Involuntary Rotations of a Steering Device Induced by Voluntary Rotations of the Head and Maintained Eccentric Head Positions

In a series of 4 experiments, the authors examined involuntary rotations of a steering device (handlebar or wheel) that were associated with periodic head rotations and eccentric head positions. Periodic head rotations resulted in isodirectional involuntary rotations of a horizontally arranged steering device of very small amplitude. When the orientation of a steering wheel was changed to vertical and to a backward tilt, the involuntary rotations were in the opposite direction. That pattern of results is consistent with the assumption that small movements of the shoulder girdle, which are associated with head turns and which cannot be prevented by mechanical immobilization of the shoulder, are propagated to the wheel, but is not consistent with previous suggestions that involuntary rotations of a steering device can result from the action of the tonic neck reflex. Effects that correspond to the pattern of the tonic neck reflex were found only when a spring-centered handlebar was held in an eccentric position; maintenance of the eccentric position was facilitated when the participant's head was turned in the opposite direction. The findings strongly suggest that head movements can result in involuntary movements of a steering device via different mechanisms.     

Visuomotor rotations of varying size and direction compete for a single internal model in motor working memory

When participants adapt to equal and opposite visuomotor rotations in close temporal proximity, memory of the 1st is not consolidated. The authors investigated whether this retrograde interference depends on the use of equal and opposite rotations. On Day 1, different groups of participants adapted to a -30 degrees rotation followed 5 min later by rotations of +30 degrees, +60 degrees, or -60 degrees. On Day 2, all groups were retested on the -30 degrees rotation. Either retrograde interference (in groups who adapted to rotations of opposite sign on Day 1) or retrograde facilitation (in the remaining group) was observed. In all groups, learning of the 2nd rotation resulted in unlearning of the first, indicating that all visuomotor rotations compete for common working memory resources.     

Involuntary Rotations of a Steering Device Induced by Voluntary Rotations of the Head and Maintained Eccentric Head Positions

In a series of 4 experiments, the authors examined involuntary rotations of a steering device (handlebar or wheel) that were associated with periodic head rotations and eccentric head positions. Periodic head rotations resulted in isodirectional involuntary rotations of a horizontally arranged steering device of very small amplitude. When the orientation of a steering wheel was changed to vertical and to a backward tilt, the involuntary rotations were in the opposite direction. That pattern of results is consistent with the assumption that small movements of the shoulder girdle, which are associated with head turns and which cannot be prevented by mechanical immobilization of the shoulder, are propagated to the wheel, but is not consistent with previous suggestions that involuntary rotations of a steering device can result from the action of the tonic neck reflex. Effects that correspond to the pattern of the tonic neck reflex were found only when a spring-centered handlebar was held in an eccentric position; maintenance of the eccentric position was facilitated when the participant's head was turned in the opposite direction. The findings strongly suggest that head movements can result in involuntary movements of a steering device via different mechanisms.     

Face viewpoint effects about three axes: the role of configural and featural processing

We directly compared recognition for faces following 0 degrees-75 degrees viewpoint rotation about the yaw, pitch, and roll axes. The aim was to determine the extent to which configural and featural information supported face recognition following rotations about each of these axes. Experiment 1 showed that performance on a sequential-matching task was viewpoint-dependent for all three types of rotation. The best face-recognition accuracy and shortest reaction time was found for roll rotations, then for yaw rotations, and finally the worst accuracy and slowest reaction time was found for pitch rotations. Directional differences in recognition were found for pitch rotations, but not for roll or yaw. Experiment 2 provided evidence that, in all three cases, viewpoint-dependent declines in recognition were primarily driven by the loss of configural information. However, it also appeared that significant featural information was lost following yaw and pitch (but not roll) rotations. Together, these findings show that unfamiliar-face recognition is viewpoint-dependent following rotation about each axis (and in each direction), and that performance is based on the availability of configural and, to a lesser extent, featural information.     

Eccentric head positions bias random generation of leftward and rightward handle-bar rotations

We explored the effects of eccentric head positions on rapid rotations of a handle-bar in a modified randomization task. Subjects had to generate a random sequence of leftward and rightward handle-bar rotations; each pre-selected rotation was produced in response to a visual signal as rapidly as possible. Eccentric head positions induced a bias in that handle-bar rotations in the direction of the eccentric head position were chosen more frequently than handle-bar rotations in the opposite direction. This is consistent with previous evidence on a spatial coupling. In contrast to response selection, response initiation was not affected by eccentric head positions. The kinematic characteristics, however, differed: rotations in the direction of the eccentric head position were of larger amplitude and longer duration than rotations in the opposite direction. This difference may have been secondary to a difference in the start positions of the handle-bar, which were shifted in the direction opposite to the eccentric head position.     

