Subjective Magnitude Estimation Research Articles

Factors Involved in Tactile Texture Perception Through Probes

An understanding of texture perception by robotic systems can be gained by examining human texture perception through a probe. As with texture perception in direct touch with the finger, texture perception by indirect touch by means of a probe is multidimensional, comprising rough, hard and sticky texture continua. In this study we describe variability among individual subjects in probe-mediated texture perception, and compare similarities and differences of texture perception between direct touch and indirect touch. The results show variability among subjects, as individual subjects may choose to rely on different texture dimensions, and examine the texture surface using different scanning velocities and contact forces. Despite the fact that the subjects use different scanning velocities and forces, they discriminate textures reliably and make subjective magnitude estimates consistently along a texture continuum when indirectly exploring texture surfaces with a probe. These data will be potentially useful in designing robotic sensory systems and understanding of sensory feedback, which is essential to teleoperations.

Tactile Speed Scaling: Contributions of Time and Space

A major challenge for the brain is to extract precise information about the attributes of tactile stimuli from signals that co-vary with multiple parameters, e.g., speed and texture in the case of scanning movements. We determined the ability of humans to estimate the tangential speed of surfaces moved under the stationary fingertip and the extent to which the physical characteristics of the surfaces modify speed perception. Scanning speed ranged from 33 to 110 mm/s (duration of motion constant). Subjects could scale tactile scanning speed, but surface structure was essential because the subjects were poor at scaling the speed of a moving smooth surface. For textured surfaces, subjective magnitude estimates increased linearly across the range of speeds tested. The spatial characteristics of the surfaces influenced speed perception, with the roughest surface (8 mm spatial period, SP) being perceived as moving 15% slower than the smoother, textured surfaces (2-3 mm SP). Neither dot disposition (periodic, non periodic) nor dot density contributed to the results, suggesting that the critical factor was dot spacing in the direction of the scan. A single monotonic relation between subjective speed and temporal frequency (speed/SP) was obtained when the ratings were normalized for SP. This provides clear predictions for identifying those cortical neurons that play a critical role in tactile motion perception and the underlying neuronal code. Finally, the results were consistent with observations in the visual system (decreased subjective speed with a decrease in spatial frequency, 1/SP), suggesting that stimulus motion is processed similarly in both sensory systems.

Ereigniskorrelierte funktionelle Magnetresonanztomographie zur Erforschung der zerebralen Schmerzverarbeitung

Neurofunctional magnetic resonance imaging (fMRI) offers the possibility to map cerebral activity; non-invasively. The development of event-related techniques during the past years allows to study brain processes with high spatial and temporal resolution. Based on these techniques, EPI- and FLASH sequences were developed in this study, to investigate cerebral processing of experimental thermal pain stimulation. Phasic and tonic stimulation paradigms were developed with an MR-compatible contact thermode. Functional mapping of pain-relevant areas was performed with these paradigms, as well as a specification of the temporal characteristics of the activation. Further, a randomized paradigm with several stimulus intensities could differentiate graded functional responses, dependent on stimulus intensity in specific „regions-of-interest”. In this design, randomizing the stimulus order reduced habituation effects, while continuous subjective magnitude estimation of the stimuli kept attention of subjects maximal.

Effects of stimulus intensity on signals from human somatosensory cortices.

We recorded somatosensory evoked magnetic fields (SEFs) to left median nerve electric stimulation from seven healthy subjects. The stimulus intensity was varied in three sessions: sensory stimuli evoked a clear tactile sensation without any movement, weak motor stimuli exceeded the motor threshold, and strong motor stimuli caused a vigorous movement. Responses were modelled with sources in the contralateral primary somatosensory cortex (SI), the contralateral and ipsilateral secondary somatosensory cortices (SIIs) and the contralateral posterior parietal cortex (PPC). The amplitude of the 20 ms response from the SI cortex and the subjective magnitude estimations followed the stimulus intensity whereas signals from the three other areas saturated already at the level of the motor threshold. The results implicate differential roles for various somatosensory cortices in intensity coding.

A psychophysical study of the mechanisms of sensory recovery following nerve injury in humans.

