Magnitude Estimation Procedure Research Articles

Road Users Fail to Appreciate the Special Optical Properties of Retroreflective Materials

Objective To determine whether typical road users appreciate the special optical properties of retroreflective materials. Background Retroreflective surfaces reflect light back towards the source of the illumination. All drivers benefit from retroreflective materials, as they are required on road signs, on large trailers, in lane delineation, and other traffic control devices. Retroreflective markings can also greatly enhance the conspicuity of pedestrians at night, but pedestrians typically underuse retroreflective markings. One possible reason is that pedestrians may not appreciate the special optical properties of retroreflective materials. Method Two experiments tested whether observers could correctly predict that retroreflective materials appear remarkably bright when illuminated by a source that is aligned with the observers’ eyes. Observers used a magnitude estimation procedure to predict how bright retroreflective and non-retroreflective stimuli would appear during a demonstration designed to highlight retroreflectivity. They then judged the brightness again during the demonstration. Results In general, observers underestimated how bright retroreflective stimuli would be and overestimated how bright diffuse reflective and fluorescent stimuli would be. The underestimates for retroreflective stimuli were particularly striking when the observers had not closely examined the stimuli in advance. Conclusion The fact that road users do not appreciate retroreflectivity may help explain why pedestrians underuse retroreflective markings at night. Application Educational interventions could prove useful in this domain.

On the difficulty to think in ratios: a methodological bias in Stevens\u2019 magnitude estimation procedure

In the field of new psychophysics, the magnitude estimation procedure is one of the most frequently used methods. It requires participants to assess the intensity of a stimulus in relation to a reference. In three studies, we examined whether difficulties of thinking in ratios influence participants’ intensity perceptions. In Study 1, a standard magnitude estimation procedure was compared to an adapted procedure in which the numerical response dimension was reversed so that smaller (larger) numbers indicated brighter (darker) stimuli. In Study 2, participants first had to indicate whether a stimulus was brighter or darker compared to the reference, and only afterwards they estimated the magnitude of this difference, always using ratings above the reference to indicate their perception. In Study 3, we applied the same procedure as in Study 2 to a different physical dimension (red saturation). Results from Study 1 (N = 20) showed that participants in the reversal condition used more (less) extreme ratings for brighter (darker) stimuli compared to the standard condition. Data from the unidirectional method applied in Study 2 (N = 34) suggested a linear psychophysical function for brightness perception. Similar results were found for red saturation in Study 3 (N = 36) with a less curved power function describing the association between objective red saturation and perceived redness perception. We conclude that the typical power functions that emerge when using a standard magnitude estimation procedure might be biased due to difficulties experienced by participants to think in ratios.

Perceived discomfort for typical helicopter vertical sine vibrations for seated participants

Vibrations contribute to helicopter’s ride comfort. This study aimed to determine the relationship between main rotor vertical excitations and discomfort. Fifty-three participants, seated on a helicopter seat fixed to a vibration test bench, evaluated the discomfort of vertical sinusoidal vibrations using a magnitude estimation procedure. Stimuli had a frequency between 15 and 30 Hz and a level between 0.32 and 3.16 m/s2. The average discomfort was shown related to vibration velocity using Steven’s power law, without any frequency dependence. The exponent depended on velocity and was 1.18 for higher velocities (approx. above 0.008 m/s) and 0.65 for velocities below that limit.

Glutamate is down-regulated and tinnitus loudness-levels decreased following rTMS over auditory cortex of the left hemisphere: A prospective randomized single-blinded sham-controlled cross-over study