Head movements while steering around bends

In this study, the determinants of head motions (rotations) when driving around bends were investigated when drivers viewed the scene through a head-mounted display. The scene camera was either fixed or coupled to head motions along 2 or 3 axes of rotation. Eight participants drove around a triangular circuit and the range and speed of head rotations, the correlations between head rotations and lateral acceleration, and the coupling between the different axes of head rotation were calculated. Results showed that substantial head rotations were made even when head rotations had no influence on the direction of the camera, suggesting a strong motor coupling between steering actions and head motion. Head roll was determined, at least in part, by the gravito-inertial force, contradicting earlier results reported in the literature.     

Comparing viewer and array mental rotations in different planes

Participants imagined rotating either themselves or an array of objects that surrounded them. Their task was to report on the egocentric position of an item in the array following the imagined rotation. The dependent measures were response latency and number of errors committed. Past research has shown that self-rotation is easier than array rotation. However, we found that imagined egocentric rotations were as difficult to imagine as rotations of the environment when people performed imagined rotations in the midsagittal or coronal plane. The advantages of imagined self-rotations are specific to mental rotations performed in the transverse plane.     

Head rotations in the play of Hanuman langurs (Semnopithecus entellus): description and analysis of function

Although head rotations are frequent patterns in play behavior in many mammalian species and differ from head movements used in other contexts, they have not been quantitatively described and their function remains unclear. The head rotations occurring in the play behavior of free-ranging Hanuman langurs (Semnopithecus entellus) were described from videotaped sequences. The authors tested 2 possible hypotheses about their function. Either the head rotations serve to create unexpected situations and should therefore occur in both solitary and social play and also be very variable, or they serve as play signals and should therefore occur only in social play and be ritualized. If head rotations have both functions, they should be less variable in social play. The data revealed that head rotations were very variable and were present both in solitary and social play. Furthermore, there was no difference in the variability between the head rotations present in the 2 types of play. The results do not support the function of head rotations as play signals but, rather, suggest that head rotations may serve to create unexpected situations in play.     

Continuous visual cues trigger automatic spatial target updating in dynamic scenes

Dynamic tasks often require fast adaptations to new viewpoints. It has been shown that automatic spatial updating is triggered by proprioceptive motion cues. Here, we demonstrate that purely visual cues are sufficient to trigger automatic updating. In five experiments, we examined spatial updating in a dynamic attention task in which participants had to track three objects across scene rotations that occurred while the objects were temporarily invisible. The objects moved on a floor plane acting as a reference frame and unpredictably either were relocated when reference frame rotations occurred or remained in place. Although participants were aware of this dissociation they were unable to ignore continuous visual cues about scene rotations (Experiments 1a and 1b). This even held when common rotations of floor plane and objects were less likely than a dissociated rotation (Experiments 2a and 2b). However, identifying only the spatial reference direction was not sufficient to trigger updating (Experiment 3). Thus we conclude that automatic spatial target updating occurs with pure visual information.     

Aiming error under transformed spatial mappings suggests a structure for visual-motor maps

Transformed spatial mappings were used to perturb normal visual-motor processes and reveal the structure of internal spatial representations used by the motor control system. In a 2-D discrete aiming task performed under rotated visual-motor mappings, the pattern of spatial movement error was the same for all Ss: peak error between 90 degrees and 135 degrees of rotation and low error for 180 degrees rotation. A two-component spatial representation, based on oriented bidirectional movement axes plus direction of travel along such axes, is hypothesized. Observed reversals of movement direction under rotations greater than 90 degrees are consistent with the hypothesized structure. Aiming error under reflections, unlike rotations, depended on direction of movement relative to the axis of reflection (see Cunningham & Pavel, in press). Reaction time and movement time effects were observed, but a speed-accuracy tradeoff was found only for rotations for which the direction-reversal strategy could be used. Finally, adaptation to rotation operates at all target locations equally but does not alter the relative difficulty of different rotations. Structural properties of the representation are invariant under learning.     

The drawbridge phenomenon: representational reasoning or perceptual preference?

