Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Proprioception”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2005

Acute Effects of Static and Proprioceptive Neuromuscular Facilitation Stretching on Muscle Strength and Power Output.

Context: Stretching is commonly used as a technique for injury prevention in the clinical setting. Our findings may improve the understanding of the neuromuscular responses to stretching and help clinicians make decisions for rehabilitation progression and return to play.Objective: To examine the short-term effects of static and proprioceptive neuromuscular facilitation stretching on peak torque (PT), mean power output (MP), active range of motion (AROM), passive range of motion (PROM), electromyographic (EMG) amplitude, and mechanomyographic (MMG) amplitude of the vastus lateralis and rectus femoris muscles during voluntary maximal concentric isokinetic leg extensions at 60 and 300 degrees .s.Design: A randomized, counterbalanced, cross-sectional, repeated-measures design.Setting: A university human research laboratory.Patients or Other Participants: Ten female (age, 23 +/- 3 years) and 9 male (age, 21 +/- 3 years) apparently healthy and recreationally active volunteers.Intervention(s): Four static or proprioceptive neuromuscular facilitation stretching exercises to stretch the leg extensor muscles of the dominant limb during 2 separate, randomly ordered laboratory visits.Main Outcome Measure(s): The PT and MP were measured at 60 and 300 degrees .s, EMG and MMG signals were recorded, and AROM and PROM were measured at the knee joint before and after the stretching exercises.Results: Static and proprioceptive neuromuscular facilitation stretching reduced PT (P = .051), MP (P = .041), and EMG amplitude (P = .013) from prestretching to poststretching at 60 and 300 degrees .s (P < .05). The AROM (P < .001) and PROM (P = .001) increased as a result of the static and proprioceptive neuromuscular facilitation stretching. The MMG amplitude increased in the rectus femoris muscle in response to the static stretching at 60 degrees .s (P = .031), but no other changes in MMG amplitude were observed (P > .05).Conclusions: Both static and proprioceptive neuromuscular facilitation stretching caused similar deficits in strength, power output, and muscle activation at both slow (60 degrees .s) and fast (300 degrees .s) velocities. The effect sizes, however, corresponding to these stretching-induced changes were small, which suggests the need for practitioners to consider a risk-to-benefit ratio when incorporating static or proprioceptive neuromuscular facilitation stretching.

Journal Article↗
PubMed2004

Amelioration of symptoms by enhancement of proprioception in patients with joint hypermobility syndrome.

OBJECTIVE: Joint hypermobility syndrome (JHS) is characterized by an association between joint hypermobility and musculoskeletal pains, the latter occurring in the absence of any objective indicator of rheumatic disease. The lack of a recognizable disease marker makes this condition difficult to identify and manage. We previously observed that patients with JHS have impaired proprioception compared with that of a matched control group. The purpose of this study was to investigate whether a home-based exercise program could produce objective enhancement of proprioception as well as alleviate symptoms in JHS. METHODS: A threshold detection paradigm was used to assess knee joint proprioception, balance was assessed using a balance board, and quadriceps and hamstring strength were measured by an isokinetic dynamometer. A visual analog scale was used to assess musculoskeletal pain, and quality of life was evaluated by a Short Form 36 questionnaire. Assessments were performed before and after an 8-week program of progressive closed kinetic chain exercises. RESULTS: Following the exercise program, proprioceptive acuity increased in 16 of 18 subjects and was very significantly improved overall (P < 0.001). There was a comparable improvement in performance on the balance board (P < 0.001), and quadriceps and hamstring strength also increased significantly. Symptomatic improvement also occurred, in terms of both pain (P = 0.003) and quality-of-life (P = 0.029 for physical functioning; P = 0.008 for mental health) scores. CONCLUSION: Appropriate exercises lead not only to symptomatic improvement, but also to demonstrable enhancement of objective parameters such as proprioception.

Adolescent↗
PubMed2000

Bilateral proprioceptive defects in patients with a unilateral anterior cruciate ligament reconstruction: a comparison between patients and healthy individuals.