Twenty-four subjects were studied before and up to 1 year after surgery that produced injury to a major sensory branch of the trigeminal nerve. We employed a battery of 11 psychophysical tests, in which the neural mechanisms underlying performance are understood, to study the basis of recovery following nerve injury. Immediately after nerve injury, sensation was profoundly impaired in all subjects. In the following weeks and months, the recovery of performance proceeded in an orderly fashion. Although the rates of recovery varied between subjects, the order of recovery between tasks did not. The recovery rates fell into three distinct categories. Recovery in one task, brush-stroke directional discrimination, was most rapid. Two weeks after nerve injury, 52% of subjects could discriminate brush-stroke direction; by 3 months only one subject could not perform this task. The second category comprised recovery rates for pain thresholds for noxious heat, cold and mechanical stimuli, and to preinjury performance in tasks assessing touch and vibration detection, two-point discrimination, cooling detection and subjective magnitude estimation of mechanical force. The third, slowest group included recovery rates for warming detection and grating orientation discrimination. Early recovery to preinjury performance levels in the brush-stroke direction and one-point versus two-point discrimination tasks was correlated with later recovery to near normal performance in the grating orientation task. The grating orientation task was unique in providing a measure that corresponded consistently with the subjects' reports of sensory deficits. Our psychophysical findings are consistent with neurophysiological data showing that the major primary afferent fibre classes reinnervate the skin at a similar rate. A hypothesis that accounts for the psychophysical findings in this study is that differences in recovery rates between tasks is determined largely by their relative dependencies on functional innervation density. Alternative hypotheses are considered.

Lidocaine Test in Neuralgia

MARCHETTINI, P.; LACERENZA, M.; MARANGONI, C.; PELLEGATA, G.; SOTGIU, M. L.; SMIRNE, S. Author Information

Lidocaine test in neuralgia

Ten patients with organic nerve injury causing chronic neuropathic pain were tested for the effects of intravenous lidocaine versus saline upon psychophysical somatosensory variables. The variables assessed were the subjective magnitude of pain, area of mechanical hyperalgesia and presence and magnitude of thermal heat/cold hyperalgesia. The study methods applied to evaluate these conditions were the conventional testing of somatosensory submodalities with area mapping and the subjective magnitude estimation of spontaneous pain. It was found that spontaneous pain and mechanical hyperalgesia were consistently improved, transiently, by intravenous administration of lidocaine in all 10 patients; areas of hyperalgesia which extended beyond the territory of the nerve also improved transiently. Spontaneous pain and mechanical hyperalgesia, but not hypoesthesia, were transiently improved by injection of saline in only 1 of the 10 patients. This outcome is probably due to a placebo effect. This improvement is in keeping with the inhibition of anomalous neural impulses which can be generated anywhere along the sensory channels responsible for generating spontaneous pain and hyperalgesia. Thus, intravenous lidocaine is proposed as a diagnostic aid in the examination of patients complaining of complex sensory disorders associated with nerve injury. The transient pain relief may allow a fuller identification of the area of sensory loss.

Multi-unit activity in sensory fibers is related to intensity of sensation evoked by air-puff stimulation of the glabrous hand in man

An analysis of a multi-unit activity (MUA) recorded from the median nerve at the wrist was undertaken to study intensity coding in the peripheral somatosensory system. Brief air-puff stimuli were applied over the glabrous hand to obtain neural and psychophysical responses. The detection threshold (So) was determined and 6 above-threshold stimulus intensities (So + 0.25 kg/cm2, So + 1.25 kg/cm2, So + 2.50 kg/cm2, So + 3.75 kg/cm2, So + 5.00 kg/cm2, and So + 6.25 kg/cm2) were adopted for magnitude estimation. MUA was recorded for the 6 stimulus intensities and for the threshold (So) level. Response duration, number and frequency of the MUA were evaluated as candidate coding parameters for stimulus intensity. A simple power function with an exponent of 1.03 provided an adequate description of the magnitude estimation function. Similarly, stimulus-response functions of the 3 parameters defining the MUA were well represented by straight lines in double logarithmic plots, with the function of the MUA number having the highest power exponent (0.98) and also the highest correlation coefficient. The results suggest that the total number of MUA, representing spatial recruitment, is the most relevant coding parameter for the subjective magnitude estimation of the stimulus intensity.