Using a prospective randomized single-blinded sham-controlled cross-over design, we studied the efficacy of low frequency (1-Hz) repetitive transcranial magnetic stimulation (rTMS) over auditory cortex of the left temporal lobe as an experimental treatment modality for noise-induced tinnitus. Pre/post outcome measures for sham vs. active rTMS conditions included differential changes in tinnitus loudness, self-perceived changes in the Tinnitus Handicap Questionnaire (THQ), and neurochemical changes of brain metabolite concentrations using single voxel proton magnetic resonance spectroscopy (1H-MRS) obtained from left and right auditory cortical areas. While no subject in our sample had complete abatement of their tinnitus percept, active but not sham rTMS significantly reduced the loudness level of the tinnitus perception on the order of 4.5 dB; improved subscales in several content areas on the THQ, and down regulated (reduced) glutamate concentrations specific to the auditory cortex of the left temporal lobe that was stimulated.In addition, significant pair-wise correlations were observed among questionnaire variables, metabolite variables, questionnaire-metabolite variables, and metabolite-loudness variables. As part of this correlation analysis, we demonstrate for the first time that active rTMS produced a down regulation in the excitatory neurotransmitter glutamate that was highly correlated (r = 0.77, p < 0.05) with a reduction in tinnitus loudness levels measured psychoacoustically with a magnitude estimation procedure. Overall, this study provides unique information on neurochemical, psychoacoustic, and questionnaire-related profiles which emphasizes the emerging fields of perceptual and cognitive MRS and provides a perspective on a new frontier in auditory and tinnitus-related research.

Sweeteners in Diet Chocolate Ice Cream: Penalty Analysis and Acceptance Evaluation

According to the consumers’ demand for healthy and nutritional food without loss of sensory perception, a study based on sucrose substitution appears to be interesting for the food industries. Thus, this study associated the most significant attributes of diet chocolate ice cream aimed to obtain a high acceptance. The difference between the ice cream samples was related to sucrose concentration (12, 14, 16, 18 and 20%). Groups of 122 potential consumers of chocolate ice creams took part in an affective test using a nine-centimeter unstructured scale. The same group analyzed the samples using a 7-point Just About Right scale (JAR) regarding sweetness, chocolate flavor and smoothness. A Penalty analysis was used to identify potential directions for the ice cream’s improvement, based on consumer tests. After choosing the best formulation of the sucrose sample, a magnitude estimation procedure was performed. The sweeteners used to replace the sucrose were: sucralose, stevioside, neotame, neosucralose and an aroma blend (aroma/sucrose). Penalty analysis based on JAR scales showed that smoothness and chocolate flavor were the most penalizing sensory characteristics causing significant drop in chocolate ice cream acceptability. Thus, the aroma compound and neosucralose blend showed the best sucrose replacements.

Board #157 - Research Abstract Transitioning from FLS Penrose Drains to Human Cadaver Tissue

Hypothesis Recently, Britt et al. measured the difference in mental workload when transitioning from the FLS system to fresh cadavers.1 They trained their participants to proficiency2 for intracorporeal suturing on the rubber FLS Penrose drains and observed substantial increases in suturing times and subjective workload when the participants attempted to suture bowel tissue. There are many reasons why mental workload would be higher for the cadaver over the FLS simulator. Our goal was to address one possibility: perceived differences in the properties of the rubber drain and cadaver bowel tissue. We hypothesized that differences in the stiffness and elasticity of human bowel tissue and the rubber drains contribute to the increased mental workload. To explore this idea, we used the psychophysical scaling method of magnitude estimation.3-4 Participants assigned comparative numerical values to the properties of the bowel tissue to identify potential perceived differences between the two media. Methods Eight surgical assistants (SA) participated in this IRB approved study. They were trained to proficiency in intracorporeal suturing on the FLS system. They practiced suturing on the FLS Penrose drains for 30 minutes and then performed three sutures in the bowel of a fresh cadaver using Stryker high definition endoscopic towers and Stryker 10 mm 30 degree scopes. The fresh cadavers were soft embalmed using the Modified Thiel method with nitrate salts to maintain tissue flexibility and allow insufflation. The participants used the magnitude estimation procedure and provided estimates for stiffness and elasticity. They were told to consider the Penrose drain as the standard with a value of 100 and to provide numerical estimates of the perceived differences in sensation of the bowel tissue (e.g., if the bowel tissue felt half as stiff as the drain they should give it the number 50). Results Data from five of SA students were available for analysis. The magnitude estimates were analyzed with one sample t tests as deviations from the standard. The perceived elasticity increased from 100 to 174 (SD = 25), t(4) = 6.59, p < .003, Cohen’s D = .86. Regarding stiffness, the reported values decreased from 100 to 81 (SD = 40.1) which was not significant, p > .05. However, all but one participant reported a decrease in stiffness. With that participant removed, the decrease in stiffness dropped from 100 to 71 (SD = 21.3), t(3) = 4.53, p < .02, Cohen’s D = .81. Conclusion The results show that participants did indeed perceive differences between the human bowel tissue and the rubber Penrose drains. Specifically, they rated the elasticity of the human bowel nearly two times greater than that of the rubber drain. The bowel tissue was rated slightly less stiff than the rubber drain. Although the estimates were obtained with a small sample the Cohen’s D values for both properties were quite large indicating a large effect. These results suggest that differences in properties of the cadaver tissue and the rubber drain are clearly perceivable and may contribute to the increased workload observed by Britt et al.1 when trainees transition from FLS to a more realistic surgical environment.