Two experiments investigated whether infants would look longer at a rotating "drawbridge" that appeared to violate physical laws because they knew that it was causally impossible, as claimed by R. Baillargeon, E. S. Spelke, and S. Wasserman (1985) and R. Baillargeon (1987a). Using a habituation paradigm, they reported that infants looked longer at a display that appeared impossible (rotated 180 degrees while an obstructing box was behind it) than at one that appeared possible (rotated only 112 degrees, appearing to stop at the box). Experiment 1 eliminated habituation to 180 degree screen rotations. Still, infants looked longer at the 180 degree impossible rotations. Critically, however, infants also looked longer at possible 180 degree rotations in Experiment 2, in which no obstruction was present. Moreover, no difference in effect size was found between the 2 experiments. These findings indicate that infants' longer looking at 180 degree rotations is due to simple perceptual preference for more motion. They question R. Baillargeon's (1987a) claim that it is due to infants' representational reasoning about physically impossible object permanence events.     

Implicit and explicit components of dual adaptation to visuomotor rotations

Concurrent adaptation to two different visuomotor transformations has been shown to be possible as long as discriminative contextual cues are available. The authors examined explicit and implicit components of visually cued dual adaptation in younger and older adults. They found that only young adults, but not old adults, produced appropriate adaptive shifts of hand-movement direction to compensate for the visuomotor rotations. Aftereffects, conceived as a measure of implicit knowledge, were only poorly developed. Furthermore, only participants in the younger group exhibited systematic explicit knowledge of the visuomotor rotations. Subsequent analyses revealed strong correlations between the quality of explicit knowledge and the overall visuomotor adaptation. Thus, visually cued dual adaptation to two opposite visuomotor rotations is primarily mediated by conscious strategic corrections based on explicit knowledge of the transformations, a process, which is selectively impaired in older adults.     

LOCALISATION ET RECHERCHE DE L'OBJET CACHE CHEZ L'ENFANT DE 16 A 24 MOIS

Three experiments were conducted, in order to investigate the spatial organization in children between 16 and 24 months. All experiments were based on a task requiring a search for an object with three possible hiding places. Between hiding and search, the relative positions of subject and apparatus were modified. In experiment 1, two kinds of rotations were compared: rotations involving the child himself versus rotations of the apparatus. Performances were better in the latter case. Experiments 2 and 3 showed that the three spatial positions were not equivalent for subjects. In particular, the proximal position relative to the subject was clearly privileged when the rotations were done in a horizontal plane. However, this privilege did not appear when the rotations were done in a frontal plane.     

Too much anticipation? Large anticipatory adjustments of grasping movements to minimal object manipulations

When humans grasp objects, the grasps foreshadow the intended object manipulation. It has been suggested that grasps are selected that lead to medial arm postures, which facilitate movement speed and precision, during critical phases of the object manipulation. In Experiment 1, it has been tested whether grasp selections lead to medial postures during rotations of a dial. Participants twisted their arms considerably before grasping the dial, even when the upcoming dial rotation was minimal (5°). Participants neither assumed a medial posture at any point during a short rotation, nor did they assume any of the postures involved in short rotations in the opposite direction. Thus, grasp selections did not necessarily lead to specific postures at any point of the object manipulation. Experiment 2 examined the effect of various grasps on the speed of dial rotations. A medial initial grasp resulted in the fastest dial rotations for most rotation angles. Spontaneously selected grasps were more excursed than necessary to maximize dial rotation speed. This apparent overshot might be explained by participants’ sensitive to the variability of their grasps and is in line with the assumption that grasps facilitate control over the grasped object.     

Mental rotation of objects retrieved from memory: a functional MRI study of spatial processing

This functional MRI study examined how people mentally rotate a 3-dimensional object (an alarm clock) that is retrieved from memory and rotated according to a sequence of auditory instructions. We manipulated the geometric properties of the rotation, such as having successive rotation steps around a single axis versus alternating between 2 axes. The latter condition produced much more activation in several areas. Also, the activation in several areas increased with the number of rotation steps. During successive rotations around a single axis, the activation was similar for rotations in the picture plane and rotations in depth. The parietal (but not extrastriate) activation was similar to mental rotation of a visually presented object. The findings indicate that a large-scale cortical network computes different types of spatial information by dynamically drawing on each of its components to a differential, situation-specific degree.     

Effects of the axis of rotation and primordially solicited limb of high level athletes in a mental rotation task

A recent set of studies has investigated the selective effects of particular physical activities that require full-body rotations, such as gymnastics and wrestling (Moreau, Clerc, Mansy-Dannay, & Guerrien, 2012; Steggemann, Engbert, & Weigelt, 2011), and demonstrated that practicing these activities imparts a clear advantage in in-plane body rotation performance. Other athletes, such as handball and soccer players, whose activities do require body rotations may have more experience with in-depth rotations. The present study examined the effect of two components that are differently solicited in sport practices on the mental rotation ability: the rotation axis (in-plane, in-depth) and the predominantly used limb (arms, legs). Handball players, soccer players, and gymnasts were asked to rotate handball and soccer strike images mentally, which were presented in different in-plane and in-depth orientations. The results revealed that handball and soccer players performed the in-depth rotations faster than in-plane rotations; however, the two rotation axes did not differ in gymnasts. In addition, soccer players performed the mental rotations of handball strike images slower. Our findings suggest that the development of mental rotation tasks that involve the major components of a physical activity allows and is necessary for specifying the links between this activity and the mental rotation performance.     