Proprioception of the knee was measured in 20 patients with reconstructed anterior cruciate ligaments and in 19 age-matched controls. The mean time from surgery was 2 years. Three tests of proprioception were used: (a) threshold to detection of passive motion from 20 and 40 degrees toward flexion and extension, (b) active reproduction of a 30 degrees passive angle change, and (c) visual reproduction of a 30 degrees passive angle change. The aim was a complete, bilateral, proprioceptive evaluation of patients who had undergone reconstruction of the anterior cruciate ligament. As compared with those in the control group, the knees with reconstructed anterior cruciate ligaments had a higher threshold to detection of passive motion in the extension trials from 20 and 40 degrees (p = 0.0003 and 0.04, respectively) and in the flexion trials from 20 and 40 degrees (p = 0.004 and 0.0008, respectively). When the uninjured knees of the patients were compared with those in the control group, higher values for threshold to detection of passive motion were found in the flexion trials from 20 degrees (p = 0.002) and 40 degrees (p = 0.02). Thus, decreased proprioceptive ability was present in some measurements of these patients after reconstructive surgery, not only in injured knees but also in uninjured knees, as compared with the reference group. The functional relevance of these findings was not investigated in this study, but the results suggest that bilateral proprioceptive considerations should be made when evaluating prognostic factors, treatment, and risk of contralateral knee injury in patients with reconstructed anterior cruciate ligaments.

Adult↗
PubMed1996

Proprioception and joint stability.

In the present paper the current clinical knowledge about proprioception is given for the shoulder, knee, ankle, elbow and the radiocarpal joint. Proprioceptive capabilities are decreased after joint injuries such as ACL or meniscus tears, shoulder dislocation, ankle sprain and in joints with degenerative joint disease. Some surgical procedures seem to restore the proprioceptive abilities; others do not. Elastic knee bandages or ankle braces increase different proprioceptive factors like ankle reproduction capability or sports-specific abilities. The present information on proprioception will influence our clinical practice in the future. We should choose surgical procedures that not only reconstruct the anatomy, but also the neurophysiologic feed-back mechanism.

Algorithms↗
PubMed2006

[The influence of a controlled active motion splint on proprioception after anterior cruciate ligament plasty. A prospective randomized study].

BACKGROUND: A ruptured anterior cruciate ligament (ACL) leads to both mechanical and functional instability. Functional instability is caused by proprioceptive deficit. The aim of this study was to determine whether the proprioceptive deficit can be reduced by using a controlled active motion (CAM) splint postoperatively. PATIENTS AND METHODS: A total of 50 patients with ACL rupture were randomized into two groups. After ACL plasty the PT group received postoperative physiotherapy, while the CAM group were managed with a CAM splint and physiotherapy. Proprioceptive ability was measured with a passive angle-reproduction test. RESULTS: On the day of discharge 80% of the patients in the CAM group and 25% in the PT group had a reduced proprioceptive deficit. Overall the main measured value in the CAM group improved by 83.7%, but deteriorated by 39.3% in the PT group. There was no significant difference between the CAM group and a healthy control group. CONCLUSION: Using a CAM splint in addition to physiotherapy after ACL plasty in comparison to physiotherapy alone decreases the proprioceptive deficit significantly. We recommend the use of a CAM splint in the postoperative management following ACL plasty.

Anterior Cruciate Ligament↗
PubMed1996

[Proprioceptive capacity of the knee joint area in patients after rupture of the anterior cruciate ligament].

In 30 healthy volunteers with clinically inconspicuous knee joints the proprioception of the knee joint was evaluated by an angle reproduction test. With the same set-up we documented the effect of an elastic knee bandage. We could not document any differences between the left and the right knee joint or between men and women, but at the mid-range of motion, proprioception was worse compared to the end range of motion. The applied elastic knee bandage significantly improved the position sense. Additionally 25 patients with an isolated rupture of the anterior cruciate ligament were evaluated. Fourteen patients were examined preoperatively 11 after operative ACL reconstruction. Preoperatively proprioception was significantly poorer than in the control group. We were able to show a positive influence of a knee bandage on the proprioception of the injured knee as well. Patients after ACL reconstruction showed no significantly better proprioception than the preoperative group.

Adult↗
PubMed1997

[Proprioceptive capacities of patients with retropatellar knee pain with special reference to effectiveness of an elastic knee bandage].

