Perception Of Position Research Articles

Somatic graviception

Psychophysical experiments show that the perception of posture is to a large degree affected by hitherto unknown graviceptors in the human trunk. By remote control subjects move themselves radially along their spinal axis over the horizontal platform of a rotating centrifuge until they feel horizontal. Normal subjects then set the centrifuge axis on average at 22–28 cm caudal of the meatus, neuromectomized subjects at 45–55 cm. Hence the mass centroid of these receptors should be situated near the last ribs. Evaluation of the residual faculties of paraplegic patients lead to the conclusion that somatic graviception is mediated by two distinctly localized inputs, the first entering the spinal cord at the 11th thoracic segment, and the second reaching the brain cranial of the 6th cervical segment, presumably via the N. phrenicus or the N. vagus. The effect of the first named input is abolished after bilateral nephrectomy. This proves that the kidneys affect gravity perception. But whether they function like statoliths or in another way cannot yet be decided. For the second input, however, the results show unequivocally that it yields gravity information through the inertia of a mass in the body. It is hypothesized that this mass may be that of the blood in the large vessels. This is corroborated by the effect of shifting blood craniad by means of positive pressure to the legs. It is inferred that the inertial forces are measured by mechanoreceptors in the structures that mechanically support the large vessels, rather than by baroreceptors.

The role of ocular torsion in visual measures of vestibular function

This brief review highlights problems in the interpretation of results about perceived postural roll-tilt of human subjects undergoing roll-tilt around their naso-occipital axis, when visual stimuli are used as a means of indicating perception. The otolithic stimulus, which causes the changes in perceived posture, also causes the eyes to roll (or tort). In turn, the altered torsional position of the eye causes the perceived orientation of visual stimuli to change. Consequently, indicators of postural perception, which rely on visual stimuli, are a confounded combination of two factors; the person's perceived postural roll-tilt, and the effect of the otolithic stimulus on ocular torsional position. Consequently, setting of a visual stimulus do not permit direct unambiguous interpretation of a subject's perceived postural roll-tilt.

Perception of posture of short duration in the spatial and temporal domains

Twenty normal male university students with a mean age of 21.4 years, body weight of 66.2 kg, and height of 170 cm, were asked to acquire nine postures, and in the last two they were asked to exert either pushing or pulling forces for periods ranging from 5 to 15 seconds. Their posture was recorded photographically, the duration of activities was measured using a stopwatch and the force exerted during pushing and pulling was recorded using a load cell and force monitor (ST-1). The subjects were asked to estimate their postures immediately after each activity using a three-dimensional mannequin and a line drawing on a paper according to instructions provided before. They were also asked to estimate the duration and force exerted using their judgement and record. After the completion of all activities they recorded all their estimations (except mannequin) again on the same day, a week later and four weeks later. The estimates were compared with actual values through Student's t-test Stooping and twisting were accurately estimated and recalled. Side bending, pushing, and pulling were consistently significantly different from actual ( p < 0.05). Whereas the memory of posture estimates was stable for the period of study, the duration estimates deteriorated with passage of time. The force assessment during pushing activity was significantly different ( p < 0.01) from actual but the pulling forces were estimated and recalled accurately.

Representations Systems, Perceptual Position, and Presence in Immersive Virtual Environments

This paper discusses factors that may contribute to the participant's sense of presence in immersive virtual environments. We distinguish between external factors, that is those wholly determined by the hardware and software technology employed to generate the environment, and subjective factors, that is how sensory inputs to the human participant are processed internally. The therapeutic technique known as neurolinguistic programming (NLP) is used as a basis for measuring such internal factors. NLP uses the idea of representation systems (visual, auditory, and kinesthetic) and perceptual position (egocentric or exocentric) to code subjective experience. The paper also considers one external factor, that is how the virtual environment represents a participant—either as a complete body, or just an arrow cursor that responds to hand movements. A case-control pilot experiment is described, where the controls have self-representation as an arrow cursor, and the experimental group subjects as a simple virtual body. Measurements of subjects' preferred representation systems and perceptual positions are obtained based on counts of types of predicates and references used in essays written after the experiment. These, together with the control variable (possession/absence of a virtual body), are used as explanatory variables in a regression analysis, with reported sense of presence as the dependent variable. Although tentative and exploratory in nature, the data analysis does suggest a relationship between reported sense of presence, preferred representation system, perceptual position, and an interaction effect between these and the virtual body factor.

