Psychophysical Scaling Research Articles

Deriving individualized control over music synthesis via inversion of psychophysical scaling results

Computer-based interactive music generation systems have an advantage over acoustic instruments with respect to the flexibility of the human interface for their control. Whereas human performers must conform to the relatively invariant constraints of acoustic instruments, a computer interface can be rapidly updated with regard to changes in user preferences and performance requirements. This paper will describe a software environment that executes miniature psychophysical scaling experiments for a single user of an interactive music generation system in order to derive individualized control over music synthesis via inversion of the obtained psychophysical scaling results. A case study will be presented in which the system has been used to control parametric synthesis of musical timbres using an electronic musical keyboard, providing automatic perceptual mapping of synthesis parameters within their musically useful range. More in-depth exploration of the timbral similarities between a user-selected set of synthesis patches resulted in low-dimensional control structures that could be used to organize musical timbres in preparation for composition or performance.

Amantadine Sulfate Reduces Experimental Sensitization and Pain in Chronic Back Pain Patients

We investigated if established psychophysical measures of enhanced experimental sensitization in chronic musculoskeletal pain can be reduced by adjuvant treatment with a N-methyl-d-aspartate receptor antagonist, amantadine sulfate, and whether a reduction in sensitization might be accompanied by a concurrent improvement in clinical pain. Sensitization was evaluated by an experimental tonic heat model of short-term sensitization with concurrent subjective and behavioral psychophysical scaling. Twenty-six patients with chronic back pain were included in the randomized, double-blind, placebo-controlled study and received daily dosages of either placebo or 100 mg of amantadine sulfate during a 1-wk treatment. Participants completed quantitative sensory testing of pain thresholds and experimental sensitization before and after treatment and clinical pain ratings before, during, and after treatment. Experimental sensitization and clinical pain were reduced in patients receiving verum. Initially, experimental sensitization was enhanced in patients, with early sensitization at nonpainful intensities of contact heat and enhanced sensitization at painful intensities, as shown previously. After 1 wk of treatment, experimental sensitization was reduced with amantadine sulfate but not with placebo. We conclude that adjuvant chronic pain treatment with N-methyl-d-aspartate receptor antagonists might be beneficial for chronic pain if enhanced sensitization is involved and that the quantitative sensory test of temporal summation may be used to verify this.

Examining the validity of numerical ratios in loudness fractionation

Direct psychophysical scaling procedures presuppose that observers are able to directly relate a numerical value to the sensation magnitude experienced. This assumption is based on fundamental conditions (specified by Luce, 2002), which were evaluated experimentally. The participants' task was to adjust the loudness of a 1-kHz tone so that it reached a certain prespecified fraction of the loudness of a reference tone. The results of the first experiment suggest that the listeners were indeed able to make adjustments on a ratio scale level. It was not possible, however, to interpret the nominal fractions used in the task as "true" scientific numbers. Thus, Stevens's (1956, 1975) fundamental assumption that an observer can directly assess the sensation magnitude a stimulus elicits did not hold. In the second experiment, the possibility of establishing a specific, strictly increasing transformation function that related the overt numerals to the latent mathematical numbers was investigated. The results indicate that this was not possible for the majority of the 7 participants.

Gender differences in rankings of joint motion stressfulness based on psychophysical scaling

The purpose of this study was to propose rankings of postural stress for joint motions and joints for male and female subjects. The rankings were based on perceived discomfort for joint motions. Twenty male and 10 female subjects with no history of musculoskeletal disorders participated in the laboratory experiments. The free modulus method of magnitude estimation was employed in order to measure discomfort ratings for joint motions. The discomfort levels of female subjects for the joint motions investigated were, on the whole, larger by about 28% than those of males ( p < 0.01 ). Three ranking systems, classified by the joint motions and joints, the joints, and the types of joint motions, were proposed. The rankings varied depending upon the joint motions and joints as well as the subjects’ gender. All female rankings were higher than male's, except for shoulder lateral rotation and joint motion of external rotation. In both males and females, the hip had the largest discomfort values of all joints, while the elbow showed lower discomfort than any other joint. It is recommended that the gender-based rankings be used for more precisely reflecting gender differences of postural stress. Relevance to industry Awkward and extreme postures can increase the risk of musculoskeletal disorders. Ranking systems for assessment of stressfulness of body deviations around different joints can be used for quantifying the magnitude for physical exposure to poor working postures. This study investigates perceived discomforts depending upon the levels of varying joint motions, and presents three ranking systems for the stressfulness of joint motions.

