Early perception-action coupling: eye movements and the development of object perception

We investigated the scanning strategies used by 2- to 3.5-month-old infants when viewing partly occluded object displays. Eye movements were recorded with a corneal reflection system as the infants observed stimuli depicting two rod parts above and below an occluding box. Stimulus parameters were chosen on the basis of past research demonstrating the importance of motion, occluder width, and edge alignment to perception of object unity. Results indicated that the infants tailored scanning to display characteristics, engaging in more extensive scanning when unity perception was challenged by a wide occluder or misaligned edges. In addition, older infants tended to scan the lower parts of the displays more frequently than did younger infants. Exploration of individual differences, however, revealed marked contrasts in specific scanning styles across infants. The findings are consistent with views of perceptual development stressing the importance of information processing skills and self-directed action to the acquisition of object knowledge.     

Synchronising self-displacement with a cross-traffic gap: How does the size of traffic vehicles impact continuous speed regulations?

In this article, we investigated what visual information is used by drivers at a road crossing when they want to synchronize their displacement with that of an incoming traffic train. We made the hypothesis that synchronizing self-displacement with that of a traffic gap shares the same perceptual-motor basis as interception tasks. While a large body of literature demonstrates that bearing angle is used to control interception, another range of studies points to optical size and expansion as playing a critical role in collision avoidance. In order to test the hypothesis of the exclusive use of bearing angle in road crossing task, we manipulated the optical size and expansion of oncoming traffic elements independently of bearing angle variations. We designed a driving simulator study in which participants were to adjust their approach speed in order to cross a road junction within a moving traffic gap. We manipulated the initial offset of participants with the traffic gap, the geometry of the road junction and the way optical size of oncoming traffic elements evolves over the course of a trial. Our results showed an effect of optical size and optical expansion manipulations eventhough, we also found similar displacement profiles as in interception studies. This demonstrates that bearing angle could not explain alone the control of such a complex perceptual-motor task. We discuss these results with regard to similar results in other fields of literature.     

Representative design: Does the addition of a defender change the execution of a basketball shot?

ObjectiveThe aim of this study was to examine the influence of a defender on the performance of a motor skill from an invasion sport.DesignHighly skilled basketball players performed different variations of basketball shots using a randomised test schedule.MethodParticipants completed a total of 30 test trials comprising 6 trials of 5 different shot types in both defended and undefended conditions.ResultsThe presence of a defender led to significant changes in several behavioral measures including faster shot execution times, longer jump times, and an increase in the amount of time that the ball spent in the air as it travelled to the basket after being released from the shooter's hand. These behavioral changes were accompanied by an overall decline in shooting accuracy of over 20%. Defended shots also tended to elicit greater amounts of movement variability which, when interpreted in conjunction with the other findings, suggests that participants were attempting to adapt their movements to accommodate for the changing demands of the performance environment. Comparisons across different shot types revealed that the influence of the defender was generally context and task dependent.ConclusionsThe results have important implications for representative task design, and highlight how the manipulation of key information sources can have a marked effect upon behavioral responses.     

Infant manual exploration of composite substrates

Everyday environments, even small regions within reach, vary dramatically in terms of material composition. Adapting one's manual behavior to such transitions can be considered to be an important element of skilled action. To investigate the origins of this ability, we presented 8-month-olds (n=24) and 10-month-olds (n=24) hard or soft objects on a composite tabletop substrate that was half rigid and half flexible. Results indicated infants explored the objects selectively and geared their manual behaviors, with or without an object in hand, to the particular substrate they contacted. More broadly, the study suggests that infant manual exploration is flexible even in the face of abrupt transitions in material structure. Such flexibility may support early attempts at problem solving and tool use.     

Keeping the driver in the loop in conditionally automated driving: A perception-action theory approach

In this paper we investigated if keeping the driver in the perception–action loop during automated driving can improve take-over behavior from conditionally automated driving. To meet this aim, we designed an experiment in which visual exposure (perception) and manual control exposure (action) were manipulated. In a dynamic driving simulator experiment, participants (n = 88) performed a non-driving related task either in a head-up display in the windshield (high visual exposure) or on a head-down display near the gear shift (low visual exposure). While driving, participants were either in an intermittent control-mode with four noncritical take-over situations (high manual control exposure), or in a continuous automation-mode throughout the ride (low manual control exposure). In all conditions, a critical take-over had to be carried out after an approximately 13 min ride. Measurements of take-over behavior showed that only high visual exposure had an effect on hands-on reaction time measurements. Both visual exposure and manual control exposure had small to medium sized main effects on time to system deactivation, the maximum velocity of the steering wheel, and the standard deviation of the steering wheel angle. The combined high visual – and high manual control exposure condition led to 0.55 s faster reaction time and 37% less steering variability in comparison to the worst case low visual – and low manual control exposure condition. Together, results corroborate that maintaining visual exposure and manual control exposure during automated driving can be efficacious and suggest that their positive effects are additive.     