In the presented study, knee joint proprioception of 43 patients with a patellar pain syndrome of the knee joint was evaluated. In a control group, the proprioception of 30 healthy volunteers with clinical and an-amnestic inconspicous knee joints was examined. We tested the proprioceptive capability of the subjects with a passive angle reproduction test. Additionally, all knee joints were measured with and without an elastic knee bandage. The patient group showed significant deterioration of angle reproduction capability (13.2 degrees +/- 6.1 degrees) compared to the control group (7.8 degrees +/- 2.8 degrees). After applying an elastic knee bandage, the angle reproduction capability significantly improved to 9.2 degrees +/- 4.5 degrees. Proprioception of the contralateral, noninvolved knee joint in the patients (11.6 degrees +/- 6.3 degrees) was worse compared to the control group. Applying an elastic knee bandage did not significantly improve the proprioception of the uninjured knee joint.

Adult↗
PubMed2006

Clinical measurements of proprioception, muscle strength and laxity in relation to function in the ACL-injured knee.

A knee injury with anterior cruciate ligament (ACL) rupture may cause deficits in proprioception, increased laxity and decreased muscle strength. Although it may be common knowledge that these factors affect knee function, only a few studies have been performed where this has been investigated in the clinical situation, and the results are not conclusive. The purpose of this study was therefore to investigate how and to what extent proprioception, laxity and strength affect knee joint function and evaluate if the methods commonly used for estimating these factors clinically seem to be relevant. The study encompassed 36 patients with ACL deficiency. A single-leg hop test for distance and subjective rating of knee function were defined as dependent variables and analyzed separately in stepwise linear regression models where proprioception, knee joint laxity, hamstrings and quadriceps strength, age and sex were defined as independent variables. Higher threshold values (poorer proprioception), increased side-to-side difference of anterior laxity and poorer strength significantly predicted shorter length of the hop test. Higher rating of subjective function corresponded to female gender, lesser side-to-side difference of anterior laxity and better proprioception.

Adolescent↗
PubMed2001

Can proprioception really be improved by exercises?

There is little question that ankle disc training can improve ankle muscle motor performance in a unipedal balance task, most likely through improved strength and coordination [62] and possibly endurance. How much of the observed improvement in motor performance is due to improved ankle proprioception remains unknown. We have reviewed a number of theoretical ways in which training might improve proprioception for moderately challenging weight-bearing situations such as balancing on one leg. Although the relevant experiments have yet to be performed to test this hypothesis, any improvement would theoretically help to reduce injuries at these moderate levels of challenge. We question, however, whether these exercises can ever improve the reactive response required to prevent injury under the most challenging time-critical situations. If confirmed, this limitation needs to be acknowledged by authors and practitioners alike. Alternative protective strategies for the most challenging time-critical situations should be sought. We conclude that, despite their widespread acceptance, current exercises aimed at "improving proprioception" have not been demonstrated to achieve that goal. We have outlined theoretical scenarios by which proprioception might be improved, but these are speculative. The relevant experiments remain to be conducted. We argue that even if they were proven to improve proprioception, under the best circumstances such exercises could only prevent injury under slow to intermediate rate provocations to the joint musculoligamentous complex in question.

Afferent Pathways↗
PubMed2002

The perception of body orientation after neck-proprioceptive stimulation. Effects of time and of visual cueing.

Different sensory systems (e.g. proprioception and vision) have a combined influence on the perception of body orientation, but the timescale over which they can be integrated remains unknown. Here we examined how visual information and neck proprioception interact in perception of the "subjective straight ahead" (SSA), as a function of time since initial stimulation. In complete darkness, healthy subjects directed a laser spot to the point felt subjectively to be exactly straight ahead of the trunk. As previously observed, left neck muscle vibration led to a disparity between subjective perception and objective position of the body midline, with SSA misplaced to the left. We found that this displacement was sustained throughout 28 min of continuous proprioceptive stimulation, provided there was no visual input. Moreover, prolonged vibration of neck muscles leads to a continuing disparity between subjective and objective body orientation even after offset of the vibration; the longer the preceding vibration, the more persistent the illusory deviation of body orientation. To examine the role of vision, one group of subjects fixated a central visual target at the start of each block of continuous neck vibration, with SSA then measured at successive intervals in darkness. The illusory deviation of SSA was eliminated whenever visual input was provided, but returned as a linear function of time when visual information was eliminated. These results reveal: the persistent effects of neck proprioception on the SSA, both during and after vibration; the influence of vision; and integration between incoming proprioceptive information and working memory traces of visual information.

Adult↗
PubMed2000

Neck proprioceptive inputs to primate vestibular nucleus neurons.