Estimação de magnitude do estresse, pelos alunos de graduação, quanto ao cuidado de enfermagem

Estresse é definido como uma resposta fisiológica, psicológica e comportamental de um indivíduo que procura adaptar-se e ajustar-se às pressões internas e externas. O objetivo foi verificar o estresse do aluno de enfermagem frente aos cuidados realizados. Utilizamos métodos psicofísicos diretos, escala de razão e emparelhamento intermodal. A amostra constou de 15 discentes, matriculados no 3º semestre de enfermagem de uma instituição de ensino. Foi realizada a validação psicofísica da escala de razão dos cuidados de enfermagem através do método de emparelhamento intermodal. Os dados foram coletados usando-se questionário com 15 cuidados de enfermagem, em que a tarefa do aluno consistia em estimar um número a cada cuidado que fosse proporcional à quantidade de estresse que essa proporciona ao ser executada. Obteve-se, como resultado, que a sondagem vesical de demora é considerada o cuidado mais estressante, e que a verificação de temperatura foi considerado o cuidado menos estressante. É necessário a continuidade dos estudos, oferecendo outras comparações e com outras amostras de população.

참여형 멀티미디어 시스템 사용자 감성평가를 위한 다차원 심물리학적 척도 체계

A comprehensive psychophysical scaling system. multiple-modality magnitude estimation system (MMES) has been designed to measure subjective multidimensional human perception. Unlike paper-based magnitude estimation systems. the MMES has an additional auditory peripheral cue that varies with corresponding visual magnitude. As the simplest. purely psychological case. bimodal divided-attention conditions were simulated to establish the superiority of the MMES. Subjects were given brief presentations of pairs of simultaneous stimuli consisting of visual line-lengths and auditory white-noise levels. In the visual or auditory focused-attention conditions. only the line-lengths or the noise levels perceived should be reported respectively. On the other hand. in the divided-attention conditions. both the line-lengths and the noise levels should be reported. There were no significant differences among the different attention conditions. Human performance was better when the proportion of magnitude in stimulus pairs were identically presented. The additional auditory cues in the MMES improved the correlations between the magnitude of stimuli and MMES values in the divided-attention conditions.<br/>

Utilização de julgamentos psicofísicos para investigação da inteligibilidade de fala no ruído em ouvintes com audição normal e perda auditiva

A inteligibilidade de fala no ruído foi investigada neste estudo utilizando-se julgamentos psicofísicos em grupos de jovens ouvintes com audição normal, e em jovens e idosos com perda auditiva. Foram utilizadas escalas intervalar e de razão para se estimar a inteligibilidade de sentenças apresentadas ipsilateralmente com ruído "cocktail" em diferentes relações sinal/ruído. De acordo com os resultados obtidos, a inteligibilidade das sentenças aumenta conforme aumenta a relação sinal/ruído, nos três grupos. Foram encontradas diferenças significativas entre os grupos quanto a inteligibilidade das sentenças. As escalas psicofísicas foram válidas e confiáveis para mensurar a inteligibilidade de fala. Entretanto, outros estudos são necessários antes de sua utilização na prática clínica.

Joint angles of isocomfort for female subjects based on the psychophysical scaling of static standing postures

This study investigated the joint angles of isocomfort (JAIs) for females based on the psychophysical scalings for static standing postures held for 60 s, which were obtained in a laboratory experiment. The subjects were instructed to rate their comfort levels for varyious joint postures by using the free modulus method of magnitude estimation. The comfort scores for the joint postures and the related verbal comfort categories were subjected to regression analysis in order to obtain the JAIs corresponding to verbal categories. The results showed that the JAIs were significantly different depending upon the joints and joint postures investigated (p < 0.01), and that the JAIs for female subjects were significantly different than those for males (p < 0.01) which had been obtained in an earlier study (Kee and Karwowski, 2001). Compared to the corresponding range of joint motion values, the JAIs for hip postures were the smallest of all joint postures dealt with in this study, while those for the neck were the largest of all postures, which means that hip postures are more stressful than any other joint posture. Based on this study, it is recommended that the gender-based JAI values should be used for design applications.

