results point to early childhood sensitivity to the musical features that motivate adults to move to music. High groove music may therefore prove especially effective at facilitating early auditory-motor integration. A video abstract of this article can be viewed at https://youtu.be/vli0-6N12Ts.

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.

The multisensory cocktail party problem in children: Synchrony-based segregation of multiple talking faces improves in early childhood.

Extraction of meaningful information from multiple talkers relies on perceptual segregation. The temporal synchrony statistics inherent in everyday audiovisual (AV) speech offer a powerful basis for perceptual segregation. We investigated the developmental emergence of synchrony-based perceptual segregation of multiple talkers in 3-7-year-old children. Children either saw four identical or four different faces articulating temporally jittered versions of the same utterance and heard the audible version of the same utterance either synchronized with one of the talkers or desynchronized with all of them. Eye tracking revealed that selective attention to the temporally synchronized talking face increased while attention to the desynchronized faces decreased with age and that attention to the talkers' mouth primarily drove responsiveness. These findings demonstrate that the temporal synchrony statistics inherent in fluent AV speech assume an increasingly greater role in perceptual segregation of the multisensory clutter created by multiple talking faces in early childhood.

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).

The multisensory cocktail party problem in adults: Perceptual segregation of talking faces on the basis of audiovisual temporal synchrony.

Social interactions often involve a cluttered multisensory scene consisting of multiple talking faces. We investigated whether audiovisual temporal synchrony can facilitate perceptual segregation of talking faces. Participants either saw four identical or four different talking faces producing temporally jittered versions of the same visible speech utterance and heard the audible version of the same speech utterance. The audible utterance was either synchronized with the visible utterance produced by one of the talking faces or not synchronized with any of them. Eye tracking indicated that participants exhibited a marked preference for the synchronized talking face, that they gazed more at the mouth than the eyes overall, that they gazed more at the eyes of an audiovisually synchronized than a desynchronized talking face, and that they gazed more at the mouth when all talking faces were audiovisually desynchronized. These findings demonstrate that audiovisual temporal synchrony plays a major role in perceptual segregation of multisensory clutter and that adults rely on differential scanning strategies of a talker's eyes and mouth to discover sources of multisensory coherence.

Aggregate context effects in music processing.

Control of stimulus confounds is an ever-present, and ever-important, aspect of experimental design. Typically, researchers concern themselves with such control on a local level, ensuring that individual stimuli contain only the properties they intend for them to represent. Significantly less attention, however, is paid to stimulus properties in the aggregate, aspects that, although not present in individual stimuli, can nevertheless become emergent properties of the stimulus set when viewed in total. This paper describes two examples of such effects. The first (Case Study 1) focuses on emergent properties of pairs of to-be-performed tones on a piano keyboard, and the second (Case Study 2) focuses on emergent properties of short, atonal melodies in a perception/memory task. In both cases these sets of stimuli induced identifiable tonal influences despite being explicitly created to be devoid of musical tonality. These results highlight the importance of monitoring aggregate stimulus properties in one's research, and are discussed with reference to their implications for interpreting psychological findings quite generally.

Listeners perceive complex pitch-temporal structure in melodies.

In typical Western music, important pitches occur disproportionately often on important beats, referred to as the tonal-metric hierarchy (Prince & Schmuckler, 2014, Music Perception, 31, 254-270). We tested whether listeners are sensitive to this alignment of pitch and temporal structure. In Experiment 1, the stimuli were 200 artificial melodies with random pitch contours; all melodies had both a regular beat and a pitch class distribution that favored one musical key, but had either high or low agreement with the tonal-metric hierarchy. Thirty-two listeners rated the goodness of each melody, and another 41 listeners rated the melodies' metric clarity (how clear the beat was). The tonal-metric hierarchy did not affect either rating type, likely because the melodies may have only weakly (at best) established a musical key. In Experiment 2, we shuffled the pitches in 60 composed melodies (scrambling pitch contour, but not rhythm) to generate versions with high and low agreement with the tonal-metric hierarchy. Both ratings of goodness (N = 40) and metric clarity (N = 40) revealed strong evidence of the tonal-metric hierarchy influencing ratings; there was no effect of musical training. In Experiment 3, we phase-shifted, rather than shuffled, the pitches from the composed melodies, thus preserving pitch contour. Both rating types (goodness N = 43, metric clarity N = 32) replicated the results of Experiment 2. These findings establish the psychological reality of the tonal-metric hierarchy.

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.

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.

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.

Postural response to predictable and nonpredictable visual flow in children and adults.

Children's (3-5years) and adults' postural reactions to different conditions of visual flow information varying in its frequency content was examined using a moving room apparatus. Both groups experienced four conditions of visual input: low-frequency (0.20Hz) visual oscillations, high-frequency (0.60Hz) oscillations, multifrequency nonpredictable visual input, and no imposed visual information. Analyses of the frequency content of anterior-posterior (AP) sway revealed that postural reactions to the single-frequency conditions replicated previous findings; children were responsive to low- and high-frequency oscillations, whereas adults were responsive to low-frequency information. Extending previous work, AP sway in response to the nonpredictable condition revealed that both groups were responsive to the different components contained in the multifrequency visual information, although adults retained their frequency selectivity to low-frequency versus high-frequency content. These findings are discussed in relation to work examining feedback versus feedforward control of posture, and the reweighting of sensory inputs for postural control, as a function of development and task context.

Infants' perceptions of constraints on object motion as a function of object shape.

Three studies examined young infants' ability to distinguish between expected and unexpected motion of objects based on their shape. Using a preferential-looking paradigm, 8- and 12-month-old infants' looking time towards expected and unexpected motion displays of familiar, everyday objects (e.g., balls and cubes) was examined. Experiment 1 demonstrated that two factors drive infants' preferential fixations of object motion displays. Both 8- and 12-month-olds displayed a tendency to look at rotating information over non-rotating, stationary visual information. In contrast, only 12-month-olds showed a tendency to look at object motions that were inconsistent or "unexpected" based on shape. After controlling for the preference for more complex (rolling) by adding rolling motion to both displays (Experiment 2), 12-month-olds' ability to distinguish between expected and unexpected motion displays was facilitated. Experiment 3 provided a control by demonstrating that the preference for the unexpected object motion was not due to any other motion properties of the objects. Overall, these results indicate that 12-month-old infants have the ability to recognize the role that object shape plays in constraining object motion, which has important theoretical implications for the development of object perception.

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).

Prospection and its relationship to instrumental activities of daily living in patients with mild traumatic brain injury with cognitive impairment.

OBJECTIVE: Prospection is the ability to plan ahead by creating a series of intentions and sequential steps to achieve a particular goal. The current study examined whether prospection was compromised in patients who had sustained a mild traumatic brain injury (mTBI) and who claimed to be disabled because of their chronic cognitive impairment, as operationalized by an inability to achieve goals (e.g. return to work) well after their expected recovery. METHOD: This study employed the Tower of London (TOL) to measure prospection and compared two groups of patients who sustained a mTBI who both presented with cognitive impairment, but were or were not disabled in terms of their real world functioning (as defined by their instrumental activities of daily living, IADLs). RESULTS: The results revealed that the TOL could reliably discriminate between these two groups. In subsequent structural equation modelling, TOL scores were used to create a prospection model that was able to predict IADLs functioning. CONCLUSIONS: This study demonstrates that prospection is a critical component of one's ability to function independently following the onset of a mTBI when chronic cognitive impairment is evident and that clinicians should routinely investigate prospection in this context.