Loudness perception and speech intensity control in Parkinson's disease

The aim of this study was to examine loudness perception in individuals with hypophonia and Parkinson's disease. The participants included 17 individuals with hypophonia related to Parkinson's disease (PD) and 25 age-equivalent controls. The three loudness perception tasks included a magnitude estimation procedure involving a sentence spoken at 60, 65, 70, 75 and 80dB SPL, an imitation task involving a sentence spoken at 60, 65, 70, 75 and 80dB SPL, and a magnitude production procedure involving the production of a sentence at five different loudness levels (habitual, two and four times louder and two and four times quieter). The participants with PD produced a significantly different pattern and used a more restricted range than the controls in their perception of speech loudness, imitation of speech intensity, and self-generated estimates of speech loudness. The results support a speech loudness perception deficit in PD involving an abnormal perception of externally generated and self-generated speech intensity. Learning outcomesReaders will recognize that individuals with hypophonia related to Parkinson's disease may demonstrate a speech loudness perception deficit involving the abnormal perception of externally generated and self-generated speech intensity.

Effect of sound duration on loudness estimates of increasing and decreasing intensity sounds

The influence of sound duration on global loudness of non-stationary stimuli was investigated. Loudness of 2 and 6-s increasing and decreasing intensity sounds with different ranges of intensity-variation was assessed using a magnitude estimation procedure. Results once again uphold the existence of a loudness difference between the two patterns: while they only differ in their temporal profile, increasing sounds were perceived louder than decreasing sounds. In addition, global loudness estimates were increased with duration for the two types of sounds, and a small but significant interaction occurred between type and duration. A contrast analysis revealed that while global loudness of increasing and decreasing sounds raised with duration in a similar way in the case of low and moderate intensities (below 75 dB SPL), global loudness was significantly more affected by duration with increasing than with decreasing intensity profiles for high-intensity stimuli. This result suggests the existence of an underlying memory process combined with a “peak-end rule” as being responsible for the loudness asymmetry typically observed between the two types of intensity-pattern being judged [Susini et al. (2010). “End level bias on direct loudness ratings of increasing sounds” J. Acoust. Soc. Am. EL 128(4), 163–168].

Influence of measurement method and context of presentation on the loudness difference between increasing and decreasing intensity sounds

Four experiments were conducted to assess the loudness of both increasing and decreasing intensity sounds using different methods and context of presentation as between-subjects factors. In Exp 1 and Exp 2, loudness was assessed directly by using magnitude estimation procedures, with increasing and decreasing sounds presented respectively either in the same block or in separate blocks. In the other two experiments, loudness was measured by the mean of pairwise comparisons. While increasing and decreasing sounds were compared with each other in Exp 3, they were compared respectively with constant-intensity sounds in Exp 4. Two-intervals, 2AFC interleaved-adaptive procedures were used to prevent from potential biases. As a result, very similar trends were observed in the four experiments. In particular, the loudness difference between increasing and decreasing sounds always felt within the same range: decreasing intensity sounds need to be about 3 dB louder that increasing sounds to be perceived with equal loudness. This study thus indicates that this loudness asymmetry actually corresponds to a true perceptual effect and is not due to any experimental bias, since a clear consistency across the results was found using different measurement methods and context of presentation.

Vibrotactile perceived intensity for mobile devices as a function of direction, amplitude, and frequency.