Multi-unit activity in sensory fibers is related to intensity of sensation evoked by air-puff stimulation of the glabrous hand in man

An analysis of a multi-unit activity (MUA) recorded from the median nerve at the wrist was undertaken to study intensity coding in the peripheral somatosensory system. Brief air-puff stimuli were applied over the glabrous hand to obtain neural and psychophysical responses. The detection threshold (So) was determined and 6 above-threshold stimulus intensities (So + 0.25 kg/cm 2, So + 1.25 kg/cm 2, So + 2.50 kg/cm 2, So + 3.75 kg/cm 2, So + 5.00 kg/cm 2, and So + 6.25 kg/cm 2) were adopted for magnitude estimation. MUA was recorded for the 6 stimulus intensities and for the threshold (So) level. Response duration, number and frequency of the MUA were evaluated as candidate coding parameters for stimulus intensity. A simple power function with an exponent of 1.03 provided an adequate description of the magnitude estimation function. Similarly, stimulus-response functions of the 3 parameters defining the MUA were well represented by straight lines in double logarithmic plots, with the function of the MUA number having the highest power exponent (0.98) and also the highest correlation coefficient. The results suggest that the total number of MUA, representing spatial recruitment, is the most relevant coding parameter for the subjective magnitude estimation of the stimulus intensity.

Experimental pain thresholds and plasma beta-endorphin levels during exercise

Experimental pain thresholds (electrical intracutaneous finger and dental pulp stimulation) and plasma hormone levels (beta-endorphin, cortisol, and catecholamines) were measured in ten healthy sportive men before, during, and after progressively more strenuous physical exercise. In a double-blind study conducted on two different days, 20 mg of the opioid-antagonist naloxone or placebo was administered prior to exercise. A significant pain threshold elevation was found during exercise for finger (ANOVA, P less than 0.004) and dental pulp stimulation (P less than 0.01). Pain threshold elevation was most pronounced during maximal exertion, at which time the subjects reported the greatest subjective fatigue. Thresholds remained elevated 10-15 min after the end of exercise, and, 60 min after exercise, thresholds returned to baseline values. The subjective magnitude estimation of suprathreshold stimuli was significantly reduced (P less than 0.0001) 5-10 min after exercise. Plasma beta-endorphin, cortisol, and catecholamines increased significantly (P less than 0.0005, all values) during exercise. Plasma beta-endorphin levels did not correlate significantly with pain thresholds (r = -0.37, NS). Naloxone failed to affect pain thresholds, although beta-endorphin and cortisol increased significantly more (P less than 0.02) during exercise after naloxone. It is concluded that short-term, exhaustive physical exercise can evoke a transient elevation in pain thresholds. This exercise-induced elevation in pain threshold does not, however, appear to be directly related to plasma endorphin levels.

Acceptability of text‐to‐speech systems: Its quantification using magnitude estimtion and its relationship to intelligibility and naturalness in various degrees of distortion

Because there are no physical measurements that quantify perceptual attributes of synthesized speech, subjective tests must be used. In this project the possibility of directly scaling acceptability via magnitude estimation is assessed. One hundred and twenty subjects took part in the study. Seven different synthesizers and three types of background noise were employed. The results are discussed in light of the following questions. (1) What is the relationship between acceptability on one hand and naturalness and intelligibility on the other in various degrees of distortion? (2) Are the objective intelligibility scores and subjective magnitude estimations highly correlated in all conditions? (3) Do the relative ratings produced by different groups of subjects agree? (4) Are the ratings on an absolute scale? (5) Are the ratings invariant to the stimulus set and range size? (6) Are the ratings practice invariant? (7) Do the ratings depend on the subject's familiarity with the test material?

Peripheral mechanisms of somatic pain.

In the last two decades, considerable advances have been made in our understanding of the mechanisms of pain. Studies correlating subjective magnitude estimations of pain in man with activity in single nerve fibers in experimental animals, and microneurographic recordings in awake humans, have provided convincing evidence for the role of specific nociceptors and labelled lines for signalling pain sensation in the normal skin. The response properties of the different types of nociceptive afferents, both myelinated and unmyelinated, from skin, muscle, and joints make them ideal candidates for signalling pain sensations. Cutaneous inflammation from any cause results in hyperalgesia. Cutaneous hyperalgesia at the site of an injury, i.e., primary hyperalgesia, can be explained by sensitization of nociceptors. This sensitization is likely due to local release of chemical mediators in the inflamed area. The metabolites of arachidonic acid (eicasonoids) and bradykinin appear to play an important role in the sensitization of nociceptors. Similar inflammation-induced changes in response properties of fine articular afferents might explain the pain of acute arthritis. The neuropeptide substance P released from primary afferents may also play an important role in the pathogenesis of arthritis. The mechanism of hyperalgesia in the region surrounding the injury, i.e., secondary hyperalgesia, is less well understood, and probably results from changes both in the peripheral and central nervous systems. While considerable advances have been made in our understanding of the mechanisms of acute pain, the pathophysiology of most chronic pain states is still unclear. We hope that future studies in experimental animals, and careful psychophysical testing and microneurographic recordings in chronic pain patients, will lead to a better understanding of the pathophysiology of pain.

