Imitation among infants in a day-care center and the development of locomotion

To examine the relationship between imitation and locomotor development among peers during infancy, we observed free play in a class of infants in a day-care center over a one-year period. The analysis included 16 infants (mean age was 8.3 months (SD=2.3) at the beginning of the observation) and 5 caregivers. The longitudinal data were divided into the crawling, cruising, and walking periods, and the imitation of object manipulation that took place among the infants during each period was analyzed. With the development of locomotion, peer-to-peer imitation became frequent. Infants who had acquired the ability to walk demonstrated imitation more frequently in triadic interactions than in dyadic interactions. Imitation took place between infants, but it was often mediated by caregivers rather than directly between infants. The results suggest that the acquisition of locomotor skills is a link in a developmental cascade from motor development to infant peer interaction. However, it is reasonable to interpret the results as indicating that the development of locomotion does not directly affect infant interactions in isolation, but rather that walking increases both the sharing and manipulation of objects with caregivers and proximity to peers, and their combined effects form a cascade.     

Bio-inspired intent communication for automated vehicles

Various external human-machine interfaces (eHMIs) have been proposed that communicate the intent of automated vehicles (AVs) to vulnerable road users. However, there is no consensus on which eHMI concept is most suitable for intent communication. In nature, animals have evolved the ability to communicate intent via visual signals. Inspired by intent communication in nature, this paper investigated three novel and potentially intuitive eHMI designs that rely on posture, gesture, and colouration, respectively. In an online crowdsourcing study, 1141 participants viewed videos featuring a yielding or non-yielding AV with one of the three bio-inspired eHMIs, as well as a green/red lightbar eHMI, a walk/don’t walk text-based eHMI, and a baseline condition (i.e., no eHMI). Participants were asked to press and hold a key when they felt safe to cross and to answer rating questions. Together, these measures were used to determine the intuitiveness of the tested eHMIs. Results showed that the lightbar eHMI and text-based eHMI were more intuitive than the three bio-inspired eHMIs, which, in turn, were more intuitive than the baseline condition. An exception was the bio-inspired colouration eHMI, which produced a performance score that was equivalent to the text-based eHMI when communicating ‘non-yielding’. Further research is necessary to examine whether these observations hold in more complex traffic situations. Additionally, we recommend combining features from different eHMIs, such as the full-body communication of the bio-inspired colouration eHMI with the colours of the lightbar eHMI.     

Is it really too far? Overestimating walk time and distance reduces walking

In this paper we use an intercept survey of 1,297 people at seven locations in New Jersey to answer three questions about perceived distances and walk times to nearby destinations. First, we seek to clarify conflicting results from the literature by asking: what factors are associated with perceived distance and walk times? Like other studies, we find that people overestimate both walk times and distances. We find that characteristics of the route matter. People are more likely to overestimate in car-dependent locations, along routes with many turns or barriers, or for destinations that are relatively closer. In terms of personal characteristics, experience walking and familiarity with the area both lead to lower estimates, while concerns about crime, getting lost, or carrying something heavy increase estimates. Next, we explore whether overestimating walk times and distances reduces the likelihood of walking. We find that people who overestimate are less likely to walk, everything else equal. Together, these results suggest that wayfinding campaigns that clarify the travel time to nearby destinations and ease the fear of getting lost are likely to improve perceptions and increase walking. We make an additional contribution by highlighting important differences between our university and town center samples, which raises questions about the reliance on student samples in research.     

The acquisition of complex predicates in japanese specifically language-impaired and normally developing children

Japanese exhibits two different types of morphological processes. Some morphologically complex predicates are generated within the domain of the lexicon, whereas others are generated outside the domain of the lexicon. An elicited production task involving both types of complex predicates was administered to six Japanese children with specific language impairment (JSLI) and six children with normal language development (JNLD). The JSLI children experienced significant difficulty forming the lexicon-external complex predicates but much less difficulty with the lexicon-internal complex predicates while the performance of the JNLD children exhibited no such asymmetry. These preliminary results suggest that the deficit of SLI affects the ability to construct implicit procedural rules for morphology that are generated outside the lexicon while their lexical operations for morphology that are generated within the domain of the lexicon remain relatively unimpaired.     

Sources of autonomy support,subjective vitality and physical activity behaviour associated with participation in a lunchtime walking intervention for physically inactive adults

ObjectivesBased on Basic Needs Theory (BNT: Deci & Ryan, 1985), this study examined longitudinal relationships between autonomy support from two sources, psychological need satisfaction, subjective vitality and self-reported physical activity during a walking intervention for physically inactive adults. We proposed that autonomy support provided via a walk leader and the overall programme would independently predict change in subjective vitality and physical activity from baseline to week 16 (post-intervention) and at four month follow-up. Further, we proposed that direct relationships among sources of autonomy support and outcomes would be mediated by autonomy, relatedness, and competence need satisfaction.DesignA longitudinal examination.MethodsParticipants (N = 69; n = 63 females, n = 6 males) from a 16-week walking programme completed a multi-section questionnaire measuring the aforementioned variables at three time points, including a four month post-intervention follow-up.ResultsBoth hypotheses were partly supported. Autonomy support from the walk leader positively predicted changes in subjective vitality from baseline to week 16 and in physical activity from baseline to follow-up. Autonomy support from the programme positively predicted changes in subjective vitality from baseline to week 16. Finally, autonomy gained from the walk leader mediated the relationship between autonomy support and subjective vitality, and between perceived autonomy support and physical activity.ConclusionsFindings indicate that autonomy support from both a walk leader and wider programme can predict psychological need satisfaction, subjective vitality and physical activity. Clinicians and researchers implementing future walking interventions may increase physical activity and subjective vitality by facilitating psychological need satisfaction through autonomy support from both sources.     