Postural alignment in standing: A repeatability study

Interpretation of any postural changes over time relies on the knowledge that the person's perception of comfortable erect posture remains sufficiently constant. This study measured the repeatability of sagittal spinal alignment during one day, and the degree of variability in that alignment measured subsequently four, eight and 12 days, and 16 and 24 months later. Normal women, pregnant women and women with low back pain, in the age range of 15 to 34 years, were included in the study. Spinal curvature was determined using a clinometer, while an electro-goniometer attached to callipers determined the degree of pelvic tilt. Results demonstrated that on any one day, a consistent postural alignment is assumed (in terms of spinal curvature and pelvic inclination) when an individual is asked to stand comfortably erect. In addition, in the normal, symptom-free, young adult subject, the perception of posture, and therefore postural alignment remains constant for at least two years.

Neurolinguistic programming training, trait anxiety, and locus of control.

Training in the neurolinguistic programming techniques of shifting perceptual position, visual-kinesthetic dissociation, timelines, and change-history, all based on experiential cognitive processing of remembered events, leads to an increased awareness of behavioral contingencies and a more sensitive recognition of environmental cues which could serve to lower trait anxiety and increase the sense of internal control. This study reports on within-person and between-group changes in trait anxiety and locus of control as measured on the Spielberger State-Trait Anxiety Inventory and Wallston, Wallston, and DeVallis' Multiple Health Locus of Control immediately following a 21-day residential training in neurolinguistic programming. Significant with-in-person decreases in trait-anxiety scores and increases in internal locus of control scores were observed as predicted. Chance and powerful other locus of control scores were unchanged. Significant differences were noted on trait anxiety and locus of control scores between European and U.S. participants, although change scores were similar for the two groups. These findings are consistent with the hypothesis that this training may lower trait-anxiety scores and increase internal locus of control scores. A matched control group was not available, and follow-up was unfortunately not possible.

On Narrative Studies and Narrative Genres

In the past two or three decades, students of narrative have very much consolidated and developed our knowledge by isolating, (re)characterizing, and (re)classifying a large number of features distinctive of or pertinent to (verbal) narrative (see Adam 1985; Genette 1980, 1988; Mitchell 1981; Prince 1987; Scholes and Kellogg 1966). In the area of narrative discourse (that of the narrating rather than the narrated, the representing and not the represented), for instance, Genette and others (e.g., Bal 1985; Chatman 1978; Rimmon-Kenan 1983; Todorov 1981) have described the temporal orders that a narrative text can follow, the anachronies (flashbacks and flash-forwards) that it can exhibit, the achronic (undatable) structures that it can accommodate. Furthermore, they have characterized narrative speed and its canonical tempos (ellipsis, summary, scene, stretch, and pause). They have investigated narrative frequency (the relationship between the number of times an event happens and the number of times it is recounted), examined narrative distance (the extent of narratorial mediation) and narrative point of view (the perceptual or conceptual position according to which the narrated events are depicted), studied the types of discourse that a text can adopt to report the utterances and thoughts of characters, and analyzed the major kinds of narration (posterior, anterior, simultaneous, intercalated) as well as their modes of combination (two different acts of narration can be linked through a simple

Perceptual Position and Competitive Brand Strategy in a Two-Dimensional, Two-Brand Market

Brand positioning and competitive reaction are important determinants of optimal brand strategy. Analyses of brand strategy have focused on optimal pricing and positioning issues using either empir...

Perceptual Position and Competitive Brand Strategy in a Two-Dimensional, Two-Brand Market

Brand positioning and competitive reaction are important determinants of optimal brand strategy. Analyses of brand strategy have focused on optimal pricing and positioning issues using either empirical models of perceptions and preferences, game theory to examine competition, or both. However, the important issues of advertising and distribution strategy have not been fully addressed. This paper analyzes competition and strategy between two brands that compete in a two-dimensional market with advertising and distribution spending, in addition to prices and product positions. In particular, for a unimodal taste distribution of ideal points we show how • optimal competitive (Nash equilibrium) marketing mix levels and profits depend on the positions of both brands, • brands can reposition to increase profit and under what conditions these strategies imply minimum versus maximum differentiation positioning equilibria, and • how the intensity of advertising and distribution competition affect equilibrium brand positions.

Perceptual segregation and retinal position.

This study is concerned with the dependence of perceptual segregation performance on the retinal position at which the performance is evaluated. Segregation performance consisted in detecting a target texture composed of line elements of constant length and orientation embedded in a background texture. The background texture was made up of the same line elements as the target texture but the background line elements were set at 90 deg to the target elements. Results showed that, at least for 40- and 50-ms presentation times, this task could be much more effectively completed outside the fovea centralis than within this area. These findings indicate that extrafoveal areas of the retina may make a significant and previously underestimated contribution to perceptual segregation.