The Analysis of Verbal Explanations for Marital Separation: Implications for Attribution Theory1

The main purpose of this study was to analyze the structure and content of real‐life attributions, using these data to examine some important theoretical and empirical issues in attribution theory. The causal attributions examined came from free‐response verbal protocols of explanations for marital separation of 29 males and 33 females living in New Zealand. Respondents gave causal importance weghts to the attributions from their verbal protocols, utilizing the technique of subjective magnitude estimation. Ipsative data, representing perceived causal responsibility for different attribution targets (self, ex‐spouse, external factors, etc.), were derived from these weights, and the impact a range of independent variables exerted on these derived free‐response attribution percentages was examined. Evidence is presented which supports the validity and reliability of this technique. The normative data gathered was found to be both consistent and inconsistent with different aspects of attribution theory. The implications for attribution theory are discussed.

The Concept of Colourfulness and its Use for Deriving Grids for Assessing Colour Appearance

AbstractA technique of subjective magnitude estimation has been used to assess a set of pseudosurface colours, each having a luminance factor of 0.2. Three adaptation conditions corresponding to daylights D65 and D50 and tungsten light SA were used. The experimental technique and data analysis represent an improvement on that previously reported. The concept of colourfulness, as opposed to chroma or saturation, has been introduced with considerable success. The loci of constant hue and colourfulness were derived in u',v' chromaticity space and the results compared with predictions obtained using the Bartleson adaptation equations.

Direct Magnitude Estimation Scales in Public Opinion Surveys

Direct magnitude estimation scales, patterned after S. S. Stevens's work in psychophysics, provide precise, reliable measures. The use of the scales in three surveys demonstrates that they can be used in telephone surveys of a general population. Because the scales are relatively easy to construct, the researcher is able to go into the field more quickly than if he had developed scales through other methods. Since respondents arrange the stimuli on the scale, rather than have the researcher structure the stimuli into categories for respondents, the measures are relatively free of researcher predispositions and bias. The scales' most important use is in providing measures that can be used in theory building. Researchers should benefit from data that allow one to use powerful statistical techniques without violating data assumptions. Diana Stover Tillinghast is an Assistant Professor of Communication at Stanford University. The author is grateful to Kay Magill, Stanford Ph.D. candidate, for her substantial contribution to the work reported here. The surveys were conducted for the San Jose Mercury News. Public Opinion Quarterly ? 1980 by The Trustees of Columbia University Published by Elsevier North-Holland, Inc. 0033-362X/80/0044-377/$1.75 This content downloaded from 207.46.13.129 on Mon, 27 Jun 2016 05:25:02 UTC All use subject to http://about.jstor.org/terms 378 DIANA STOVER TILLINGHAST ducted by the University of Michigan's Survey Research Center. The Laboratory for Behavioral Research at the State University of New York at Stony Brook developed the scales used in one wave of a national panel study designed to test a learning model of support for the U. S. Supreme Court (Lodge et al., 1976). The researchers validated adjectival descriptor scales by using three cross-modality matching procedures-magnitude estimation, hand grip intensity, and sound pressure intensity-demonstrating not only that researchers can build regression-free, psychophysically valid ratio scales to measure the intensity of opinion, but also that these scales can be used in field surveys. The scales discussed in this article were adapted from Stevens's direct, subjective magnitude estimation scale for use in telephone surveys of a general population. In Stevens's early loudness experiments, a subject was presented with a standard tone, which had been assigned a numerical value, and was asked to judge the loudness of other tones in relation to the fixed standard (Stevens, 1956). Later, Stevens (1975) adopted a no-standard procedure, in which subjects assigned any number to the first stimulus and assigned successive numbers in such a way that they reflected their subjective impressions. Although the no-standard procedure is preferred by psychophysicists, the lack of a flxed standard bothers many social scientists (Hamblin, 1974). The scales have the following ratio-scale properties: (1) respondents use the scale to rank order the stimuli, (2) the size of the distances between numbers is known and has meaning, and (3) the scale has an absolute zero, meaning that the number zero is assigned when none of the property being measured is possessed (Nunnally, 1967; Torgerson, 1958). However, some researchers argue that subjective magnitude estimation scales provide only interval level measures. For example, Krantz et al. (1971) contend that subjective intensity is an interval scale. The scale provides researchers with two advantages: (1) fundamental measurement and (2) the ability to use the more powerful methods of statistical analyses without violating assumptions of the data (see Torgerson, 1958, and Hamblin, 1974). For more than three decades, researchers have argued whether Likert-type ordinal scales, the most common ordinal scales used in surveys as well as in much social science research, should be treated like interval scales for purposes of analysis (see Hewes, 1978). The beauty of the magnitude estimation scale is that the question of whether it is an interval scale does not arise because the distances between points on the scale are known and represent equal psychological distances along the continuum being measured. This content downloaded from 207.46.13.129 on Mon, 27 Jun 2016 05:25:02 UTC All use subject to http://about.jstor.org/terms DIRECT MAGNITUDE ESTIMATION SCALES 379

