Joint drumming: social context facilitates synchronization in preschool children

The human capacity to synchronize body movements to an external acoustic beat enables uniquely human behaviors such as music making and dancing. By hypothesis, these first evolved in human cultures as fundamentally social activities. We therefore hypothesized that children would spontaneously synchronize their body movements to an external beat at earlier ages and with higher accuracy if the stimulus was presented in a social context. A total of 36 children in three age groups (2.5, 3.5, and 4.5 years) were invited to drum along with either a human partner, a drumming machine, or a drum sound coming from a speaker. When drumming with a social partner, children as young as 2.5 years adjusted their drumming tempo to a beat outside the range of their spontaneous motor tempo. Moreover, children of all ages synchronized their drumming with higher accuracy in the social condition. We argue that drumming together with a social partner creates a shared representation of the joint action task and/or elicits a specific human motivation to synchronize movements during joint rhythmic activity.     

The rapid development of explicit gaze judgment ability at 3 years

Two studies examined development of the ability to judge what another person is looking at. In Study 1, 54 2- to 4-year-olds judged where someone was looking in real-life, photograph, and drawing formats. A minority of 2-year-olds, but a majority of older children, passed all tasks, suggesting that the ability arises at around 3 years of age. Study 2 examined the fine-grained gaze judgment of 76 3- to 6-year-olds and 15 adults using gaze differences of 10° and 15°. Development of gaze judgment was gradual, from chance at 3 years of age to near adult-level performance at 6 years of age. Although performance was better when a congruent head turn was included, 3-year-olds were still at chance on 10° head turn trials. The findings suggest that the ability to explicitly judge gaze is novel at 3 years of age and develops slowly thereafter. Therefore, the ability does not develop out of earlier gaze following. General implications for the evolution and development of gaze processing are discussed.     

Relationship Between Balance Recovery From a Forward Fall and Lower-Limb Rate of Torque Development

Abstract

The authors examined the relationship between the maximum recoverable lean angle via the tether-release method with early- or late-phase rate of torque development (RTD) and maximum torque of lower-limb muscle groups in 56 young healthy adults. Maximal isometric torque and RTD at the hip, knee, and ankle were recorded. The RTD at 50-ms intervals up to 250?ms from force onset was calculated. The results of a stepwise multiple regression analysis, early RTD for hip flexion, and knee flexion were chosen as predictive variables for the maximum recoverable lean angle. The present study suggests that some of the early RTD in the lower limb muscles, but not the maximum isometric torque, can predict the maximum recoverable lean angle.     

Conceptual agreement theory

For some time now, psychological inquiry on reference has assumed that reference is achieved through causal links between words and entities (i.e., direct reference). In this view, meaning is not relevant for reference or co-reference. We argue that this view may be germane to concrete objects, but not to diffuse objects (that lack clear spatio-temporal limits, thus preventing the use of direct reference in interactions). Here, we propose that meaning is the relevant dimension when referring to diffuse entities, and introduce Conceptual Agreement Theory (CAT). CAT is a mathematized theory of meaning that specifies the conditions under which two individuals (or one individual at two points in time) will infer they share a diffuse referent. We present the theory, and use stereotype stability and public opinion as case studies to illustrate the theory’s use and scope.     

Joint attention with the mother and the father at 10 months of age

Joint attention capabilities were assessed in 52 10-month-olds observed independently with their mothers and fathers in a semi-structured toy-play condition. Mothers and fathers were indistinguishable in terms of total number of behaviours aimed at engaging their infant in joint attention. However, infants responded more to mothers' bids for attention than to fathers' bids. Contrastingly, infants tended to display more initiating joint attention behaviours while interacting with their fathers. Although parents did not differ in terms of sensitivity, fathers were less intrusive than mothers. Results are discussed in terms of the specificities of mother-infant and father-infant interaction and how the paternal role should be highlighted in the case of infant's joint attention development.     

Is social inhibition of return due to action co-representation?