A Computerized Multiple-modality Magnitude Estimation System (MMES) for Effective Measurement of Subjective Multidimensional Human Perception

Cognitive attention conditions of multimedia system users were represented by simple operations of two vector sets: stimulus and human information processing channels. A vector-set model illustrated how humans use cognitive attention resources. A comprehensive psychophysical scaling system (MMES) has been designed to measure subjective multidimensional human perception. Unlike paper-based magnitude estimation systems, the MMES has an additional auditory peripheral cue that varies with corresponding visual magnitude. As the simplest, purely psychological case, bimodal dividedattention conditions were simulated to establish the superiority of the MMES. Subjects were given brief presentations of pairs of simultaneous stimuli consisting of visual line-lengths and auditory white-noise levels. In the visual or auditory focused-attention conditions, only the line-lengths or the noise levels perceived should be reported respectively; on the other hand, in the divided-attention conditions, both the line-lengths and the noise levels should be reported. There were no significant differences among the different attention conditions (no divided-attention decrement). Human performance was better when the proportion of magnitude in stimulus pairs were identically presented (cross-modal congruity effect). The additional auditory cues in the MMES improved the correlations between the magnitude of stimuli and MMES values in the divided-attention conditions.

Which color is more colorful, the lighter one or the darker one?

AbstractTo answer a question often asked in industrial color reproduction, a series of highly chromatic color samples of the same CIELAB hue but of small variations of CIELAB chroma and lightness were prepared and scaled for perceived colorfulness. The results indicate that lightness contributes to the perceived colorfulness as defined by the observers according to their everyday color experiences. For the samples used, colorfulness can be modeled by factoring in the CIELAB L* value in addition to CIELAB C*. The results show that colorfulness, as implied in our everyday color experiences, can be a complex perceptual attribute. A newer psychophysical scaling model is also presented, since Thurstone's Case V model was shown to be inadequate. © 2003 Wiley Periodicals, Inc. Col Res Appl, 28, 168–174, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10142

Cross-modal perceptual integration of spatially and temporally disparate auditory and visual stimuli

Under certain conditions, auditory and visual information are integrated into a single unified percept even when they originate in different locations in space. The present study shows how this illusion, known as the ventriloquism effect, depends on spatial, temporal and cognitive factors. A method of psychophysical scaling was employed in combination with simple auditory–visual stimuli (tone bursts and flashing light spots) that were presented with various spatiotemporal disparities. Participants either judged their impression of the likelihood of a common cause (Experiment 1) or spatial alignment (Experiment 2) or synchrony of sound and light (Experiment 3). In all three experiments the participants’ judgements depended significantly on temporal disparity whereas influences of spatial disparity were significant in Experiments 1 and 2. Optimum scores were always obtained when auditory stimuli were presented with a delay of 50–100 ms after the visual stimuli. These results demonstrate that both temporal and spatial proximity of the two stimuli are critical for the experience of phenomenal causality. On the other hand, spatio–temporal ranges for optimal perception of phenomenal causality in Experiment 1 were significantly larger than predicted by simultaneous detection of spatial and temporal disparities. This finding suggests that auditory–visual binding was further facilitated by additional, cognitive, factors, associated with the specific instruction to judge the likelihood of a common cause. Obviously, these instructional influences may reflect similar perceptual effects, as have been shown previously by increasing the complexity or cognitive compellingness of auditory–visual stimuli.

Vibrotaction and texture perception

Several recent studies support Katz's hypothesis that vibrotaction plays a role in the perception of tactile textures with elements too small and closely spaced to be processed spatially. For example, eliminating vibration by preventing movement of a stimulus surface across the skin compromises psychophysical scaling and discrimination of fine, but not coarse, textures. Fine-texture discrimination is also impaired when vibrotactile channels are desensitized by adaptation. A role for vibrotaction in texture perception is plausible, given the keenness of this submodality: the sensory qualities produced by a sinusoidal vibration uniquely specify its frequency and amplitude, and subjects can distinguish some complex vibrations that differ in waveform but have the same spectral components. Finally, imposed vibration can modify the perceived texture of a haptically-examined surface. Taken together, these lines of evidence support the view that vibrotaction is both necessary and sufficient for the perception of fine tactile textures.