Dimensions of perception of posture in dance

This study reports a preliminary investigation designed to assess the possibility of using a semantic differential in the appraisal of expressive characteristics of posture in dance. Twenty still photographs of postures displayed by one female dancer were judged on 25 bipolar scales by 50 Ss. Ratings of eight of these Ss were used for estimating reliabilities of the scales — resulting in elimination of five scales. Intercorrelation matrices of the 20 remaining scales were obtained for each of the 42 remaining Ss. Consideration of homogeneity of the distribution of these matrices led to the exclusion of four of them, leaving 38 matrices for further analysis. After random division of these matrices into two equally sized subgroups, principal component analyses with VARIMAX rotation were carried out on the average intercorrelation matrix for each subgroup. This resulted in two very similar three-factor solutions. The three factors, identified as similar to Osgood's well-known factors of activity, evaluation and potency, accounted for about 55% of the total variance. The results, discussed in terms of Berlyne's conception, suggest that the semantic differential may be a reliable instrument for measuring connotations of posture in dance.

Profit Maximizing Perceptual Positions: An Integrated Theory for the Selection of Product Features and Price

An important component of marketing strategy is to “position” a product in perceptual space. But to realize a perceptual position we must model the link from physical characteristics to perceptual dimensions and we must use this model to maximize profit. This paper integrates psychological theories on how consumers process information with economic models and psychometric measurement, and it develops a theory for selecting physical features and price to achieve a profit maximizing perceptual position. The theory begins with a Lancaster-like transformation from goods space to characteristics space and investigates the implications of a mapping to a third space, perceptual space. We show that all products efficient in perceptual space must be efficient in characteristics space but not conversely. But consumers vary in their preference and the way they perceive products. Thus we introduce distributional components to the theory and derive both geometric and analytic methods to incorporate this consumer heterogeneity. Next, we investigate costs and derive a perceptual expansion path along which a profit maximizing position must exist. Conjoint analysis and quantal choice models provide the measurements to implement the theory. The theory is illustrated with a hypothetical example from the analgesics market and some of the potential psychometric measurements are illustrated with an empirical application in the communications market.

Discrimination between trunk and head rotation: A study comparing neuronal data from the cat with human psychophysics

Kinesthetic information from labyrinthine and neck receptors is required for reflex control and conscious perception of posture and movement. This study considers (1) the neuronal responses to horizontal labyrinthine and neck stimulation and their interaction both in the anterior suprasylvian (AS) cortex and in the vestibular nuclei (VN) of cats, and (2) human turning sensation related to these stimuli. Convergence of labyrinthine (L) and neck (N) input of comparable sensitivity was found in 80% of the AS neurons and in only 27% of the VN neurons. At both sites, the on-direction of L-responses as well as N-responses was either to the ipsilateral or to the contralateral side (type I and type II responses, respectively). When combining the two stimuli during head rotation, the two inputs could be synergistic (same on-direction) or antagonistic (opposite on-directions). Their interaction consisted of either an additive or subtractive summation leading to enhanced or depressed interaction responses. These interaction patterns are compatible with the subtractive and additive mechanisms which have been proposed to be essential for the stabilisation of the trunk and of the head, respectively. The psychophysical experiments showed that human turning sensations depend on the part of the body to which they are referred. Subjects taking the trunk as reference, reported similar turning sensations during both labyrinthine and neck stimulation, and weak or no turning sensation during head rotation. This suggests an antagonistic interaction of the two inputs. In subjects taking the head as reference, neck stimulation induced an illusionary sensation of head turning. Its direction was such that it would be synergistic with the vestibularly induced sensation of head turning during isolated head rotation. Thus, there appear to exist parallels between the basic operations performed by neurons in cat and by human subjects during labyrinthine-neck interactions.

THE RELATIONSHIP OF THE VESTIBULAR AND PROPRIOCEPTIVE SYSTEMS TO DYSFUNCTION IN VERTICALITY PERCEPTION, POSTURE AND MOVEMENT, AFTER STROKE

The extent to which verticality perception influences posture and movement is of considerable importance to the physiotherapist. To determine the relative contributions of the vestibular and proprioceptive systems to visuo-spatial perception after stroke and the relationship of verticality perception to body alignment and utilisation of space during movement, a study was undertaken in the Department of Physiotherapy, University of Queensland. Forty stroke patients, divided into experimental groups on the basis of quality of verticality perception, were selected for study, while twenty two 'non-stroke' subjects, matched for age and sex, formed a control group. Measurements were taken of proprioception, body alignment, utilisation of space during movement, verticality perception and duration of post rotational nystagmus. Analyses of the correlations between these various modalities revealed those features which are of most significance to the perception of verticality, posture and movement of the stroke patient. From these results, implications for the physiotherapy management of the stroke patient with problems in verticality perception, body alignment and utilisation of space during movement, have been drawn.

