The development of children's and adults' use of kinematic cues for visual anticipation and verbal prediction of action.

Expectations about how others' actions unfold in the future are crucial for our everyday social interactions. The current study examined the development of the use of kinematic cues for action anticipation and prediction in 3-year-olds, 4-year-olds, 10-year-olds, and adults in two experiments. Participants observed a hand repeatedly reaching for either a close or far object. The motor kinematics of the hand varied depending on whether the hand reached for the close or far object. We assessed whether participants would use kinematic cues to visually anticipate (Experiment 1; N=98) and verbally predict (Experiment 2; N=80) which object the hand was going to grasp. We found that only adults, but not 3- to 10-year-olds, based their visual anticipations on kinematic cues (Experiment 1). This speaks against claims that action anticipations are based on simulating others' motor processes and instead provides evidence that anticipations are based on perceptual mechanisms. Interestingly, 10-year-olds used kinematic cues to correctly verbally predict the target object, and 4-year-olds learned to do so over the trials (Experiment 2). Thus, kinematic cues are used earlier in life for explicit action predictions than for visual action anticipations. This adds to a recent debate on whether or not an implicit understanding of others' actions precedes their ability to verbally reason about the same actions.

The eyes know it: Toddlers' visual scanning of sad faces is predicted by their theory of mind skills.

The current research explored toddlers' gaze fixation during a scene showing a person expressing sadness after a ball is stolen from her. The relation between the duration of gaze fixation on different parts of the person's sad face (e.g., eyes, mouth) and theory of mind skills was examined. Eye tracking data indicated that before the actor experienced the negative event, toddlers divided their fixation equally between the actor's happy face and other distracting objects, but looked longer at the face after the ball was stolen and she expressed sadness. The strongest predictor of increased focus on the sad face versus other elements of the scene was toddlers' ability to predict others' emotional reactions when outcomes fulfilled (happiness) or failed to fulfill (sadness) desires, whereas toddlers' visual perspective-taking skills predicted their more specific focusing on the actor's eyes and, for boys only, mouth. Furthermore, gender differences emerged in toddlers' fixation on parts of the scene. Taken together, these findings suggest that top-down processes are involved in the scanning of emotional facial expressions in toddlers.

Differential effects of others' emotional cues on 18-month-olds' preferential reproduction of observed actions.

Infants use others' emotional signals to regulate their own object-directed behavior and action reproduction, and they typically produce more actions after having observed positive as compared to negative emotional cues. This study explored infants' understanding of the referential specificity of others' emotional cues when being confronted with two actions that are accompanied by different emotional displays. Selective action reproduction was measured after 18-month-olds (N = 42) had observed two actions directed at the same object, one of which was modeled with a positive emotional expression and the other with a negative emotional expression. Across four trials with different objects, infants' first actions matched the positively-emoted actions more often than the negatively-emoted actions. In comparison with baseline-level, infants' initial performance changed only for the positively-emoted actions, in that it increased during test. Latencies to first object-touch during test did not differ when infants reproduced the positively- or negatively-emoted actions, respectively, indicating that infants related the cues to the respective actions rather than to the object. During demonstration, infants looked relatively longer at the object than at the model's face, with no difference in positive or negative displays. Infants during their second year of life thus capture the action-related referential specificity of others' emotional cues and seem to follow positive signals more readily when actively selecting which of two actions to reproduce preferentially.

Using breastfeeding images to promote breastfeeding among young adults.

Young adults' reactions to breastfeeding images were assessed using varied approaches. In Study 1, participants viewed posters from a breastfeeding campaign; many anticipated negative reaction to the campaign. In Study 2, participants viewed novel infant-feeding posters; breastfeeding posters were viewed for less time than bottle-feeding posters, regardless of the task assigned. In Study 3, participants were asked to rate their comfort level viewing infant-feeding images; greater discomfort was reported for breastfeeding images. Taken together, we argue that many young adults expect, and experience, discomfort viewing breastfeeding, but it is important to continue using breastfeeding images in promotion efforts.

Infants' perception of actions and situational constraints: an eye-tracking study.