심물리학적 방법을 이용한 여성의 안락 동작범위

This study aims to provide joint angles of comfort for females, based on the psychophysical scaling method Ten female subjects participated in the experiment for measuring perceived discomfort for varying joint motions. The subjects were instructed to maintain given joint motions for a minute, and to rate their perceived discomfort for the motions during a minute's rest by using the free modulus method of the magnitude estimation. Joint angles of comfort were calculated from the regression equations based on the experimental results, in which levels of joint motions were used as independent variables and perceived discomforts as dependent variables. The results showed that joint angles of comfort for the joint motions investigated were much smaller than full range of motions for corresponding joint motions. The ratios of joint angle of comfort to its range of motion for the hip were found to be smallest of all joint motions dealt with in this study, and those for the neck were the largest. In addition, comfortable joint angles for females were much smaller than those for males. It is recommended that when designing or evaluating workplaces ergonomically, different comfortable joint angles should be applied according to workers' or population's gender.br/

Why is binocular visual space distorted compared to physical space ?

We propose the independent scalar learning elements summation (ISLES) model, a neural network model for the developmental learning of binocular visual space. When applied to the phenomena of Hering's horopter and the locus of perceived egocentric equidistance, this model provides a better qualitative explanation than the Luneburg theory. This model provides physical explanations for the differences among individual subject data, by accounting for the spatial distribution of the visual experiences for learning the perception. When the perceptions are classified via psychophysical scaling, their class logically determines the learning signal in this model. As a result, the same ISLES model can predict each phenomenon when a subject learns the physical loci under various conditions.

Comparison of self-report, video observation and direct measurement methods for upper extremity musculoskeletal disorder physical risk factors

The prevention of work-related musculoskeletal disorders has become a national priority in many countries. Increasingly, attempts are made to quantify those exposures that increase risk in order to set exposure limit values. This study used commonly employed field measurement methods and tools in order to perform an inter-method comparison between three primary methods of risk factor exposure assessment: self-report questionnaires, observational video analysis and direct measurement. Extreme posture duration, repetition, hand force (estimated from electromyography) and movement velocity were assessed for 18 subjects while performing each of three jobs processing tree seedlings. Results indicated that self-reports were the least precise assessment method, which consistently overestimated exposures for each of the measured risk factors. However, adjustment of the reports as psychophysical scales may increase agreement on a group level. Wrist flexion/extension duration and repetition were best measured by electrogoniometer. Electrogoniometric measures of wrist deviation duration and frequency were less precise than video analysis. Forearm rotation duration and repetition, grip force and velocity appeared to be best quantified by direct measurement as measured by electrogoniometer and electromyography (EMG) (as root-mean-square amplitude). The results highlight the fact that it is as important to consider and report estimated measurement error in order to reduce potential exposure misclassification in epidemiologic studies.

Comparison of self-report, video observation and direct measurement methods for upper extremity musculoskeletal disorder physical risk factors

The prevention of work-related musculoskeletal disorders has become a national priority in many countries. Increasingly, attempts are made to quantify those exposures that increase risk in order to set exposure limit values. This study used commonly employed field measurement methods and tools in order to perform an inter-method comparison between three primary methods of risk factor exposure assessment: self-report questionnaires, observational video analysis and direct measurement. Extreme posture duration, repetition, hand force (estimated from electromyography) and movement velocity were assessed for 18 subjects while performing each of three jobs processing tree seedlings. Results indicated that self-reports were the least precise assessment method, which consistently overestimated exposures for each of the measured risk factors. However, adjustment of the reports as psychophysical scales may increase agreement on a group level. Wrist flexion/extension duration and repetition were best measured by electrogoniometer. Electrogoniometric measures of wrist deviation duration and frequency were less precise than video analysis. Forearm rotation duration and repetition, grip force and velocity appeared to be best quantified by direct measurement as measured by electrogoniometer and electromyography (EMG) (as root-mean-square amplitude). The results highlight the fact that it is as important to consider and report estimated measurement error in order to reduce potential exposure misclassification in epidemiologic studies.

Improved Data Modeling for Text-Dependent Speaker Recognition Using Sub-Band Processing

A growing body of recent work documents the potential benefits of sub-band processing over wideband processing in automatic speech recognition and, less usually, speaker recognition. It is often found that the sub-band approach delivers performance improvements (especially in the presence of noise), but not always so. This raises the question of precisely when and how sub-band processing might be advantageous, which is difficult to answer because there is as yet only a rudimentary theoretical framework guiding this work. We describe a simple sub-band speaker recognition system designed to facilitate experimentation aimed at increasing understanding of the approach. This splits the time-domain speech signal into 16 sub-bands using a bank of second-order filters spaced on the psychophysical mel scale. Each sub-band has its own separate cepstral-based recognition system, the outputs of which are combined using the sum rule to produce a final decision. We find that sub-band processing leads to worthwhile reductions in both the verification and identification error rates relative to the wideband system, decreasing the identification error rate from 3.33% to 0.56% and equal error rate for verification by approximately 50% for clean speech. The hypothesis is advanced that, unlike the wideband system, sub-band processing effectively constrains the free parameters of the speaker models to be more uniformly deployed across frequency: as such, it offers a practical solution to the bias/variance dilemma of data modeling. Much remains to be done to explore fully the new paradigm of sub-band processing. Accordingly, several avenues for future work are identified. In particular, we aim to explore the hypothesis of a practical solution to the bias/variance dilemma in more depth.