The contribution of neck proprioceptive signals to signal processing in the vestibular nucleus was studied by recording responses of secondary horizontal canal-related neurons to neck rotation in the squirrel monkey. Responses evoked by passive neck rotation while the head was held stationary in space were compared with responses evoked by passive whole body rotation and by forced rotation of the head on the trunk. Most neurons (76%; 45/59) were sensitive to neck rotation. The nature and strength of neck proprioceptive inputs varied and usually combined linearly with vestibular inputs. In most cases (94%), the direction of the neck proprioceptive input was "antagonistic" or "reciprocal" with respect to vestibular sensitivity and, consequently, reduced the vestibular response during head-on-trunk rotation. Different types of vestibular neurons received different types of proprioceptive input. Neurons whose firing behavior was related to eye position (position-vestibular-pause neurons and position-vestibular neurons) were often sensitive to the position of the head with respect to the trunk. The sensitivity to head position was usually in the same direction as the neuron's eye position sensitivity. Non-eye-movement related neurons and eye-head-velocity neurons exhibited the strongest sensitivity to passive neck rotation and had signals that were best related to neck velocity. The results suggest that neck proprioceptive inputs play an important role in shaping the output of the primate vestibular nucleus and its contribution to posture, gaze and perception.

Animals↗
PubMed1998

The contribution of vision and proprioception to judgements of finger proximity.

We sought to determine whether an increase in judged egocentric distance created by increasing vergence-specified distance would be negated when participants pointed at their own finger. It was found that ocular position dominates limb proprioception in the judgement of finger distance in the sagittal plane when vision is available. In contrast, an increase in perceived egocentric distance was largely attenuated by the presence of limb proprioception in reduced visual cue conditions. We conclude that the relative contribution of vergence to perceived distance depends upon the strength of the vergence effort signal when there are other cues present. Furthermore, if the distance percept includes a major contribution from retinal cues, then the visual component will dominate the limb proprioception component. If the visual component is largely determined by vergence information, limb proprioception will make a significant contribution and actually dominate when the vergence effort signal is weak. The results extend previous studies that have found a similar relationship between ocular position and limb proprioception in the perception of a finger's location in the coronal plane.

Adult↗
PubMed1998

Interactions between vestibular and proprioceptive inputs triggering and modulating human balance-correcting responses differ across muscles.

Interactions between proprioceptive and vestibular inputs contributing to the generation of balance corrections may vary across muscles depending on the availability of sensory information at centres initiating and modulating muscle synergies, and the efficacy with which the muscle action can prevent a fall. Information which is not available from one sensory system may be obtained by switching to another. Alternatively, interactions between sensory systems and the muscle to which this interaction is targeted may be fixed during neural development and not switchable. To investigate these different concepts, balance corrections with three different sets of proprioceptive trigger signals were examined under eyes-open and eyes-closed conditions in the muscles of normal subjects and compared with those of subjects with bilateral peripheral vestibular loss. The different sets of early proprioceptive inputs were obtained by employing three combinations of support surface rotation and translation, for which ankle inputs were nulled, normal or enhanced, the knees were either locked or in flexion, and the trunk was either in flexion or extension. Three types of proprioceptive and vestibulospinal interactions were identified in muscles responses. These interactions were typified by the responses of triceps surae, quadriceps, and paraspinal muscles. The amplitudes of stretch responses at 50 ms after the onset of ankle flexion in triceps surae muscles were related to the velocity of ankle stretch. The amplitude of balance-correcting responses at 100 ms corresponded more with stretch of the biarticular gastrocnemius when the knee was re-extended at 60 ms. Absent stretch reflexes at 50 ms in triceps surae with nulled ankle inputs caused a minor, 12-ms delay in the onset of balance-correcting responses in triceps surae muscles. Vestibular loss caused no change in the amplitude of balance-correcting responses, but a negligible decrease in onset latency in triceps surae even with nulled ankle inputs. Stretch responses in quadriceps at 80 ms increased with the velocity of knee flexion but were overall lower in amplitude in vestibular loss subjects. Balance-correcting responses in quadriceps had amplitudes which were related to the directions of initial trunk movements, were still present when knee inputs were negligible and were also altered after vestibular loss. Stretch and unloading responses in paraspinals at 80 ms were consistent with the direction of initial trunk flexion and extension. Subsequent balance-correcting responses in paraspinals were delayed 20 ms in onset and altered in amplitude by vestibular loss. The changes in the amplitudes of ankle (tibialis anterior), knee (quadriceps) and trunk (paraspinal) muscle responses with vestibular loss affected the amplitudes and timing of trunk angular velocities, requiring increased stabilizing tibialis anterior, paraspinal and trapezius responses post 240 ms as these subjects attempted to remain upright. The results suggest that trunk inputs provide an ideal candidate for triggering balance corrections as these would still be present when vestibular, ankle and knee inputs are absent. The disparity between the amplitudes of stretch reflex and automatic balance-correcting responses in triceps surae and the insignificant alteration in the timing of balance-correcting responses in these muscles with nulled ankle inputs indicates that ankle inputs do not trigger balance corrections. Furthermore, modulation of balance corrections normally performed by vestibular inputs in some but not all muscles is not achieved by switching to another sensory system on vestibular loss. We postulate that a confluence of trunk and upper-leg proprioceptive input establishes the basic timing of automatic, triggered balance corrections which is then preferentially weighted by vestibular modulation in muscles that prevent falling. (ABSTRACT TRUNCATED)

