Adaptation to visual displacement with active and passive limb movements: effect of movement frequency and predictability of movement

Three experiments were performed to evaluate the influence of active and passive limb movements on adaptation to visual displacement. Over a wide frequency range (0·5-1·25 Hz) with constant amplitude, 30°, significant adaptation was achieved with active and passive movements. When arm movement frequency was constant at 1·0 Hz but amplitude of movement was varied, less adaptation was achieved for both active and passive movements than when amplitude was held constant. Even at a frequency above that of most naturally occurring limb movements, 1·67 Hz, and with variable amplitude motion, significant adaptation was achieved with active and passive limb movements. These findings emphasize the importance of visual-proprioceptive discordances for adaptation to visual displacement when only sight of the hand is permitted. Significant differences did not appear between the active and passive movement conditions in any of the experiments.     

Emmert's law in the dark: active and passive proprioceptive effects on positive visual afterimages

The relationship between apparent size and apparent distance is given by Emmert's law, which states that a retinal image is proportional in size to the distance of the surface it is projected upon. This principle also applies to retinal afterimages in that they, too, will change in apparent size if distance cues suggest that the location of the object onto the retinal image has been altered. It has also been known for some time that non-retinal cues can produce quantitative and qualitative effects on an afterimage when it is viewed in the dark. In the present two studies, positive afterimages of an observer's hand, as well as objects held by that hand, were used as targets to investigate the effects on size-constancy scaling of moving the hand to and fro along the line of sight for different distances in the dark. Results show that, when observers focus on a held object, the changes in size predicted by Emmert's law occur in response to both active and passive proprioceptive or haptic cues. The most intriguing result consisted of the finding that, when only the hand is the target, there appears to be a limit to the decrease in apparent hand size. It appears that the visual system 'refuses' to size-scale the hand below a limit it accepts as representative or acceptable of 'its' hand.     

Adaptation to visual rearrangement: Role of sensory discordance

The relative contributions of proprioceptive and efferent information in eliciting adaptation to visual rearrangement were studied under two conditions of visual stimulation. Subjects permitted sight of their forearm under normal room illumination showed significant adaptation when the forearm was (a) moved up and down under the action of tonic vibration reflexes, (b) voluntarily moved through the same trajectory at the same pace, (c) viewed while still, and (d) viewed while the margins of the elbow were vibrated. The reflex movement condition elicited significantly greater adaptation than the other conditions. Subjects allowed only sight of a point source of light attached to their hand showed significant adaptation when the forearm was (a) reflexly moved, (b) voluntarily moved through the same trajectory at the same rate, (c) passively moved, (d) still, and (e) vibrated while still. Less adaptation occurred as the amount of proprioceptive information about limb position was decreased. The adaptation elicited by voluntary movements of the forearm and by reflex movements did not differ significantly. It is concluded that corollary-discharge signals may not be crucial in adaptation to visual rearrangement; a more important factor appears to be discordance between proprioceptive and visual information.     

Visual tracking of active and passive movements of the hand

Two experiments were performed to evaluate the influence of movement frequency and predictability on visual tracking of the actively and the passively moved hand. Four measures of tracking precision were employed: (a) saccades/cycle, (b) percent of pursuit movement, (c) eye amplitude/arm amplitude, (d) asynchrony of eye and hand at reversal. Active and passive limb movements were tracked with nearly identical accuracy and were always vastly superior to tracking an external visual target undergoing comparable motion. Proprioceptive information about target position appears to provide velocity and position information about target location. Its presence permits the development of central eye-movement programmes that move the eyes in patterns that approximate but do not exactly match, temporally or spatially, the motion of the hand.     

Eye movements and hazard perception in active and passive driving

ABSTRACT

Differences in eye movement patterns are often found when comparing passive viewing paradigms to actively engaging in everyday tasks. Arguably, investigations into visuomotor control should therefore be most useful when conducted in settings that incorporate the intrinsic link between vision and action. We present a study that compares oculomotor behaviour and hazard reaction times across a simulated driving task and a comparable, but passive, video-based hazard perception task. We found that participants scanned the road less during the active driving task and fixated closer to the front of the vehicle. Participants were also slower to detect the hazards in the driving task. Our results suggest that the interactivity of simulated driving places increased demand upon the visual and attention systems than simply viewing driving movies. We offer insights into why these differences occur and explore the possible implications of such findings within the wider context of driver training and assessment.     