Rational action understanding requires that infants evaluate the efficiency of a movement in achieving a goal with respect to situational constraints. In contrast, recent accounts have highlighted the impact of perceptual characteristics of the demonstrated movement or constraints to explain infants' behavior in so-called rational imitation tasks. The current study employed eye tracking to investigate how 13- to 15-month-old infants distribute their visual attention to different aspects of an action demonstration. In three tasks (touchlight, house, and obstacle), infants watched videos in which a model performed an unusual action while she was or was not restricted by situational constraints. Infants' overall looking to the demonstration as well as looking to four segments of the video (initial segment, constraint demonstration, action performance, and final segment) and to specific areas (constraint area of interest [AOI] and action AOI) was analyzed. Overall, infants looked longer at the demonstration in the constraint condition compared with the no-constraint condition. The condition differences occurred in the two video segments where the constraint or action was displayed and were especially profound for the constraint AOI. These findings indicate that infants processed the situational constraints. However, the pattern of condition differences varied slightly in the three tasks. In sum, the data imply that infants process perceptual characteristics of the movement or constraints and that low-level perceptual processes interact with higher level cognitive processes in infants' action perception.

Infants use compression information to infer objects' weights: examining cognition, exploration, and prospective action in a preferential-reaching task.

The present research used a preferential-reaching task to examine whether 9- and 11-month-olds (n=144) could infer the relative weights of two objects resting on a soft, compressible platform. Experiment 1 established that infants reached preferentially for the lighter of 2 boxes. In Experiments 2-4, infants saw 2 boxes identical except in weight resting on a cotton wool platform. Infants reached prospectively for the lighter box, but only when their initial exploratory activities provided critical information. At 11 months, infants succeeded as long as they first determined that the platform was compressible; at 9 months, infants succeeded only if they also explored the boxes and thus had advance knowledge that they differed in weight.

Infant pupil diameter changes in response to others' positive and negative emotions.

It has been suggested that infants resonate emotionally to others' positive and negative affect displays, and that these responses become stronger towards emotions with negative valence around the age of 12-months. In this study we measured 6- and 12-month-old infants' changes in pupil diameter when presented with the image and sound of peers experiencing happiness, distress and an emotionally neutral state. For all participants the perception of another's distress triggered larger pupil diameters. Perceiving other's happiness also induced larger pupil diameters but for shorter time intervals. Importantly, we also found evidence for an asymmetry in autonomous arousal towards positive versus negative emotional displays. Larger pupil sizes for another's distress compared to another's happiness were recorded shortly after stimulus onset for the older infants, and in a later time window for the 6-month-olds. These findings suggest that arousal responses for negative as well as for positive emotions are present in the second half of the first postnatal year. Importantly, an asymmetry with stronger responses for negative emotions seems to be already present at this age.

Experience matters: 11-month-old infants can learn to use material information to predict the weight of novel objects.

In contrast to previous findings, this study demonstrates that 11-month-old infants are able to learn the relationship between object material and object weight when exploring different objects that provided a systematic covariation of both object features. This guides their action in a subsequent preferential-reaching task.

Generalization gradients and representation modes after absolute and relative discrimination learning in young chickens.

Perceptual relativity has become a central issue in animal psychophysics. In order to assess how the interplay of training experience and stimulus dimension might affect perceptual relativity, we investigated the role of 'absolute' and 'relative' training on the learning and representation of stimuli from two dimensions that might favor absolute or relative encoding to a different degree. Young chicks learned to discriminate 3D-objects by either color or size. During 'absolute' training always the choice of the same stimulus of a simultaneously presented pair was reinforced, while choice of the larger (smaller) or greener (bluer) stimulus was reinforced during 'relative' training. Overall, discrimination learning was faster with relative training, but size learning profited more from 'relative' training than color learning. Post-training generalization tests revealed a combined effect of training experience and stimulus dimension: a higher amount of absolute encoding occurred with absolute training and color learning, while relative choices prevailed with relative training and size learning.

The link between maternal interaction style and infant action understanding.