Vibrotactile rendering is an emerging interaction method for information transmission in mobile devices, replacing or supplementing visual and auditory displays. To design effective vibrotactile actuators or display algorithms, an understanding of the perceived intensity (strength) of their vibrations is essential. This paper aims to build a robust model for the perceived intensities of mobile device vibrations, which can be immediately used by engineers and application designers. To this end, we carried out two psychophysical experiments using absolute magnitude estimation procedures. In Experiment I, we investigated the effects of vibration direction and device weight on the perceived intensity of mobile device vibrations. The vibration directions tested (height, width, and depth), and the device weights (90-130 g) were determined considering those of contemporary mobile devices. Only the vibration direction was found to be a statistically significant factor, showing the highest perceived intensities along the height direction of a mobile device. In Experiment II, we measured the perceived intensities of vibrations with various amplitudes and frequencies along the three vibration directions. Then, for each direction, a psychophysical magnitude function and equal sensation contours were constructed based on Stevens' power law, which clearly visualize the consequences of vibration parameter changes on the resulting perceptual strength. In addition, we found a monotonic relationship between the physical power of vibration absorbed by the hand and the resulting perceived intensity. This suggests that the former, which is greatly easier to acquire in practice, is a reliable predictor of the latter. We expect that the results of this study can provide immediate knowledge about the perceptual strength of vibrations that engineers and applications developers will find useful.

Modeling user experience: A case study on a mobile device

User experience (UX) consists of all aspects of interactions between a user and a product. Recently, many studies have been conducted to define the UX concept, but few studies have attempted to quantify UX. This paper proposed quantification models that integrate major elements of UX into a single index. A variety of models were proposed and evaluated including compensatory (i.e. simple linear, polynomial and S-shaped value) and non-compensatory (i.e. conjunctive and disjunctive) models. A case study with a commercial tablet PC was conducted in which a total of 26 subjects participated in a laboratory environment. Each participant performed a pretest ensuring the ability to make ratio judgments and then evaluated predefined dimensions with the modified magnitude estimation procedure. A total of 22 hierarchical dimensions were evaluated such as overall UX, its elements (i.e. usability, affect and user value) and sub-elements. Both compensatory and non-compensatory models had high performance in terms of goodness of fit. The results of this study are expected to help product or service designers develop indices representing an overall UX value. Relevance to industryThis study proposed quantification models that aggregate elements of UX. Although the UX index has been controversial, the single value developed by the models can be expected to help decision-makers understand about products or services intuitively.

Psychophysical and Neural Evidence for Emotion-Enhanced Perceptual Vividness

Highly emotional events are associated with vivid "flashbulb" memories. Here we examine whether the flashbulb metaphor characterizes a previously unknown emotion-enhanced vividness (EEV) during initial perceptual experience. Using a magnitude estimation procedure, human observers estimated the relative magnitude of visual noise overlaid on scenes. After controlling for computational metrics of objective visual salience, emotional salience was associated with decreased noise, or heightened perceptual vividness, demonstrating EEV, which predicted later memory vividness. Event-related potentials revealed a posterior P2 component at ∼200 ms that was associated with both increased emotional salience and decreased objective noise levels, consistent with EEV. Blood oxygenation level-dependent response in the lateral occipital complex (LOC), insula, and amygdala predicted online EEV. The LOC and insula represented complimentary influences on EEV, with the amygdala statistically mediating both. These findings indicate that the metaphorical vivid light surrounding emotional memories is embodied directly in perceptual cortices during initial experience, supported by cortico-limbic interactions.

Annoyance perception of environmental noises by hearing impaired listeners

Annoyance perception of environmental noises is an important topic in many fields, including transportation, environmental studies and hearing aid design. While annoyance perception of normal hearing (NH) listeners has been studied extensively (e.g. Fastl & Zwicker 2006, Versfeld & Vos 1997, Alayrac et al 2010, Palmer et al 2006), data on annoyance perception of hearing impaired (HI) listeners is scant. In this study, we investigate the annoyance perception of typical environmental noises by both NH and HI listeners, using listeners with unilateral hearing loss. We use the magnitude estimation procedure to obtain the annoyance ratings and a paired-comparison method to obtain the annoyance preference for different environmental noises. The experimental data are analyzed to reveal the underlying dimensions of annoyance perception and differences between NH and HI listeners. A functional model for annoyance perception is developed for both HI and NH listeners. Finally, potential applications of our results are discussed in the context of hearing aid design.