Two-step communication for the interaction between automated vehicles and pedestrians

An important challenge of automated vehicles (AV) will be the cooperative interaction with surrounding road users such as pedestrians. One solution to compensate for the missing driver-pedestrian interaction might be explicit communication via external human machine interfaces (eHMIs). Additionally, implicit communication such as a vehicle pitch motion might support AVs when interacting with pedestrians. While previous work explored various explicit and implicit communication cues, these concepts communicated the intention of the AV at one single time point. Currently, empirical findings on two-step communication lack so far. In this study, we empirically test the effect of a two-step AV communication that uses an implicit cue at a long distance and subsequently provides an implicit or explicit cues at a short distance. We compared its efficiency to single-step communication concepts providing implicit or explicit cues at the shorter distance only. To explore whether the right communication cue is used at the right distance, we analyzed pedestrians’ fixations while approaching an AV using an eye tracking device.We conducted a virtual reality study (N = 30) with AV communication concept that provided an active pitch motion or an eHMI and compared them with a two-step AV communication concept that provided an additional active pitch motion at a long distance when approaching the pedestrian. Furthermore, we recorded pedestrians’ fixation behavior while the AV approached.Consistently to previous work, single-step AV communication showed a beneficial effect on crossing behavior. Pedestrians initiated their crossing earlier while approaching an AV with an active pitch motion or an eHMI compared to the baseline condition. While active pitch motion reduced subjective safety feeling, eHMI increased it. However, the two-step communication concept did not further improve pedestrians’ crossing initiation times and their safety feeling. The pattern of fixation behavior differed as a function of AV distance. When the approaching AV was far away, pedestrians exclusively looked at the environment. During the approach, pedestrians gradually fixated the bumper and the hood and only then the windshield of the AV. Hence, it seems to be useful to present an AV intent communication at a certain distance from the pedestrian. These findings posit the importance of considering pedestrians’ fixation behavior when developing communication concepts between AVs and pedestrians.     

Physiological markers of traffic-related stress during active travel

Understanding perceptions of safety and comfort (PSC) while walking or cycling is essential to accommodating and encouraging active travel, but current measures of PSC, primarily surveys, suffer from validity and reliability issues. Physiological markers of stress like electrodermal activity and heart rate variability have been proposed as alternative, objective measures of PSC. This paper presents a literature summary and conceptual framework examining the use of physiological stress markers during walking and cycling. The existing studies of active traveller stress markers report inconsistent findings and account for limited controls. We propose a comprehensive conceptual framework to describe the array of dynamic stimuli experienced during active travel, with complex appraisals and multidimensional stress responses that feedback to travel behaviour and stimuli exposure, and culminate in a set of physiological outcomes triggered by activation of the autonomic nervous system – all moderated by numerous personal and trip-related factors. The key challenge of inferring traffic-related fear or discomfort from physiological markers measured on-road is potential confounding effects of: (1) non-traffic factors that induce or modify stress responses, (2) traffic factors that induce stress responses not associated with safety or comfort, and (3) personal and environmental factors that directly influence physiological measurements outside of a stress response. No physiological stress marker has yet been shown to be reliable for on-road active travellers, particularly not for inter-subject comparisons. Physiological markers have the potential to provide high-resolution, objective information about pedestrian and cyclist PSC, but further research, particularly controlled experiments, and more precise study framing are needed to ensure validity and address moderating and confounding factors.     

The effect of instruction to synchronize over step frequency while walking with auditory cues on a treadmill

Walking to a pacing stimulus has proven useful in motor rehabilitation, and it has been suggested that spontaneous synchronization could be preferable to intentional synchronization. But it is still unclear if the paced walking effect can occur spontaneously, or if intentionality plays a role. The aim of this work is to analyze the effect of sound pacing on gait with and without instruction to synchronize, and with different rhythmic auditory cues, while walking on a treadmill.Firstly, the baseline step frequency while walking on a treadmill was determined for all participants, followed by experimental sessions with both music and footstep sound cues. Participants were split into two groups, with one being instructed to synchronize their gait to the auditory stimuli, and the other being simply told to walk. Individual auditory cues were generated for each participant: for each trial, cues were provided at the participant’s baseline walking frequency, at 5% and 10% above baseline, and at 5% and 10% below baseline.This study’s major finding was the role of intention on synchronization, given that only the instructed group synchronized their gait with the auditory cues. No differences were found between the effects of step or music stimuli on step frequency.In conclusion, without intention or cues that direct the individual’s attention, spontaneous gait synchronization does not occur during treadmill walking.