Adult↗
PubMed1999

From balance regulation to body orientation: two goals for muscle proprioceptive information processing?

This study was based on the assumption that the central processing of proprioceptive inputs that arise from numerous muscles contributes to both awareness and control of body posture. The muscle-spindle inputs form a "proprioceptive chain" which functionally links the eye muscles to the foot muscles. Here, we focused on the specific contribution of two links in the control of human erect posture by investigating how proprioceptive messages arising from ankle and neck muscles may be integrated by the central nervous system. Single or combined mechanical vibrations were applied to different muscle tendons at either one (ankle or neck) or both (ankle plus neck) body levels. The amplitude and the specific direction of the resulting oriented body tilts were analyzed by recording the center of foot pressure (CoP) through a force platform with four strain gauges. The results can be summarized as follows: (1) the vibration-induced whole-body tilts were oriented according to the muscles stimulated; furthermore, the tilts were in opposite directions when neck or ankle muscles on the same side of the body were stimulated; (2) except for the ankle antagonist muscles, co-vibrating adjacent or antagonist muscles at the same body level (ankle or neck) resulted in body sways, whose orientation was a combination of those obtained by stimulating these muscles separately; and (3) likewise, co-vibrating ankle and neck muscles induced whole-body postural responses, whose direction and amplitude were a combination of those obtained by separate vibration. We conclude that the multiple proprioceptive inputs originating from either one or both body levels may be co-processed in terms of vector-addition laws. Moreover, we propose that proprioceptive information from ankle and neck muscles may be used for two tasks: balance control and body orientation, with central integration of both tasks.

Adult↗
PubMed1999

Proprioceptive control of multijoint movement: unimanual circle drawing.

The present experiments addressed whether proprioception is used by the central nervous system (CNS) to control the spatial and temporal characteristics of unimanual circle drawing. Circle drawing is a multijoint movement, in which the muscles crossing the elbow and the shoulder are sequentially activated. The spatial and temporal characteristics of circle drawing depend on the precise coordination of these sequential activation patterns, and proprioception is ideally suited to support this coordination. Blindfolded human subjects produced a counterclockwise circular drawing motion (diameter = 16 cm) with the dominant arm at a repetition rate of 1/s. In some trials, 60-70 Hz vibration was applied to the tendons of the biceps brachii and/or the anterior deltoid. Spatial parameters measured from hand-movement data included the x- and y-axis diameters, circularity, and drift of the hand in the workspace. Vibration of either the biceps brachii or the anterior deltoid caused subjects to draw circles with decreased diameter, with changes in circularity, and with a systematic drift of the hand. These distortions to circle drawing by tendon vibration demonstrate that the CNS uses proprioceptive information to accomplish the spatial characteristics of this motor task. Simultaneous vibration of both muscles produced a drift that exceeded the individual vibration effects, which suggests that the CNS combined proprioceptive information related to elbow and shoulder rotation to control the movement of the hand. The temporal characteristics of circle drawing were quantified from joint angle data. While vibration did not significantly influence the relative phase between elbow and shoulder rotation, the variability of the phase relationship increased significantly, which suggests that proprioception contributes to phase stabilization. During circle drawing, elbow flexion-extension movements were produced with limited activation of the biceps. Nevertheless, biceps vibration distorted the circle metrics, suggesting that a muscle's significance as a sensory transducer is independent of its activity level.