Random and systematic effects of neural noise on low-level and high-level pattern vision

The visual system never perfectly represents the physical world. Rather, neural noise sometimes perturbs perception of simple shapes, especially when they are viewed briefly. Neural noise can randomly influence perception, but may also systematically distort perception, as in feature exaggeration. We examined these random and systematic influences of neural noise on curvature perception when short contour segments were presented alone (primarily involving low-level processing) and when they were embedded as the mouths within schematic faces (involving high-level object processing). Inverted-and-scrambled versions of the faces were used to control for a potential effect of crowding. To detect perceptual noise with high sensitivity, we used a procedure developed by Baldassi, Megna, and Burr (2006) in which brief presentations were comprised of an array of straight segments with either one curved target or no curved targets. The task was to report the curvature of the segment that appeared most curved using a magnitude-estimation procedure. Random noise was estimated as the variance of the reported curvatures for displays where curved targets were absent. Curvature exaggeration was measured as the average difference between the reported curvature and the actual curvature of the target. Random noise in curvature perception was greater when segments were presented within faces or inverted-scrambled faces compared to when they were presented alone, suggesting that crowding increased random perceptual noise. Curvature exaggeration, in contrast, was substantial when segments were presented alone or within inverted-scrambled faces, whereas exaggeration was weakest (reduced by ∼40%) when segments were presented within faces. This pattern of curvature exaggeration may reflect the possibility that systematic exaggeration is beneficial in low-level processing because a unique feature may become more salient, but could be harmful in high-level processing because perceptual exaggeration of facial expressions may lead to socially inappropriate responses.

Apparent motion during saccadic suppression periods

Sensitivity to many visual stimuli, and, in particular, image displacement, is reduced during a change in fixation (saccade) compared to when the eye is still. In these experiments, we studied the sensitivity of observers to ecologically relevant image translations of large, complex, real world scenes either during horizontal saccades or during fixation. In the first experiment, we found that such displacements were much less detectable during saccades than during fixation. Qualitatively, even when trans-saccadic scene changes were detectable, they were less salient and appeared slower than equivalent changes in the absence of a saccade. Two further experiments followed up on this observation and estimated the perceived magnitude of trans-saccadic apparent motion using a two-interval forced-choice procedure (Experiment 2) and a magnitude estimation procedure (Experiment 3). Both experiments suggest that trans-saccadic displacements were perceived as smaller than equivalent inter-saccadic displacements. We conclude that during saccades, the magnitude of the apparent motion signal is attenuated as well as its detectability.

Direct Magnitude Estimation of Articulation Rate in Boys With Fragile X Syndrome

To compare the perceived articulation rate of boys with fragile X syndrome (FXS) with that of chronologically age-matched (CA) boys and to determine segmental and/or prosodic factors that account for perceived rate. Ten listeners used direct magnitude estimation procedures to judge the articulation rates of 7 boys with FXS only, 5 boys with FXS and a diagnosis of autism spectrum disorder (ASD), and 12 CA boys during sentence repetition. Sentences had similar articulation rates in syllables per second as determined acoustically. Four segmental/prosodic factors were used to predict perceived rate: (a) percentage consonants correct, (b) overall fundamental frequency (F(0)) level, (c) sentence-final F(0) drop, and (d) acoustically determined articulation rate with the final word of the sentence excluded. Boys with FXS and ASD were judged to talk faster than CA controls. Multiple linear regression indicated that articulation rate with the final word of the sentence excluded and sentence-final F(0) drop accounted for 91% of the variance for perceived rate. Descriptions of speakers with FXS as having fast and/or fluctuating articulation rates may be influenced by autism status. Also, atypical sentence-final prosody may be related to perceived rate in boys with FXS and ASD.