The influence of spatial reference frames on imagined object- and viewer rotations.

The human visual system can represent an object's spatial structure with respect to multiple frames of reference. It can also utilize multiple reference frames to mentally transform such representations. Recent studies have shown that performance on some mental transformations is not equivalent: Imagined object rotations tend to be more difficult than imagined viewer rotations. We reviewed several related research domains to understand this discrepancy in terms of the different reference frames associated with each imagined movement. An examination of the mental rotation literature revealed that observers' difficulties in predicting an object's rotational outcome may stem from a general deficit with imagining the cohesive rotation of the object's intrinsic frame. Such judgments are thus more reliant on supplementary information provided by other frames, such as the environmental frame. In contrast, as assessed in motor imagery and other studies, imagined rotations of the viewer's relative frame are performed cohesively and are thus mostly immune to effects of other frames.     

The effects of eccentric head positions on leftward and rightward turns of a handle-bar

We explored the structural constraints on concurrent movements and/or positions of the head and a steering device by means of a reaction-time task. In the first experiment, subjects had to respond rapidly to an imperative stimulus by way of rotating a handle-bar to the left or to the right and back to the central position while they maintained a left or right eccentric position of the head. Latency of the handle-bar responses did not depend on whether their initial directions were toward the eccentric head position or in the opposite direction, but kinematic characteristics did: iso-directional movements were of larger amplitude and longer duration until peak excursion. In the second experiment, the imperative stimuli for handle-bar rotations were presented at variable intervals after the head had been moved from the central to one of the eccentric positions and before its predictable return movement. Kinematic characteristics of the handle-bar rotations depended on the left and right eccentric head positions in the same way as in Experiment 1, but now iso-directional movements had a longer reaction time than movements in the direction of the forthcoming return movement of the head. These findings suggest that specifications of head-movement directions facilitate concurrent specifications of handle-bar rotations in the same direction and inhibit specifications of handle-bar rotations in the opposite direction, consistent with the notion of cross-talk during motor programming.     

Does a visual reference help ballet dancers turn more successfully?

In dance, performing multiple rotations around the longitudinal axis is a complex task that can only be accomplished proficiently by highly skilled dancers. However, this extraordinary skill has been investigated sparsely. The few studies to date have focused on the biomechanical analysis of ballet rotations. However, none have investigated the influence of visual information on continuous rotations, such as Fouettés or à la Seconde turns. Therefore, the present study aims to examine the role of a visual reference on balance control and the dance-specific head coordination – spotting – during turning performance of highly skilled ballet dancers. To this end, 12 participants performed 12 Fouettés (females) or à la Seconde turns (males) with and without a visual reference. As dependent measures, we analysed balance control (i.e., supporting foot path length), spotting duration, head isolation, and orientation (i.e., deviation of pelvis from the front). A linear mixed model was performed to analyse the influence of the visual conditions overall and over the continued performance of 12 consecutive rotations. The results revealed that overall, path length was significantly smaller in the condition without a visual reference. Spotting duration and head isolation did not differ significantly between conditions. Moreover, dancers oriented themselves better towards the front in the condition with a visual reference. When looking closer into the progression of performance over each consecutive rotation, highly skilled ballet dancers significantly decreased the supporting foot path length, and improved orientation when turning with a visual reference. On the other hand, without a visual reference, the dancers increased the spotting duration over time. Additionally, dancers increased head isolation towards the end of the turns in both conditions. These findings suggest that a visual reference helps ballet dancers sustain performance of consecutive rotations, mainly in optimising balance control and orientation. Thus, the more rotations a ballet dancer must turn, the more relevant a visual reference becomes for sustaining successful performance.     

Personality Factors and Adult Attachment Affecting Job Mobility

Past research has revealed that individuals' job mobility is affected by factors such as job satisfaction, specific career enhancing attributes and job availability. This study examined personality factors predicting voluntary internal and external job mobility. Three types of voluntary job mobility measures were studied: dissatisfaction changes, job improvement changes and job rotations within companies. These mobility measures were related to the Big Five personality factors, sensation seeking and adult attachment. Results showed that demographic variables and sensation seeking contributed to the variance in external job changes. Internal job rotations were not related to any of the demographic and personality variables.