When two individuals alternate reaching responses to visual targets presented on a shared workspace, one individual is slower to respond to targets occupying the same position as their partner’s previous response. This phenomenon is thought to be due to processes that inhibit the initiation of a movement to a location recently acted upon. However, two distinct forms of the inhibition account have been posited, one based on inhibition of an action, the other based on inhibition of an action and location. Furthermore, an additional recent explanation suggests the phenomenon is due to mechanisms that give rise to action congruency effects. Thus the three different theories differ in the degree to which action co-representation plays a role in the effect. The aim of the present work was to examine these competing accounts. Three experiments demonstrated that when identical actions are made, the effect is modulated by the configuration of the visual stimuli acted upon and the perceptual demands of the task. In addition, when the co-actors perform different actions to the same target, the effect is still observed. These findings support the hypothesis that this particular joint action phenomenon is generated via social cues that induce location-based inhibition of return rather than being due to shared motor co-representations.     

Infant twins’ social interactions with caregivers and same-age siblings

The study of twin behavior offers the opportunity to study differential patterns of social and communicative interactions in a context where the adult partner and same-age peer are equally familiar. We investigated the development of social engagement, communicative gestures, and imitation in 7- to 25-month-old twins. Twin dyads (N = 20 pairs) participated in 10-min, semi-structured play sessions, with the mother seated in a chair completing paperwork for half the session, and on the floor with her children for the other half. Overall, twins engaged more with their mothers than with their siblings: they showed objects and imitated speech and object use more frequently when interacting with their mothers than with their siblings. When the mother was otherwise engaged, the twins played with toys separately, observed each other's toy play, or were unengaged. These results demonstrate that adult scaffolding of social interactions supports increased communicative bids even in a context where both familiar peers and adults are available as communicative partners.     

Perceptuomotor rules as prediction tools in (joint) action: The case of orientation perception

The human action system has a layered structure supporting a cascade of partially overlapping information processes in multiple, interlinked representational spaces. Apart from the mirror neuron system which through motor resonance mediates one's understanding of the action goals of one's partner, perceptuomotor rules like Fitts' law, the Isogony Principle, and sequencing heuristics provide further sources of prediction in (joint) action. The present study focuses on a perceptuomotor rule that describes how the orientation of framed, tilted objects is perceived and acted upon by individuals. In two experiments involving the Rod-and-Frame Illusion (RFI) participants were asked to perform delayed responses that consisted either of (1) making a perceptual judgment in a forced-choice paradigm, or (2) rotating and propelling a hand-held cylinder. Irrespective of response type, the effects of the RFI proved robust and constant. The relevance of the findings for prediction in joint-action tasks is discussed.     

Eye'm lovin' it! The role of gazing awareness in mimetic desires

Recent studies showed that people evaluate objects more favorably when these objects are gazed-at by others, an effect coined as “mimetic desire”. In two studies, we tested whether mimetic desire stems from an automatic form of learning by examining one dimension of automaticity, i.e., people's awareness of the object-gaze association. Participants saw 6 neutral art paintings associated with a female gazing toward two of the paintings, away from two of the paintings, and closing her eyes with respect to the last two paintings. After the exposition phase, participants evaluated the paintings and performed a contingency-awareness test. Importantly, participants' responses on this test were genuinely driven by memory and not by inferences from liking. Results show that participants preferred objects that were gazed-at but only when they were aware of the object-gaze association. Hence, despite the adaptive function of joint attention, its impact on valence acquisition does not seem to qualify as an implicit learning process.     

Notes on selective influence, probabilistic causality, and probabilistic dimensionality

The paper provides conceptual clarifications for the issues related to the dependence of jointly distributed systems of random entities on external factors. This includes the theory of selective influence as proposed in Dzhafarov [(2003a). Selective influence through conditional independence. Psychometrika, 68, 7-26] and generalized versions of the notions of probabilistic causality [Suppes, P., & Zanotti, M. (1981). When are probabilistic explanations possible? Synthese, 48, 191-199] and dimensionality in the latent variable models [Levine, M. V. (2003). Dimension in latent variable models. Journal of Mathematical Psychology, 47, 450-466]. One of the basic observations is that any system of random entities whose joint distribution depends on a factor set can be represented by functions of two arguments: a single factor-independent source of randomness and the factor set itself. In the case of random variables (i.e., real-valued random entities endowed with Borel sigma-algebras) the single source of randomness can be chosen to be any random variable with a continuous distribution (e.g., uniformly distributed between 0 and 1).