Eye movements in active visual search: A computable phenomenological model

We present a computational model and corresponding computer simulations that mimic phenomenologically the eye movement trajectories observed in a conjunctive visual search task. The element of randomness is captured in the model through a Monte Carlo selection of a particular eye movement based on its probability, which depends on three factors, adjusted to match to the observed saccade amplitude distribution, forward bias in consecutive saccades, and return rates. Memory is assumed to operate through tagging of objects already recognized as nontargets, which, in turn, requires their processing within the attentional area of conspicuity (AC). That AC is adjusted so that computer simulations optimally reproduce the distribution of the number of saccades, the failure rate for capturing the target, and the return rate to previously inspected locations. For their viability, computer simulations critically depend on memory’s being long-ranged. In turn, the simulations confirm the formation of circulating or spiraling patterns in the observed eye trajectories. We also relate consistently the average number of saccades per trial to the saccade amplitude distribution by modeling analytically the combined roles of the AC in attention and memory. The full Supplemental Appendix A for this article may be downloaded from http:// app.psychonomic-journals.org/content/supplemental.     

Accurate reaching after active but not passive movements of the hand: evidence for forward modeling

Converging behavioral findings support recent models of motor control suggesting that estimates of the future positions of a limb as well as the expected sensory consequences of a planned movement may be derived, in part, from efference copies of motor commands. These estimates are referred to as forward models. However, relatively little behavioral evidence has been obtained for proposed forward models that provide on-line estimates of current position. We report data from a patient (JD) who reached accurately to visualized targets with and without vision of her hand despite substantial proprioceptive loss. Additionally, we administered a double-start reaching test to examine the possibility that efference copy information could be used to estimate current limb position. JD reached accurately, without vision, to a final target after actively reaching to a landmark, but exhibited severely impaired reaching after passive movements to the landmark. This finding suggests that forward modeling of efference copy signals may provide relatively accurate estimates of current limb position for the purpose of motor planning. The possibility that such estimates may also contribute to the awareness of body position and to self-recognition is discussed.     

Electromyographic activity,H-reflex modulation and corticospinal input to forearm motoneurones during active and passive rhythmic movements

Four subjects produced coordinated movements, consisting of flexion and extension of the wrist in ipsilateral (right wrist only), contralateral (left wrist only), inphase (both wrists in flexion or both in extension) and antiphase (one wrist in flexion, the other in extension) conditions. Electromyographic (EMG) activity was recorded from right wrist flexor and extensor muscles. In one session, transcranial magnetic stimuli (TMS) of the left motor cortex, around threshold intensity, evoked short-latency responses in the right wrist extensors and flexors. In another session, the median nerve at the cubital fossa was stimulated to elicit an H-reflex in the right flexor carpi radialis (rFCR). A movement cycle was divided into 8 segments. In total, 10 identical stimuli were delivered during each segment in each condition, at two movement frequencies. The magnitude of the EMG reponses to TMS was modulated markedly during movements made in the ipsilateral condition, and in both bimanual conditions. EMG activity was greater, and motor-evoked potentials (MEPs) were larger in the antiphase condition than in the inphase condition. When the amplitudes of the MEPs were normalised with respect to background EMG, no significant differences between the bimanual conditions were obtained. For H-reflexes, significant differences between the two bimanual conditions were observed, suggesting differences in levels of excitability of the Ia afferent pathway. These differences were attributed to segmental input associated with changes in muscle length arising from limb movement, and upon descending input to the spinal cord, possibly mediated by Renshaw cell inhibition. During rhythmic passive movement of the right limb, H-reflexes were inhibited and MEPs potentiated in a cyclic fashion. Passive movement of the contralateral left limb resulted in inhibition of both responses.PsycINFO classification: 2330; 2530; 2540     

Adaptation to vertical displacement of the visual direction

Sixty Ss wore vertically displacing wedge prisms and adapted by looking at their feet for 10 min. Half of them did this while standing and the others in supine position. The latter condition produced adaptation measurable with a visual-motor test and with a test of egocentric localization, but on a purely motoric test no adaptation was apparent. Standing during the adaptation period produced no effect.     

The accuracy of aimed movements to visual targets during development: the role of visual information

Children aged 1.5 to 8 years were required to touch accurately an illuminated target lamp located on a vertical board. Movements were made when visual information was complete (target lit for 3 s, room illuminated; partial (target lit for 3 s, room dark, and reduced (target lit for 0.7 s, room dark). Dependent variables were response accuracy, reaction time, and movement time. Accuracy decreased with decreasing availability of visual information and improved with age under all conditions. Reaction times were shorter in the dark (Conditions 2 and 3) than in the light; they decreased with age up to age 5 and did not continue to decrease thereafter. Movement time did not change with age under Conditions 1 and 3 but tended to increase with age under Condition 2. Slower movements were more accurate at all ages, provided visual feedback could be utilized. Increased reliance on the strategy "slower movements yield higher accuracy" was held to account for developmental changes under Condition 2, whereas in Conditions 1 and 3 improvement in the efficiency of motor preprogramming was implicated.     