A preliminary evaluation of the reliability and validity of a self‐reported communicative functioning item pool

Background: Item banking, an approach to test development based in item response theory (IRT), is beginning to be applied to the measurement of communicative functioning in aphasia. This approach involves calibrating a set of test items responding to a particular latent trait to a common measurement scale. One method for validating such scales is to examine the degree to which obtained item calibration estimates agree with a priori item rankings based on theory or expert opinion. Aims: The purpose of this study was to evaluate the utility of magnitude estimation (ME) procedures for validating item banks containing self‐reported functional performance items, and to make a preliminary analysis of the validity of a proposed item pool for measuring self‐reported communicative functioning in aphasia. Methods & Procedures: A total of 14 raters made ME ratings of physical and communicative functioning items. These ratings were evaluated for their intra and inter‐observer reliability and, for subsets of the items, their correspondence with previously published IRT calibration estimates was also evaluated. Outcomes & Results: Intra‐rater reliability was moderate to high, and inter‐rater reliability was high. Correspondence with IRT calibrations was high for physical items, and moderate for communication items. The distribution of ME ratings for the communication items was negatively skewed. Conclusions: ME procedures have utility for investigating the validity of functional performance items. The results suggest that communicative functioning may have a more complex latent structure than physical functioning, and that the proposed item pool might benefit from the inclusion of additional items at the lower end of the scale.

Magnitude estimation reveals temporal binding at super-second intervals.

Several recent studies (e.g., Haggard, Aschersleben, Gehrke, & Prinz, 2002; Haggard & Clark, 2003; Haggard, Clark, & Kalogeras, 2002) have demonstrated a "Temporal Binding" effect in which the interval between an intentional action and its consequent outcome is subjectively shorter compared to equivalent intervals that do not involve intentional action. The bulk of the literature has relied on the "Libet Clock" (Libet, Gleason, Wright, & Pearl, 1983; but see also Engbert & Wohlschläger, 2007; Engbert, Wohlschläger, Thomas, & Haggard, 2007; Engbert, Wohlschläger, & Haggard, 2008). Here we demonstrate that Temporal Binding is a robust finding that can also be reliably achieved with a Magnitude Estimation procedure, and that occurs over intervals far greater than those previously explored. Implications for the underlying mechanisms are discussed.

(975): Individual differences scaling (INDSCAL) of noth noxious electrical stimuli and pain descriptors: A super approach to fitting Steven’s power law

The purpose of this study is to quantify jointly the subjective intensities of physical stimuli and verbal descriptors on a single scale at the interval scale level of measurement. Volunteers made similarity judgments to all pairings (120) of 8 electrical stimuli ranging from non-noxious to noxious intensities and 8 related pain and affect descriptors. INDSCAL yielded a one-dimensional group stimulus space with the physical and verbal stimulus objects interdigitated and ordered with respect to subjective intensity. These 16 stimulus objects (ordinate) were plotted against the physical intensity scale in milliwatts (mW) (abscissa). Because the scale is at the interval scale level of measurement it is possible to quantify the perceived intensities of the descriptors. A log-log transformation of the data yielded two linear functions. The lower intensity function ranged from 3 mW and the descriptor “Slight Sensation” to 63 mW and the descriptor “Moderate Sensation”. The higher intensity function, with a different slope and intercept, ranged from 88 mW and “Upsetting” to 235 mW and “Severe Pain”. These two functions represent separate neurosensory systems that mediate non-painful and painful sensations. The results also demonstrate the superiority of theINDSCAL approach over the standard magnitude estimation procedures; for, in contrast to Stevens’s finding of a single function, we found two functions over a comparable range of electrical intensities. The INDSCAL approach is superior to Stevens’s method because it also can be used to construct quantitative pain rating scales. Supported by NIDCR and the Wharton Fund for Research in Brain and Behavior.

Comment on “A strategy to rapidly determine the magnitude of great earthquakes” by W. Menke and V. Levin

We appreciate W. Menke and L. Levin's comments (Eos, 86(19), pp.185, 189, 10 May 2005) on the need to develop new seismological techniques to more accurately determine the magnitude of great earthquakes quickly. However, in the first few paragraphs, Menke and Levin suggest that the many thousands of people died because an accurate assessment of the true nature of the 26 December 2004 Sumatra earthquake was not known within the first hour after it occurred. Although this may serve as a wake‐up call to seismologists on the importance of better and more rapid magnitude estimation procedures, it should not be used to obscure the most urgent need, which is to establish an effective global tsunami warning system.