Adolescent↗
PubMed1999

Proprioceptive control of multijoint movement: bimanual circle drawing.

Proprioception is used by the central nervous system (CNS) in the control of the spatial and temporal characteristics of single joint and multiple joint movement. The present study addressed the role of proprioception in the control of bilateral cyclical movements of the limbs. Normal blindfolded human subjects drew circles simultaneously and symmetrically with the two arms (16 cm diameter, 1 /s) upon two digitizing tablets. In selected trials, vibration (60-70 Hz) was applied to the tendon of the biceps and/or anterior deltoid muscles of the dominant arm to distort the proprioceptive information from muscle spindle afferents. One goal of this study was to identify whether tendon vibration influenced the spatial characteristics of circles drawn by the vibrated, dominant arm and the non-vibrated, non-dominant arm. A second goal was to determine the effect of vibration on the temporal coupling between the two arms during circle drawing. The results revealed that tendon vibration affected the spatial characteristics of circles drawn by the vibrated arm in a manner similar to that previously found for unilateral circle drawing. During bimanual circle drawing, vibration had only a minimal effect on the spatial characteristics of the non-vibrated, non-dominant arm. Temporal interlimb coupling was quantified by the relative phasing between the arms. Without tendon vibration, the dominant arm led the non-dominant arm. Vibration of the dominant arm increased the average phase lead. In a first control experiment, vibration of the non-dominant arm decreased the phase lead of the dominant arm, or even reversed it to a non-dominant arm phase lead. In a second control experiment, the subjects performed the bimanual circle-drawing task with vision of only the vibrated arm, in which case there was no spatial distortion of the circles drawn by the vibrated arm, but the phase relation between the two arms was still shifted as if vision were completely unavailable. It was concluded that, in bimanual movements such as these, the spatial and temporal characteristics of movement are controlled independently. Whereas the spatial characteristics of hand movement seem to be controlled unilaterally, the temporal characteristics of interlimb coupling appear to be controlled by proprioceptive information from both limbs, possibly by a proprioceptive triggering mechanism.

Adult↗
PubMed2004

Proprioception and performance after anterior cruciate ligament rupture.

The aim of this study was to investigate the characteristics of proprioception in patients with an anaterior-cruciate-ligament (ACL)-injured knee and to determine whether there is a correlation between proprioception and performance. We studied 32 patients with unilateral isolated ACL ruptures. Proprioception of the knee was evaluated by examining the joint position sense. Functional performance was evaluated with the one-leg hop (OLH) and one-leg vertical jump (OLV) tests. The mean error angle of the joint position sense was 3.6+/-1.5 degrees on the intact side and 5.2+/-1.9 degrees on the injured side. The joint position sense was thus clearly reduced on the injured side (p<0.05). The distance of jumping in the OLH test and the height of jumping in the OLV test was also clearly reduced on the injured side compared with that on the intact side (p<0.01) both with and without visual control. Moreover, we found a significant correlation between proprioception and performance in the ACL-injured knees, and this correlation was more distinct with visual deprivation. In conclusion, decreased proprioception in patients with ACL deficiency reduced their functional ability.

Adolescent↗
PubMed1991

Ocular proprioception and efference copy in registering visual direction.

We measured the roles of eye muscle proprioception ("inflow") and efference copy ("outflow") in registering eye position. During monocular fixation, pressing on the side of an occluded eye results in a passive rotation, changing the proprioception without affecting oculomotor efference. As we have shown previously, a constant press on the side of the viewing eye induces active resistance to rotation, changing efference because oculomotor innervation compensates for the eyepress; the viewing eye's fixation remains constant. Using these two types of eyepress, both perceived target deviations and pointing biases in an unstructured visual field were measured in 8 subjects under efference copy, proprioception and control (no eyepress) conditions. Eye deviation was measured photoelectrically. Physiological gains of efference copy and proprioception was about 5/8 and 1/4 respectively. There was no statistically significant difference between perceptual judgement and open-loop pointing. The sum of gains of efference copy and proprioception, about 7/8, indicates incomplete registration of eye eccentricity in an unstructured field, and quantitatively accounts for several previously unexplained results in the literature.

Adult↗