Eye movements and the integration of visual memory and visual perception

Because visual perception has temporal extent, temporally discontinuous input must be linked in memory. Recent research has suggested that this may be accomplished by integrating the active contents of visual short-term memory (VSTM) with subsequently perceived information. In the present experiments, we explored the relationship between VSTM consolidation and maintenance and eye movements, in order to discover how attention selects the information that is to be integrated. Specifically, we addressed whether stimuli needed to be overtly attended in order to be included in the memory representation or whether covert attention was sufficient. Results demonstrated that in static displays in which the to-be-integrated information was presented in the same spatial location, VSTM consolidation proceeded independently of the eyes, since subjects made few eye movements. In dynamic displays, however, in which the to-be-integrated information was presented in different spatial locations, eye movements were directly related to task performance. We conclude that these differences are related to different encoding strategies. In the static display case, VSTM was maintained in the same spatial location as that in which it was generated. This could apparently be accomplished with covert deployments of attention. In the dynamic case, however, VSTM was generated in a location that did not overlap with one of the to-be-integrated percepts. In order to "move" the memory trace, overt shifts of attention were required.     

Active and passive movements give rise to different judgments of coldness

When the right index fingertip of twelve subjects was moved across a cold (15 degrees C) tile by a machine (passive-guided condition), the subjects rated the temperature of the tile as being colder than when they moved the finger across the stimulus themselves (active condition). Results confirmed that active movements were associated with an attenuation of 'coldness'. When these findings are considered alongside those of earlier experiments (see VanDoorn et al, 2005 Perception 34 231 236), it may be concluded that intentionality of movement plays some role in this attenuation.     

Adaptation of hand tracking to rotated visual coordinates

Attention, Perception, & Psychophysics - A newly developed technique, allowing continuous recording of hand movements during the tracing of lines on a horizontal writing surface, was used to...     

Effects of movement duration and visual feedback on visual and proprioceptive components of prism adaptation

While looking through laterally displacing prisms, subjects pointed sagittally 80 times at an objectively straight-ahead target, completing a reciprocal out-and-back pointing movement ever 1, 3, or 6 s. Visual feedback was available early in the pointing movement or only late at the end of the movement. Aftereffect measures of adaptive shift (obtained after every 10 pointing trials) showed adaptive change only in limb position sense (i.e., proprioceptive adaptation) when movement duration was 1 s, regardless of visual feedback condition; but as movement duration increased, adaptive change in the eye position sense (i.e., visual adaptation) increased while proprioceptive adaptation decreased, especially for the late visual feedback condition. Regardless of visual feedback condition, proprioceptive adaptation showed the maximal rate of growth with the 1-s movement duration, whereas visual adaptation showed maximal growth with the 6-s movement duration. These results provide additional support for a model of adaptive spatial mapping in which the direction of strategically flexible coordination (guidance) between eye and limb (and consequently the locus of adaptive spatial mapping) is jointly determined by movement duration and timing of visual feedback. An additional effect of movement duration is to determine the rate of discordant inputs. Maximal growth of adaptation occurs when the input rate matches the response time of the spatial mapping function.     

Eye movements and visual memory: detecting changes to saccade targets in scenes

Saccade-contingent change detection provides a powerful tool for investigating scene representation and scene memory. In the present study, critical objects presented within color images of naturalistic scenes were changed during a saccade toward or away from the target. During the saccade,the critical object was changed to another object type, to a visually different token of the same object type, or was deleted from the scene. There were three main results. First, the deletion of a saccade target was special: Detection performance for saccade target deletions was very good, and this level of performance did not decline with the amplitude of the saccade. In contrast, detection of type and token changes at the saccade target, and of all changes including deletions at a location that had just been fixated but was not the saccade target, decreased as the amplitude of the saccade increased. Second, detection performance for type and token changes, both when the changing object was the target of the saccade and when the object had just been fixated but was not the saccade target, was well above chance. Third, mean gaze durations were reliably elevated for those trials in which the change was not overtly detected. The results suggest that the presence of the saccade target plays a special role in trassaccadic integration, and together with other recent findings, suggest more generally that a relatively rich scene representation is retained across saccades and stored in visual memory.     

Profiling active and passive nonrespondents to an organizational survey

In this field study (N = 405) population profiling was introduced to examine general and specific classes of nonresponse (active vs. passive) to a satisfaction survey. The active nonrespondent group (i.e., purposeful nonresponders) was relatively small (approximately 15%). Active nonrespondents, in comparison with respondents, were less satisfied with the entity sponsoring the survey and were less conscientious. Passive nonrespondents (e.g., forgot), who represented the majority of nonrespondents, were attitudinally similar to respondents but differed with regard to personality. Nonresponse bias does not appear to be a substantive concern for satisfaction type variables--the typical core of an organizational survey. If the survey concerns topics strongly related to Conscientiousness and Agreeableness, the respondent sample may not be representative of the population.