Grids for Assessing Colour Appearance

AbstractA technique of subjective magnitude estimation has been used to assess a set of pseudosurface colours, each having a luminance equal to half that of its adapting surround. Five observers scaled each of the colours three times in each of two adaptation conditions corresponding to daylight and tungsten light at 120 cd/m2. Loci of constant hue and saturation were derived in u', v' chromaticity space for daylight and tungsten light. These grids enable the appearance of a colour to be specified from a knowledge of its chromaticity coordinates and they enable such effects as colour constancy and colour fidelity to be investigated in terms of perceived colour appearance.

Subjective Estimates of Consonant Phoneme Frequencies

Subjective magnitude estimates of the frequencies of 24 consonant phonemes were obtained from 65 university students, some with training in linguistics, by a method that had been used by Attneave (1953) for judgments of letter frequencies. Reliabilities of averaged judgments for comparably sized groups of 30 judges were estimated as in the neighbourhood of .95. Averages of logarithmically transformed judgments were correlated with log frequencies from objective counts with coefficients in the range .736 to .876 (or .764 to .907 when corrected for attenuation). Despite the high reliabilities and predictive validities, there was evidence that the judgments were strongly influenced by experienced frequencies of letters of the alphabet.

Bias-Free Loudness Judgments for White Noise

Loudness judgments are especially sensitive to experimentally induced biases. An earlier study [R. M. Warren, “Elimination of Biases in Loudness Judgments for Tones,” J. Acoust. Soc. Amer. 48, 1397–1403 (1970)] eliminated known biasing factors (by using only single judgments from large groups of unpracticed subjects and employing symmetrical response ranges), and found that half loudness (12L) for tones corresponded to half sound-pressure level (12P) or 6-dB attenuation. The present study extended this procedure to white noise, using 12 separate groups of 30 subjects. It was found that 12L = 12P from about 45 through 90 dB. This relation held for both loudspeaker and diotic headphone stimulation. These results are in agreement with the theory which considers that subjective magnitude estimates for sounds are based upon familiarity of the listener with the relation between level of stimulation and distance from the source. Half L corresponds to the effect of doubling distance and hence corresponds to 12P (or 12 sound energy). It is suggested that the sone scale, which considers 12L = 0.32P (or 10-dB attenuation), reflects the systematic influence of known biasing effects.

MEASUREMENT PROPERTIES OF SUBJECTIVE MAGNITUDE ESTIMATES OF WORD FREQUENCY1

ABSTRACTStevens' subjective magnitude estimation (SME) method was used in obtaining estimates of relative word frequency from two adult groups (15 lexicographers, 13 other adults) for 60 words ranging widely in objective frequency. Lexicographers rendered more reliable estimates, and their averaged data correlated more highly (.970) with objective log frequency than those of the second group (.923). The objective frequency of the first stimulus considered in the SME task is not related to an S‘s overall accuracy in predicting objective frequency, but accuracy is related to the S‘s tendency to perceive frequency ratios as relatively large. Subjective estimates measure something slightly different from what is indexed by currently available objective counts, and may be more valid measures of true word probability.

Measurement properties of subjective magnitude estimates of word frequency

Stevens' subjective magnitude estimation (SME) method was used in obtaining estimates of relative word frequency from two adult groups (15 lexicographers, 13 other adults) for 60 words ranging widely in objective frequency. Lexicographers rendered more reliable estimates, and their averaged data correlated more highly (.970) with objective log frequency than those of the second group (.923). The objective frequency of the first stimulus considered in the SME task is not related to an S's overall accuracy in predicting objective frequency. but accuracy is related to the S's tendency to perceive frequency ratios as relatively large. Subjective estimates measures something slightly different from what is indexed by currently available objective counts, and may be more valid measures of true word probability.