Evaluation of indoor air quality using the decibel concept based on carbon dioxide and TVOC

Two new units are proposed for the evaluation of indoor air quality using the decibel concept, which give a much better approximation of the human perception of odour intensity, compared to the CO 2 and TVOC concentration scales: the decicarbdiox and the decitvoc. On the Psycho-Physical Scale according to Yaglou, the weakest odour that can be detected by the human smell sensors is equal to 1 and corresponds to the lower limit of percentage dissatisfaction (PD) of 5.8% and is equivalent to (a) a CO 2 threshold concentration of 485 ppm — O dB (odour CO 2) — dCd (decicarbdiox), and (b) a TVOC threshold concentration of 50 μg/m 3 — O dB (odour TVOC) — O dTv (decitvoc). The upper limit is determined by the initial value of toxicity (a) CO 2 — 15,000 ppm — 134 dCd, and (b) TVOC — 25,000 μg/m 3 — 135 dTv. It is supposed that optimal values corresponding to PD=20%, admissible values to PD=30% for unadapted and adapted persons and that long-term tolerable values (determining SBS range) and short-term tolerable values (beginning of toxic range) are stated as well. The same figures used to evaluate noise can be used to evaluate air quality, additionally the contribution of individual constituents (at present acoustic and odour) to the overall quality of the environment can be ascertained. The new units dCd and dTv can express an increase or decrease in air contamination, i.e. by using air cleaners, new building materials, etc. The proposed system of dCd and dTv is compatible with BSR/ASHRAE 62-1989 R which can be used to determine the required volume of fresh air for ventilation by an improved method which takes into account different levels of required indoor air quality.

Using Psychophysics to Design Speech Warnings

An experiment is reported which applies psychophysical scaling techniques to the design of speech warnings. Participants used magnitude estimation to rate the perceived urgency of computer generated warning signal words (Deadly, Danger, Warning, Caution, Note) that varied systematically in speed. Stevens (1957) Power Law was used to model the relationship between changes in the acoustic parameter and changes in the perceived urgency of a particular signal word. The value for warning designers of the power function exponent, which quantifies and predicts the effect of acoustic changes on perceived urgency, is discussed.

A Differential Geometric Description of the Relationships among Perceptions

We present a differential geometric method for measuring and characterizing the perceptions of an observer of a continuum of stimuli. Because the method is not based on a model of perceptual mechanisms, it can potentially be applied to a wide variety of observers and to many types of visual and auditory stimuli. The observer is asked to identify which small transformation of one stimulus is perceived to be equivalent to a small transformation of a second stimulus, differing from the first stimulus by a third small transformation. The observer's identification of a number of such transformations can be used to calculate an affine connection on the stimulus manifold. This quantity describes how the observer encodes an evolving stimulus as a perceived sequence of “reference” transformations. This type of encoding is a multidimensional generalization of Fechner's method and reduces to his psychophysical scale when the stimulus manifold is one dimensional and the reference transformation is chosen to be a just noticeable difference. The intrinsic aspects of the nature of the observer's perceptions can be characterized by the curvature and torsion tensors derived from the connection. The multidimensional analogues of psychophysical scale functions exist if and only if these quantities vanish. Differences between the affine connections of two observers characterize differences between their perceptions of the same evolving stimuli. The affine connections of two observers can also be used to map a stimulus perceived by one observer onto another stimulus, perceived in the same way by the other observer. Unlike multidimensional scaling techniques, this method does not assume that the observer has a sense of distance (a metric) or that he/she can otherwise compare stimulus pairs that are oriented along perceptually different directions in the manifold. The method was used to measure the affine connections of observers of a dot moving on different background graphics; e.g., a blank screen, a grid, or two converging lines similar to those used to create the Ponzo illusion. The results comprise quantitative measurements of the background graphic's influence on each observer's perceptions of straightness, parallelism, and distance. The measurements demonstrate differences between the perceptions of the two observers.