The present study investigates whether the maternal interaction style is related to 6-month-old infants' action interpretation. We tested 6-month-olds ability to interpret an unfamiliar human action as goal-directed using a modified version of the paradigm used by Woodward, A. L. (1999). Infant's ability to distinguish between purposeful and non-purposeful behaviours. Infant Behavior & Development, 22, 145-160 and Király, I., Jovanovic, B., Prinz, W., Aschersleben, G., & Gergely, G. (2003). The early origins of goal attribution in infancy. Consciousness & Cognition, 12, 732-751. Additionally, all infants and their mothers participated in a free play situation to assess maternal interaction styles as measured by the CARE-Index. According to mothers' distinct interaction styles, infants were divided into three groups. Results suggest that at 6 months of age infants of mothers with a modestly controlling interaction style are better at interpreting a human action as goal-directed than infants of sensitive and relative unresponsive mothers. The ability to understand human action as goal-directed might be a corollary of an adaptive strategy in infancy.

Action-effect anticipation in infant action control.

There is increasing evidence that action effects play a crucial role in action understanding and action control not only in adults but also in infants. Most of the research in infants focused on the learning of action-effect contingencies or how action effects help infants to infer goals in other persons' actions. In contrast, the present research aimed at demonstrating that infants control their own actions by action-effect anticipation once they know about specific action-effect relations. About 7 and 9-month olds observed an experimenter demonstrating two actions that differed regarding the action-effect assignment. Either a red-button press or a blue-button press or no button press elicited interesting acoustical and visual effects. The 9-month olds produced the effect action at first, with shorter latency and longer duration sustaining a direct impact of action-effect anticipation on action control. In 7-month olds the differences due to action-effect manipulation were less profound indicating developmental changes at this age.

Infants' perception and production of intentional actions.

Human beings act and interact with their social environment. Thus, it is important not only to understand other individuals' actions, but also to control one's own actions. To understand intentional actions one needs to detect goals in the perceived actions of others as well as to control one's own movements in order to achieve these goals through action production. After a short review of recent studies on the development of action understanding during the first years of life, the role of action effects for action understanding is discussed. In a series of experiments the exchange between action perception and action production is demonstrated, its implications for understanding intentional actions are highlighted.

Imitating step by step: a detailed analysis of 9- to 15-month-olds' reproduction of a three-step action sequence.

To investigate what infants around their first birthday learn from observing an action sequence, 9- to 15-month-olds' imitative behavior was compared in three conditions: a demonstration group watched three target action steps and a final outcome, a control group observed only the third step and final outcome, and a baseline group received no demonstration. After a short delay, the demonstration infants of all ages produced more target actions than the control and baseline infants. Moreover, the latency to the first step was shortest in the demonstration condition. Data about the performance of the single steps in each age sample revealed which target actions were novel to the infants, and which steps were learned by observation. Infants in the control condition did not generate the unseen target action steps. It is concluded that infants' memory capacity and their ability to encode action-effect relations contribute to their imitation of an action sequence.

The role of action effects in 12-month-olds' action control: a comparison of televised model and live model.

The present study investigated differences in infant imitation after watching a televised model and a live model and addressed the issue of whether action effects influence infants' action control in both cases. In a 2x2 design, 12-month-old infants observed a live or a televised model performing a three-step action sequence, in which either the 2nd or the 3rd action step was combined with an acoustical action effect. We assumed that infants would use the observed action-effect relations for their own action control in the test phase afterwards. Even though results exhibited differences in the absolute amount of imitation between the two demonstration groups, both groups showed similar result patterns regarding the action effect manipulation: infants imitated the action step that was followed by a salient action effect more often and mostly as the first target action, emphasizing the important role of action effects in infants' action control.

The role of action effects in infants' action control.

In adults, the selection and the planning of actions are influenced by the anticipation of desired action effects. However, the role of action effects for action control in infants is still an unresolved issue. One important prerequisite for infants' action control is that infants are able to relate certain movements to certain effects. To test this assumption, it was investigated how infants' action control is affected by action effects. By applying an imitation paradigm, we studied 12- and 18-month-old infants who first observed an adult experimenter demonstrating a three-step action sequence on a toy bear. In three experimental groups, the second action step, the third action step, or no action step elicited an arbitrary sound as an additional acoustic action effect. It was coded how often each of the target actions was performed by the infant in a subsequent 90-s test phase. As predicted, the frequency of the infant's target action varied depending on which action step elicited the action effect. In both age groups, the target action that was combined with an acoustical effect was not only produced more often but also occurred with lower latency and was in most cases the first target action shown by the infants. These results are interpreted as evidence of the important role of action effects in infants' action control.