Controlling approach

In a Heartbeat: Prospective Control of Cardiac Responses for Upcoming Action Demands During Biathlon

by Dahl Benum, Van der Weel & Van der Meer

Biathlon is an Olympic winter sport combining the endurance sport of cross-country skiing with precision rifle shooting. Here, the need to prepare the body for upcoming events is particularly evident. As a high heart rate can be detrimental to shooting performance, it might be beneficial for biathletes to decrease their heart rate when approaching the shooting range, whereas heart rate should ideally be increased at the start and when facing an uphill section to cater for physiological demands. Ten national-level, junior male biathletes skied 6–8 laps in a standardized 2 km biathlon course with competition intensity, where each lap was followed by 5 shots in the standing position. Electrocardiography was continuously measured, and changes in heart rate during the 30 s leading up to the start, the uphill section, and the shooting event were analyzed. Instantaneous heart rate (IHR) increased significantly before the start and before the beginning of the uphill, whereas IHR decreased significantly before arriving at the shooting range. These findings provide evidence that biathletes anticipate forthcoming events by prospectively adjusting their heart rate upwards and downwards depending on task demands. Being able to use perceptual predictive information to optimally prepare the body for challenges that lie ahead, may have implications for expert performance in several different sports, as well as in other fields where purposeful regulation of heart rate is important for success.

Visual Control of Velocity of Approach by Pigeons when Landing

by Lee, Davies, Green & Van der Weel

Films of pigeons flying to a perch were analysed to test a theory of how speed of approach and timing of foot extension in preparation for lFilms of pigeons flying to a perch were analysed to test a theory of how speed of approach and timing of foot extension in preparation for landing are visually controlled.

Common Principle of Guidance by Echolocation and Vision

by Lee, Van der Weel, Hitchcock, Matejowsky & Pettigrew

Using echolocation, bats move as gracefully as birds through the cluttered environment, suggesting common principles of optic and acoustic guidance. We tested the idea by analysing braking control of bats (Macroderma gigas) flying through a narrow aperture with eyes covered and uncovered.

Infant catching

Prospective Control in Catching by Infants

by Van der Meer, Van der Weel & Lee

Catching a moving object requires the ability to predict the future trajectory of the object. To test whether infants can use visual information predictively, reaching for a toy moving at different speeds was investigated in six infants around 11 months of age. The toy was occluded from view by a screen during the last part of its approach. Gaze arrived at the exit side of the screen and the hand started to move forward before the toy disappeared behind the occluder; the actions were prospectively geared to certain times before the toy would reappear. In addition, hand-movement duration was found to be related to the time of reappearance of the toy-the information used to regulate the duration of hand movement being picked up before the toy disappeared behind the occluder. In a longitudinal experiment, the development of predictive reaching was investigated in two infants between the ages of 20 and 48 weeks. At all ages studied, gaze anticipated the reappearance of the moving toy. However, anticipation with hand movement of the disappearance of the toy and the ability to gear actions prospectively to the time (instead of distance) the toy was away from certain points on the track developed relatively late and marked the transition to successfully catching faster-moving toys.

A Longitudinal Study of Prospective Control in Catching by Full-term and Preterm Infants

by Kayed & Van der Meer

Prospective control when catching moving toys was studied longitudinally in full-term and preterm infants between the ages of 22 and 48 weeks. The toy’s distance and time to the catching place and its velocity were explored as possible timing strategies used by infants to start their hand movement. The aim of the study was to find evidence for a shift in timing strategy and whether there were differences between full-term and preterm infants. In addition, it was investigated how infants continuously guided their hands to the toy and whether this guidance was influenced by their use of timing strategy. The toy approached the infants from the side with different constant velocities and constant accelerations. Results showed that there was little difference between full-term and preterm infants’ use of timing strategies. Initially, infants used a distance-
or velocity-strategy, possibly causing them to have many unsuccessful catches. After a shift to a time-strategy,
infants appeared to increase the number of successful catches and performed longer and more functional tau-couplings between the hand and the toy. One preterm infant did not switch to a time-strategy, and frequently missed the moving toy. The same infant also showed less functional tau-coupling with non-controlled collisions between the hand and the toy. More follow-up research is needed to investigate whether problems with extracting the relevant perceptual information for action could be an early indication of later perceptuo-motor difficulties.

Adult Catching

Prospective Control of Eyes, Head and Hand in Catching Accelerating objects

Catching a moving object requires the ability to predict the future trajectory of the object. In this experiment, we have been collecting data on three constant accelerative approaches and measured hand, elbow, and head movements with ProReflex and eye movements with the Tobii eye-tracker. Half of the trials were recorded with an occluder (a tunnel) taking away the sight of the target for a certain period of time (see "Experimental Setup").

Tobii eye recordings were synchronized with ProReflex recordings in time and integrated into the Qualisys analysis program (see "Explanation of the Markers Used"). Initial eye-balling the data shows two different strategies in the eye data: a gaze jump to the other side of the occluder (see  "Eye-jump Strategy videoclip") and tracking the target behind the occluder (see "Eye-Tracking Strategy videoclip"). These data will be analysed in terms of tauG guidance (Lee, 2001). Initial results of these analyses will be reported here when available.

Looking

A High-Density EEG Study into the Control of Prospective Eye Movements in Adults and Infants

by Holth, Van der Meer & Van der Weel

Tracking with the head and eyes a moving object that temporarily disappears behind an occluder requires perception of object permanence (Kaufman, Csibra & Johnson, 2003) and the ability to estimate and predict the trajectory of the moving object (Rosander & Von Hofsten, 2004). This, in turn, requires prospective control of eye movements.

The perception of visual motion and control of eye movement is mainly related to the middle temporal (MT) and medial superior temporal (MST) brain areas, located adjacent at the occipital-temporal-parietal junction (Leigh & Zee, 2006).

These signals are passed on to frontal areas in the cortex, the frontal eye field (FEF), which are believed to play an important role in controlling prospective eye movements (Leigh & Zee, 2006), and the development of this control (Canfield & Kirkham, 2001).

How is the initiation of prospective eye movements timed, and do infants and adults show different brain activity time-locked to this behaviour?

Optic flow

Perception of Structured Optic Flow and Random Visual Motion in Infants and Adults: a High-density EEG Study

by Van der Meer, Fallet & van der Weel

EEG was used in 8-month-old infants and adults to study brain electrical activity as a function of perception of structured optic flow and random visual motion. Both adults and infants showed shorter latencies for structured optic flow (blue waveform) than random visual motion (red waveform), and infants showed longer latencies, particularly for random visual motion. To investigate how changes in locomotor development are related to accompanying changes in brain activity associated with visual motion perception, more data of infants with different experiences in self-produced locomotion are required.