Clinical kinesthetic experiments on the lateral pterygoid muscle and temporomandibular joint in man.

The possible kinesthetic function of proprioceptors in the lateral pterygoid muscle was clinically assessed after anesthesia of muscle and temporomandibular joint receptors, respectively. A mandibular posture was actively and repetitively produced with an average accuracy of 2.5 mm, while the accuracy decreased by about two-fold after narcotization. It is suggested that muscle spindles in the lateral pterygoid muscle as well as mechanoreceptors in the temporomandibular joint capsule are active in the perception and/or control of mandibular postures.

Relationship between the Perception and Reproduction of Body Postures

Abstract One hundred and seven college women were tested in their ability to recognize a demonstrated body posture from among similar ones and to reproduce demonstrated body postures. Two original tests were devised for this purpose. A low but statistically significant correlation (- .34) was found between the two. In addition, the subjects completed a questionnaire regarding the extent and nature of their motor experience. The extent of the individual's motor experience had a significant role in each of these abilities. The direction to be taken in reproducing the postures was found to be a complicating factor.

Postural perceptions and eye displacements produced by a resultant vector acting in the median sagittal plane of the head. II. Continuous responses along the Y axis with the subject in a vertical position, heading centripetally and centrifugally.

To confirm the observations made with the previously described centrifuge-test method (Brandt & Fluur, 1966 b), the following modifications were introduced in these experiments. (1) Only the changes along the Y axis were registered. (2) The resultant force presented was permitted to increase and then decrease without interruption at the same slow rate. (3) The subjects (inexperienced) were seated in the erect position, facing centrifugally or centripetally, and the IR-filmed eye was fixed on the target throughout the trials. (4) The apparent position of the observed indicator was obtained without the interference of any active movement of the eye.

Postural perceptions and eye displacements produced by a resultant vector acting in the median sagittal plane of the head. I. Responses along three axes by stepwise increasing phi with the subject heading centripetally in an erect and a tilted position.

Applying a previously described centrifuge-test method, the changes of position in space of an observed visual object were recorded by naive subjects exposed in darkness to a resultant vector, acting in the sagittal plane of their heads, and systematically referred to the same plane of reference (frontal plane). Simultaneously, the torsional changes of the eye were determined by means of an IR filming procedure. A comparison was made between the two responses in two attitudes, i.e., one strictly vertical, and one with the same subject tilted outwards, in both cases facing the centre, in respect to a stepwise increasing force field with angular acceleration reduced to negligible quantities. This permits the conclusion that an (apparent) displacement of the target, which occurs chiefly in a headward direction, is generally associated with a countertorsion of the eye in the opposite direction, and that the ocular change is far inferior in size to the corresponding visual phenomenon. Marked discrepancies are ...

Postural perceptions and eye displacements during the variation of a force field acting in the mid-frontal plane.

Applying a previously described centrifuge-test method, the changes of position in space along three axes of an observed target in an otherwise dark room were recorded. Ten subjects were positioned heading forwards (HF) with their left sides to the centre of the centrifuge. In order to separate directional and magnitudinal factors inherent in the produced force field, the procedure was repeated with the same subject in three positions of tilt in the frontal plane (erect = HF 0° tilt; tilted 50° inwards = HF 50° inw.; tilted 50° outwards = HF 50° outw.). Using an infrared (IR) technique, one eye was filmed, and its torsional position evaluated concurrently along the same three axes, simultaneously with the subjective data recorded. The increase in the angle formed between resultant force and physical vertical (angle Φ) generally produced an apparent clockwise rotation of the phenomenal horizontal in the two positions HF 50° inw. and HF 0° tilt, in a clear positive relation to the relative direction and als...

Encoding in the perceptual (visual) serial position effect

On the basis of the verbal loop hypothesis, specific changes in the shape of the perceptual serial position curve were predicted as a function of encoding, or verbalization length of the stimulus, and stimulus exposure time. The effects of post-stimulus delay, both with and without an interpolated task, were also explored. With eight-place binary numbers as stimuli, a group of 12 Ss was tested to evaluate the effect of these four variables—verbalization length, exposure time, delay time, and interpolated task during the delay. It was demonstrated that, as predicted, increasing the verbalization length and shortening the exposure time have similar effects. They tilt the serial position curve up on the right. The presence of an interpolated task produces an overall increase without, however, any effect on the shape of the serial position curve. Poststimulus delay, within the range used in this study, produces no clear or systematic effect.