A response binding effect in visual short-term memory

The current study aimed to investigate the effect of action on the preservation of stored feature bindings. Prior research suggests that stimuli presented after a memory array can disrupt the feature bindings of memory array items. Here, we conducted three experiments to examine whether response to targets disrupts feature bindings. Two of four letters (A, B, C, D) were presented in a memory array, and were followed by a second array containing a single target letter. After either identifying or localizing the target letter, participants were required to report the identity or location of the memory array items. There was a deficit in memory performance involving spatial repetition when participants were required to localize targets, and involving identity repetition when participants were required to identify targets. We conclude that response codes are fundamentally linked to stimulus representations, and can affect retrieval from visual working memory.     

The GROOP effect: groups mimic group actions

Research on perception–action links has focused on an interpersonal level, demonstrating effects of observing individual actions on performance. The present study investigated perception–action matching at an inter-group level. Pairs of participants responded to hand movements that were performed by two individuals who used one hand each or they responded to hand movements performed by an individual who used both hands. Apart from the difference in the number of observed agents, the observed hand movements were identical. If co-actors form action plans that specify the actions to be performed jointly, then participants should have a stronger tendency to mimic group actions than individual actions. Confirming this prediction, the results showed larger mimicry effects when groups responded to group actions than when groups responded to otherwise identical individual actions. This suggests that representations of joint tasks modulate automatic perception–action links and facilitate mimicry at an inter-group level.     

Informational constraints shape emergent functional behaviours during performance of interceptive actions in team sports

Objectives

This study aimed to explain how defenders intercept the trajectory of a passing ball by understanding how they coupled their actions to critical information sources in a competitive performance setting in team sports.

Design

Time series data on movement displacements of fifteen senior male futsal performers were recorded and digitized during nine competitive futsal games.

Method

Performance was recorded by a digital camera and digitized with TACTO software. The spatial-temporal dynamics of performers during ten intercepted and ten non-intercepted passes were compared. Time to ball interception was calculated by the difference between the time of each defender to an interception point in ball trajectory and the time of the ball’s arrival at the same interception point. Initial distances between defenders and ball and velocity data of defenders and ball over time were also recorded.

Results

Time to ball interception revealed positive values when passes were not intercepted, and negative to zero values when passes were intercepted. At the moment of pass initiation defenders’ distances to the ball constrained their possibilities for successful interception. Analysis of defenders’ adaptations to the environment revealed that continuous changes in the defenders’ velocities constrained their success of the interception.

Conclusions

Intercepted passes seemed to be influenced by the continuous regulation of a defender’s velocity relative to the ball’s trajectory. Time to ball interception is a variable that captured the emergent functional behaviours of players attempting to intercept the trajectory of a pass in the team sport of futsal.     

Unstable coupling of body sway with imposed motion precedes visually induced motion sickness

Motion sickness is preceded by differences in the quantitative kinematics of body sway between individuals who (later) become sick and those who do not. In existing research, this effect has been demonstrated only in measures of body sway, relative to the earth. However, body sway can become coupled with imposed oscillatory motion of the illuminated environment, and the nature of this coupling may differ between individuals who become sick and those who do not. We asked whether body sway would become coupled to complex oscillations of the illuminated environment, and whether individual differences in such coupling might be precursors of motion sickness. Standing participants (women) were exposed to complex oscillation of the illuminated environment. We examined the strength of coupling as a function of time during exposure. Following exposure, some participants reported motion sickness. The nature and temporal evolution of coupling differed between participants who later reported motion sickness and those who did not. Our results show that people can couple the complex dynamics of body sway with complex imposed motion, and that differences in the nature of this coupling are related to the risk of motion sickness.     

Interweaving social and manipulative development in early infancy: Some direction for infant caregiving

Early infancy has been neglected not having the best opportunities to promote social motor and cognitive development. The maturational concept considering young infants as passive beings provide a misguided view of the developmental process. The human infant is an active being from the very beginning of life. In the social and physical world, they can, by observing and imitating, perform complex actions involving different motor behaviours. In the present review we argue that imitation and manipulative actions are integrated in Expressive Action System (Reed, 1996) where baby-caregiver social interaction is the link between the use and exploration of objects in the world. We present evidence that neonatal imitation and manipulation activities are connected and thus, we propose stimulation practices based in seminal experimental designs where infants should be positioned in favourable postures to observe others acting in the world. This will have an impact on the way that early infants understand the social world and the chain of actions possible in this environment.